CISCO ODR优化大规模路由

需求说明:
　　在大规模的路由网络中,例如在一个由省-地市-县-营业点组成的四级远程互连的路由网络中,如何维护大量的营业点路由器的直连子网路由和配置营业点的静态路由成为一个巨大的负担.此案例中说明了如何利用cisco On-Demand Routing (ODR)技术来优化这种大规模路由网络的一个设想.
2.ODR简介:
　　ODR技术(IOS 12.0.5T)能够使hub and spoke网络结构中的hub路由器自动地向spoke路由器(又称为stub站点)提供缺省路由,stub站点路由器不需要运行动态路由协议,也不需要配置任何的静态路由,几乎没有系统资源的占用,就能够实现本地所有的直连子网向hub路由器的自动通告.

3.ODR需求:
　　ODR使用Cisco Discovery Protocol (CDP)在hub路由器和spoke路由器之间传递路由信息,因此需要在hub和spoke路由之间的每条链路上启用cdp协议,cdp是一个data-link层协议,可以运行在Lan/serial/frame-relay/atm等传输介质上.

配置方法
RouterA>en
RouterA#conf t
RouterA(config)#int s0
RouterA(config-if)#ip add 192.168.1.1 255.255.255.0
RouterA(config-if)#no shut
RouterA(config-if)#int e0
RouterA(config-if)#ip add 192.168.2.1 255.255.255.0
RouterA(config-if)#no shut
RouterA(config-if)#int s1
RouterA(config-if)#ip add 192.168.3.1 255.255.255.0
RouterA(config-if)#clock rate 56000
RouterA(config)#router odr


RouterB>en
RouterB#conf t
RouterB(config)#int s0
RouterB(config-if)#ip add 192.168.1.2 255.255.255.0
RouterB(config-if)#clock rate 56000
RouterB(config-if)#no shut
RouterB(config-if)#int lo0
RouterB(config-if)#ip add 10.0.0.1 255.0.0.0
RouterB(config-if)#no shut
RouterB#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is 192.168.1.1 to network 0.0.0.0

C 10.0.0.0/8 is directly connected, Loopback0
C 192.168.1.0/24 is directly connected, Serial0
o* 0.0.0.0/0 [160/1] via 192.168.1.1, 00:00:24, Serial0


RouterC>en
RouterC#conf t
outerC(config)#int e0
RouterC(config-if)#ip add 192.168.2.2 255.255.255.0
RouterC(config-if)#no shut
RouterC(config-if)#int lo0
RouterC(config-if)#ip add 168.16.1.1 255.255.0.0
RouterC(config-if)#no shut
RouterC#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.2.1 to network 0.0.0.0

C 168.16.0.0/16 is directly connected, Loopback0
C 192.168.2.0/24 is directly connected, Ethernet0
o* 0.0.0.0/0 [160/1] via 192.168.2.1, 00:00:55, Ethernet0

RouterD>en
RouterD#conf t
RouterD(config)#int s1
RouterD(config-if)#ip add 192.168.3.1 255.255.255.0
RouterD(config-if)#no shut
RouterD(config-if)#int lo0
RouterD(config-if)#ip add 156.16.5.3 255.255.0.0
RouterD(config-if)#no shut
RouterD#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is not set

C 156.16.0.0/16 is directly connected, Loopback0
C 192.168.3.0/24 is directly connected, Serial1
o* 0.0.0.0/0 [160/1] via 192.168.5.1, 00:00:40, Ethernet0