烦请讲讲这几个问题

powerfulxm

问题1.

R2#show ip route
Gateway of last resort is not set
     172.16.0.0/16 is variably subnetted, 6 subnets, 2 masks
O       172.16.1.1/32 [110/65] via 172.16.12.1, 00:03:39, Serial0/0/0  （为什么呢？）
C       172.16.2.0/24 is directly connected, Loopback0
O       172.16.3.3/32 [110/65] via 172.16.23.3, 00:00:50, Serial0/0/1    (?)
C       172.16.12.0/24 is directly connected, Serial0/0/0
C       172.16.23.0/24 is directly connected, Serial0/0/1
O       172.16.34.0/24 [110/128] via 172.16.23.3, 00:00:40, Serial0/0/1

问题2.

Routing Protocol is "ospf 110"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Router ID 172.16.2.2
  Number of areas in this router is 1. 1 normal 0 stub 0 nssa
  Maximum path: 4
  Routing for Networks:
    172.16.2.0 0.0.0.255 area 0
    172.16.12.0 0.0.0.255 area 0
    172.16.23.0 0.0.0.255 area 0
  Routing Information Sources:                  （路由信息源这部分是什么意思）
    Gateway         Distance      Last Update
    172.16.1.1           110      00:00:15
    172.16.2.2           110      00:00:06
  Distance: (default is 110)

问题3.
R4#show ip route
Gateway of last resort is not set
     172.16.0.0/16 is variably subnetted, 6 subnets, 2 masks
O       172.16.1.1/32 [110/193] via 172.16.34.3, 01:03:03, Serial0/0/0
O       172.16.2.2/32 [110/129] via 172.16.34.3, 01:03:03, Serial0/0/0
O       172.16.3.3/32 [110/65] via 172.16.34.3, 01:03:03, Serial0/0/0
O       172.16.12.0/24 [110/192] via 172.16.34.3, 01:03:03, Serial0/0/0
O       172.16.23.0/24 [110/128] via 172.16.34.3, 01:03:03, Serial0/0/0
C       172.16.34.0/24 is directly connected, Serial0/0/0

路由条目中172.16.1.1/32 [110/193] via 172.16.34.3, 01:03:03, Serial0/0/0到达172.16.1.1的度量值为什么是193呢？
cost=1+10^8/128000+10^8/128000+10^8/128000=2344啊

                               
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hljlsl

  1、换回接口路由掩码长度默认都是32为，这是换回接口的特性，尽管通告了24他也是不变的。但是可以在换回接口下修改网络类型为：ip ospf network Point-to-Point。
其他两个我也不大太理解

hljlsl

路由信息源应该就是route-id

yufengchun

安逸猪

OSPF的cost值是路由流向的入接口上的总和 串行链路默认带宽是1.544Mbps 即1544000bps
10^8/1544000=64   64*3=192  192+1=193  
注：OSPF的cost=10^8/(bps)    EIGRP是10^7/(kbps)

第一个问1楼很对 ip ospf network point-to-point是还原环回口的真实掩码信息

332104496