配置拓扑
具体配置：
1． HSRP的配置：
在LongQuan-Backup(1601)上：
int e0
ip address 22.97.80.253 255.255.255.0 secondary
ip address 21.97.80.253 255.255.255.0
no ip redirects
no logging event subif-link-status
standby PRiority 200
standby preempt
standby ip 21.97.80.1
standby ip 22.97.80.1 secondary
standby track Serial0 100/假如S0口的线路当掉了，该E口的优先权减小100，从而成为STANDBY状态
在LongQuan(2501)上：
int e0
ip address 22.97.80.254 255.255.255.0 secondary
ip address 21.97.80.254 255.255.255.0
no ip redirects
no ip directed-broadcast
standby priority 150
standby preempt
standby ip 21.97.80.1
standby ip 22.97.80.1 secondary
2.LongQuan(2500)上路由的调整：
interface Serial1.16 point-to-point
description --- 256K LianTong FR ---
ip address 22.96.229.2 255.255.255.252
ip accounting output-packets
bandwidth 1000000/调高接口带宽
frame-relay interface-dlci 16
router eigrp 1
redistribute connected
redistribute sta
network 21.0.0.0
network 22.0.0.0
distribute-list 22 out Ethernet0/过滤掉21的低METRIC值EIGRP路由
no auto-summary
!
access-list 22 permit 22.0.0.0 0.255.255.255
说明：平时正常时候，1601是局域网内两个网段的ACTIVE网关，局域网中目的地址为22网段的数据走联通线路，21网段的走电信线路；当1601的S口DOWN后，25成为主网关，一切数据都走联通线路
