OSPF问答

1.在ＯＳＰＦ中做area range到底用不用再加一条到null0的静态地址？tcp/ip v1 中 p548 中line7 中说需要加一条手工静态路由到null0 ， 可做实验发现,确实和楼上说的一样,不用手工做静态自动会发布

答：不用，自动能生成一条null0的路由。

iso 12.0(1) 以前需要手工加。

以后的版本就是自动的生成。

2.OSPF中rid修改后，如何生效，使用clear ip ospf process这条命令重新对ospf进程进行启动或重启路由器不好使？要重启所有使用ospf的router才会修改rid

答：When OSPF is configured on a router, the router interfaces are polled and interfaces that are up are enabled with OSPF. As interfaces become more complex and the amount of interfaces increase, the time for interfaces to come up also increases, and there is a slight chance that OSPF will poll the interface before its state is fully up. This can result in the interface being up, but OSPF not being enabled on it. The default number of times OSPF polls the interfaces has been increased from 0 to 10 in order to avoid this situation.

If you're running OSPF and upgrading to Cisco IOS Software release 12.0(8)S, you'll notice the ip ospf interface-retry 0 is automatically added to every interface. This value is the old default value. The new default number of retry times is 10. The router displays the old behavior so the command shows up in the configuration.

Note: The ip ospf interface-retry 0 command is harmless, and OSPF continues to function normally whether or not you change the interface retry value.

Solution

Only configure ip ospf interface-retry 10 on all interfaces if you don't want this command to appear in your router's configuration. As 10 is the new default value the command will no longer appear in the configuration.

This problem is documented as Cisco bug ID CSCdp64394. If you are a registered customer and you have logged in, you can view the bug details.

3.OSPF不能建立邻居关系的原因?

答：建立neighbor考虑如下的因素

1、hello包间隔不一致

2、netmask不匹配（p2p和vlink除外）

3、E-bit（处理外部路由的规定）

4、router dead time

5、auth