RE: Simple Doubt regarding BGP

That is interesting. I had assumed in the past that BGP would create the automatic classful distinction here. I guess that is not the case, it will simply allow you to put any entry unchecked. I knew BGP was precise before, that just further solidifies things.

Loopback1 is up, line protocol is up
  Internet address is 2.2.2.2/8
Loopback2 is up, line protocol is up
  Internet address is 3.3.3.3/32

Add network 2.2.2.2, nothing is brought in, add network 3.3.3.3, nothing is brought in. Add network 3.3.3.3 mask 255.255.255.255, now we have a network.

router bgp 100
 network 2.2.2.2
 network 3.3.3.3
 network 3.3.3.3 mask 255.255.255.255

Rack1R1(config-router)#net 3.3.3.3 mask 255.255.255.255
Rack1R1(config-router)#
*Apr 28 02:11:58.801: BGP(0): route 3.3.3.3/32 up
*Apr 28 02:11:58.801: BGP(0): nettable_walker 3.3.3.3/32 route sourced locally
*Apr 28 02:11:58.801: BGP(0): 150.1.2.2 send UPDATE (format) 3.3.3.3/32, next 150.1.1.1, metric 0, path Local

-ryan

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Paul Borghese
Sent: Monday, April 27, 2009 10:12 PM
To: Raghav Bhargava
Cc: Cisco certification
Subject: Re: Simple Doubt regarding BGP

> Hi Experts,
>
> Very basic question
>
> Suppose I have this ip address configured on my loopback Interface of R1
>
> 2.2.2.2/8
>
> Now under my BGP Process if i advertise this network as
>
>
> network 2.2.2.2
>
> OR
>
> network 2.0.0.0
>
> Now in first case I don't see this network in the BGP table of the other
> router but
> if I follow the second case the network is seen.
>
> Can anyone please explain why is it doing like this??
>

Type "show ip route" and look for the network in question. You will see
the network in the routing table will be listed as a connected route with
the address 2.0.0.0/8. The network statement must match exactly what is
in the routing table. The routing table does NOT contain 2.2.2.2/8.

I tell my students if you see the route in the routing table, but it is
not in the BGP table, check the network statement.

Take care,

Paul Borghese
GroupStudy Owner

Blogs and organic groups at http://www.ccie.net
Received on Mon Apr 27 2009 - 22:20:29 ART