[c-nsp] Loopback Advertise in OSPF

[Prabhu Gurumurthy]

Alex Cruz Farmer wrote:
> Rupert Finnigan wrote:
>> Hi,
>>
>> This maybe be a bit of an stupid question, but I'm a bit stumped as to
>> an answer.
>>
>> I'm running Multiarea OSPF on my nework, with Loopbacks configured on
>> each router. However, I currently don't advertise these loopbacks via
>> OSPF, and so connect to each router by one of their interface IP. Not
>> the best idea, me thinks...
>>
>> I wander if anyone can help my work out how's best to advertise these
>> host ip's into OSPF? Is this advisable? What group should they be
>> associated too? Are there any best practises to adhere to?
>>
>> Sorry if I'm being particularly dumb, and many thanks in advance for
>> your pearls of wisdom!
>>
> 
> Can you paste the config? Have you used redistribute connected subnets?
> 
> Thanks,
> 
> Alex.
> 
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redistribute connected? why? that would mask/mess the routing cost won't it?
I would avoid using redistribute, unless I am redistributing default routes, VPN 
network routes, and routing from another process like EIGRP, RIP etc.

Here is what I use on our network:

interface Loopback127
  description "Loopback 127 interface for SSH, RADIUS, NTP"
  ip address 10.57.127.1 255.255.255.255
  ipv6 address FDC2:C2CD:D343:127::/64 eui-64
  ipv6 ospf 127 area 0

router ospf 127
  log-adjacency-changes
  redistribute static metric 20 subnets route-map RED_OSPF
  network 10.57.41.0 0.0.0.255 area 0
  network 10.57.127.1 0.0.0.0 area 0
  network 10.57.136.0 0.0.0.255 area 0

So the router next to it would see:

O       10.57.127.1/32 [110/2] via 10.57.136.1, 1w6d, FastEthernet0/0

With the loopback being 2 hops away.

Hope this helps
Prabhu
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