Closure to “Comparison of Interface Shear Strength of Soil Nails Measured by Both Direct Shear Box
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Juniper EX系列交换机命令行配置手册目录第一章交换机基础知识 (7)1.1认识J UNIPER交换机 (7)1.2J UNOS操作系统基础 (10)1.2.1 交换机配置模式 (10)1.2.2 交换机配置结构 (11)1.2.3 TAB和空格键的使用 (16)1.2.4 用户模式和配置模式show的区别 (17)1.2.5 如何将配置转换成set命令 (20)1.2.6 commit和rollback (21)1.3EX交换机命令菜单结构 (23)第二章操作指导 (36)2.1通过CONSOLE线连接交换机 (36)2.2 SYSTEM系统参数配置 (37)2.2.1设置root密码 (38)2.2.2设置主机名 (38)2.2.3设置DNS服务器 (38)2.2.4设置日期时间 (38)2.2.5设置NTP服务器 (39)2.2.6开启远程Telnet登陆服务 (39)2.2.7开启远程Ftp服务 (40)2.2.8开启远程ssh登陆 (40)2.2.9开启远程http登陆服务 (40)2.2.10添加/删除用户 (41)2.2.10.1添加用户 (41)2.2.10.2修改用户类别 (41)2.2.10.3 修改用户密码 (42)2.2.11用户权限设置 (42)2.3VLAN配置 (44)2.3.1 VLAN配置步骤 (44)2.3.2 VLAN配置规范要求 (45)2.3.3 添加VLAN (45)2.3.4 修改端口VLAN (47)2.3.5 删除VLAN (48)2.3.6 配置VLAN网关IP (48)2.4T RUNK配置 (48)2.4.1 Trunk配置步骤 (49)2.4.2如何设置Trunk (49)2.4.3允许/禁止VLAN通过Trunk (49)2.5端口配置 (49)2.5.1端口配置规范要求 (49)2.5.2修改端口速率 (50)2.5.3修改端口工作模式 (50)2.5.4修改端口为L3模式 (50)2.5.5 修改端口为L2模式 (51)2.6生成树配置 (51)2.6.1 RSTP协议概览 (51)2.6.2 MSTP协议概览 (54)2.6.3 STP配置实例(生成树) (56)2.6.4 RSTP配置实例(快速生成树) (57)2.6.5 MSTP配置实例(多生成树协议) (63)2.7端口捆绑 (68)2.7.1 端口捆绑步骤 (68)2.8ECMP负载均衡配置 (70)2.9路由协议配置 (72)2.9.1 静态路由配置 (72)2.9.1.1添加静态路由 (72)2.9.1.2 删除静态路由 (72)2.9.1.3调整静态路由优先值 (72)2.9.1.4设置备份静态路由 (72)2.9.1.5指定静态路由下一跳端口 (73)2.9.2 OSPF配置 (73)2.9.2.1 OSPF配置步骤 (73)2.9.2.2 OSPF配置实例(单区域) (77)2.9.2.3 OSPF路由过滤 (80)2.10端口镜像 (81)2.10.1 端口镜像的概述 (81)2.10.2 端口镜像的目的 (82)2.10.3 端口镜像的功能 (82)2.10.4 端口镜像工作原理 (82)2.10.5 端口输入输出流量镜像 (84)2.10.6 带过滤条件的端口镜像 (85)2.11端口MAC地址限制 (87)2.12端口广播风暴控制 (87)2.13VRRP虚拟路由冗余协议 (88)2.13.1 VRRP概览 (88)2.13.2 VRRP工作原理 (89)2.13.3 如何配置VRRP (90)2.14BFD配置(双向转发检测) (94)2.14.1 BFD概览 (94)2.14.2 BFD介绍 (95)2.14.3 BFD的报文格式 (95)2.14.4检测模式 (97)2.14.5发送周期及检测时间 (98)2.14.6参数修改 (99)2.14.7会话建立 (99)2.14.8BFD的标准化 (102)2.14.9OSPF中配置BFD (103)2.14.10静态路由中配置BFD (103)2.15交换机F IREWALL限制功能 (104)2.15.1限制IP地址 (104)2.15.2限制MAC地址 (105)2.16V IRTUAL-C HASSIS设置 (105)2.16.1VC知识 (106)2.16.2如何建立VC组 (107)2.16.3如何扩充VC组交换机 (109)2.16.4如何利用uplink链路组成VC (110)2.16.5如何对VC组进行切换 (113)2.17SNMP配置 (113)2.17.1SNMP协议概览 (113)2.17.2SNMP基本简介 (113)2.17.3配置SNMP (114)2.18S YSLOG配置 (116)第三章交换机维护操作 (116)3.1交换机启动和关闭 (116)3.1.1 交换机重启 (116)3.1.2交换机关闭 (116)3.2配置备份和恢复 (117)3.2.1 交换机文件备份 (117)3.2.2配置文件的恢复 (119)3.3如何升级交换机OS (119)3.4如何恢复出厂设置 (120)3.5密码恢复 (120)3.6日常维护命令 (122)3.6.1查看序列号show chassis hardware (123)3.6.2查看硬件show chassis hardware (123)3.6.3查看软件版本show version (123)3.6.4查看CPU show chassis routing-engine (123)3.6.5ping命令 (123)3.6.6查看设备告警信息 show chassis alarms (123)3.6.7查看详细的硬件温度及状态信息 show chassis environment (123)3.6.8查看接口VRRP状态信息show vrrp (123)第一章交换机基础知识1.1 认识Juniper交换机产品型号端口数端口类型PoE端口数最大电源容量(包括 PoE)EX 3200-24T 2410/100/1000B-T8190 (320) W EX 3200-24P 2410/100/1000B-T24190 (600) W EX 3200-48T 4810/100/1000B-T8190 (320) W EX 3200-48P 4810/100/1000B-T48190 (930) W产品型号端口数端口类型PoE端口数最大电源容量(包括 PoE)EX 4200-24T 24 10/100/1000B-T 8 190 (320) W EX 4200-24P 24 10/100/1000B-T 24 190 (600) W EX 4200-24F 24 100B-FX/1000B-X N/A 190 (190) WEX 4200-48T 48 10/100/1000B-T 8190 (320) WEX 4200-48P 48 10/100/1000B-T 48 190 (930) WEX 3200-48T前面面板EX 3200-48T 后面面板USBGbE管理口Console可插拔uplink模块LCD电源模块风扇模块RPS 连接头至少8 PoE端口EX 4200-48T 前面面板EX 4200-48T Rear ViewVCP (Virtual Chassis Port) 0 and1USB GbE管理口Console可插拔uplink模块LCD冗余可热插拔电源模块可插拔风扇模块至少8 PoE端口1.2 Junos操作系统基础Juniper交换机支持两种配置方式:采用命令行的CLI(command-line interface)配置方式,以及采用web浏览器界面JWeb配置方式。
Configuring Module Pre-ProvisioningThis chapter describes how to configure pre-provisioning for offline interfaces or modules in the Cisco Nexus5000Series switch.This chapter includes the following sections:•Information About Module Pre-Provisioning,page1•Guidelines and Limitations,page2•Enabling Module Pre-Provisioning,page2•Removing Module Pre-Provisioning,page3•Verifying the Pre-Provisioned Configuration,page4•Configuration Examples for Pre-Provisioning,page5Information About Module Pre-ProvisioningThe pre-provisioning feature allows you to preconfigure interfaces before inserting or attaching a module toa Cisco Nexus5000Series switch.If a module goes offline,you can also use pre-provisioning to make changesto the interface configurations for the offline module.When a pre-provisioned module comes online,thepre-provisioning configurations are applied.If any configurations were not applied,a syslog is generated.The syslog lists the configurations that were not accepted.In some Virtual Port Channel(vPC)topologies,pre-provisioning is required for the configurationsynchronization feature.Pre-provisioning allows you to synchronize the configuration for an interface that isonline with one peer but offline with another peer.Supported HardwareThe pre-provisioning feature supports the following hardware:•N2K-C2148T Fabric Extender48x1G4x10G Module•N2K-C2232P Fabric Extender32x10G Module•N2K-C2248T Fabric Extender48x1G4x10G Module•N51-M16EP Cisco16x10-Gigabit Ethernet Expansion Module•N51-M8E8FP Cisco 8Port 1/2/4/8G FC and 8Port 10-Gigabit Ethernet Expansion Module •N5K-M1008Cisco 8Port Fiber Channel Expansion Module 8x SFP •N5K-M1060Cisco 6Port Fiber Channel Expansion Module 6x SFP •N5K-M1404Expansion Module 4x 10GBase-T LAN,4x Fiber Channel •N5K-M1600Cisco 6-port 10Gigabit Ethernet SFP Module 6x SFP Upgrades and DowngradesWhen upgrading from Cisco NX-OS Release 4.2(1)N2(1)and earlier releases to Cisco NX-OS Release 5.0(2)N1(1),there are no configuration implications.When upgrading from a release that supportspre-provisioning to another release that supports the feature including InService Software Upgrades (ISSU),pre-provisioned configurations are retained across the upgrade.When downgrading from an image that supports pre-provisioning to an image that does not support pre-provisioning,you are prompted to remove pre-provisioning configurations.Guidelines and LimitationsPre-provisioning has the following configuration guidelines and limitations:•When a module comes online,commands that are not applied are listed in the syslog.•If a slot is pre-provisioned for module A and if you insert module B into the slot,module B does not come online.•There is no MIB support for pre-provisioned interfaces.•Cisco DCNM is not supported.Enabling Module Pre-ProvisioningYou can enable pre-provisioning on a module that is offline.Enter the provision model model command in module pre-provisionmode.After enabling pre-provisioning,you can configure the interfaces as though they are online.NoteSUMMARY STEPS1.configuration terminal2.slot slot3.provision model model4.exit5.(Optional)copy running-config startup-configConfiguring Module Pre-ProvisioningGuidelines and LimitationsDETAILED STEPSPurposeCommand or ActionEnters global configuration mode.configuration terminalExample:switch#config t switch(config)#Step 1Selects the slot to pre-provision and enters slot configuration mode.slot slotExample:switch(config)#slot 101switch(config-slot)#Step 2Selects the module that you want to pre-provision.provision model modelExample:switch(config-slot)#provision model N2K-C2248T switch(config-slot)#Step 3Exits slot configuration mode.exitExample:switch(config-slot)#exit switch#Step 4(Optional)Copies the running configuration to the startup configuration.copy running-config startup-configExample:switch#copy running-config startup-configStep 5This example shows how to select slot 101and the N2K-C2232P module to pre-provision.switch#configure terminal switch(config)#slot 101switch(config-slot)#provision model N2K-C2232P switch(config-slot)#exitRemoving Module Pre-ProvisioningYou can remove a module that has been pre-provisioned.SUMMARY STEPS1.configuration terminal2.slot slot3.no provision model model4.exit5.(Optional)copy running-config startup-configConfiguring Module Pre-ProvisioningRemoving Module Pre-ProvisioningDETAILED STEPSPurposeCommand or ActionEnters global configuration mode.configuration terminalExample:switch#config t switch(config)#Step 1Selects the slot to pre-provision and enters slot configuration mode.slot slotExample:switch(config)#slot 101switch(config-slot)#Step 2Removes pre-provisioning from the module.no provision model modelExample:switch(config-slot)#no provision model N2K-C2248T switch(config-slot)#Step 3Exits slot configuration mode.exitExample:switch(config-slot)#exit switch#Step 4(Optional)Copies the running configuration to the startup configuration.copy running-config startup-configExample:switch#copy running-config startup-configStep 5This example shows how to remove a preprovisioned module from a chassis slot:switch(config)#slot 2switch(config-slot)#no provision model N5K-M1404switch(config-slot)#Verifying the Pre-Provisioned ConfigurationTo display the pre-provisioned configuration,perform one of the following tasks:PurposeCommand Displays provisioned modules.show provision Displays module information.show module Displays switch profile information.show switch-profile Displays the running configuration without the pre-provisioned interfaces or modules that are offline.show running-config exclude-provisionDisplays the pre-provisioned commands that were not applied to the configuration when the interface or module came online.show provision failed-configConfiguring Module Pre-ProvisioningVerifying the Pre-Provisioned ConfigurationPurposeCommand This command also displays a history of failed commands.Displays the commands that were not applied when the interface ormodule came online.show provision failed-config interface Displays the running configuration including the pre-provisioned configuration.show running-config Displays the startup configuration including the pre-provisioned configuration.show startup-configConfiguration Examples for Pre-ProvisioningThe following example shows how to enable pre-provisioning on slot 110on the Cisco Nexus 2232P Fabric Extender and how to pre-provision interface configuration commands on the Ethernet 110/1/1interface.switch#configure terminal switch(config)#slot 110switch(config-slot)#provision model N2K-C2232P switch(config-slot)#exitswitch#configure terminalEnter configuration commands,one per line.End with CNTL/Z.switch(config)#interface Ethernet110/1/1switch(config-if)#description module is preprovisionedswitch(config-if)#show running-config interface Ethernet110/1/1Time:Wed Aug 2521:29:442010version 5.0(2)N1(1)interface Ethernet110/1/1description module is preprovisionedThe following example shows the list of pre-provisioned commands that were not applied when the module came online.switch(config-if-range)#show provision failed-config 101The following config was not applied for slot 33================================================interface Ethernet101/1/1service-policy input test interface Ethernet101/1/2service-policy input test interface Ethernet101/1/3service-policy input testThis example shows how to remove all pre-provisioned modules from a slot:switch(config)#slot 2switch(config-slot)#no provision model switch(config-slot)#Configuring Module Pre-ProvisioningConfiguration Examples for Pre-ProvisioningConfiguring Module Pre-Provisioning Configuration Examples for Pre-Provisioning。
1. a device can be assigned an IP address 192.168.13.175,with the mask being 255.255.255.240True FalseFalse2.an ospf hello message carries a list of known neighborsTrue FalseTrue3.only router-LSAs and Network-LSAs are involved in intra-area route calculationsTrue FalseTrue4.only one BGP process can be configured on a routerTrue FalseTrue5.an ip-prefix-filter is used to filter ip prefixes and data packetsTrue FalseFalse6.RSTP has all functions that STP has and it is backward compatible with STP.True FalseTrue7.TO enable an eudemon in routing mode to work like a router,you need to assign ip addressesto interfaces and enable dynamic or static routing protocols on the eudemon.True FalseTrue8.The eudemon that is working in transparent mode detects processes data at layer 2.Itsinterfaces are not configured with ip addresses.True FalseTrue9.When an eudemon is working in composite mode,some of its interfaces are configured withip addresses (Layer 3 interfaces) and the other interfaces are not configured with ip addresses(Layer 2 interafces). To enable dual-system hot backup on an eudemon,you can configure the eudemon to work in composite mode.True FalseTrue10.Two Eudemons in dual-system hot backup can be working in active-active mode oractive-standby mode.True FalseTrue11.The eudemon supports load balancing between multiple uplinks.True FalseTrue12.Different virtual firewall instances on an Eudemon must be configured with the same securitypolicy.True FalseFalse13.The firewall can be working in routing mode, transparent mode,or composite mode. Thedefault mode is the composite mode.True FalseFalse14.Virtual firewalls on the Eudemon are not allowed to access each other by default unless asecurity policy is specified.True FalseTrue15.IP addresses added to the blacklist of the Eudemon cannot be deleted.True FalseFalse16.You cannot set an aging time for the blacklist of the Eudemon.True FalseFalse17.The Eudemon generates a blacklist upon detecting an attack.True FalseFalse18.The Eudemon can control traffic and connections based on IP addresses.True FalseTrue19.The firewall does not use security rules to filter packets exchanged between interfaces in thesame zone.True FalseTruework address translation (NAT) translates only IP address information.True FalseFalse21.IP unnumbered is to borrow an IP address from an interface.If an interface has multiple IPaddresses,all its IP addresses will be borrowed and the primary address will continue after these IP addresses are borrowed.True FalseFalse22.When two Eudemon are working in dual-system hot backup mode,their session tables arebacked up in real time.True FalseTrue23.After an interface on a firewall is added to a zone, the interface belongs to the zone.True FalseTrue24.Status detection is an advanced communication filtering mechanism.It checks the applicationlayer protocol and monitors the status of the connection-based application layer protocol.For all connections,the status information about each connection is maintained by ASPF and is used to dynamically determine whether to permit or deny data packets to firewalls.True FalseTrue25.The NAT multi-instance function on the Eudemon independently maintains a NAT table foreach instance to provide address translation services for instances.True FalseTrue26.The IPSec function on the Eudemon supports NAT traversal.True FalseTrue27.The NAT function enabled on the Eudemon does not greatly affect system performance.True FalseTrue28.The Eudemon does not support port mapping.True FalseFalse29.In a Land attack,the source address and destination address of an SYN packet are both the IPaddress of the attacked object or a loopback address.True FalseTrue30.The association between the IDS and firewall requires that the IDS be directly connected tothe firewall.True FalseFalse31.Security policies for the firewall are applied to interzones but not to interfaces.True FalseTrue32.The multi-channel protocol is used to establish at least two channels(sessions) forcommunications or services.True FalseTrue33.ICMP packets are sent in a smurf attack and UDP packets are sent in a Fraggle attack.True FalseTrun34.The urgent pointer in the flag field of an IPv4 packet header is generally used for 00B datatransmission.True FalseTrue35.A firewall filters packets exchanged between zones but does not filter packets exchangedbetween intefaces in the same zone.True FalseTrue36.Two Eudemon in dual-system hot backup mode can be working in active-active mode oractive-standby mode.True FalseTrue37.Two Eudemon in dual-system hot backup mode use Huawei Redundancy Protocol(HRP) toback up key information (such as configuration commands and session status) between the active and standby devices.True FalseTrue38.The Eudemon uses the blacklist technology to associate with an NIP IDS.True FalseTrue39.Qos provides services of different qualities to meet various applicationrequirements,including dedicated bandwidth, decreased packet loss ratio,short packet transmission delay, and decreased delay and jitter.True FalseTrue40.In traffic shaping,the packet whose transmission rate exceeds the rate limit will be discardedor re-markedTrue FalseFalse41.WFQ can effectively control the delay and jitter by means of configuring weights for differentservices.True FalseTrue42.Congestion occurs when a link or node is carrying so much data that its quality of servicedeteriorates.True FalseTrue43.Most fields in IP headers of packets in the same data flow are identical,You can compressthese fields to improve the link transmission.True FalseTrue44.The variation in packet delay is called jitter.True FalseTrue45.The end-to-end delay is the sum of transmission delays,processing delays,and queuing delaysalong the packet forwarding path.True FalseTrue46.The data transmission rate depends on the bandwidth.True FalseTrue47.Packet loss occurs only on the packet receiverTrue FalseFalse48.Based on specific rules,traffic classification identifies packets having the same characteristics,Traffic classification is the prerequisite and basis for differentiated services.True FalseTrue49.Congestion management provides means to manage and control traffic when trafficcongestion occurs.True FalseTrue50.The traditional packet loss policy uses the Tail-Drop method.True FalseTrue51.The IP packet has a special field to mark the Qos. For example,the last 6 bits in the Tos field ofan IPv4 packet mark the DSCP value.True FalseFalse52.In traffic shaping, the packet whose transmission rate exceeds the rate limit will be discardedor re-marked.True FalseFalse53.WFQ can effectively control the delay and jitter by means of configuring weights for differentservices.True FalseTrue54.Congestion occurs when a link or node is carrying so much data that its quality of servicedeteriorates.True FalseTrue55.Most fields in IP headers of packets in the same data flow are identical. You can compressthese fields to improve the link transmission efficiency.True FalseTrueplex traffic classification matches packets with rules and then takes actions to matchingpackets.True FalseTrue57.Traffic shaping usually buffers packets that need to be dropped by traffic policing by means ofbuffer and token bucket.True FalseTrue58.In traffic policing using two token buckets,tokens are put into the CBS bucket at thecommitted information rate(CIR),The peak burst size(PBS) bucket is filled in only after the CBS bucket is full.True FalseTrue59.The interface IP address and virtual IP address configured for VRRP must not be identical.True FalseFalse60.A VRRP virtual router can have one or more IP addresses.True FalseTrue61.The virtual router uses a virtual MAC address but not the actual MAC address of the interfaceto respond to an ARP request.True FalseTrue62.A VRRP backup group is able to track the status of an interface. If the interface configuredwith a VRRP backup group fails or any interface on the router fails,the VRRP backup group providesTrue FalseTrue63.By using VRRP, the backup router in a VRRP backup group immediately becomes the masterrouter after detecting a fault and instructs its attached hosts to perform a master/slave switchover accordingly. This ensures that services will recover within a short period of time.True FalseFalse64.The reliability of a product or a system is generally evaluated with the two indicators of Meantime to repair (MTTR) and mean time between failures(MTBF).True FalseTrue65.BFD detects the link status immediately after a BFD session is set up .if BFD parameters aremodified or deleted at one end of the BFD session,the other end will consider such a modification or deletion as a fault and services will be then affected, Therefore,exercise caution when modifying or deleting BFD parameters.True FalseFalse66.One CV packet per second is generated on the ingress LSR of the LSP and receivd by theegress LSR, this generation rate is low and allows no adjustment,hence,the CV packet is usually used for checking the availability of a common LSP.True FalseTrue67.BFD packets are classified into control packets and echo packets.True FalseTrue68.A BFD session is set up following the three-way handshake during which parameters for theBFD session are negotiated. After the BFD session is set up,modifying the detection time parameters does not take effect.True FalseFalse69.The NSF function takes effect only after the GR function is enabled on two directly connectedrouters that use static routes for communication between users in different network segments.True FalseFalse70.During the GR of dynamic routing protocols(such as OSPF and BGP)neighbor relationshipsremain unchanged.True FalseFalse71.BFD is a common fast detection technology,It implements the fast switchover function onlywhen collaborating with other fast switchoverTrue FalseTrue72.BFD (a fast detection technology) enabled on a device quickly identifies a fault and reportsthe fault to the appropriate protocol modele after detecting a master/slave switchover on the neighboring devic,this causes the protocol module to quit the GR. AS such,BFD and GR cannot be used together.True FalseFalse73.In OSPF,the process of calculating shortest path tree can be divided into two phases,calculatetransit node first,then calculate stub network.True FalseFalse74.In the process of calculating SPF tree,the cost from a node to root node equals to metriclisted in the Router LSA generated by the node.True FalseFalse75.BGP is an exterior gateway protocol,which runs among Ass,It focuses on routes control andselection of optimal routes rather than discovery and calculation of routes.True FalseTrue76.OSPF supports the combination of a group of network segments.Such a group is also calledan area.In other words,an area is a set of network segments.True FalseTrue77.The value of ospf dr-priority ranges from 0 to 255 and the default value is 64.True FalseFalse78.A broadcast and an NBMA network.each having two or more routers,must both have a DRand a BDR.True FalseFalse79.The vlink-peer command is used to specify a peer IP address for setting up a virtual link.True FalseFalse80.Different types of networks cannot establish an adjacency in the Full state.True FalseFalse81.Different network segments can be in the same OSPF area and the same network segmentcan be in different OSPF areas.True FalseFalse82.OSPF supports two authentication modes:area authentication and interfaceauthentication.The two authentication modes cannot be configured at the same time.True FalseFalse83.Each router running OSPF has a router ID,A router ID is a 32-bit integer and uniquelyidentifies a router,Hence,even of routers in different Ass,the router IDs must be different.True FalseFalse84.The most remarkable characteristic of OSPF is that OSPF supports the link-state algorithm.True FalseTrue85.OSPF directly runs over the IP protocol,Its IP protocol number is 89True FalseTrue86.If the Router Priority of a router is set to 0,this router cannot be elected as a DR or a BDR.True FalseTrue87.On a non-broadcast network,OSPF has two operating modes:NBMA and P2MPTrue FalseTrue88.By default,the cost of an OSPF interface is related to interface bandwidth.The algorithm forcalculating the cost is:True FalseTrue89.On a broadcast network or an NBMA network,not all neighbors need to set upadjacencies.Therefore,the concept about the adjacency is applicable to only the broadcast network or the NBMA network.True FalseFalse90.The NBMA mode requires all the routers in the network to be fully connected:otherwise,itdoes not function.True FalseFalse91.When two routers exchange LSDB information by exchanging DD packets,a master/slaverelationship is established between the two routers,The router with a larger router ID is the master.True FalseTrue92.If both the ospf cost and bandwidth-reference commands are configured on an interface.thevalue set in the ospf cost command is used as the cost of the interface.True FalseFalse93.The bandwidth-reference parameter is measured in Mbit/sTrue FalseTrue94.The asbr-summary command only contains the not-advertise parameter but not theadvertise parameter.True FalseTrue95.Each DD packet has a DD sequence number for packet acknowledgment.A DD sequencenumber is two-byte long.True FalseTrue96.On a broadcast network or an NBMA network,a router with a higher Router Priority is electedas a DR.True FalseFalse97.The LS Sequence Number field is used to detect expired and duplicate LSAs,This field is asigned 32-bit integer and therefore the minimum LS Sequence Number is 0x80000000True FalseFalse98.The LSAs with the same LS Sequence Number and LS age are the same LSA.True FalseFalse99.ABRs of a Stub area do not flood type-5 and type-4 LSAs to the stub area.Therefore,the stubarea does not have the external AS routing capability.ABRs of the stub area advertise a default route to the stub area to guide packet forwarding to the external of the AS.True FalseTrue100.The ABR in a Totally Stubby area will not advertise Type-3,Type-4,and Type-5 LSAs to the Totally Stubby area.Instead,the ABR will advertise a default route to the Totally Stubby area to guide forwarding of packets destined for other areas.True FalseTrue101.The ABR of an NSSA will not advertise Type-4 and Type-5 LSAs to an NSSA but can import external routes into the NSSA.True FalseTrue102.Different from a Stub area,an NSSA supports Type-5 LSAs.True FalseFalse103.ABRs advertise link status information about connected non-backbone areas to the backbone area.The backbone area then advertises the routing information about the backbone area cannot be advertised to non-backbone ares.True FalseFalse104.Type 2-external routes always take precedence over type 1-external routes True FalseFalse105.The import-route limit command is used to set the maximum number of external routers that can be imported into an OSPF process.True FalseTrue106.An Autonomous System (AS) is a set of routers under a single technical administration,using the same routing policy.True FalseTrue107.BGP peers are automatically discovered by exchanging multicast packets.True FalseFalse108.The router ID configured in the system view takes precedence over the router ID configured in the BGP view.True FalseFalse109.A failure in establishing a BGP peer relationship can be addressed by checking the TCP connectivity and BGP peer configurations.True FalseTrue110.In BGP,performing MD5 authentication between BGP peers can protect them from Dos attacks.True FalseTrue111.In the VRP,by default,the routes imported by BGP are not automatically summarized.True FalseTrue112.Based on BGP route selection rules,a local route that is automatically summarized takes precedence over a local route that is manually summarized.True FalseFalse113.Once a BGP connection is established,a BGP speaker advertises all the optimal routes in the BGP routing table to its BGP peer.True FalseTrue114.Whatever changes occur in the BGP routing table,a BGP speaker advertises all the optimal routes in the BGP routing table to its BGP peerTrue FalseFalse115.In the VRP,by default,a BGP router automatically retransmits an Update packet to its BGP peer after the outbound routing policy of the BGP peer changes.True FalseTrue116.IGP routes can be installed into the BGP routing table by running either the network or import-route command.True FalseTrue117.In the VRP,by default,a BGP router does not automatically send a Refresh to request its BGP peer to retransmit an Update packet after the inbound routing policy of the BGP peer changes.True FalseFalseing the peer connect-interface command to establish multiple peer relationships between two routers connected through multiple links is recommended.True FalseTrue119.Based on BGP route selection rules,the route with the lowest local-preference is preferred.True FalseFalse120.Based on BGP route selection rules,the route with the smallest MED value is preferred.True FalseTrue121.The origin attribute of the BGP route that is imported by using the network command is IGP True FalseTrue122.The BGP community attribute is a well-known mandatory attribute.True FalseFalse123.An ACL is used to match routing information or data packet addresses so as to filter out the unmatched routing information or data packets.True FalseTrue124.The system can perform ACL rule matching only based on the configuration order of rules.True FalseFalse125.Generally,the performance of an IP-prefix-filter is higher than that of an ACL.True FalseTrue126.An AS-path-filter is used to filter as-path attributes of BGP routes.The as-path attribute is actually a character string defined by using a regular expression.True FalseTrue127.Default routes between routers are a low-cost solution.this is because using default routes requires less system resources than maintaining a complete routing table.True FalseTrue128.An AS-path-filter uses the regular expression[0-9]+$ to indicate all as-path attributes.True FalseFalse129.Regular expressions can be used in both the community-filter and AS-path-filter to define the attribute mode used for route filteringTrue FalseTrue130.Route filtering can filter not only routing information but also link-status information.True FalseFalse131.For link-status routing protocols,filtering routes in the inbound direction actually cannot block the transmission of link-status information.the filtering effect is that routes cannot be injected into the local routing table but neighbors can still receive complete route status information and calculate complete routes.True FalseTrue132.All routing protocols can deliver default routes,supporting both forcible delivery and non-forcible delivery.True FalseFalse133.IF different routing protocols run on different networks and these networks need to share routing information,route importing can be usedTrue FalseTrue134.The route selection tool route-policy can filter and set BGP attributes based on pre-defined conditions.therefore,this tool is commonly used to define policies for BGP peers and often used in routeTrue FalseTrue135.When importing routes discovered by other routing protocols,a routing protocol may need to import only the routes that meet the conditions and set attributes of the imported routes to meet the requirement of the protocol,In such a case,a route-policy can be created.True FalseTrue136.Policy-based routing and routing policy affect the forwarding of data packets in different ways:A routing policy mainly controls packet forwarding,According to the routing policy,packets can be forwarded with no need to use a routing table:policy-based routing mainly controls the importing,advertising,and receiving of routing information so as to affect the forwarding of data packets.True FalseFalse137.The unicast and multicast technologies are both outstanding in solving the problem of one source and multiple destinations for efficient P2MP data transmission.True FalseFalse138.The IGMP protocol runs between a host and its directly connected multicast router.True FalseTrueyer 3 switch has layer 2 capability as well as layer 3 routing capabilityTrue FalseTrue140.STP distributes configuration message by sending BPDU packet to each other True FalseTrue141.A switching network has been enabled with STP protocol.To provide fast access speed to the file server for most of the users,the switch that is directly connected with file server is configured as the root bridgeTrue FalseTrue142.IF loop exists and STP is not enabled,the switch will not operate normally True FalseTrue143.RSTP adopts fast convergence mechanism,So,there is no forward delay interval in RSTP True FalseFalse144.Two switches are directly connected to each other and they are working in full duplex mode.By default,RSTP will consider the link between the switches as point-to-point linkTrue FalseTrue145.In RSTP network environment,a port can be set as edge port when it is directly connected with terminalTrue FalseTrue146.In a switching network that runs RSTP,the topology change notification message will not be sent when the switch detects that the Alternate port is faile.True FalseTrue147.VLANs isolate broadcast domains,eliminates broadcast storms,and enhances information securityTrue FalseTrue148.Before establishing a network,we must create VLANs,the users that do not need to communicate with each other should be added to the same VLAN for isolationTrue FalseFalse149.The port isolation function can isolate the ports on the same switchTrue FalseTrue150.When configuring VLAN mapping,you must set the priority of outer VLAN ID True FalseFalse151.On a switch running GVRP,each interface is considered as a participant.the participants can exchange informationTrue FalseTrue152.A switching network has been enabled with STP protocol,To provide fast access speed to the file server for most of the users,the switch that is directly connected with file server isconfigured as the root bridgeTrue FalseTrue153.When configuring VLAN mapping,you must set the priority of outer VLAN ID True FalseFalse154.QinQ provides a simplified layer 2 VPN tunnelTrue FalseTrue155.The STP protocol cannot prevent MAC address table flapping caused by loops on the layer 2 networkTrue FalseFalse156.According to the MSTP protocol,each MST instance calculates an independent spanning tree by using the RSTP algorithmTrue FalseTrue157.The traditional antivirus system prevents viruese on each node separately and may fail to prevent many security threatsTrue FalseTrue158.NAC is an end-to-end security solution.it protects network security from user terminals instead of network devicesTrue FalseTrue159.If 802.1x authentication is enabled on an interface,MAC address authentication (enabled by the mac-authen enable command) and direct authentication(enabled by the direct-authen enable command) cannot be enabled on the interfaceTrue FalseTrue160.The option field in DHCP messages uses the CLV modeTrue FalseTrue161.The option field in DHCP messages has a fixed length of four bytesTrue FalseFalse162.If only some devices on a network run MPLS (MPLS domain is encapsulated in the IP packet header),labels are generated only for direct routes of devices running bels are not generated for the routes originated from other devices running IP protocolsTrue FalseTrue163.The core of the MPLS technology is label switching.True FalseTrue164.In MPLS VPN configuration,you can choose from various types of routing protocols to configure between PEs and CEs.any type of routes can be imported to a VPN instance by using the import commandTrue FalseTrue165.VRF refers to VPN instance.It is an entity that a PE maintains for its directly connected site True FalseTrue166.On an MPLS VPN network,CEs and PEs can use the same routing protocol or different routing protocols to exchange routing information,the routing protocols are independent from one anotherTrue FalseTrue。
C H A P T E R54-1Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-0154Configuring Storm ControlThis chapter describes how to configure port-based traffic control on the Catalyst 4500 series switch.This chapter consists of these sections:•About Storm Control, page 54-1•Enabling Broadcast Storm Control, page 54-3•Enabling Multicast Storm Control, page 54-4•Disabling Broadcast Storm Control, page 54-5•Disabling Multicast Storm Control, page 54-5•Displaying Storm Control, page 54-6NoteFor complete syntax and usage information for the switch commands used in this chapter, first look at the Cisco Catalyst 4500 Series Switch Command Reference and related publications at this location:/en/US/products//hw/switches/ps4324/index.htmlIf the command is not found in the Catalyst 4500 Series Switch Command Reference, it will be found in the larger Cisco IOS library. Refer to the Cisco IOS Command Reference and related publications at this location:/en/US/products/ps6350/index.htmlAbout Storm ControlThis section contains the following subsections:•Hardware-Based Storm Control Implementation, page 54-2•Software-Based Storm Control Implementation, page 54-2Storm control prevents LAN interfaces from being disrupted by a broadcast storm. A broadcast storm occurs when broadcast packets flood the subnet, creating excessive traffic and degrading network performance. Errors in the protocol-stack implementation or in the network configuration can cause a broadcast storm.54-2Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-01Chapter 54 Configuring Storm ControlAbout Storm ControlSoftware Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-01Chapter 54 Configuring Storm ControlEnabling Broadcast Storm ControlEnabling Broadcast Storm ControlTo enable storm control, perform this task:The following example shows how to enable storm control on interface:Switch# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Switch(config)# interface fa3/1Switch(config-if)# storm-control broadcast level 50Switch(config-if)# endSwitch# show storm-controlInterface Filter State Broadcast Multicast Level --------- ------------- --------- --------- -----Fi3/1 Forwarding Enabled Disabled 50.00% Switch# show int fa2/1 capabilities FastEthernet2/1Model: WS-X4148-RJ45V-RJ-45 Type: 10/100BaseTX Speed: 10,100,autoCommandPurposeStep 1Switch# configure terminalEnters global configuration mode.Step 2Switch(config)# interface interface-id Enters interface configuration mode and enter the port to configure.Step 3Switch(config-if)# storm-control broadcast level [high level ]Configures broadcast storm control.Specifies the upper threshold levels for broadcast traffic. The storm control action occurs when traffic utilization reaches this level.(Optional) Specifies the falling threshold level. The normaltransmission restarts (if the action is filtering) when traffic drops below this level for interfaces that support software-based suppression.NoteFor ports that perform hardware-based suppression, the lower threshold is ignored.NoteFor the Catalyst 4500-X Series Switch, on ports operating at 1Gigabit, thresholds less than 0.02% are not supported.Step 4Switch(config-if)# storm-control action {shutdown | trap }Specifies the action to be taken when a storm is detected.The default is to filter out the broadcast traffic and not to send out traps.The shutdown keyword sets the port to error-disable state during a storm. If the recover interval is not set, the port remains in shutdown state.Step 5Switch(config-if)# exit Returns to configuration mode.Step 6Switch(config)# endReturns to privileged EXEC mode.Step 7Switch# show storm-control [interface ] broadcastDisplays the number of packets suppressed.Step 8Switch# copy running-config startup-config(Optional) Saves your entries in the configuration file.Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-01Chapter 54 Configuring Storm ControlEnabling Multicast Storm ControlDuplex: half,full,auto Auto-MDIX: noTrunk encap. type: 802.1QTrunk mode: on,off,desirable,nonegotiate Channel: yesBroadcast suppression: percentage(0-100), hw Multicast suppression: percentage(0-100), hw Flowcontrol: rx-(none),tx-(none) VLAN Membership: static, dynamic Fast Start: yes CoS rewrite: yes ToS rewrite: yesInline power: yes (Cisco Voice Protocol) SPAN: source/destination UDLD: yes Link Debounce: no Link Debounce Time: no Port Security: yes Dot1x: yesMaximum MTU: 1552 bytes (Baby Giants) Multiple Media Types: no Diagnostic Monitoring: N/AEnabling Multicast Storm ControlCatalyst 4900M, Catalyst 4948E, Supervisor Engine 6-E, Supervisor Engine 6L-E, Supervisor Engine 7-E, and Supervisor Engine 7L-E support per-interface multicast suppression, which allows you to subject incoming multicast and broadcast traffic to interface-level suppression.NoteMulticast and broadcast suppression share a common threshold per interface. Multicast suppression takes effect only if broadcast suppression is enabled. Disabling broadcast suppression on an interface also disables multicast suppression.To enable multicast suppression, perform this task:The following example shows how to enable multicast suppression on ports that have broadcast suppression already enabled:Switch# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Switch(config)# int fa3/1Switch(config-if)# storm-control broadcast include multicastCommandPurposeStep 1Switch# configure terminalEnters global configuration mode.Step 2Switch(config)# interface interface-id Enters interface configuration mode and enter the port to configure.Step 3Switch(config-if)# storm-control broadcast include multicast Enables multicast suppression.Step 4Switch(config-if)# exit Returns to configuration mode.Step 5Switch(config)# endReturns to privileged EXEC mode.Step 6Switch# show storm-controlVerifies the configuration.Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-01Chapter 54 Configuring Storm ControlDisabling Broadcast Storm ControlSwitch(config-if)# end Switch#Switch# show storm-controlInterface Filter State Broadcast Multicast Level --------- ------------- --------- --------- -----Fi3/1 Forwarding Enabled Enabled 50.00%Disabling Broadcast Storm ControlTo disable storm control, perform this task:The following example shows how to disable storm control on interface.Switch# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Switch(config)# int fa3/1Switch(config-if)# no storm-control broadcast level Switch(config-if)# endSwitch# show storm-controlInterface Filter State Broadcast Multicast Level --------- ------------- --------- --------- -----Switch#Disabling Multicast Storm ControlTo disable multicast suppression, perform this task:CommandPurposeStep 1Switch# configure terminalEnters global configuration mode.Step 2Switch(config)# interface interface-id Enters interface configuration mode and enter the port to configure.Step 3Switch(config-if)# no storm-control broadcast levelDisables port storm control.Step 4Switch(config-if)# no storm-control action {shutdown | trap }Disables the specified storm control action and returns to default filter action.Step 5Switch(config-if)# exit Returns to configuration mode.Step 6Switch(config)# endReturns to privileged EXEC mode.Step 7Switch# show storm-control broadcast Verifies your entries.Step 8Switch# copy running-config startup-config(Optional) Saves your entries in the configuration file.CommandPurposeStep 1Switch# configure terminalEnters global configuration mode.Step 2Switch(config)# [no ] storm-control broadcast include multicastEnables and disables multicast suppression.Step 3Switch(config-if)# no storm-control broadcast levelDisables port storm control (broadcast and multicast).Chapter54 Configuring Storm Control Displaying Storm ControlCommand PurposeStep4Switch(config-if)# end Returns to configuration mode.Step5Switch(config)# end Returns to privileged EXEC mode.Displaying Storm ControlNote Use the show interface capabilities command to determine the mode in which storm control is supported on an interface.The following example shows an interface that supports broadcast suppression in software (sw):Switch# show int fa2/1 capabilitiesFastEthernet2/1Model: WS-X4148-RJ45V-RJ-45Type: 10/100BaseTXSpeed: 10,100,autoDuplex: half,full,autoAuto-MDIX: noTrunk encap. type: 802.1QTrunk mode: on,off,desirable,nonegotiateChannel: yesBroadcast suppression: percentage(0-100), hwMulticast suppression: percentage(0-100), hwFlowcontrol: rx-(none),tx-(none)VLAN Membership: static, dynamicFast Start: yesCoS rewrite: yesToS rewrite: yesInline power: yes (Cisco Voice Protocol)SPAN: source/destinationUDLD: yesLink Debounce: noLink Debounce Time: noPort Security: yesDot1x: yesMaximum MTU: 1552 bytes (Baby Giants)Multiple Media Types: noDiagnostic Monitoring: N/ANote Use the show interfaces counters storm-control command to display a count of discarded packets.Switch# show interfaces counters storm-controlPort Broadcast Multicast Level TotalSuppressedPacketsFa2/1 Enabled Disabled 10.00% 46516510Gi3/1 Enabled Enabled 50.00% 0Switch# show storm-controlInterface Filter State Broadcast Multicast Level--------- ------------- --------- --------- -----Fa2/1 Blocking Enabled Disabled 10.00%Gi3/1 Link Down Enabled Enabled 50.00%Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SGOL-25340-01。
一、为什么需要关闭和重新开启路由器或交换机某一接口在网络管理和维护过程中,有时需要关闭和重新开启路由器或交换机某一接口。
这可能是因为接口出现故障,需要重新初始化,或者需要进行某些配置调整,需要临时关闭接口。
无论是哪种情况,正确的操作命令对于网络的正常运行和维护非常重要。
二、路由器某一接口关闭并重新开启的命令1. 进入路由器的接口配置模式2. 找到需要关闭的接口3. 输入关闭接口的命令4. 输入重新启用接口的命令5. 退出接口配置模式具体的操作步骤如下:1. 进入路由器的接口配置模式在路由器的全局配置模式下,输入命令“interface 接口类型接口编号”进入接口配置模式。
如果需要关闭和重新启用以太网0/0接口,就输入命令“interface Ethernet0/0”。
2. 找到需要关闭的接口在接口配置模式下,找到需要关闭的接口。
可以通过命令“show interface”查看当前各个接口的状态,确认需要关闭和重新启用的接口编号。
3. 输入关闭接口的命令输入命令“shutdown”关闭接口,确保在关闭接口之前已经确认其不会影响整个网络的正常运行。
关闭接口后,可以通过命令“show interface”再次确认接口的状态。
4. 输入重新启用接口的命令输入命令“no shutdown”重新启用接口,确保在重新启用接口之前已经确认故障已经得到解决或者配置已经调整合适。
重新启用接口后,可以通过命令“show interface”再次确认接口的状态。
5. 退出接口配置模式输入命令“exit”退出接口配置模式,回到路由器的全局配置模式或者用户 EXEC 模式。
三、交换机某一接口关闭并重新开启的命令与关闭和重新启用路由器接口类似,关闭和重新启用交换机某一接口也有相应的命令操作步骤。
1. 进入交换机的接口配置模式2. 找到需要关闭的接口3. 输入关闭接口的命令4. 输入重新启用接口的命令5. 退出接口配置模式具体的操作步骤如下:1. 进入交换机的接口配置模式在交换机的全局配置模式下,输入命令“interface 接口类型接口编号”进入接口配置模式。
Swift中的Closures(闭包)详解Swift 中的Closures(闭包)详解在Swift没有发布之前,所有⼈使⽤OC语⾔编写Cocoa上的程序,⽽其中经常被⼈们讨论的其中之⼀ -- Block ⼀直备受⼤家的喜爱。
在Swift 中,同样有这样的⼀个⾓⾊,⽤于当开发者需要异步执⾏的之后使⽤的⼀种语法 - Closure。
中⽂翻译为闭包。
闭包出了可以进⾏异步执⾏之外,它的完整使⽤还依赖闭包本⾝的变量、常量的捕获。
闭包捕获并存储对它们定义的上下⽂中的任何常量和变量的引⽤,这也就意味着,你可以在任何时候异步执⾏闭包的时候获取之前的所有的环境变量。
⽽实际上,闭包类似于Swift 中的匿名函数,在上⼀篇⽂章中,介绍了⾼阶函数和嵌套函数,它们和闭包有者不可分割的⼀些联系。
⽐如,最简单的闭包起始就是⼀个⾼阶函数,只是在闭包做为参数变量的时候,闭包是匿名、书写时实现。
当对于⼀般的⾼阶函数,闭包更轻量级。
本⽂介绍⼏种闭包的形式,以及⼀些闭包的特性。
⼀、闭包的基本形式这是⼀个最基本的闭包的形式:{ (parameters) -> return type instatements}闭包中,包含三要素:参数,返回类型,闭包体。
其中参数和返回类型可以忽略,但是⼀个闭包体必需存在,实际上就算在闭包体⾥⾯,什么都不写,闭包体本⾝还是以不执⾏任何代码的形式存在。
reversedNames = names.sorted(by: { (s1: String, s2: String) -> Bool inreturn s1 > s2})这是⼀个⾼阶函数,同时,也是⼀个闭包的基本使⽤。
包含了参数及类型,返回值类型,闭包体。
我们可以简写闭包的形式,采⽤内联的⽅式书写:reversedNames = names.sorted(by: { (s1: String, s2: String) -> Bool in return s1 > s2 } )在闭包中,因为包含了上下⽂的变量和常量的引⽤,并做了类型推断,所以,实际上,对于闭包的参数来说,类型是固定的,当然返回的类型也是固定的,swift允许开发者书写时省略。
EDS-P510A Series8+2G-port Gigabit PoE+managed Ethernet switches with8IEEE802.3af/at PoE+portsFeatures and Benefits•8built-in PoE+ports compliant with IEEE802.3af/at•Up to36W output per PoE+port•3kV LAN surge protection for extreme outdoor environments•PoE diagnostics for powered-device mode analysis•2Gigabit combo ports for high-bandwidth and long-distance communication •Operates with240watts full PoE+loading at-40to75°C•Supports MXstudio for easy,visualized industrial network management•V-ON™ensures millisecond-level multicast data and video network recoveryCertificationsIntroductionMoxa’s EDS-P510A Series has810/100BaseT(X),802.3af(PoE),and802.3at(PoE+)-compliant Ethernet ports,and2combo Gigabit Ethernet ports. The EDS-P510A-8PoE Ethernet switches provide up to30watts of power per PoE+port in standard mode and allow high-power output of up to36 watts for industrial heavy-duty PoE devices,such as weather-proof IP surveillance cameras with wipers/heaters,high-performance wireless access points,and IP phones.The EDS-P510A Ethernet Series is highly versatile,and the SFP fiber ports can transmit data up to120km from the device to the control center with high EMI immunity.The Ethernet switches support a variety of management functions,as well as STP/RSTP,Turbo Ring,Turbo Chain,PoE power management,PoE device auto-checking,PoE power scheduling,PoE diagnostic,IGMP,VLAN,QoS,RMON,bandwidth management,and port mirroring.The EDS-P510A Series is designed with3kV surge protection for harsh outdoor applications to increase the reliability of PoE systems.Additional Features and Benefits•Supports different PoE output settings(High-power36W,Forceand Legacy modes)to maximize powered device compatibility•Supports Smart PoE functions(PoE diagnosis,PD failure check,PoE scheduling,PoE Event Warning)to enhance PoE operationalefficiency•Command line interface(CLI)for quickly configuring majormanaged functions•DHCP Option82for IP address assignment with different policies•Supports EtherNet/IP and Modbus TCP protocols for devicemanagement and monitoring•Turbo Ring and Turbo Chain(recovery time<20ms@250switches),1RSTP/STP,and MSTP for network redundancy•Compatible with PROFINET protocol for transparent datatransmission•IGMP snooping and GMRP for filtering multicast traffic•Port-based VLAN,IEEE802.1Q VLAN,and GVRP to ease networkplanning•QoS(IEEE802.1p/1Q and TOS/DiffServ)to increase determinism•Port Trunking for optimum bandwidth utilization•TACACS+,IEEE802.1X,SNMPv3,HTTPS,and SSH to enhancenetwork security•Lock port function for blocking unauthorized access based on MACaddress•SNMPv1/v2c/v3for different levels of network management•RMON for proactive and efficient network monitoring•Bandwidth management to prevent unpredictable network status•Port mirroring for online debugging•Automatic warning by exception through email and relay output1.Gigabit Ethernet recovery time<50msSpecifications Ethernet InterfaceCombo Ports(10/100/1000BaseT(X)or100/ 1000BaseSFP+)2Full/Half duplex modeAuto MDI/MDI-X connection Auto negotiation speedPoE Ports(10/100BaseT(X),RJ45connector)8Full/Half duplex modeAuto MDI/MDI-X connectionAuto negotiation speedStandards IEEE802.1D-2004for Spanning Tree ProtocolIEEE802.1p for Class of ServiceIEEE802.1Q for VLAN TaggingIEEE802.1s for Multiple Spanning Tree ProtocolIEEE802.1w for Rapid Spanning Tree ProtocolIEEE802.1X for authenticationIEEE802.3for10BaseTIEEE802.3ab for1000BaseT(X)IEEE802.3ad for Port Trunk with LACPIEEE802.3af/at for PoE/PoE+outputIEEE802.3u for100BaseT(X)and100BaseFXIEEE802.3x for flow controlIEEE802.3z for1000BaseSX/LX/LHX/ZXEthernet Software FeaturesFilter GMRP,GVRP,IGMP v1/v2,Port-based VLANIndustrial Protocols EtherNet/IP,Modbus TCPManagement Back Pressure Flow Control,BOOTP,DDM,DHCP Option66/67/82,DHCP Server/Client,Fiber check,Flow control,IPv4/IPv6,LLDP,Port Mirror,RARP,RMON,SMTP,SNMP Inform,SNMPv1/v2c/v3,Syslog,Telnet,TFTPMIB Bridge MIB,Ethernet-like MIB,MIB-II,P-BRIDGE MIB,Q-BRIDGE MIB,RMON MIBGroups1,2,3,9,RSTP MIBRedundancy Protocols LACP,Link Aggregation,MSTP,RSTP,STP,Turbo Chain,Turbo Ring v1/v2 Security HTTPS/SSL,Port Lock,RADIUS,TACACS+,SSHTime Management NTP Server/Client,SNTPSwitch PropertiesIGMP Groups1024MAC Table Size8KMax.No.of VLANs64Packet Buffer Size1MbitsPriority Queues4VLAN ID Range VID1to4094Serial InterfaceConsole Port RS-232(TxD,RxD,GND),10-pin RJ45(19200,n,8,1)DIP Switch ConfigurationEthernet Interface Turbo Ring,Master,Coupler,ReserveInput/Output InterfaceAlarm Contact Channels1,Relay output with current carrying capacity of0.5A@48VDC Digital Input Channels1Digital Inputs Max.input current:8mA+13to+30V for state1-30to+3V for state0Power ParametersInput Voltage48VDC,Redundant dual inputsOperating Voltage44to57VDCInput Current 5.36A@48VDCPower Consumption(Max.)Max.17.28W full loading without PDs’consumptionPower Budget Max.240W for total PD consumptionMax.36W for each PoE portConnection2removable2-contact terminal block(s)Overload Current Protection SupportedReverse Polarity Protection SupportedPhysical CharacteristicsHousing MetalIP Rating IP30Dimensions79.2x135x105mm(3.12x5.31x4.13in)Weight1030g(2.28lb)Installation DIN-rail mounting,Wall mounting(with optional kit) Environmental LimitsOperating Temperature EDS-P510A-8PoE-2GTXSFP:-10to60°C(14to140°F)EDS-P510A-8PoE-2GTXSFP-T:-40to75°C(-40to167°F) Storage Temperature(package included)-40to85°C(-40to185°F)Ambient Relative Humidity5to95%(non-condensing)Standards and CertificationsSafety UL508EMC EN55032/24EMI CISPR32,FCC Part15B Class AEMS IEC61000-4-2ESD:Contact:6kV;Air:8kVIEC61000-4-3RS:80MHz to1GHz:20V/mIEC61000-4-4EFT:Power:2kV;Signal:2kVIEC61000-4-5Surge:Power:2kV;Signal:2kVIEC61000-4-6CS:10VIEC61000-4-8PFMFHazardous Locations Class I Division2Railway EN50121-4Traffic Control NEMA TS2Freefall IEC60068-2-31Shock IEC60068-2-27Vibration IEC60068-2-6MTBFTime708,972hrsStandards Telcordia(Bellcore),GBWarrantyWarranty Period5yearsDetails See /warrantyPackage ContentsDevice1x EDS-P510A Series switchCable1x DB9female to RJ4510-pinInstallation Kit4x cap,plastic,for RJ45port2x cap,plastic,for SFP slotDocumentation1x quick installation guide1x product certificates of quality inspection,Simplified Chinese1x product notice,Simplified Chinese1x warranty cardNote SFP modules need to be purchased separately for use with this product. DimensionsOrdering InformationModel NameCombo Ports10/100/1000BaseT(X)or100/1000BaseSFP+PoE Ports10/100BaseT(X),RJ45ConnectorOperating Temp.EDS-P510A-8PoE-2GTXSFP28-10to60°C EDS-P510A-8PoE-2GTXSFP-T28-40to75°CAccessories(sold separately)SoftwareMXview Industrial network management software designed for converged automation networksStorage KitsABC-02-USB Configuration backup and restoration tool,firmware upgrade,and log file storage tool for managedEthernet switches and routers,0to60°C operating temperatureABC-02-USB-T Configuration backup and restoration tool,firmware upgrade,and log file storage tool for managedEthernet switches and routers,-40to75°C operating temperatureSFP ModulesSFP-1FELLC-T SFP module with1100Base single-mode with LC connector for80km transmission,-40to85°Coperating temperatureSFP-1FEMLC-T SFP module with1100Base multi-mode with LC connector for4km transmission,-40to85°Coperating temperatureSFP-1FESLC-T SFP module with1100Base single-mode with LC connector for40km transmission,-40to85°Coperating temperatureSFP-1G10ALC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for10km transmission;TX1310nm,RX1550nm,0to60°C operating temperatureSFP-1G10ALC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for10km transmission;TX1310nm,RX1550nm,-40to85°C operating temperatureSFP-1G10BLC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for10km transmission;TX1550nm,RX1310nm,0to60°C operating temperatureSFP-1G10BLC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for10km transmission;TX1550nm,RX1310nm,-40to85°C operating temperatureSFP-1G20ALC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for20km transmission;TX1310nm,RX1550nm,0to60°C operating temperatureSFP-1G20ALC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for20km transmission;TX1310nm,RX1550nm,-40to85°C operating temperatureSFP-1G20BLC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for20km transmission;TX1550nm,RX1310nm,0to60°C operating temperatureSFP-1G20BLC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for20km transmission;TX1550nm,RX1310nm,-40to85°C operating temperatureSFP-1G40ALC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for40km transmission;TX1310nm,RX1550nm,0to60°C operating temperatureSFP-1G40ALC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for40km transmission;TX1310nm,RX1550nm,-40to85°C operating temperatureSFP-1G40BLC WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for40km transmission;TX1550nm,RX1310nm,0to60°C operating temperatureSFP-1G40BLC-T WDM-type(BiDi)SFP module with11000BaseSFP port with LC connector for40km transmission;TX1550nm,RX1310nm,-40to85°C operating temperatureSFP-1GEZXLC SFP module with11000BaseEZX port with LC connector for110km transmission,0to60°C operatingtemperatureSFP-1GEZXLC-120SFP module with11000BaseEZX port with LC connector for120km transmission,0to60°C operatingtemperatureSFP-1GLHLC SFP module with11000BaseLH port with LC connector for30km transmission,0to60°C operatingtemperatureSFP-1GLHLC-T SFP module with11000BaseLH port with LC connector for30km transmission,-40to85°C operatingtemperatureSFP-1GLHXLC SFP module with11000BaseLHX port with LC connector for40km transmission,0to60°C operatingtemperatureSFP-1GLHXLC-T SFP module with11000BaseLHX port with LC connector for40km transmission,-40to85°Coperating temperatureSFP-1GLSXLC SFP module with11000BaseLSX port with LC connector for500m transmission,0to60°C operatingtemperatureSFP-1GLSXLC-T SFP module with11000BaseLSX port with LC connector for500m transmission,-40to85°Coperating temperatureSFP-1GLXLC SFP module with11000BaseLX port with LC connector for10km transmission,0to60°C operatingtemperatureSFP-1GLXLC-T SFP module with11000BaseLX port with LC connector for10km transmission,-40to85°C operatingtemperatureSFP-1GSXLC SFP module with11000BaseSX port with LC connector for300/550m transmission,0to60°Coperating temperatureSFP-1GSXLC-T SFP module with11000BaseSX port with LC connector for300/550m transmission,-40to85°Coperating temperatureSFP-1GZXLC SFP module with11000BaseZX port with LC connector for80km transmission,0to60°C operatingtemperatureSFP-1GZXLC-T SFP module with11000BaseZX port with LC connector for80km transmission,-40to85°C operatingtemperaturePower SuppliesDR-120-48120W/2.5A DIN-rail48VDC power supply with universal88to132VAC or176to264VAC input byswitch,or248to370VDC input,-10to60°C operating temperatureDR-75-4875W/1.6A DIN-rail48VDC power supply with universal85to264VAC or120to370VDC input,-10to60°C operating temperatureDRP-240-48DIN-rail48VDC power supply with240W/5A,85to264VAC,or120to370VDC input,-10to70°Coperating temperatureSDR-480P-48DIN-rail48VDC power supply with480W/10A,90to264VAC,or127to370VDC input,(current sharingup to3840W),-25to70°C operating temperatureWall-Mounting KitsWK-46-01Wall-mounting kit,2plates,8screws,46x66.8x2mmRack-Mounting KitsRK-4U19-inch rack-mounting kit©Moxa Inc.All rights reserved.Updated Nov12,2018.This document and any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of Moxa Inc.Product specifications subject to change without notice.Visit our website for the most up-to-date product information.。
IP通信网络基础知识第一章,网际互连基础把一个大的网络划分为一些小的网络就称为网络分段,这些工作由路由器,交换机和网桥来按成。
引起LAN通信量出现足赛的可能原因如下:1.在一个广播域中有太多的主机2.广播风暴3.组播4.低的带宽路由器被用来连接各种网络,并将数据包从一个网络路由到另一个网络。
默认时,路由器用来分隔广播域,所谓广播域,是指王端上所有设备的集合,这些设备收听送往那个王端的所有广播。
尽管路由器用来分隔广播域,但重要的是要记住,路由器也用来分隔冲突域。
在网络中使用路由器有两个好处:1.默认时路由器不会转发广播。
2.路由器可以根据第三层(网络层)信息对网络进行过滤。
默认时,交换机分隔冲突域。
这是一个以太网术语,用来描述:某个特定设备在网段上发送一个数据包,迫使同一个网段上的其他设备都必须主要道这一点。
在同一时刻,如果两个不同的设备试图发送数据包,就会产生冲突域,此后,两个设备都必须重新发送数据包。
网际互连模型当网络刚开始出现时,典型情况下,只能在同一制造商的计算机产品之间进行通信。
在20世纪70年代后期,国际标准化组织创建了开放系统互联参考模型,也就是OSI七层模型。
OSI模型时为网络而构建的最基本的层次结构模型。
下面是分层的方法,以及怎样采用分层的方法来排除互联网络中的故障。
分层的方法参考模型时一种概念上的蓝图,描述了通信是怎样进行的。
他解决了实现有效通信所需要的所有过程,并将这些过程划分为逻辑上的组,称为层。
参考模型的优点OSI模型时层次化的,任何分层的模型都有同样的好处和优势。
采用OSI层次模型的优点如下,当然不仅仅是这些:1.通过网络组件的标准化,允许多个提供商进行开发。
2.允许各种类型网络硬件和软件相互通信。
3.防止对某一层所作的改动影响到其他的层,这样就有利于开发。
OSI参考模型OSI模型规范重要的功能之一,是帮助不能类型的主机实现相互之间的数据传输。
OSI模型有7个不同的层,分为两个组。
Discussion of“Reliability Evaluation of Cross-Hole Sonic Logging for Bored Pile Integrity”by D.Q.Li,L.M.Zhang,andW.H.TangSeptember2005,V ol.131,No.9,pp.1130–1138.DOI:10.1061/͑ASCE͒1090-0241͑2005͒131:9͑1130͒Joram M.Amir,F.ASCE11Chairman, Ltd.,85Hanassi St.,Herzlia46399,Israel.E-mail:imamir@During the last decade cross-hole sonic logging,alternatively re-ferred to as ultrasonic cross-hole testing of piles͑ASTM2002͒, has established itself as the preferred method for quality control of bored piles͑alias caissons and drilled shafts͒.While the prin-ciples lying behind the test are now well understood,there is still disagreement as to the number of access tubes that are necessary to perform the test.This subject has a clear economic conse-quence:While increasing the number of access tubes in a pile may improve the test’sflaw detection capability,these tubes carry a price tag in material,workmanship,and increased testing costs. The effort made by the authors to determine the optimal number of access tubes for each situation should therefore be com-mended.For the paper presented to qualify as a practical guide,it has to fulfill certain conditions:1.The work has to address the technical features specific to thetest.2.It should be based on reasonable assumptions,commensuratewith observed facts and common knowledge.3.The mathematical treatment must be rigorous.Being guided by these criteria,the discusser would like to raise certain reservations related to the methodology followed by the authors.These are presented in the following paragraphs.Technical FeaturesTypically,two distinct parameters are measured in the ultrasonic cross-hole test:first arrival time͑FAT͒and relative energy ͑ASTM2002͒.Each of these has its special significance in the interpretation of the test results.Certainflaws are better expressed in FAT terms,while others have more influence on the relative energy.It is regrettable,therefore,that in discussing inspection probability the authors do not mention which of these two they refer to.Furthermore,the heterogeneity of concrete may cause test re-sults to exhibit large scatter͑Amir et al.2004͒.Under these con-ditions,a defect of a given size may escape detection when its effect on the test results is of the same order as the scatter.In such a noisy environment,the definition of what constitutes an anomaly is rather arbitrary,with different codes providing differ-ent prescriptions.The Chinese code͑MOC2003͒,for instance, defines as anomalous any result in which the apparent wave ve-locity deviates from the mean by,or a prescribed number of standard deviations.The authors tacitly circumvent this crucial problem by assuming those detection thresholds are independent of the signal-to-noise ratio.Validity of AssumptionsThe authors make several assumptions,among which the most important are1.On the basis of Fleming et al.͑1992͒,the authors assume thata defect may occupy,with equal likelihood,any positionwithin the pile cross section.However,a careful study of the numerous photographs provided by Fleming et al.͑1992͒clearly shows that most of them depict defects in the periph-ery.O’Neil͑1991͒explains this phenomenon,to which many practitioners can testify from personal experience͑Fig.1͒,by the interaction of the rising concrete column and the slurry with the surrounding soil,groundwater,temporary casing, and reinforcement cage—all located at the pile’s periphery.The widespread usage of the terms“necking”or“waisting”in describing pile integrity attests to this phenomenon.2.The authors claim that what they define as the“encounteredprobability”of a defect depends only on its size.Evidently, this is necessarily incorrect:While an air void of a few mil-limeters caused by tube debonding is clearly detected,a de-fect two orders of magnitude larger may escape detection if it is located farther away from a tube.Thus,defect position is not less and maybe more important than its size.To illustrate this point,afinite element simulation of the Fig.1.Typical defect in bored pile constructed with polymer slurrycross-hole test was run,using the Plaxis program,for three cases:no defect;circular defect,5wavelengths in diameter halfway between the transmitter and receiver;and circular defect,5wavelengths in diameter,close to the transmitter.The results of the simulation,presented as horizontal dis-placement versus time,are reasonably similar to those ob-tained in a real test.The results ͑Fig.2͒show that a defect halfway between the tubes is hardly discernible,while an identical one located close to the emitter ͑or in fact to the receiver ͒is easily detected:the FAT is at least 20%larger,and the maximum amplitude 75%͑or 12dB ͒smaller.3.In defining the detection probability for a defect in a pile ͑Eq.4͒,the authors adopt results developed for cracks in metal.The validity of this analogy is,however,not self-evident.Concrete in piles,unlike metal,is far from homogeneous,and typical defects in piles are not well-defined features but of rather fuzzy character.Thus,the detection threshold of defects in piles must be much higher.d.The authors assume that waves propagate in straight lines.While this may be true for homogeneous media,it is not necessarily so in heterogeneous materials like concrete ͑Santamarina et al.2001͒.Even in a homogeneous medium with inclusions of foreign materials,waves will travel in curved paths to go around those inclusions and minimize arrival time ͑Fermat’s postulate ͒.AnalysisIn Eq.1the authors express inspection probability P ͑x ͒as a prod-uct of encountered probability P ͑E ͉x ͒and the detection probabil-ity P ͑D ͉E ,x ͒,both dependent on defect size x .Since the law of multiplication is only applicable to statistically independent prob-abilities ͑Bulmer 1967͒,the use of Eq.1is not justified.SummaryThe treatise presented by the authors appears to be based on sim-plifying assumptions that seem to contradict both empirical evi-dence and accepted principles.Moreover,the statistical treatment of the problem is flawed,and above all,the authors do not address the specific parameters that characterize real-life cross-hole tests.As a result,the validity of their results is questionable,and extra caution is deemed necessary in the application of their conclu-sions to practical situations.ReferencesAmir,J.M.,Amir,E.I.,and Felice,C.W.͑2004͒.“Acceptance criteria for bored piles by ultrasonic testing.”Proc.,Int.Conf.on Application of Stress Wave Theory to Piling ,Kuala Lumpur.Bulmer,M.G.͑1967͒.Principles of statistics ,Dover,New York,17.O’Neill,M.W.͑1991͒.“Construction practices and defects in drilled shafts.”Transportation Research Record ,Washington,D.C.,6–14.Santamarina,J.C.,Klein,A.,and Fam,M.A.͑2001͒.Soils and waves ,Wiley,Chichester,212.Fleming,W.G.K.,Weltman,A.J.,Randolph,M.P.,and Elson,W.K.͑1992͒.Piling engineering ,2nd Ed.,Wiley,New York.Ministry of Construction ͑MOC ͒.͑2003͒.Technical code for testing of building foundation piles (JGJ 106-2003),Beijing.Closure to “Reliability Evaluation ofCross-Hole Sonic Logging for Bored Pile Integrity”by D.Q.Li,L.M.Zhang,and W.H.TangSeptember 2005,V ol.131,No.9,pp.1130–1138.DOI:10.1061/͑ASCE ͒1090-0241͑2005͒131:9͑1130͒D.Q.Li 1;L.M.Zhang 2;and W.H.Tang 31Associate Professor,State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan Univ.,Wuhan,China;formerly,Postdoctoral Research Associate,Hong Kong Univ.of Science and Technology,Kowloon,Hong Kong.E-mail:dianqing@ 2Associate Professor,Dept.of Civil Engineering,Hong Kong Univ.of Science and Technology,Clear Water Bay,Kowloon,Hong Kong.E-mail:cezhangl@ust.hk 3Chair Professor,Dept.of Civil Engineering,Hong Kong Univ.of Science and Technology,Clear Water Bay,Kowloon,Hong Kong.E-mail:wtang@ust.hkThe authors are grateful to Dr.Joram M.Amir for his thoughtful discussion.Technical FeaturesThe authors did not consider the detection capability of cross-hole sonic logging ͑CSL ͒directly from the technical features of CSL such as first arrival time and relative energy.Instead,the detection probability for bored piles considered in this paper is based on past CSL performance.A detection probability function by Yang and Trapp ͑1975͒is used,and the minimum detectable void size and the detectable void size with certainty are selected basedonFig.2.Pile with no defect ͑thin line ͒,with defect halfway between tubes ͑a ͒,and with defect close to transmitter ͑b ͒past CSL detection performance for bored piles͑Table2in thepaper͒.The discusser proposes to explore the detection probability ofCSL based on technical features of CSL.This can certainly addphysical understanding to the issue.This approach may at thesame time,as pointed out by the discusser,be rendered ineffectiveby the heterogeneity of concrete and locations of anomalies͑seeFig.2of the Discussion͒.Validity of AssumptionsAs mentioned by O’Neill͑1991͒,defects such as necking and soilinclusions may be located at a pile’s periphery,while defects suchas voids and cracks can be located at any position within the pileshaft.For simplicity,it is assumed that the defect location is uni-formly distributed over the cross section of the pile in the paper.This assumption may somewhat overpredict the encounteredprobability of CSL.The concepts of encountered probability and inspection prob-ability cannot be confused.The chance that a defect may be foundby an integrity test is quantified through the inspection probabilityrather than the encountered probability alone.This is an importantpoint that this paper attempts to clarify.Encountered probabilitydepends only on the defect size and the arrangement of accesstubes.The encountered probability referred to by the discusser isactually the inspection probability as defined by the authors.The effect of defect location on the inspection probability hasbeen taken into consideration through the detection probabilitydefined in this study,which is illustrated in Fig.4in the paper.InFig.4,y is the distance from the center of the defect to the chordand is used to account for the effect of defect location.The effectis quantified in the subsequent analysis through Fig.5and Eqs.͑12͒and͑13͒in the paper.For instance,for a defect with a diam-eter of200mm,the detection probability is1.0for the case whenthe defect is located at the center of the signal path and0for thecase when the defect is randomly located within the pile crosssection.Obviously,the detection probability can differ consider-ably based on the difference in the defect location,though thedefect size remains the same.Consequently,the probability that an inspection willfind a defect can differ considerably.The detection probability function shown in Eq.͑4͒in the paper is obtained based on data from ultrasonic inspection of fatigue cracks in metal structures͑Yang and Trapp1975͒.With regard to integrity testing for large-diameter bored piles,no de-tection probability functions have ever been reported in the litera-ture.In this paper,Eq.͑4͒is assumed to apply equally well to CSL for large-diameter bored piles.It should be noted that the detection thresholds for defects have been determined based on experimental results of CSL for large-diameter bored piles rather than results of cracks in metals.The detection thresholds of de-fects are133.3and200mm in Eqs.͑12͒and͑13͒for the two cases considered in the paper.Both of them are considerably higher than10mm for cracks in metal structures͑Ichikawa1985͒or1.0mm for magnetic inspection͑Guedes Soares and Garbatov 1996͒.Following Hassan and O’Neill͑1998͒,the authors assumed that a cross-hole sonic logging test can scan the path between the two access tubes with a width of about2,whereis the wave length.The discusser is correct when he says that waves may travel in curved paths to go around inclusions.This will affect both the encountered probability and the detection probability and is certainly worthy of further study.AnalysisA defect inspection requires the intersection of two events, namely͑1͒the defect must be encountered,and͑2͒the defect must be detected.Eq.͑1͒describes that the intersection probabil-ity can be expressed as the product of the encountered probability and the conditional probability that the defect will be detected if it has been encountered͑that is,the detection probability͒.Clearly, both the encountered probability and detection probability are re-lated to the defect size.The inspection probability will be zero if the defect is not encountered or if the defect is encountered but not detected by the CSL.SummaryThe major points in the discussion seem to have arisen from confusion between the encountered probability and the inspection probability.A thrust of this paper is to clarify the concepts of encountered probability,detection probability,and inspection probability.The paper provides a quantitative guidance for the number of access tubes for CSL based on past CSL performance. Indeed some assumptions are made for the analysis of the en-countered probability and detection probability.The results pre-sented in this paper are accordingly valid to the degree these assumptions are met.ReferencesGuedes Soares,C.,and Garbatov,Y.͑1996͒.“Fatigue reliability of the ship hull girder accounting for inspection and repair.”Reliab.Eng.Syst.Saf.,51͑3͒,341–351.Hassan,K.M.,and O’Neill,M.W.͑1998͒.“Structural resistance factors for drilled shafts with minor defects.”Final Rep.,Phase I,Dept.of Civil and Environmental Engineering,Univ.of Houston,Houston. Ichikawa,M.͑1985͒.“A theoretical study of defect detection probability of nondestructive inspection.”Reliability Engineering,10,175–182. O’Neill,M.W.͑1991͒.“Construction practices and defects in drill shafts.”Transportation Research Record,Washington,D.C.,6–14. Yang,J.N.,and Trapp,J.W.͑1975͒.“Reliability analysis of fatigue-critical aircrafts structures under random loading and periodic inspec-tions.”Technical Rep.,AFML-TR-75-29,Air Force Materials Laboratory,Washington,D.C.Discussion of“Comparison of Interface Shear Strength of Soil Nails Measured by Both Direct Shear Box Tests and Pullout Tests”by Lok-Man Chu and Jian-Hua Yin September2005,V ol.131,No.9,pp.1097–1107.DOI:10.1061/͑ASCE͒1090-0241͑2005͒131:3͑1097͒K.S.Li1and S.R.Lo21Director,Victor Li and Associates Ltd.,Hong Kong.2Associate Professor,School of Aerospace,Civil and Mechanical Engineering Univ.of New South Wales at ADFA,Australia.Although several tens of thousands of soil nails are installed an-nually to stabilize slopes in Hong Kong,there have been very few,if any,local detailed laboratory studies,on the pullout resis-tance soil nails under Hong Kong conditions.The authors’study is a significant step toward a better understanding of the factors controlling pullout resistance of soil nails.In Hong Kong,soil nails are commonly installed in existing slopes to stabilize soil and sometimes they are installed in newly formed cut slopes for temporary excavations.The construction method involves forming a drillhole,inserting a deformed bar, and grouting gravity.When some preliminaryfindings of this paper were presented earlier by Chu and Yin͑2004͒in a seminar in Hong Kong,Li made the following remarks,which are believed to be applicable to the present paper.Geotechnical structure behaviors are highly dependent on the method of construction.In the study of a soil nail’s behavior,it is of paramount importance to mimic its method of construction.When a stable drillhole is formed,the radial stress in the vi-cinity of the soil face will be close to zero,which is completely different from the test conditions devised by the authors in which the applied stress was exerted only after installation of the model soil nail.Consequently,the results presented by the authors maynot necessarily be representative of the actual behavior in thefield.In this discussion,the writers would like to elaborate the abovepoints further and share some thoughts on possible mechanismsby which soil nails develop their pullout resistance.In this dis-cussion the term“soil nail”includes the annulus of grout aroundthe deformed bar.The stress state around a drillhole is illustratedin Fig.1.Before a drillhole is formed,the soil at the drillhole location is subjected to the overburden pressurevЈ͓Fig.1͑a͔͒. After a drillhole has been formed,stability of the hole is main-tained by the arching effect,and hence the radial stress at the soilface must be close to zero͓see Fig.1͑b͔͒.After installation,asmall effective radial stress will be reintroduced with gravitygrouting.In other words,both the stress path and the stress statein the vicinity of the nails in thefield are significantly differentfrom that in the laboratory study presented by the authors.If the initial stress acting normal to the soil nail is small,it isinteresting to speculate the possible mechanisms for the develop-ment of pullout resistance.Soil DilatancyDuring a pull-out test,soils in the vicinity of a nail will be subjectto significant shearing.The additional normal stress induced bythe mechanism of constrained dilatancy͑Lo2003͒will cause fric-tion,and hence pullout resistance will develop along the soil nail.Preliminary numerical studies using Mohr-Coulomb elastic-plastic model with a nonassociativeflow rule presented by Lo ͑2002͒clearly showed the significance of dilatancy.Loose soils have a small potential for soil dilation,and one may expect soil nails installed in such soils to have low pull-out resistance.How-ever,field data indicate that soil nails installed in loosefill,for instance,can sometimes develop a significant pullout resistance. Other factors must contribute to this outcome.Interface DilationDrillholes installed using techniques in Hong Kong have over-break.Such drillholes will generate interface dilatancy during shearing in a manner similar to the development of side resistance in a rock socketed pile in weak rock.Physical BondingWhen the drillhole is grouted,cement grout will permeate into the soils.The soil nail and the soils around it are mechanically bonded by the cement grout.Pullout resistance may then develop as a result of adhesion between the soil/soil-nail interface.Alter-natively,the shear plane may move into the virgin soil,leading to a significant,larger“equivalent nail diameter”and thus a signifi-cantly larger pullout resistance.To obtain meaningful results that can lead to the improved soil nail design and construction practices in Hong Kong,it is impor-tant that laboratory tests be devised to model the actualfield conditions and to ascertain which one or combination of the above mechanisms are dominant.For instance,if bonding is im-portant,one may perhaps recommend a higher water-cement ratio and the use of retarder for the cement grout,and a longer grouting period to encourage better permeation of the material into the soils.Pressure grouting may also be used to either improvegrout Fig.1.Stress state around drillholepermeation or to introduce higher normal stress at the soil-nail interface.According to data presented by the authors,the pullout resis-tance of soil nails increases approximately linearly with applied stress.Additional studies,both laboratory and numerical,are needed before making recommendations for the current design practice for the following reasons:1.The issues of soil arching and constrained dilatancy shouldbe addressed as discussed above.In this respect,it is inter-esting to note the design practice of tunnel lining.Tunnel engineers do not increase the thickness of tunnel lining for a deep tunnel in proportion with the thickness of overburden above a tunnel.Soil relaxation that occurs after the formation of a drillhole and before the grouting of the soil nail will also affect the normal stress acting on installed soil nails.The influence of the arching effect on pullout resistance can be studied by exerting the applied stressfirst before installing the model soil nail and varying the thickness of soil cover above the test nail.2.Because the nails are significantly stiffer than the surround-ing soil,the vertical stress in the vicinity of the nail may be significantly higher than the applied stress.3.The authors installed the test soil nails using coring methods.In Hong Kong,soil nails are installed by percussive method, and soil cuttings areflushed out of the drillholes with com-pressed air.This is expected to create a rougher drillhole with higher overbreak and hence more significant interface dila-tion than would be created using coring method.4.In thefield,soil nails are installed in an inclined position toenable cement grout to stay in the drillhole and produce a small hydraulic head to facilitate permeation of cement grout into the soil.In the authors’study,the test nails are installed horizontally and permeation of cement grout into the soil may not be as effective as in the prototype soil nails.5.The use of soil nails in Hong Kong is not restricted to steepslope.For gentler slopes,the determination ofvЈbecomes problematic.The current Hong Kong practice assumes vЈϷ␥h for soil nails installed in a uniform soil above the ground water table͓see Fig.1͑a͔͒.This assumption is true only for horizontal ground.It will be useful if researchers can perform numerical analyses to calibrate current Hong Kong practice and,if necessary,develop an alternative simple cal-culation model͑maybe with the aid of design charts͒for the design of soil nails.ReferencesChu,L.M.,and Yin,J.H.͑2004͒.“Testing study on the interface be-tween soil and soil nail.”Proc.,24th Annual Seminar:Recent Ad-vances in Geotechnical Engineering,Geotechnical Division,the Hong Kong Institution of Engineers,Hong Kong.Lo,S.R.͑2002͒.“Nail pullout:The influence of dilatancy angle.”Lecture Notes for Seminar and Workshop on Geotechnical Modeling,Centre for Research and Professional Development,123–127.Lo,S.-C.R.͑2003͒.“The influence of constrained dilatancy on pullout resistance of geosynthetic strap reinforcement.”Geosynthet.Int., 10͑2͒,47–55.Closure to“Comparison of Interface Shear Strength of Soil Nails Measured by Both Direct Shear Box Tests and Pullout Tests”by Lok-Man Chu and Jian-Hua YinSeptember2005,V ol.131,No.9,pp.1097–1107.DOI:10.1061/͑ASCE͒1090-0241͑2005͒131:9͑1097͒Lok-Man Chu1and Jian-Hua Yin21Dept.of Civil and Structural Engineering,The Hong Kong Polytechnic Univ.,Hung Hom,Kowloon,Hong Kong,China.2Professor and Head of Soil Mechanics Laboratory,The Hong Kong Polytechnic Univ.,Dept.of Civil and Structural Engineering,Hung Hom,Kowloon,Hong Kong,China.E-mail:ceihvin@.hkThe authors would like to express sincere thanks to the two dis-cussers for their insightful discussion on our paper and valuable suggestions for further studies.The discussers make two remarks on our research project:͑1͒the construction process of a soil nail should have been simulated in the laboratory soil pullout tests and͑2͒a vertical pressure was appliedfirst before the installation of the soil nail in the test so that the stress release in drilling of the hole was not considered and the behavior measured in the lab might not be representative of the actual behavior in thefield.The authors agree with the discussers that the simulation of the soil nail installation process is very important.The authors would like to mention that the study presented in the paper was not intended to simulate the installation process but rather to measure the fundamental shear strength of the interface between the ce-ment grout͑soil nail surface͒and the surrounding soil.The per-formance of a soil nail in a slope,including the elements of the construction process,such as drilling a hole and grouting,is con-sidered to be a boundary value problem.A numerical method based on the continuous mechanics shall be used to solve this boundary value problem.This method shall take into account of stress equilibrium,strain-displacement compatibility,proper con-stitutive equations for the soil and the soil-nail interface,and proper boundary conditions.Here,the constitutive equations for the soil and the soil-nail interface are for the fundamental behav-ior,also called elementary behavior.The behavior measured in our laboratory soil nail pullout tests is,in fact,the elementary behavior of the soil-nail interface.The soil nail pullout tests in the paper were very much like direct shear box tests.The results from such pullout tests can be used to obtain the fundamental͑or el-ementary͒soil-nail interface shear strength parameters.The authors are happy to report that a new study has been carried out,using a new soil nail pullout box with comprehensive instrumentation,to simulate the soil nail installation process and to investigate the influence of overburden pressure,the degree of water saturation,and cement slurry pressure grouting.Based on the new test results,a new paper titled“Laboratory Testing Study on the Influence of Overburden Pressure on Soil Nail Pullout Resistance in Compacted Completely Decomposed Granite Fill”by Li-Jun Su,Terence C.F.Chan,Herman Y.K.Shiu,S.L.Chiu, and Jian-Hua Yin has been submitted to this journal for review and possible publication.This new study simulated the perfor-mance of a segment of a soil nail in the actualfield condition.Inthis new paper,the whole construction process and soil nail pull-out,including the soil pressure caused by hole drilling͑stress release͒and changes caused by grouting and soil nail pull out, was closely monitored.The results from this new study indicate that the soil nail pullout resistance is not influenced by the over-burden pressure.This new paper will address some of the discuss-ers’concerns in greater detail.The discussers present the mechanisms that affect the pullout resistance of a soil nail in thefield—that is,dilatancy of soil, dilatancy of the nail-soil interface,and physical bonding.The authors appreciate the insightful analysis of the mechanisms. These mechanisms have been mostly investigated in our new studies using a new soil nail pullout box.The discussers observe that the soil nail pullout resistance from tests presented in the paper increased with the applied ver-tical stress.This is true for elementary tests because the old pull-out box tests were similar to direct shear box tests.The discussers make suggestions for further studies on a few important issues:͑1͒the issues of soil arching and constrained dilatancy,͑2͒the stress concentration on the soil nail as it is stiffer,͑3͒different coring methods such as the percussive method,͑4͒inclination of a soil nail hole with a small gravity head for grouting pressure, and͑5͒the determination of the vertical effective stress on the soil nail surface installed in a slope.The authors appreciate the valuable suggestions.The authors would like to report that we conducted a preliminary study of issues͑2͒and͑3͒.Issues͑1͒and ͑4͒have been investigated in our new study using a new soil nail pullout box.Issue͑5͒has not been addressed by us but has been pointed out by other researchers as well.。