From: Donghai Zhang (zdh1207@gmail.com)
Date: Sat Aug 04 2007 - 10:42:16 ART
Dear Prasad,
I think you're right. the C route is indeed there even when BB1 is
disconncted.I think you could try another way. Since you need to make sure
BB1 is ACTIVE otherwise you would not advertise the default route. So you
have to let R1 know if BB1 is alive. There is a way to solve this. Make a
Rip between R1 and BB1, from which R1 should learn a route(say,a Loopback
address)from BB1.If the learned route disappear,then R1 knows it lose the
connection to BB1.Here is the configuration:
R1
router rip
version 2
no auto
network 204.12.0.0
route-map RIP
match ip address 1
access-list 1 permit 3.0.0.0
router os 1
default-information originate route-map RIP
BB1
int loopback 1
ip add 3.3.3.3 255.255.255.0
router rip
version 2
no auto
network 3.0.0.0
network 204.12.0.0
------------------------------------------------------
Now you got what you want.
2007/8/4, Prasad Shemrudkar (pshemrud) <pshemrud@cisco.com>:
>
> Hi,
>
> I have a situation wherein there are 2 routers say R1 and BB1 connected
> to a switch. The subnet is 204.12.1.0/24. R1 needs to conditionally
> advertise a default route in ospf domain if it is CONNECTED to BB1. Now
> I have used the following configuration on R1 but do not think its
> correct (for the reason explained below the configuration).
>
> router ospf 1
> router-id 150.1.3.3
> log-adjacency-changes
> area 0 authentication message-digest
> area 23 virtual-link 150.1.2.2
> area 34 authentication
> area 34 virtual-link 150.1.4.4
> redistribute connected subnets route-map CONNECTED
> redistribute rip subnets route-map RIP-->OSPF
> network 191.1.13.3 0.0.0.0 area 13
> network 191.1.23.3 0.0.0.0 area 23
> network 191.1.34.3 0.0.0.0 area 34
> default-information originate route-map DEFAULT
> !
> route-map DEFAULT permit 10
> match ip address prefix-list BB1
> !
> ip prefix-list BB1 seq 10 permit 204.12.1.0/24
>
> My point is, that since both router connect on Ethernet (via switch),
> even if BB1 looses connectivity to the switch, the directly connected
> route "C 204.12.1.0/24 is directly connected, Ethernet1/0" will still
> be shown in R1's routing table (as that one is still connected) and
> hence R1 will continue advertising the default route in OSPF even though
> there is no connectivity between R1 and BB1.
>
> I dunno but got a feeling, have a wrong logic as the solution has
> configured it the same way too!!
>
> Thanks in Advance,
>
> Prasad
>
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