BGP培训试题有答案
华为数通试题
数通试题部门：__________姓名：___________分数：__________总分：100分时间：60分钟基础知识 (共60分)一. 判断题【本大题共 10 小题，每题 1 分，共 10 分。
对的在（）内打“√”，错的在（）内打“×”。
】1.如果从网络一端某台PC 设备无法ping 通远端的另一台PC，则说明二者之间建立TCP连接的相应路由信息仍然没有建立。
（）标准答案：错2.在 OSPF 协议中规定骨干区域不能配置成STUB 区域，虚连接不能穿过 STUB区域。
（）标准答案：对3.OSPF 是直接承载在IP 之上的，协议号是89。
由于 IP 是无连接、不可靠的，因此为了确保 OSPF 协议本身工作的可靠性，在运行 OSPF 的路由器中，对所有发给邻居的协议报文，都需要对方予以确认。
（）标准答案：错4.LDP 协议的主要作用是产生标签、建立LSP。
（）标准答案：对5.在 ISIS 中， System ID 必须是路由器上的IP 地址。
（）标准答案：错6.在 ISIS 中，在一台路由器上配置多个NET 时，必须保证它们的System ID 都相同。
（V ）答案：对7.计算机网卡的 MAC 地址是 IETF 统一给各个厂家分配的，全球唯一。
（ X ）标准答案：错8. 动态路由协议RIP 、 IGRP、 OSPF、 IS-IS 都支持 VLSM 。
（）标准答案：错9.端口聚合就是将多个端口聚合在一起，以实现对出 /入负荷在各成员端口中进行分担。
（）标准答案：对10.DHCP 在 PC 客户端与 DHCP 服务器之间建立、保持一个 TCP 连接，使得客户端 PC 自动获取一个暂时固定的IP 地址。
（）标准答案：错二. 单选题【本大题共 10 小题，每题 2 分，共 20 分。
每题只有一个正确选项，请将正确答案填入（）。
】1. 将 172.16.100.0/24 和 172.16.106.0/24 地址聚合应该选择那种表达方式。
通信网络试题库(附答案)
通信网络试题库（附答案）一、单选题（共53题，每题1分，共53分）1.BGP协议能够避免路由环路是因为（）A、BGP通过在每条路由上标识发送者Router ID来避免环路B、BGP 协议是基于链路状态的路由协议，从算法上避免了路由环路C、BGP 协议通过水平分割和毒性逆转来避免路由环路D、在AS 内部从IBGP 邻居学到的路由不再向另一个IBGP 邻居转发，在路由的AS-Path 属性中记录着所有途经的AS，BGP 路由器将丢弃收到的任何一条带有本地AS 的路由，避免了AS 间的路由环路正确答案：D2.干线光缆工程中，绝大多数为（）光纤；而尾纤都是（）光纤A、松套，紧套B、紧套，紧套C、松套，松套D、紧套，松套正确答案：A3.为什么说共享介质的以太网存在一定的安全隐患（）A、一个冲突域内的所有主机都能够看到其他人发送的数据帧，即使目的MAC 地址并非自己B、所有的用户都在同一网段C、一些拥有较高权限的用户可以查找到网段内的其它用户，获得敏感数据D、共享介质的以太网容易产生冲突问题，导致帧报文丢失正确答案：C4.下列哪个业务不属于TMS系统监视的业务（）A、雷电定位B、调度电话C、电视电话会议D、安全自动装置正确答案：A5.SDH从时钟的工作方式有（）A、锁定工作方式、自由振荡工作方式B、保持工作方式和自由运行工作方式C、自由运行工作方式和自由振荡工作方式D、锁定工作方式、保持工作方式和自由运行工作方式正确答案：D6.TMS系统中，业务风险点分析包含的资源对象，哪项不是（）A、站点B、业务C、光缆D、设备正确答案：B7.以太网交换机一个端口在接收到数据帧时，如果没有在MAC地址表中查找到目的MAC地址，通常如何处理A、把以太网帧复制到所有端口B、把以太网帧单点传送到特定端口C、把以太网帧发送到除本端口以外的所有端口D、丢弃该帧正确答案：C8.PPP协议的协商报文中，什么参数用来检测链路是否发生自环（）A、MRUB、MTUC、MagicNumberD、ACCM正确答案：C9.适时引入1000kV特高压输电，可为直流多馈入的受端电网提供坚强的（）支撑，有利于从根本上解决500kV短路电流超标和输电能力低的问题A、电压和频率B、电压和无功C、电压和有功D、频率和有功正确答案：B10.IP地址中，网络部分全0表示（）A、主机地址B、网络地址C、所有主机D、所有网络11.对于STM-1而言，AU-PTR的传输速率为（）A、8kbpsB、64kbpsC、576kbpsD、4.608Mbps正确答案：C12.基于MPLS标签最多可以标示出几类服务等级不同的数据流（）A、256B、8C、2D、64正确答案：B13.下面关于OSPFLSA格式的描述，不正确的是（）A、LS age字段表示LSA已经生存的时间，单位是秒B、LS type字段标识了LSA的格式和功能C、第一类LSA中Advertising Router字段产生此LSA的路由器的Router IDD、LS sequence number越小则LSA越新正确答案：D14.TMS中配线模块横竖排显示方式，可选择横向或竖向显示，该属性为空时默认（）显示A、反向B、竖向C、横向D、正向正确答案：C15.某AR2200路由器通过OSPF和RIPv2同时学习到了到达同一网络的路由条目，通过OSPF学习到的路由的开销值是4882，通过RIPv2学习到的路由的跳数是4，则该路由器的路由表中将有（）A、RIPv2路由B、OSPF和RIPv2C、OSPF 路由D、两者都不存在16.SCADA中前置机担负着（）等任务A、保存所有历史数据B、对电网实时监控和操作C、数据通信及通信规约解释D、基本SCADA功能和AGC/EDC控制与显示正确答案：C17.一台交换机具有24个100Mbps端口和2个1000Mbps端口，如果所有端口都工作在全双工状态，那么交换机总带宽应为（）A、9.6GbpsB、8.8 GbpsC、4.8GbpsD、6.4 Gbps正确答案：B18.雷电放电时，（）在附近导体上产生静电感应和电磁感应A、直击雷B、传导C、感应雷D、地电位反击正确答案：C19.TMS系统中的告警类型不包括以下哪一项（）A、频闪告警B、根告警C、衍生告警D、原生告警正确答案：D20.RIP路由算法所支持的最大HOP数为（）A、10B、32C、16D、15正确答案：D21.传输网管采集程序出现问题，则下列哪个页面会出现提示（）A、通信网络监视B、业务分类监C、监视信息统计D、工况监视正确答案：D22.自动发电控制（AGC）是按电网调度中心有控制目标将指令发送有关发电厂或机组，通过电厂或机组的自动控制装置，实现对（）的自动控制A、锅炉B、发电机C、电流D、断路器正确答案：B23.监控管理系统的工作方式是（）A、虚电路传送方式B、数据报方式C、令牌传送方式正确答案：C24.检修票中影响最高等级下列选项中不存在的（）A、总部B、地市公司市C、省公司D、国网信通正确答案：D25.不属于衡量电能质量指标的因素是（）A、谐波B、线路损耗C、电压D、频率正确答案：B26.220kV线路高频保护的保护范围为（）A、两侧结合滤波器之间B、两侧阻波器之间C、两侧独立CT之间D、两侧收发讯机之间正确答案：C27.电力调度数据网划分为逻辑隔离的实时子网和非实时子网，分别连接（）A、非控制区、控制区B、生产区、非生产区C、控制区、非控制区D、非生产区、生产区正确答案：C28.在SDH传输中，当本端收至RSBBE码，对端反应为（）A、字节间插B、同步复用C、发对告D、无对告正确答案：D-DSF表示是什么器件（）A、色散位移光纤B、非色散位移光纤C、非零色散位移光纤D、普通光纤正确答案：C30.按照同步光纤网传输标准（SONET），OC-3的数据速率为（）Mb/sA、150.336B、155.52C、622.08D、2488.32正确答案：B31.G.652单模光纤在（）波长上具有零色散的特点A、1625nmB、850nmC、1550nmD、1310nm正确答案：D32.TMS系统中，下列关于光路路由的路由组成正确的是（）A、光缆段纤芯—传输设备光端口—ODF端子—传输设备光端口—光缆段B、ODF端子—传输设备光端口—光缆段纤芯—传输设备光端口—ODF端子C、传输设备光端口—ODF端子—光缆段纤芯—ODF端子—传输设备光端口D、ODF端子—传输设备光端口—光缆段纤芯—传输设备光端口—光缆段纤芯正确答案：C33.缺陷单的基本信息中缺陷类型不包括（）A、光缆缺陷B、待查C、其他D、设备缺陷正确答案：C34.在同等条件下，以下哪种技术使用的功耗最低（）A、ZigBeeB、蓝牙C、WiFiD、以上都不是正确答案：A35.分析判断用户话机摘机和挂机的情况属于模拟用户线接口的（）基本功能A、馈电B、监视C、码型变换D、均衡正确答案：B36.IMS域内的核心功能实体使用___协议作为其呼叫和会话的控制信令A、MGCPB、SIPC、H.323D、SIGTRAN正确答案：B37.Kompella方式中，分配VC标签的协议是（）B、MP-BGPC、RSVPD、手工配置正确答案：B38.ROADM所能控制的波长范围，与DWDM系统所用的波段适配，其工作范围为（）A、1565nm~1625nmB、1530nm~1565nmC、1310 nm~1510 nmD、1527nm~1568nm正确答案：D39.用一个VLAN的24口交换机对网络分段，产生几个冲突域，几个广播域（）A、1，24B、24，1C、1，1D、24，24正确答案：B40.电源设备监控单元的（）是一种将电压或电流转换为可以传送的标准输出信号的器件A、逆变器B、控制器C、传感器D、变送器正确答案：D41.LTE中系统带宽在哪个信道中承载（）A、PBCHB、PDCCHC、PDSCHD、PHICH正确答案：A42.TMS系统中，以下选项中与检修票无关联的是（）A、运行记录B、设备退运单C、检修计划项D、方式单正确答案：B43.下面那个DWDM中的器件对温度最敏感，需要采取温控措施（）A、AWGB、耦合器C、介质膜合分波器D、衍射光栅正确答案：A44.L3MPLS-VPN网络中，P设备必须要维护的信息有（）A、vpn-instanceB、私网LSPC、私网路由D、公网路由正确答案：D45.BGP是在（）之间传播路由信息的动态路由协议A、主机B、子网C、区域(area)D、自治系统(AS)正确答案：D46.整个电力二次系统原则上分为两个安全大区（）A、生产控制大区、管理信息大区B、生产控制大区、生产应用大区C、实时控制大区、信息管理大区D、实时控制大区、生产管理大区正确答案：A47.下列关于K1、K2字节说法正确的是（）A、K1指示倒换请求的原因B、K2指示提出倒换请求的工作系统序号C、K1指示复用段接受侧备用系统倒换开关所桥接到的工作系统序号；传送自动保护倒换信令，使网络具备自愈功能D、K2的b5位为“1”表示1+1 APS，b5位为“0”表示1:n APS正确答案：A48.对于分组交换方式的理解，下列说法中错误的是（）A、每个分组都载有接收方和发送方的地址标识，分组可以不需要任何操作而直接转发，从而提高了效率B、分组交换包括基于帧的分组交换和基于信元的分组交换C、传输的信息被划分为一定长度的分组，以分组为单位进行转发D、分组交换是一种基于存储转发的交换方式正确答案：A49.与TUP消息中CLF、CBK、UBM相对应的ISUP消息是（）A、RLCB、RESC、RELD、UBL正确答案：C50.OSPF协议中划分区域的做法有很多优势，下列说法错误的是（）A、减少了区域内LSDB中链路状态信息的数量，降低了运行OSPF协议对路由器性能的要求B、可以将相同功能性或者地理位置的路由器划分在一个区域内，以便于管理。
IGP-BGP综合实验及答案
1、IGP综合实验BRIDGE（3分）RIP（6分）EIGRP（9分）OSPF(12分) REDISTRIBUTE （2分）IPV6（3分）BGP（16）MULTICAST （3分）IOS（6分）SEC（6分）QOS（6分）一，地址描述:1.1 R1-R5都有一个LO0 IP ADD = 10.10.X.X X=ROUTER NUMBER比如R1 的LO0 =10.10.1.1 ....1.2 R1-R3 E0 地址为：1.1.123.X/27 X=ROUTER NO.1.3 R2-R4 的广域网接口为: 1.1.234.X/29 X=ROUTER NO.1.4 R4-R5 的广域网接口为: 1.1.45.X/24 X=ROUTER NO.二，BRIDGE:(3分)2.1 如图所示, 配置R1-R3的以太地址，2.2 如图所示, 配置R2-R4之间物理接口的IP ADDRESS,2.3 R2-R4之间的FRAME-RELAY是全互连的，要求只用图中所示的PVC,2.4配置R4-R5之间链路为PPP, 并配置相应接口的地址，请消除32位的主机路由。
2.5配置R1-R5的LO02.6配置完成后测试各链路应能正常通讯。
三，RIP （6分）基本配置：（1分）3.1 R1，R3的E0运行RIP VERSION 2，（1分）⏹高级配置: （3分）3.2 使R1,R3仅向E0发送更新，不要向其他接口发送,所有的更新都是明细路由（1分）Interface e0 ; passive-interface default ; no passive-interface e0;3.3 请确保它们之间的VERSION 2的更新是通过BROADCAST发送的。
（1分）ip rip v2-broadcast3.4 如果在R1、R2、R3的以太网段里有一些VER 2的RIP更新包，但UPDATE SOURCE是150.1.1.1，很显然R1是不会收这些包的，在R1上做配置，使它可以收到这些路由。
[BGP协议]BGP面试问题
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[BGP协议]BGP面试问题1. 什么是BGP协议？BGP（Border Gateway Protocol）是一种用于互联网核心路由器之间交换路由信息的协议。
它是TCP/IP协议族中的一员，用于实现互联网的路由选择和自治系统之间的互联互通。
2. BGP协议有哪些特点？- 自治系统之间的路由协议： BGP协议用于自治系统（AS）之间的路由选择，通过交换网络中的路由信息，实现不同自治系统之间的互通。
自治系统之间的路由协议： BGP协议用于自治系统（AS）之间的路由选择，通过交换网络中的路由信息，实现不同自治系统之间的互通。
- 路径矢量协议： BGP协议使用路径矢量方式来选择和传送路由信息，每个AS都维护了一张路由表，通过比较各个路径的属性来选择最优路径。
路径矢量协议： BGP协议使用路径矢量方式来选择和传送路由信息，每个AS都维护了一张路由表，通过比较各个路径的属性来选择最优路径。
- 可靠性和稳定性： BGP协议通过各种机制确保路由信息的可靠性和稳定性，例如，通过周期性的心跳消息来检测邻居路由器的连通性，并利用持续时间计数器来避免路由环路的发生。
可靠性和稳定性：BGP协议通过各种机制确保路由信息的可靠性和稳定性，例如，通过周期性的心跳消息来检测邻居路由器的连通性，并利用持续时间计数器来避免路由环路的发生。
- 适应大规模网络： BGP协议能够适应大规模网络环境，支持成千上万个路由器的连接，并能够处理数量庞大的路由信息。
适应大规模网络： BGP协议能够适应大规模网络环境，支持成千上万个路由器的连接，并能够处理数量庞大的路由信息。
- 基于TCP连接：BGP协议使用TCP协议来建立可靠的连接，确保路由信息的可靠传输和交换。
基于TCP连接： BGP协议使用TCP协议来建立可靠的连接，确保路由信息的可靠传输和交换。
- 灵活的策略控制： BGP协议支持灵活的策略控制，自治系统可以通过配置路由策略来影响路由选择过程。
hcip路由题库
以下是关于HCIP路由题库的题目和答案：1.问题：路由器收到包含如下属性地两条BGP路由，请根据BGP选路规则选出最优路由。
2.选项：3. A.最优路由为路由M，由于其AS Path比路由N短。
4. B.最优路由为路由N，由于其MED比路由M小。
5. C.最优路由为路由N，由于其AS Path比路由M长。
6. D.最优路由为路由M，由于其MED比路由N大。
7.答案：A8.解析：该题匹配BGP路由优选的第四条，则选出答案A BGP路由优选规则优选Preferred-Value属性值最大的路由。
优选Local_Preference属性值最大的路由。
本地始发的BGP路由优于从其他对等体学习到的路由，本地始发的路由优先级：优选手动聚合>自动聚合>network>import>从对等体学到的。
优选MED属性值最小的路由。
优选从EBGP对等体学来的路由（EBGP路由优先级高于IBGP路由）。
优选到Next_Hop的IGP度量值最小的路由。
优选具有最小IP地址的对等体通告的路由。
9.问题：在路由表中存在到达同一个目的网络的多个路由条目，这些路由称之为？10.选项：11. A.次优路由 B.多径路由 C.等价路由 D.默认路由12.答案：C13.解析：在一台路由设备上，如果有多条路由去往同一目的网络并且他们的开销COST一样我们称之为等价路由。
答案A次优路由是指两条路由的COST不相同，答案B和D为干扰项。
14.问题：直连路由默认优先级为多少？15.选项：16. A.直连路由优先级低于动态路由B.直连路由优先级低于静态路由C.直连路由优先级最高 D.直连路由需要管理员手动配置目的网络和下一跳地址17.答案：C18.解析：直连路由默认优先级为0，优先级最高，所以AB是错误的。
故选B。
以上是HCIP路由题库的部分题目和答案，希望对您有所帮助。
bgp面试题目(3篇)
第1篇一、BGP基础概念1. 题目：请简要介绍BGP的作用和在网络中的地位。
解析：BGP（Border Gateway Protocol）是一种用于自治系统（AS）之间的路由协议。
它允许不同自治系统之间的路由器交换路由信息，从而实现网络的互联互通。
BGP在网络中的地位是连接不同自治系统的桥梁，是互联网路由的基础。
2. 题目：BGP有哪些版本？各版本之间的主要区别是什么？解析：BGP目前有四个版本，分别是BGP-1、BGP-2、BGP-3和BGP-4。
其中，BGP-1和BGP-2主要用于内部网关协议（IGP）之间的路由信息交换，而BGP-3和BGP-4是针对自治系统之间的路由协议。
BGP-3和BGP-4的主要区别在于，BGP-4支持IPv6，而BGP-3仅支持IPv4。
3. 题目：BGP的报文类型有哪些？各报文类型的作用是什么？解析：BGP的报文类型包括开放报文（Open）、更新报文（Update）、保活报文（Keepalive）和通知报文（Notification）。
开放报文用于建立BGP会话；更新报文用于交换路由信息；保活报文用于维持BGP会话；通知报文用于报告错误。
二、BGP路由属性1. 题目：请列举BGP的主要路由属性，并说明它们的作用。
解析：BGP的主要路由属性包括：（1）AS路径（AS Path）：记录了路由信息从起始自治系统到达当前自治系统的路径，用于判断路由的可达性和稳定性。
（2）本地优先级（Local Preference）：用于控制同一自治系统内部的路由选择，提高本地路由的优先级。
（3）MED（Multi-Exit Discriminator）：用于表示同一自治系统内部不同出口的相对质量，用于判断出口的选择。
（4）原子聚合（Atomic Aggregate）：用于表示多个子网的路由聚合信息，提高路由信息的交换效率。
（5）团体属性（Community）：用于表示路由的团体属性，如组织内部的路由、公益路由等。
SP-面试题-----BGP
1. Which three items are BGP enhancements to traditional distance vector routing protocols? (Choose three.)reliable updatesuse of triggered updates onlyenhanced securityrich metrics答案:ABD2. What are three characteristics of an AS? (Choose three.)uses IGPs for intradomain routinguses EGPs for interdomain routingis a collection of networks under a common administrative authorityconsists of a group of network domains答案:ABC3. Which three scenarios are common scenarios where BGP is used? (Choose three.)a customer with a connection to multiple service providersservice provider networks acting as transit systems and forwarding external traffic through their networka single-site customer intranet with complex administrative policies between departmentsas the core routing protocol in very large enterprise networks答案:ABD4. What are three recommended BGP use guidelines for multihomed customer networks? (Choose three.)Most multihomed customers should use BGP with their service providers.Most multihomed customers should forward routing information that is received from one provider to the other provider.The multihomed customer must have its own public AS number.Multihomed customers should use a provider-independent, public address space.答案:ACD5. Which three attributes are BGP mandatory well-known attributes? (Choose three.)next-hopweightAS-pathorigin答案:ACD6. Which three possible values are assigned to the BGP origin attribute? (Choose three.)IGPEGPunknowninternal答案:ABC7. In which two ways can the BGP next-hop attribute be modified? (Choose two.)If the next-hop attribute is in the same IP subnet as the receiving router, the attribute is unchanged; otherwise, it is set to the IP address of the sending router.The next-hop attribute is always set to the IP address of the sending router.The next-hop attribute is modified only when BGP packets exit an AS.The BGP next-hop attribute is modified only when BGP packets traverse point-to-point links.答案:AB8. Which three statements regarding the BGP AS-path attribute are true? (Choose three.)The local AS number is prepended to the AS path each time that the route crosses an AS boundary.The AS that originally injected the route into BGP is always found at the rightmost end of the AS path.The AS-path attribute can be used to avoid routing loops.BGP routes with an empty AS path were injected into BGP from outside the local AS.答案:ABC9. What is indicated by a state of "Idle" in the output of the show ip bgp summary command?The router is currently not attempting to establish a connection with a neighbor.The connection to the configured neighbor has timed out.The connection to a BGP neighbor has been established, and no errors have been received on the connection.The connection to a BGP neighbor has been established, and no packets have been sent.答案:A10. What are two ways in which local networks are advertised into the BGP routing protocol process? (Choose two.)automatically, after a BGP neighbor session is establishedmanually, with the network commandthrough redistribution into the BGP processby advertising them to the BGP table on the router after Cisco Discovery Protocol discovers connected networks答案:BC11. What are two situations when is it appropriate to disable automatic summarization in BGP? (Choose two.)when BGP neighbors are not configured to advertise aggregate routes to upstream providerswhen the classless variant of the network command is usedwhen you are using a classless IGP in the ASwhen the effects of automatic summarization of IGP-to-BGP redistribution are not desired答案:BD12. Which three BGP attributes are displayed for each route in the BGP table when you are using the show ip bgp command? (Choose three.)weightcommunitiesoriginAS-path答案:ACD13. Which two parameters must you configure with the neighbor command to establish a BGP session with an external neighbor? (Choose two.)neighbor IP addresssubnet mask of the IP networkremote AS numberlocal AS number答案:AC14. Which two of the following statements about configuring BGP timers are accurate? (Choose two.)Changing the BGP default holdtime and keepalive timers is usually not recommended.The neighbor timers command sets the timers for a specific BGP peer or peer group.The timers bgp command sets the timers for a specific BGP peer or peer group.Holdtime indicates the frequency (in seconds) with which the Cisco IOS software sends messages to its peer.答案:AB15. Which two of the following are characteristics of the string component of the neighbor {ip-address | peer-group-name} password string command? (Choose two.)can contain any alphanumeric characters, including spacescase-sensitive password of up to 100 charactersfirst character can be a numbercannot specify a password in the format "number-space-anything"答案:AD16. Which two of the following statements about the classless behavior of BGP are correct? (Choose two.)When an exact match is not found in the IP routing table a matching prefix is automatically configured on the router.In the network ip-prefix-address mask subnet-mask command, the prefix does not have to match an entry in the IP routing tableTo advertise classless networks into BGP (a subnet or a supernet), you can use the network command with the mask keyword and the subnet mask specified.If the keyword mask and the subnet mask are omitted, the network is assumed to have its natural mask according to the network class.答案:CD17. What are two benefits of using route aggregation in BGP? (Choose two.)It ensures that even if aggregate networks are down, the aggregate is advertised, which eliminates black holes.It reduces the amount of memory that is used in the router to store the BGP table.It reduces route flapping and its effects on router CPU resources.BGP attribute granularity is maintained, which ensures optimal path selection.答案:BC18. Which two of the following are characteristics of the BGP Conditional Route Injection feature? (Choose two.)allows you to originate a prefix into a BGP routing table without the corresponding matchenabled with the bgp inject-map exist-map commandallows conditional injecting or replacing more specific prefixes with less specific prefixesallows origination of a prefix into a BGP routing table only with the corresponding match答案:AB19. Which two of the following are characteristics of the BGP Support for TTL Security Check feature? (Choose two.)should be configured on only one participating routerprevents BGP sessions from expiring even if keepalive packets are not received before the session timer expiresprotects the EBGP peering session by comparing the value in the TTL field of received IP packets against a hop count that is configured locally for each EBGP peering session.supports both directly connected peering sessions and multihop EBGP peering sessions答案:CD20. Which two of the following are functions of the show ip bgp summary command? (Choose two.)displays BGP memory usedisplays BGP neighbors and status of communication with themlocates problems in BGP sessions that are up and establisheddisplays the BGP routing table答案:AB21. Which two of the following statements about the show ip bgp command that is used to monitor the BGP routing table are accurate? (Choose two.)The show ip bgp command shows an abbreviated list of information about each route, displaying one line per prefix.The show ip bgp command shows a full list of information about each route, displaying one line per prefix.All of the BGP attributes that are associated with the route are displayed on the line.If the BGP table contains more than one route to the same network, the routes are displayed on successive lines of the command output.答案:BD22. What are the three most common session startup issues that you can experience when configuring basic BGP? (Choose three.)BGP neighbors do not become active.BGP routing loops cause black holes.A BGP neighbor is active, but the BGP session is not established.The BGP neighbor state oscillates between Idle and Active.答案:ACD23. What will result from attempting to open a BGP connection with a neighbor that has not been properly configured for BGP?The BGP session will remain in the Idle state.The neighbor session will be established, and the session startup parameters will be negotiated over the TCP session.The BGP session will be immediately terminated with a TCP RST packet.The BGP session will become "stuck in Active state".答案:C1. What are the two key functions of a transit AS? (Choose two.)to filter out routes that do not belong to customers of the service providerto provide Internet connectivity to customers of the service providerto propagate routes between remote autonomous systemsto route packets between remote networks答案:CD2. Which two statements are true regarding the AS-path attribute as it relates to IBGP? (Choose two.)Each router in the AS appends its AS number to the AS path on outgoing BGP updates.The AS path inside an AS will be empty for routes originating inside a neighboring AS.The AS-path attribute is not used to detect routing loops inside an AS.The AS-path attribute is not modified within the AS.答案:CD3. How is the BGP next-hop attribute processed over an IBGP connection?The next-hop address is set to the address of the receiving router.The next-hop address is not modified over the IBGP session.The next-hop address is set to the IP address of the nearest EBGP peer.The next-hop attribute is set to the IP address of the nearest EBGP peer; if no external AS connection has been configured, the next hop is set to the default gateway that is configured on the router.答案:B4. Which two statements are true of the full-mesh requirement in IBGP? (Choose two.)The IBGP mesh must be a logical full mesh.A physical full mesh must be maintained within the IBGP AS.Because of BGP split horizon, no router can relay IBGP information within the AS.All routers within the AS must be directly connected to ensure correct delivery of BGP routing information.答案:AC5. Which three statements regarding the next-hop-self configuration in BGP are true? (Choose three.)Changing the next-hop attribute might cause suboptimal routing.The configuration changes how the next-hop attribute is processed at edge routers.The configuration announces the local IP address as the BGP next hop in outgoing updates that are sent to the specified neighbor.The configuration removes the requirement for the IGP to carry reachability information for intra-AS destinations.答案:ABC6. Why must all EBGP peers be reachable by all BGP-speaking routers within the transit AS?BGP-speaking routers in a transit AS use the next-hop-self attribute to find their EBGP neighbors.EBGP peers in a transit AS use the length of the AS path to decide which BGP route to install in the routing table.When BGP routes are used in the routing table, the router checks how it would have reached the next-hop address, and it installs the BGP route with the same forwarding indication as for the route that is used to reach the next-hop IP address.All BGP peers do not need to speak to each other within a transit AS.答案:C7. What are three differences between IBGP and EBGP sessions? (Choose three.)Route selection rules slightly prefer IBGP routes.Routes that are learned from IBGP peers are not advertised to other IBGP peers.EBGP peers are directly connected, and IBGP peers are usually distant.By default, no BGP attributes are changed in IBGP updates.答案:BCD8. What are two reasons why you must run IBGP on all routers within a transit backbone? (Choose two.)so routers can properly forward packets toward all external destinationsto ensure that a full mesh exists among all routers in the ASto allow routers to properly process the BGP next-hop attributebecause IGPs cannot scale large enough to handle redistribution of BGP routes答案:AD9. If a transit backbone has IBGP running on all routers, what are two reasons why it is still necessary to use an IGP? (Choose two.)to provide routing information that is needed to establish the IBGP sessionsto resolve next-hop references that are used in recursive routingso that BGP routes can be properly transported through the ASto provide user workstations with a network default gateway答案:AB10. What are two reasons why the AD is an important consideration for BGP network design? (Choose two.)The AD affects how routes are selected for use in the IP routing table.The AD controls how routing information is entered into the BGP table.If a route is advertised by both an IGP and through EBGP, the router will prefer the external route.The AD is not a large concern to BGP design, because the router will always choose the route that is advertised by the protocol that is best suited to reach the destination.答案:AC11. With regard to recursive route lookups, what are two ways in which CEF is different from traditional Cisco IOS switching mechanisms such as route caching? (choose two)Traditional Cisco IOS switching mechanisms wait for the first packet to arrive before recursive lookup can take place.New entries in the IP routing table will trigger a recursive lookup in traditional Cisco IOS switching mechanisms.CEF prebuilds a complete IP forwarding table based on the IP routing table.CEF will build a FIB directly from the entries in the BGP table before any BGP packets arrive at the router.答案:AC12. When you are configuring the BGP neighbor session, what differentiates an EBGP neighbor from an IBGP neighbor?The keyword internal is at the end of the neighbor command.IBGP neighbors will have the same AS number specified.A description for the internal or external neighbor must be attached with the neighbor description command.Directly connected neighbors will automatically form an EBGP session.答案:B13. Which two steps are required when you use a loopback interface for IBGP peering sessions? (Choose two.)Ensure that the loopback interfaces are reachable through an IGP.Ensure that the two neighbors are directly attached.Verify that each router has multiple physically redundant paths.Configure a neighbor statement with the update-source command.答案:AD14. Why is it important to disable BGP synchronization in a transit backbone?IGPs can support the routing requirements of full Internet routing, and hence synchronization is no longer necessary.Because BGP redistribution into an IGP is no longer practical, enabling the synchronization feature is no longer applicable.Synchronization requires all BGP transit routes to be explicitly mapped to an exit point, creating too much administrative overhead.Synchronization requires BGP attributes to be properly mapped to IGP metrics for BGP routing across the transit backbone to function properly, creating too much overhead.答案:B15. What are two negative ramifications of the full-mesh requirement that is imposed by IBGP? (Choose two.)administrative difficulty of applying an AS-wide routing policyrequirement to use next-hop-self for proper routing to external destinationslarge number of TCP sessionsunnecessary duplication of routing traffic答案:CD16. What are two scalability tools that you can use to overcome the full-mesh requirement for IBGP sessions? (Choose two.)confederationsfloating static routesroute reflectorsdisabling BGP synchronization答案:AC17. Which three of the following are the most common BGP implementation problems? (Choose three.)IBGP sessions do not reach the Established state.TCP window size is set incorrectly.Routing information that is received via IBGP is never selected.The best BGP route is never installed in the routing table.答案:ACD18. What are three common situations that prevent IBGP sessions from starting? (Choose three.)The IBGP session has been configured to peer to a loopback interface, but update-source has not been configured on the neighbor.An access-list filter is blocking access to TCP port 179.The IBGP session has been configured to peer to a loopback interface, but the loopback interface has not been administratively enabled with the no shutdown command.The IBGP session has been configured to peer to a loopback interface, but the interfaces are not reachable via the IGP.答案:ABD19. Which common issue could prevent IBGP best routes from being inserted into the IP routing table?failure to disable BGP synchronizationfailure to disable BGP split horizonlack of a route to the BGP next hop for the IGPfailure to inject a default route into the IGP答案:A20. Which two of the following statements about solving IBGP synchronization problems are accurate? (Choose two.)Throughput suffers when BGP is synchronized.IGPs cannot scale to contain all Internet routes.BGP synchronization consumes too much of the router memory resources.To allow routers to forward packets to prefixes that their IGP is not aware of, but areWhen synchronized, data packets must follow a fixed path through the AS even if a better path becomes available. 答案:BD21. What are two reasons why a customer would want to connect to two ISPs? (Choose two.)to expand capacity for Internet trafficto better protect confidential information as it travels through the Internetto provide redundancy to mission-critical services that are offered over the Internetto efficiently route Internet traffic to two different divisions within the company答案:AC22. What are the two technical requirements for multihomed customers? (Choose two.)The ISPs must assign a range of IP network numbers to the customer.The customer network must exchange BGP information with each ISP network.In most cases, the customer must have its own public AS number.The customer network must not use AS-path filters.答案:BC23. Which statement about the need to influence BGP route selection in a service provider environment is accurate?If both ISP connections terminate in one single customer router, only some routes that are received from the primary ISP can be assigned a BGP weight.In most cases, it is more optimal to reach other customers connected to the backup ISP via the backup link, compared with reaching them via the primary link.All routes that are received from the primary ISP over the primary link are assigned a local preference value, which is lower than the default value of 100.When one ISP connection terminates in one single customer router, all routes that are received from that ISP are assigned a BGP weight.答案:B24. Which two potential multihomed network issues can be prevented with IP prefix filters? (Choose two.)the propagation of private AS numbersthe propagation of private addresses that are used in the networkthe propagation of unreachable next-hop addressesthe propagation of more specific prefixes from an address range答案:BD25. Which three goals represent appropriate reasons to apply AS-path filters? (Choose three.)to ensure that only locally originated routes are announcedto limit routes that are advertised from IBGP neighborsto select a subset of all routes based on their originating ASto limit neighbor route updates to specific AS-originated routes答案:ACD1. What is the difference between the regular expressions "_100_" and "_100$"?The first expression refers to routes that have the substring "100" in their AS paths; the second expression refers only to routes that are directly connected to AS 100.The first expression refers to routes that have the substring "100" in their AS paths; the second expression refers only to routes that originated in AS 100.The first expression refers to routes that go through AS 100; the second expression refers to routes that originated in AS 100.The first expression refers to routes that are directly connected to AS 100; the second expression refers to routes that originated in AS 100.答案:C2. Which three steps are required to apply a new inbound routing policy to a neighbor? (Choose three.)Define an AS-path access-list.Attach the AS-path filter to inbound or outbound updates for a specific BGP neighbor.Send incoming and outgoing AS-path filters to the BGP neighbor.Force the updates to go through the new filter.答案:ABD3. What are two reasons that a multihomed customer needs prefix-lists? (Choose two.)to ensure that only valid IP prefixes are announced to the ISPsto set a limit on the number of prefixes that can be accepted from the ISPsto prevent the customer from receiving its own IP prefixes from the ISPto verify that the customer has received full Internet route tables答案:AC4. Which three of the following choices are advantages of prefix-lists over access-lists? (Choose three.)significant performance improvement on long filterssupport for incremental updatesability to consist of any number of lines, each of which indicates a test and a resultflexibility答案:ABD5. When you define prefix-lists, what are two reasons to use sequence numbers? (Choose two.)to reference the associated access-list for the prefix-list entryto provide a means of linking an AS-path filter-list to the prefix-listto provide an execution order for prefix-list entriesto provide a means of inserting or deleting list entries答案:CD6. Which of the following statements is accurate about the ge and le parameters in the ip prefix-list global configuration command required to configure prefix-list filters?No match is assumed when neither ge nor le is specified.The range is assumed to be from ge-value to 142 only if the ge attribute is specified.The range is assumed to be from len to 32 only if the le attribute is specified.An exact match is assumed when neither ge nor le is specified.答案:D7. Which of the following statements about implementing prefix-lists in a BGP network is accurate?You can optionally apply filter-lists and prefix-lists on either incoming or outgoing neighbors in any combination.You can optionally apply filter-lists and prefix-lists only on outgoing neighbors in any combination.Either the incoming prefix-list or the incoming filter-list must permit the routes that are received from a neighbor before they are accepted into the BGP table.Outgoing routes must pass the outgoing prefix-list before being transmitted to the neighbor.答案:A8. How can you apply the same prefix-list to multiple BGP neighbors on a router?by configuring a neighbor prefix-list statement for each BGP peerby configuring a neighbor distribute-list statement for each neighborby using the BGP peer-group option with the neighbor statementby configuring the prefix-list as a global filter under the BGP routing process答案:C9. How can you use the show ip prefix-list command to display the prefix-list entry that matches a specific prefix and length?not a feature of the show ip prefix-list commandby specifying the detail keywordwith the longer keyword to display all matches except those with more specific entriesby specifying the first-match keyword答案:D10. Which of the following best describes the capabilities of the proprietary ORF type that is supported on Cisco routers?standard BGP communities filteringextended BGP communities filteringAS-path filteringprefix-list filtering答案:D11. What are two key benefits to using outbound route filtering? (Choose two.)conserves CPU cyclesimproves securityreduces bandwidth that is used by unnecessary routing updatesincreases neighbor availability答案:AC12. Which two of the following statements about BGP prefix-based outbound route filtering are accurate? (Choose two.)uses BGP ORF send and receive capabilities to minimize the number of BGP updates that are sent between BGP peers can limit the number of unwanted routing updatesincreases the amount of resources required to receive and discard routes that would otherwise be filtered outcan be used to increase the amount of processing on a router that is not accepting full routes from a service provider network 答案:AB13. What are two methods of determining that a router has ORF capabilities exchange configured? (Choose two.)show running-config | begin bgp commandshow ip bgp negotiate commandshow ip bgp neighbors commandshow ip prefix-list command答案:AC14. What are two prerequisites before you can configure ORF prefix-list functionality? (Choose two.)A route refresh must be sent using the clear ip bgp command.A BGP peering session between the ORF routers must be up and running.ORF capabilities must be enabled on both routers.You must configure a prefix-list filter on the receiving router.答案:BC15. Which of the following statements about the function of a route-map is accurate?A route-map cannot be used to modify attributes of the permitted routes.A route-map is a filter that uses a series of match conditions, and that which is denied by the route-map is dropped.A route-map is less complex than the access-list.Each route-map statement starts with a series of match clauses.答案:B16. Which three of the following statements are accurate about the BGP Route-Map Policy List Support feature? (Choose three.)The BGP Route-Map Policy List Support feature allows a network operator to group route-map match clauses into named lists called policy-lists.The AND and OR semantics in the route-map function differently for policy-lists than for match and set clauses.To create a BGP policy-list, use the ip policy-list command in policy-map configuration mode.To configure a route-map to evaluate and process a BGP policy-list in a route-map, use the match policy-list command in route-map configuration mode.答案:ACD17. Which two of the following are functions of the BGP Route-Map Continue feature? (Choose two.)provides the ability to pause if a sequence number is not specifiedprovides the capability to execute additional entries in a route-map after an entry is executed with successful match and setclausesallows modularization of network policy configuration so that repeated policy definitions can be expanded within the same route-mapallows configuration and organization of more modular policy definitions to reduce the number of policy configurations that are repeated within the same route-map答案:BD18. Which three BGP attributes can you set using route-maps? (Choose three.)MEDadministrative distanceweight metricnext-hop答案:ACD19. What are two reasons for using route-map sequence numbers? (Choose two.)to allow insertion or deletion of route-map entriesto order the execution sequence of route-map match clausesto provide an ordered execution sequence for the route-mapto map between prefix-list statements and route-map match clauses答案:AC20. Which two steps must you complete to use inbound soft configuration functionality? (Choose two.)Clear the BGP session inbound on the local router.Clear the BGP session outbound on the remote router.。
07 排错练习-4(bgp)
BGP故障排错：
一个CCNP网络工程师在配置下面BGP互连网络时，出现了一些错误，导致不能正常通信。
请你对此进行故障排错，确保每个AS内的局域网（lo1表示的网络）可以相互通信，并且AS300访问AS200内的170.1.0.0/16的网络优选走R5。
（时间60分钟，满分100分，共10处错误，排除一个得10分。
）
说明：
1、各路由器loopback 1 的接口，表示各个局域网，BGP只要求学习局域网路由。
2、各路由器loopback 0 的地址分别为1.1.1.1 ---- 6.6.6.6，要求用环回接口建立内部和外部BGP邻居关系。
思路提示：
先检查IGP路由，确保各路由器环回口可达（OSPF、EIGRP问题）；接下来检查BGP 的邻居关系问题；最后检查BGP路由通告和路径控制问题。
调试命令：
R#sh ip route ospf
R#sh ip ospf neighbor
R#sh ip route eigrp
R#sh ip eigrp neighbors
R#sh run | b route
R#sh ip bgp summary
R#sh ip bgp。
(完整版)路由考试题(含答案)
路由协议考试题姓名：_____________ 成绩：____________一、单选题1、在NE16路由器所实现的RIP V1和RIP V2中，下列说法哪些是正确的？D 。
A、RIP V1报文支持子网掩码B、RIP V2报文支持子网掩码，但需要特殊配置C、RIP V1只支持报文的简单口令认证，而RIP V2支持MD5认证D、RIP V2缺省打开路由聚合功能2、在以下OSPF和IS-IS的比较中，那一项不属于两者的相同点。
A、两者都是动态路由协议B、两者都属于链路状态路由协议C、两者都支持VLSMD、两者都使用IP协议报文来承载路由信息3、在BGP协议中，路由信息是承载在 C 报文里面给邻居发送过去的。
A、NotificationB、OpenC、UpdateD、KeepliveE、Routing4、一台运行OSPF的路由器，它的一个接口属于区域0，另一个接口属于区域9，并且引入了5条静态路由，则该路由器至少会生成几条LSA？ D 。
A、5B、7C、8D、9E、105、下列那些OSPF报文中会出现完整的LSA信息？ D 。
A、HELLO报文（Hello Packet）；B、DD报文（Database Description Packet）；C、LSR报文（Link State Request Packet）；D、LSU报文（Link State Update Packet）；E、LSAck报文（Link State Acknowledgmen Packet）；6、LSAck报文是对下列那些OSPF报文的确认？ D 。
A、HELLO报文（Hello Packet）；B、DD报文（Database Description Packet）；C、LSR报文（Link State Request Packet）；D、LSU报文（Link State Update Packet）；E、LSAck报文（Link State Acknowledgmen Packet）；7、OSPF选举DR、BDR时会使用如下的那些报文？ A 。
专业题库-Juniper设备单选(144题)
答案：A
C-J-DX-23
路由-RIP
中
RIPv2 的更新被送到一个目的地址 _____. A. 224.0.0.5 B. 224.0.0.6 C. 224.0.0.9 D. 224.0.0.10
ห้องสมุดไป่ตู้
答案：C
C-J-DX-24
路由-RIP
高
RIP 的更新将被送走，使用 _______. A. TCP port 250 B. TCP port 520 C. UDP port 250 D. UDP port 520
) 答案：D
C-J-DX-19
路由-其他
低
从Static, RIP, OSPF, 和IS-IS几种协议学到了151.10.0.0/16路由，路由器将优选哪种协议？ A. Static B. RIP C. OSPF D. IS-IS
答案：A
C-J-DX-20
路由-其他
低
以下不会在路由表里出现的是。（ A、下一跳地址 B、网络地址 C、度量值 D、MAC地址
MPLS
中
推入一层MPLS标签的报文比原来IP报文多几个字节？ A:4 B:8 C:16 D:32
答案:A
C-J-DX-28
MPLS
中
在MPLS 的PHP（Penultimate Hop Popping)倒数第二跳弹出技术中，PHP动作通常发生在何种情况: A:MPLS流量从P->PE,在P上面执行外层有标签弹出 B:MPLS流量从P2->P1->PE,在P2上面执行外层标签弹出 C:MPLS流量从P->PE,在P上面执行所有标签弹出 D:以上对不是
答案：A
C-J-DX-3
QoS
高
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BGP协议培训考试题
一、 单选题：（4*5=20）
1、以下说法错误的是（C ）
A. IGP是内部网关协议，功能是完成数据包在AS 内部的路由选择。
B. EGP是外部网关协议，功能是完成数据包在AS 间的路由选择。
C. 自治系统AS相当于OSPF中的AREA，是拥有相同选路策略的由单一管理机构来管理的
路由器的集合。
D. BGP协议是一种外部网关协议。
2、关于BGP协议消息类型的描述，错误的是（D ）
A. Open——建立BGP 连接
B. Keepalive——检测和维护BGP连接
C. Update——发送BGP 路由更新以及撤销路由
D. connect——保持BGP的连接状态
E. Route-Refresh——通知对等体自己支持路由刷新能力
3、关于命令的说法，错误的是（ C）
A. 这是配置BGP协议中的一个命令
B. 这是BGP中的更新源命令
C. 此命令的作用是改变改BGP路由的下一跳地址
4、关于下图的说法中，错误的是（B ）
A. 图中显示的是BGP的邻居信息
B. 64523是本设备所属的AS号
C. 2d07h34m是指BGP邻居建立的时长
5、BGP 协议是能够有效的防止路由环路的，究其原因为（A ）
A. 在路由的AS-Path 属性中记录着所有途经的AS，BGP 路由器将丢弃收到的任何一条带
有本地AS 的路
由，避免了AS 间的路由环路
B. BGP 协议是基于链路状态的路由协议，从算法上避免了路由环路
C. BGP 协议通过水平分割和毒性逆转来避免路由环路
D. 在AS 内部从IBGP 邻居学到的路由不再向其他BGP邻居转发
二、 多选题（5*5=25）
1、以下说法正确的是：（ABCD ）
A. BGP是一种外部网关协议（EGP），与OSPF、RIP等内部网关协议（IGP）不同，其着眼
点不在于发现和计算路由，而在于控制路由的传播和选择最佳路由。
B. BGP使用TCP作为其传输层协议（监听端口号为179），提高了协议的可靠性。
C. 路由更新时，BGP只发送更新的路由，大大减少了BGP传播路由所占用的带宽，适用于
在Internet上传播大量的路由信息。
D. BGP从设计上避免了环路的发生。
2、以下说法正确的是：（ BCD ）
A. IBGP(Internal BGP)：指单个AS内部的路由器之间的BGP连接,属于IGP协议
B. EBGP(External BGP)：指AS之间的BGP连接，属于EGP协议
C. 对于EBGP，邻居处于不同的自治域，邻居之间一般直接连接，否则需要配置静态路由
并设置消息的TTL值(缺省为1)，即配置EBGP多跳ebgp_multihop
D. 对于IBGP，邻居处于同一个AS 内部，邻居之间不必直连，BGP的信息可以通过非BGP
的拓扑进行传递
3、BGP发布路由时采用如下策略，正确的是（ABCDEF ）
A. 存在多条有效路由时，BGP Speaker只将最优路由发布给对等体。
B. BGP Speaker只把自己使用的路由发布给对等体。
C. BGP Speaker从EBGP获得的路由会向它所有BGP对等体发布（包括EBGP对等体和IBGP
对等体）。
D. BGP Speaker从IBGP获得的路由不向它的IBGP对等体发布。
E. BGP Speaker从IBGP获得的路由发布给它的EBGP对等体（在不使能BGP与IGP同步特
性的情况下）。
F. 连接一旦建立，BGP Speaker将把自己所有BGP路由发布给新对等体。
4、关于BGP协议的邻居状态描述，正确的是：（ACD）
A. 空闲（Idle）：这是BGP刚启动后的第一个状态
B. 连接（Connect）：BGP重新启动TCP连接时的状态
C. OPEN发送（Open sent）：TCP连接成功后，BGP开始发送OPEN消息,并等待对方的
OPEN消息时的状态
D. OPEN证实（Open confirm）：接收到邻居OPEN消息后，BGP等待Keepalive消息或
者Notification消息时的状态
5、对于BGP协议的路由属性，正确的是：（ABC）
A. ORIGIN属性标示路径信息的来源
B. AS_PATH属性由一系列AS路径组成，防止路由循环，并用于路由的过滤和选择
C. NEXT_HOP?属性定义了到达目的地下一跳的设备IP地址
D. MED属性帮助其外部的邻居路由器选择一个较好的入口路径，一条路由的MED值越
大，其优先级越高
三、 判断题（3*5=15）
1. 烽火的MPLS L3VPN需要BGP协议传递私网路由，分发外层标签。X
2. 如果BGP邻居状态为FULL，说明BGP邻居已经建立成功X
3. BGP路由黑洞的问题可以通过在AS域内建立全BGP邻居来解决V
4. RT值就是BGP协议中的一个团体扩展属性。V
5. 大规模的网络中，BGP路由表十分庞大，为了解决这个问题，必须组建fullmesh网络。
X
四、 简答题：（20*2=40）
1、 如果IBGP邻居一直无法建立，可能的原因为：
1) 光缆中断
2) 单盘损坏
3) TCP连接中断
4) 公网路由出现问题
5) RCU单盘故障
6) 互联接口IP不正确
7) BGP实例配置中，缺少更新源命令
8) 地址族（address family）配置错误
答出5个满分，少一个口4分
2、 BGP选择路由的策略有什么
1) BGP优选Preference值较小的本地始发路由。这个优先级是IP路由表（管理路由
表）中各个协议路由（包括直连路由和静态路由）的Preference值，可以通过命
令display ip routing-table查看。Preference值越小，优先级越高；
2) 如果不同协议路由的Preference值相同，系统会按照如下的顺序优选一种协议路
由：OSPF、IS-IS Level-1、IS-IS Level-2、EBGP（包含BGP Aggregate）、Static、
RIP、OSPF_ASE、IBGP；
3) 优选本地优先级（Local_Pref）最高的路由；
4) 优选聚合路由（聚合路由优先级高于非聚合路由）；
5) 优选AS路径（AS_Path）最短的路由；
6) 比较Origin属性，依次选择Origin类型为IGP、EGP、Incomplete的路由；
7) 优选MED值最低的路由；
8) 优选从EBGP学来的路由（EBGP路由优先级高于IBGP路由）；
9) 优选AS内部IGP的Metric最低的路由；
10) 优选Router ID最小的路由器发布的路由。
一个条目2分，共20分。