BGP: routing table

Unanswered Question
Nov 30th, 2009

Hello everybody,

I have a strange situation, please explain me why it happend

From BGP peer I have recieved 4 prefixes:

2 prefixes x.x.x.x/16 and two prefexis with /24.

about the first two prefexis (/16) everything fine.

i can see it via: sh ip bgp a.a.a.a/16; sh ip bgp b.b.b.b/16

sh ip bgp neighbors A.A.A.A routes

*> a.a.a.a/16     x.x.85.30             0    400      0 AS1 AS2 i
*> b.b.b.b/16     x.x.85.30             0    400      0 AS1 AS2 i
*> c.c.0.0         x.x.85.30             0    400      0 AS1 AS2 i
*> d.d.0.0          x.x.85.30             0    400      0 AS1 AS2 i

but i can't see the last two prefixes into the routing table at all:

sh ip bgp c.c.0.0/24;  sh ip bgp d.d.0.0/24
% Network not in table

I can see this ranges from another peer, but with /18...

Why this prefixes are not in the routing table, they are even more specific routes...

--

Have a nice day,

Dmitry

I have this problem too.
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Eugene Khabarov Mon, 11/30/2009 - 05:24

Please, show us "show run  | section bgp" output.

Maybe route-maps or prefix-list filter out this updates?

N.B.

>>but i can't see the last two prefixes into the routing table at all:

You can't see it in bgp table, not in routing table.

Show us output

sh ip route a.a.a.a

sh ip route c.c.c.c

kozorezdi Mon, 11/30/2009 - 05:38

Hello,

sh ip route c.c.0.0 255.255.255.0
% Subnet not in table
sh ip route d.d.0.0 255.255.255.0
% Subnet not in table

we  don't think about incoming route-map, there only: set local-preference 400.

and i told before i can see all 4 prefixes by the command : sh ip bgp neighbors x.x.x.x routes

it shows the situation after the filter.

i am checking the situation on the local router(local routing table)...

Thank you in advance,

Dmitry

milan.kulik Wed, 12/02/2009 - 00:57

Hi,

if I understand correctly both are class C subnets, so /24 is the default subnet mask for them?

Doesn't

sh ip bgp c.c.0.0

and

sh ip bgp d.d.0.0

without any subnet mask work then?

If yes, I guess you are running an IOS version with some default subnet mask bug.

BR,

Milan

kozorezdi Wed, 12/02/2009 - 04:03

The partner has stopped to announce this prefixes, so it is hard to make any conclusions...

Thank you for your support!

ps. but it looks very strange ...

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