loopback love...

loopback  interfaces are an absolute good...

i'm sure i've said it before but loopbacks are a great way to troubleshoot your routing protocol without a lot of effort...

when you sh ip route, loopbacks are easily spotted, especially if you've assigned contextually significant addresses... ie, r1 gets lo0 1.1.1.1, r2 gets 2.2.2.2, etc.

but you knew this and that's why whenever you build a router or a mls you always include loopbacks as part of your configuration, and you never forget to add them as networks to your routing protocol...

correct...


r1#sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O IA    2.2.2.2 [110/2] via 10.1.1.2, 00:08:13, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/66] via 10.1.1.2, 00:08:13, FastEthernet0/0
     4.0.0.0/32 is subnetted, 1 subnets
O IA    4.4.4.4 [110/130] via 10.1.1.2, 00:08:13, FastEthernet0/0
     10.0.0.0/30 is subnetted, 3 subnets
O IA    10.1.1.8 [110/129] via 10.1.1.2, 00:08:13, FastEthernet0/0
C       10.1.1.0 is directly connected, FastEthernet0/0
O IA    10.1.1.4 [110/65] via 10.1.1.2, 00:08:13, FastEthernet0/0
r1#