[原创]怎么解释ip unnumered与RIP的种种情况??

2006年11月17日 10547点热度 0人点赞 1条评论

下面的所有实验用RIPV1的收发机制怎么来解释其路由表结果?

拓扑:(lo0)R1(S1/1)----------------(S1/0)R2

相同的主类，都有子网，相同的子网掩码长度
R1
interface Loopback0
ip address 172.16.1.1 255.255.255.0
interface Serial1/1
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0

R2
interface Loopback0
ip address 172.16.2.2 255.255.255.0
interface Serial1/0
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0
结果：
R1:Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 3 subnets
R       172.16.0.0 [120/1] via 172.16.2.2, 00:00:07, Serial1/1
C       172.16.1.0 is directly connected, Loopback0
R       172.16.2.0 [120/1] via 172.16.2.2, 00:00:07, Serial1/1

R2:Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 3 subnets
R       172.16.0.0 [120/1] via 172.16.1.1, 00:00:07, Serial1/0
R       172.16.1.0 [120/1] via 172.16.1.1, 00:00:07, Serial1/0
C       172.16.2.0 is directly connected, Loopback0
相互PING都能通

相同主类，都含子网，不同的子网掩码长度
R1：配置不变，R2LO0地址改为ip add 172.16.65.2 255.255.192.0
结果：
R1Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 3 subnets
R       172.16.0.0 [120/1] via 172.16.65.2, 00:00:02, Serial1/1
C       172.16.1.0 is directly connected, Loopback0
R       172.16.64.0 [120/1] via 172.16.65.2, 00:00:02, Serial1/1
R2：Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
R       172.16.0.0/18 [120/1] via 172.16.1.1, 00:00:05, Serial1/0
R       172.16.1.0/32 [120/1] via 172.16.1.1, 00:00:05, Serial1/0
C       172.16.64.0/18 is directly connected, Loopback0
想不通为什么出现上面的路由表结果~~~~~
R1上PING 172.16.65.2不同，R2 ping 172.16.1.1也不通。
不通:R1的3个子网全是/24掩码，没有172。16。65。2这样的可匹配的网络。
R2上PING 172.16.1.1的时候172.16.0.0/18可以匹配，但是到了R1后R1回不来也不通。

相同主类，都无子网
R1
interface Loopback0
ip address 172.16.1.1 255.255.0.0
interface Serial1/1
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0

R2
interface Loopback0
ip address 172.16.2.2 255.255.0.0
interface Serial1/0
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0
结果：
两边都是主类直连，无其他路由，显然不能相互PING通。（这也不符合要求，2路由器接口处于相同网段）
C 172.16.0.0/16 is directly connected, Loopback0

总结：相同主类，必须具有相同的子网掩码才能正常在RIP/IGRP下工作。

不同主类，都有子网，子网掩码长度相同
R1
interface Loopback0
ip address 172.16.1.1 255.255.255.0
interface Serial1/1
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0

R2
interface Loopback0
ip address 182.16.2.2 255.255.255.0
interface Serial1/0
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 182.16.0.0
结果：
R1:Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, Loopback0
     182.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
R       182.16.2.0/32 [120/1] via 182.16.2.2, 00:00:19, Serial1/1
R       182.16.0.0/16 [120/1] via 182.16.2.2, 00:00:19, Serial1/1

R2:Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
R       172.16.0.0/16 [120/1] via 172.16.1.1, 00:00:16, Serial1/0
R       172.16.1.0/32 [120/1] via 172.16.1.1, 00:00:16, Serial1/0
     182.16.0.0/24 is subnetted, 1 subnets
C       182.16.2.0 is directly connected, Loopback0
相互都能PING通，双方都将对方的子网号用/32标记成主机路由，从 version 11.0(2)开始都自动为对方产生一个主类条目。

不同主类，都有子网，子网掩码长度不同
R1
interface Loopback0
ip address 172.16.1.1 255.255.255.0
interface Serial1/1
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0

R2
interface Loopback0
ip address 182.16.2.130 255.255.255.128
interface Serial1/0
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 182.16.0.0
结果：
R1:
Gateway of last resort is not set

     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, Loopback0
     182.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
R       182.16.2.128/32 [120/1] via 182.16.2.130, 00:00:12, Serial1/1
R       182.16.0.0/16 [120/1] via 182.16.2.130, 00:00:12, Serial1/1

R2:Gateway of last resort is not set

     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
R       172.16.0.0/16 [120/1] via 172.16.1.1, 00:00:21, Serial1/0
R       172.16.1.0/32 [120/1] via 172.16.1.1, 00:00:21, Serial1/0
     182.16.0.0/25 is subnetted, 1 subnets
C       182.16.2.128 is directly connected, Loopback0
相互都能PING通，双方都将对方的子网号用/32标记成主机路由，从 version 11.0(2)开始都自动为对方产生一个主类条目。

不同主类，都无子网
R1
interface Loopback0
ip address 172.16.1.1 255.255.0.0
interface Serial1/1
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 172.16.0.0

R2
interface Loopback0
ip address 182.16.2.2 255.255.0.0
interface Serial1/0
ip unnumbered Loopback0
serial restart-delay 0
router rip
network 182.16.0.0
结果：
R1:Gateway of last resort is not set

C 172.16.0.0/16 is directly connected, Loopback0
R 182.16.0.0/16 [120/1] via 182.16.2.2, 00:00:08, Serial1/1< /p>

R2:Gateway of last r
esort is not set

R 172.16.0.0/16 [120/1] via 172.16.1.1, 00:00:23, Serial1/0
C 182.16.0.0/16 is directly connected, Loopback0
相互都能PING通，从 version 11.0(2)开始都自动为对方产生一个主类条目

总结：不同主类，怎么着在RIP/IGRP下都通。

上面的所有实验用RIPV1的收发机制怎么来解释其路由表结果?

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094e8d.shtml
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9e0.shtml

本作品采用知识共享署名-非商业性使用 4.0 国际许可协议进行许可

文章评论

这种玩意好像没啥研究价值吧，实际工程不可能这么干啊。
而且这跟RIP本身没关系啊，有类协议都一样的原则，条目过主类边界后使用原始主类掩码，不过主类边界用接收路由器接口的掩码，因为条目不带前缀长度。只不过那个“主类网络号/掩码”的条目是Cisco IOS自己加的。
这是Cisco IOS对无编号接口在路由进程内的应用的一种折衷。原则是：RTR_A(S0)--RTR_B(S0)拓扑中，如果使用有类协议，并且如果A带有一个子网化的网络、且其主类网络号码跟B所带网络的主类网络号码不同的情况下，B需要为A的子网添加一个到其主类网络的路由条目，反之亦然。