Re: Pervasive BGP and routing loops.
Tony Li <tli@cisco.com> Tue, 23 May 1995 00:40 UTC
Received: from ietf.nri.reston.va.us by IETF.CNRI.Reston.VA.US id aa15889;
22 May 95 20:40 EDT
Received: from [132.151.1.1] by IETF.CNRI.Reston.VA.US id aa15885;
22 May 95 20:40 EDT
Received: from interlock.ans.net by CNRI.Reston.VA.US id aa18785;
22 May 95 20:40 EDT
Received: by interlock.ans.net id AA43624
(InterLock SMTP Gateway 3.0 for iwg-out@ans.net);
Mon, 22 May 1995 20:23:50 -0400
Message-Id: <199505230023.AA43624@interlock.ans.net>
Received: by interlock.ans.net (Protected-side Proxy Mail Agent-2);
Mon, 22 May 1995 20:23:50 -0400
Received: by interlock.ans.net (Protected-side Proxy Mail Agent-1);
Mon, 22 May 1995 20:23:50 -0400
Date: Mon, 22 May 1995 17:23:39 -0700
Sender: ietf-archive-request@IETF.CNRI.Reston.VA.US
From: Tony Li <tli@cisco.com>
To: rxg@proteon.com
Cc: bgp@ans.net, rxg@proteon.com
In-Reply-To: <199505222257.PAA04852@beasley.cisco.com> (rxg@proteon.com)
Subject: Re: Pervasive BGP and routing loops.
AS 1 AS 2
----- -----
| 1 | -----/---- | 2 |
----- -----
\ /
----------\---------------/-----------
/ \ AS 3
\ /
----- -----
| 4 |--/-- | 3 |
----- -----
IBGP
- R1 starts advertising route to 128.185.128.0/17
- Both R3 and R4 now have two paths to get to 128.185.128.0/17, and the
best one happens to be via R4.
- R1 reboots with a changed policy, and starts advertising 128.185.0.0/16
So rebooting at this point should break the R1-R2 and R1-R4 TCP
connections, causing R2 and R4 to retract all of the 128.185.128.0/17
advertisements. Thus, at best, what follows should be a transient.
In that light...
- During which time (when the connection to R1 is lost) R4 thinks that
it can get to 128.185.128.0/17 via R3.
One of two possibilities...
- R3 thinks it can get to 128.185.128.0/17 via R4.
But this is contradictory. Recall that R3 can ONLY advertise the
route that it is using. It _cannot_ advertise the R2 route and then
use the R4 route.
Tony
- Pervasive BGP and routing loops. Radha Gowda
- re: Pervasive BGP and routing loops. toconnor
- Re: Pervasive BGP and routing loops. Tony Li
- Re: Pervasive BGP and routing loops. Radha Gowda