Possible IOS bug w/respect to incorrect nexthop advert

One of our peers recently upgraded to IOS to:

Cisco Internetwork Operating System Software
IOS (tm) RSP Software (RSP-PV-M), Version 12.1(4)E, EARLY DEPLOYMENT
RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2000 by cisco Systems, Inc.
Compiled Tue 07-Nov-00 14:23 by eaarmas
Image text-base: 0x60010958, data-base: 0x60F7C000

ROM: System Bootstrap, Version 11.1(8)CA1, EARLY DEPLOYMENT RELEASE
SOFTWARE (fc1)
BOOTFLASH: RSP Software (RSP-BOOT-M), Version 12.1(4)E, EARLY DEPLOYMENT
RELEASE SOFTWARE (fc1)

Ever since this upgrade, we've been seeing the following behavior:

When they announce prefixes to us, sometimes they get it right, as in, the
nexthop is set correctly and sometimes they get it wrong as in, the cisco
picks a random address from it's configured addresses and sends the
nexthop as that address.

Example getting it right:

2001/04/06 13:51:42 BGP: 209.115.127.21 rcvd UPDATE w/ attr: nexthop 209.115.127.21, origin i, path 6259 6461 11042 8390 8431
2001/04/06 13:51:42 BGP: 209.115.127.21 rcvd 195.230.6.0/24
2001/04/06 13:51:42 BGP: 209.115.127.21 rcvd 195.230.7.0/24

Examples getting it wrong:

2001/04/06 13:52:10 BGP: 209.115.127.21 rcvd UPDATE w/ attr: nexthop 216.28.125.77, origin i, path 6259 3549 701 7871
2001/04/06 13:52:10 BGP: 209.115.127.21 rcvd UPDATE about 206.162.212.0/22 -- DENIED due to: non-connected next-hop;

2001/04/06 13:57:57 BGP: 209.115.127.21 rcvd UPDATE w/ attr: nexthop 216.28.126.221, origin i, path 6259 7018 14046 14046
2001/04/06 13:57:57 BGP: 209.115.127.21 rcvd UPDATE about 216.241.140.0/23 -- DENIED due to: non-connected next-hop;

This behavior began when the peer upgraded their IOS.

Is this a documented issue or has anyone else seen this behavior?

John,

Looks like they are hitting:

CSCdt06780
Externally found severe defect: Resolved (R)
Constant BGP flaps due to malformatted BGP updates

Fixed in 12.1(5.6)E and 12.1(6)E is on CCO.

I'd have to see the debugs from their side to know
for sure.

If you want to send me their email or reply
and cc them privately I'll make sure it's corrected.

rodney