活用修改SRV记录来手动更改域控制器的冗余和负载均衡

拓扑图：

配置参数：
R1：
access-list 10 permit 192.168.5.0 0.0.0.255 //配置匹配的流量
route-map ospf permit 10 //创建一个路由图配置要匹配的流量
match ip address 10 //关联要匹配的流量
set metric 1 //设置匹配流量的度量值为1
route-map ospf permit 20 //接着用上面的路由图，配置序号为20，设置其它的流量
set metric 2 //设置其它的流量的度量值为2
router ospf 1
redistribute rip subnets //在OSPF里重发布RIP，让R4可以学习到
network 192.168.3.0 0.0.0.255
area 0
router rip
version 2
redistribute ospf 1 route-map
ospf //在RIP里重发布OSPF，并应用上面配置好的路由图，达到
分流（两台设备[R1,R3]配置不同的度量值）和热备（动态路由可以动态感知网络拓扑的变化，动态的将度量值小的路由装进路由表）的效果 ！！！
network 192.168.1.0
no auto-summary

R2:
access-list 20 permit 192.168.6.0 0.0.0.255
route-map ospf permit 10
match ip address 20
set metric 1
route-map ospf permit 20
set metric 2
router ospf 1
redistribute rip subnets
network 192.168.4.0 0.0.0.255
area 0
router rip
version 2
redistribute ospf 1 route-map
ospf
network 192.168.2.0
no auto-summary
测试：
r5#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.100.2 YES NVRAM
up up
r5#traceroute
192.168.5.1
1 192.168.100.1 1032 msec 20 msec 4 msec
2 192.168.1.2 16 msec 8 msec 60 msec
3 192.168.3.2 32 msec 12 msec *
r5#traceroute 192.168.6.1
1 192.168.100.1 32 msec 16 msec
16 msec
2 192.168.2.2 12 msec 28 msec
32 msec
3 192.168.4.2 16 msec 32 msec *
r5#
可以看出要去192.168.5.0的网络走左边，去192.168.6.0的网络走右边！！！

配置成功后路由表是这样的：
R2:
R 192.168.4.0/24 [120/2] via 192.168.2.2,
00:00:17, Ethernet1/1
[120/2] via
192.168.1.2, 00:00:11, Ethernet1/0
192.168.5.0/32 is subnetted,
1 subnets
R 192.168.5.1 [120/1] via 192.168.1.2,
00:00:11, Ethernet1/0
192.168.6.0/32 is subnetted,
1 subnets
R 192.168.6.1 [120/1] via 192.168.2.2,
00:00:17, Ethernet1/1
C 192.168.1.0/24 is directly
connected, Ethernet1/0
C 192.168.2.0/24 is directly
connected, Ethernet1/1
C 192.168.100.0/24 is directly
connected, FastEthernet0/0
R 192.168.3.0/24 [120/2] via
192.168.2.2, 00:00:17, Ethernet1/1
[120/2] via
192.168.1.2, 00:00:11, Ethernet1/0
可以看出，R2通过R1学习到192.168.5.0并且为1跳，通过R3学习到192.168.6.0并且为1跳。
现在来测试一下，将R1的E0/0（连着R4的接口）down掉，看看会发现什么现象：
R1:
r1(config)#int
e0/0
r1(config-if)#sh
r1(config-if)#shutdown
R2:
r2#sh ip rou
R 192.168.4.0/24 [120/2] via
192.168.2.2, 00:00:12, Ethernet1/1
192.168.5.0/32 is subnetted,
1 subnets
R 192.168.5.1 [120/2] via 192.168.2.2,
00:00:12, Ethernet1/1
192.168.6.0/32 is subnetted,
1 subnets
R 192.168.6.1 [120/1] via
192.168.2.2, 00:00:12, Ethernet1/1
C 192.168.1.0/24 is directly
connected, Ethernet1/0
C 192.168.2.0/24 is directly
connected, Ethernet1/1
C 192.168.100.0/24 is directly
connected, FastEthernet0/0
R 192.168.3.0/24 [120/2] via
192.168.2.2, 00:00:12, Ethernet1/1
r2#
可以看出R2是通过R3学习到的192.168.5.0的路由的，它的跳数为2，R5要去192.168.5.0的路由要走右边，因为左边的R1的上连端口down掉了。这样达到了热备的效果！！！

现在把R1的E0/0再开启，看看会是什么效果：
R1:
r1(config)#int
e0/0
r1(config-if)#no
shutdown
R2:
r2#
SH IP ROU
R 192.168.4.0/24
[120/2] via 192.168.2.2, 00:00:05, Ethernet1/1
[120/2] via 192.168.1.2,
00:00:25, Ethernet1/0

192.168.5.0/32 is subnetted, 1 subnets
R 192.168.5.1 [120/1] via 192.168.1.2,
00:00:25, Ethernet1/0

192.168.6.0/32 is subnetted, 1 subnets
R 192.168.6.1 [120/1] via 192.168.2.2,
00:00:05, Ethernet1/1
C
192.168.1.0/24 is directly connected, Ethernet1/0
C
192.168.2.0/24 is directly connected, Ethernet1/1
C
192.168.100.0/24 is directly connected, FastEthernet0/0
R
192.168.3.0/24 [120/2] via 192.168.2.2, 00:00:05, Ethernet1/1
[120/2] via 192.168.1.2,
00:00:25, Ethernet1/0
r2#
可以看出，R2通过动态路由感知到网络拓扑的变化，动态地学习到了度量值优的路由，然后入进入路由表里！！！本文出自 “Yolo” 博客，请务必保留此出处http://4708948.blog.51cto.com/4698948/1130037