CCIE实验笔记之－－－第2章 WAN协议（PPP）－5
[b][size=5][size=10.5pt][color=#000000]2.4[size=10.5pt]实验[/size][/color][/size][size=10.5pt]：[/size][size=10.5pt]PPP[/size][size=10.5pt]备份配置[/size][/size][/b]
[b][size=4][size=10.5pt][color=#000000]2.4.1
[size=10.5pt]实验内容[/size][/color][/size][/size][/b]
本次实验主要目的是测试同步链路的PPP模拟线路备份，因环境不具备，模拟线路使用一条同步链路代替。
l
路由协议使用eigrp
l
协议使用PPP
注：链路备份的配置方法有通过动态路由协议实现的，在本实验中使用backup interface这命令来实现。
[b][size=4][size=10.5pt][color=#000000]2.4.2
[size=10.5pt]实验拓扑[/size][/color][/size][/size][/b]
路由器A和B有两条线路相连，当第1条链路中断后第2条自动启用，第1条链路为DDN线路，第2条线路模拟作为模拟拨号线路。分别配置一个loopback接口模拟LAN。
图2-4 PPP链路的备份
[img]http://www.cnfan.net/cisco/uploadfile/200707/20070703104329228.JPG[/img]
[b][size=4][size=10.5pt][color=#000000]2.4.[/color][/size][size=10.5pt][color=#000000]3
[size=10.5pt]所需设备[/size][/color][/size][/size][/b]
l
带有两个串口路由器两台
l
V.35公头线缆两条
l
V.35母头线缆两条
l
PC两台
[b][size=4][size=10.5pt][color=#000000]2.4.[/color][/size][size=10.5pt][color=#000000]4
[size=10.5pt]实验步骤[/size][/color][/size][/size][/b]
配置步骤
第1步 配置PPP
第2步 在主串口上配置backup interface
命令格式为:
Backup interface[i] interface_name_or_type[/i]
在下面三种情况下备份链路才启用：
l
主链路由于数据链路层问题停止工作
l
主链路上的负载达到特定的阈值
l
主链路上的负载超过特定的阈值
主链路到备份链路及备份链路回到主链路之间的切换，延迟时间可以设置。
设置延迟时间命令格式：
Backup delay { enable-delay | never}{disable-delay | vever}
设置负载量备份的命令格式：
Backup load {enable-threshold | never}{disable-load | never}
注：配置完backup interface后，备份接口马上进入备份状态。
[b][size=4][size=10.5pt][color=#000000]2.4.[/color][/size][size=10.5pt][color=#000000]5
[size=10.5pt]完整配置[/size][/color][/size][/size][/b]
例2-10 实验的完整配置
[b]A router:[/b]
hostname A
ip subnet-zero
!
interface Loopback1
ip address 10.10.10.1 255.255.255.0
!
interface Serial1/0
backup interface Serial1/1
ip address 1.1.1.1 255.255.255.252
encapsulation ppp
serial restart_delay 0
clockrate 115200
!
interface Serial1/1
ip address 2.2.2.1 255.255.255.252
encapsulation ppp
serial restart_delay 0
!
router eigrp 100
network 1.1.1.0 0.0.0.255
network 10.10.0.0 0.0.255.255
no auto-summary
no eigrp log-neighbor-changes
!
ip classless
[b]B router:[/b]
hostname B
!
ip subnet-zero
!
interface Loopback1
ip address 10.10.20.1 255.255.255.0
!
interface Serial1/0
backup interface Serial1/1
ip address 1.1.1.2 255.255.255.252
encapsulation ppp
no ip mroute-cache
serial restart_delay 0
!
interface Serial1/1
ip address 2.2.2.2 255.255.255.252
encapsulation ppp
serial restart_delay 0
!
router eigrp 100
network 1.1.1.0 0.0.0.255
network 10.10.0.0 0.0.255.255
no auto-summary
no eigrp log-neighbor-changes
!
ip classless
[b][size=4][size=10.5pt][color=#000000]2.4.[/color][/size][size=10.5pt][color=#000000]6
[size=10.5pt]验证配置[/size][/color][/size][/size][/b]
l
使用show interface serial [i]port_number/slot_number[/i]
例2-11 配置完backup interface s1/1后show interface serial 1/1显示的结果
Serial1/1 is standby mode, line protocol is down ＜－standby mode
Hardware is M4T
Internet address is 2.2.2.1/30
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, crc 16, loopback not set
Restart-Delay is 0 secs
LCP Closed, multilink Closed
Closed: OSICP, BRIDGECP, TAGCP, IPCP, CCP, CDPCP, LLC2, IPXCP, NBFCP
BACP, ATCP, IPV6CP
Last input 00:00:22, output 00:00:11, output hang never
Last clearing of "show interface" counters 01:47:36
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
5349 packets input, 1269893 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
5350 packets output, 1269519 bytes, 0 underruns
0 output errors, 0 collisions, 3 interface resets
0 output buffer failures, 0 output buffers swapped out
3 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up
l
Show ip route 命令显示路由信息，手动将s1/0接口down掉后，出现的信息
例2-12
主备份链路切换后路由的变化信息
A#sho 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
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/30 is directly connected, Serial1/0
C 1.1.1.2/32 is directly connected, Serial1/0
10.0.0.0/24 is subnetted, 2 subnets
C 10.10.10.0 is directly connected, Loopback1
D 10.10.20.0 [90/2297856] via 1.1.1.2, 00:00:28, Serial1/0
A#ping 10.10.20.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.20.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/110/256 ms
A#traceroute 10.10.20.1
Type escape sequence to abort.
Tracing the route to 10.10.20.1
1 1.1.1.2 312 msec 48 msec *
A#
03:20:46: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down
03:20:49: %LINK-3-UPDOWN: Interface Serial1/1, changed state to up [color=red] ＜－注意此处[/color]
03:26:04: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/1, changed state to up
A#sho 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
2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 2.2.2.2/32 is directly connected, Serial1/1
C 2.2.2.0/30 is directly connected, Serial1/1
10.0.0.0/24 is subnetted, 2 subnets
C 10.10.10.0 is directly connected, Loopback1
D 10.10.20.0 [90/2297856] via 2.2.2.2, 00:00:14, Serial1/1
A#
[b]注：[/b]例2-12中的灰色部分的时间间隔很大，在后面遭遇问题章节中再详述。
[b][size=4][size=10.5pt][color=#000000]2.4.[/color][/size][size=10.5pt][color=#000000]7
[size=10.5pt]遭遇问题[/size][/color][/size][/size][/b]
[b]问题：[/b]Backup 接口不能工作，interface 已经up 了，但是line protocol始终不能up
[b]原因：[/b]由于是手动down掉router A的serial s1/0接口，但是该接口上配置了backup interface s1/1，down掉该接口后，backup interface命令随之down掉而失效。这样就导致backup interface 无法正常工作，处于standby mode/disable状态，不能激活该接口。
[b]解决方法：[/b]在router B上取消backup interface s1/1的命令，手动down掉router B的serial1/1接口。
页:
[1]