© 2003, Cisco Systems, Inc. All rights reserved. 1 配置 IS-IS 中间系统

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-2 本节大纲 : 一，配置 ISIS 中间系统 二，指定 ISIS 路由器类型；指定 ISIS 路由器接口 类型； IS-IS Metric ； 三， ISIS 路由汇总 四，在 NBMA 中配置 ISIS ：

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-3 一, 配置 ISIS 中间系统 Step 1: 定义区域, 决定哪些接口要使用 ISIS. Step 2: 启动 ISIS 路由协议. Clns routing Router isis Step 3: 在路由器上配置好 NET. Net Step 4: 在路由器合适接口上启动集成 ISIS. Interface ethernet 0 Ip address Ip router isis

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-4 Step 1: Define Area and Addressing Area determined by NET prefix( 区域决定前缀 ) –Assign to support two-level hierarchy. Addressing: –IP: Plan to support summarization. –CLNS: Prefix to denote area. System ID must be unique.

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-5 Step 2: Enable IS-IS on the Router router isis [tag] router(config)# Enable the IS-IS routing protocol – tag—name for a process When routing of CLNS packets is also needed, use the clns routing command

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-6 Step 3: Configure the NET net network-entity-title Router(config-router)# Configure an IS-IS NET address for the routing process

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-7 Step 4: Enable Integrated IS-IS ip router isis [tag] clns router isis [tag] ip router isis [tag] clns router isis [tag] router(config-if)# Includes an interface in an IS-IS routing process

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-8 IS-IS Configuration Steps: Simple Integrated IS-IS Example Clns routing router isis net ! interface ethernet 0 ip address ip router isis ! interface serial 0 ip address ip router isis The configured router acts as IP-only L1/L2 router.

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-9 二，优化 ISIS 路由－将 R5 改成 L2-only Change router type on R1, R4, and R5 Change interface levels on R2

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-10 二，优化 ISIS 路由－将 R5 改成 L2-only 没有必要要求 R2 向 R1 ， R4 发送 L2 hello 包，将 R1 ， R4 设为 L1 路由器，由于是串行链路，要求 将 metric 值设为 35 （ 10/0 － 63 ）。 R2 通过以太网和一台 L2 路由器互连，请将其 ISIS 链路类型设为 L2-only 。

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-11 二，指定 ISIS 路由器类型 is-type {level-1 | level-1-2 | level-2-only} Router(config-router)# Configure the IS-IS level globally on a router; the default is L1/L2. L1 ：路由器只学习本区域内的路由, 也称为站点路由器，因 为它们使站点 ES 之间互联, 并将其连接到网络的其余部分。 L-1-2 ：这个路由器同时运行两套路由算法，既可做为站点 路由器也可做为区域路由器。 L2 ONLY ：路由器只负责区域间的路由转发，这个路由器 是主干的一部分，不与同一区域中的 1 层路由器交互路由信 息。

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-12 二，指定 ISIS 路由器接口类型 isis circuit-type {level-1 | level-1-2 | level-2-only} Router(config-if)# Configure the type of adjacency on an interface; the default is L1/L2. \\ 在某些 L1 、 L2 层路由器上，要指定某些接口的类型；因此： Level-1:L1 路由器； Level-2:L2 路由器；如果邻居也配置为 LEVEL-1 且至少具有一个相同 的区域地址，则同时建立 1 层和 2 层邻居关系；如果不存在相同的区域 ，则建立 2 层邻居关系，这是缺省配置。 Level-2-only: 如果其他的路由器是 2 层或者 1/2 层且接口配置为 1/2 层或 2 层，建立 2 层连接。此接口如终不会建立 1 层邻居关系。

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-13 二， Change IS-IS Metric isis metric metric {level-1 | level-2} Router(config-if)# Configure the metric for an interface; the default is 10. Metric value is from 如： Interface s0 isis metric 5 level-2

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-14 Change IS-IS Metric c2511(config)#int s0 c2511(config-if)#isis metric 5 level-2 c2511(config-if)#isis metric ? Default metric c2511(config-if)#isis metric 60 ? Delay metric level-1 Apply metric to level-1 links level-2 Apply metric to level-2 links c2511(config-if)#isis metric 60 level-2

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-15 三， IP Summarization summary-address prefix mask [level-1 | level-2 | level-1-2] Router(config-router)# P3R1(config-router)# summary-address level-2 Creates summary （缩小路由表，减少 LSP 流量并防 止路由波动，降低内存需求，降低 CPU 使用率） Default is level 2 Example: Summarizes /23 into level 2

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-16 在 NBMA 中使用点到点接口运行 ISIS ： interface s0 encapsulation frame-relay interface s0.1 point-to-point ip address ip router isis frame-relay interface-dlci 100 interface s0.2 point-to-point ip address ip router isis frame-relay interface-dlci 200 interface s0.3 point-to-point ip address ip router isis frame-relay interface-dlci 300

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-17 在 NBMA 中使用多点接口运行 ISIS ： 注意：此环境要全网状结构，才能实现全网的互联。 如果在实际中，只要求与中心结点相连，分支设备之间均需通信，则可使用中心 / 分支环境；这时要为中心路由器设置一个合适的优 先级。 C2501(config)#int s0 C2501(config-if)#ip router isis C2501(config-if)#isis priority ? Priority value C2501(config-if)#isis priority 1 C2501(config-if)# interface s0 encapsulation frame-relay interface s0.2 multipoint ip address ip router isis frame-relay map clns 100 broadcast frame-relay map clns 200 broadcast frame-relay map clns 300 broadcast 注： CLNS ：无连接网络服务，也就是说不存在任何保证，数据可能丢失，损坏，次序错乱或者重复。

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-18 五， ISIS 排错命令： Show ip route Show isis route Show clns route—NET 地址 Show isis database—clear isis Show isis topology Show clns protocol Show clns neighbors Show clns interface serial 0

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-19 Example R2# show ip protocols Routing Protocol is "isis" Sending updates every 0 seconds Invalid after 0 seconds, hold down 0, flushed after 0 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: isis Address Summarization: None Routing for Networks: Serial0 Ethernet0 Routing Information Sources: Gateway Distance Last Update :11: :11: :11:44 Distance: (default is 115) Displays the parameters and current state of the active routing protocol processes Router# show ip protocols

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-20 Example R2#show ip route isis i L /8 [115/10] via , Serial0 i L /8 [115/10] via , Ethernet0 i L /8 [115/20] via , Ethernet0 Displays the current state of the routing table show ip route [address [mask]] | [protocol [process-id]] router#

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-21 Is Integrated IS-IS Running R2# show ip protocols Routing Protocol is "isis" Sending updates every 0 seconds Invalid after 0 seconds, hold down 0, flushed after 0 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: isis Address Summarization: None Routing for Networks: Serial0 Ethernet0 Routing Information Sources: Gateway Distance Last Update :11: :11: :11:44 Distance: (default is 115) Displays the parameters and current state of the active routing protocol processes Router# show ip protocols

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-22 Level 1 and Level 2 Topology Table R1# show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA R1 -- R2 10 R2 Se0 *HDLC* R4 10 R4 Se1 *HDLC* R2# show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA R1 10 R1 Se0 *HDLC* R2 -- R4 10 R4 Se1 *HDLC* IS-IS paths to level-2 routers System Id Metric Next-Hop Interface SNPA R2 -- R5 10 R5 Et bb5.9e20

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-23 Level 1 and Level 2 Topology Table R1# show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA R1 -- R2 10 R2 Se0 *HDLC* R4 10 R4 Se1 *HDLC* R2# show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA R1 10 R1 Se0 *HDLC* R2 -- R4 10 R4 Se1 *HDLC* IS-IS paths to level-2 routers System Id Metric Next-Hop Interface SNPA R2 -- R5 10 R5 Et bb5.9e20

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-24 Intra-Area Routing on R1 R1# show clns route CLNS Prefix Routing Table , Local NET Entry R1# show isis route IS-IS Level-1 Routing Table - version 312 System Id Next-Hop Interface SNPA Metric State R2 R2 Se0 *HDLC* 10 Up L2-IS R4 R4 Se1 *HDLC* 10 Up R1 -- Default route out of area - (via 1 L2-attached IS) System Id Next-Hop Interface SNPA Metric State R2 Se0 *HDLC* 10 Up

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-25 Intra-Area and Inter-Area Routing on R2 R2# show clns route CLNS Prefix Routing Table , Local NET Entry [110/10] via R5, IS-IS, Up, Ethernet [110/0] via R2, IS-IS, Up R2# show isis route IS-IS Level-1 Routing Table - version 47 System Id Next-Hop Interface SNPA Metric State R4 R4 Se1 *HDLC* 10 Up R1 R1 Se0 *HDLC* 10 Up

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-26 Simple Troubleshooting: What About CLNS Protocol? R2# show clns protocol IS-IS Router: System Id: IS-Type: level-1-2 Manual area address(es): Routing for area address(es): Interfaces supported by IS-IS: Serial0 - IP Ethernet0 - IP Redistribute: static (on by default) Distance for L2 CLNS routes: 110 RRR level: level-1 Generate narrow metrics: level-1-2 Accept narrow metrics: level-1-2 Generate wide metrics: none Accept wide metrics: none

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-27 Are Adjacencies Established? R2# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol R1 Se0 *HDLC* Up 28 L1 IS-IS R5 Et c92.de4c Up 20 L2 IS-IS R2# show clns interface serial 0 Serial0 is up, line protocol is up Checksums enabled, MTU 1500, Encapsulation HDLC ERPDUs enabled, min. interval 10 msec. RDPDUs enabled, min. interval 100 msec., Addr Mask enabled Congestion Experienced bit set at 4 packets CLNS fast switching disabled CLNS SSE switching disabled DEC compatibility mode OFF for this interface Next ESH/ISH in 12 seconds Routing Protocol: IS-IS Circuit Type: level-1 Interface number 0x1, local circuit ID 0x101 Level-1 Metric: 10, Priority: 64, Circuit ID: R2.00 Number of active level-1 adjacencies: 1 Next IS-IS Hello in 5 seconds

© 2003, Cisco Systems, Inc. All rights reserved. BSCI 2.0—7-28 LAB: 1, 多区域 ISIS 网络 2, 路由汇总 3, 在 NBMA 的网络中实现 ISIS ( 关键：做点到点的子接口 ; 多点中要指定中心 路由器的优先级 :isis priority 0—127, 缺省为 64; 优先级为 0 的不参与 DIS 竞争 )