From: Joe A (groupstudy@comcast.net)
Date: Thu Oct 24 2002 - 22:34:48 GMT-3
Can anyone think of a reason why a router would take in a full table
from an iBGP peer and then reduce the table down to about 20600 routes?
I have configued both iBP peers to accept full tables.
The scenario is this:
ISP_A (AS X) ISP_B (AS Y)
| |
| |
eBGP eBGP
| |
| |
RTR_A-------------iBGP (AS Z)-------------RTR_B
RTR_A accepts a full table from ISP_A, and RTR_B accepts a full table
from ISP_B. RTR_A and RTR_B then advertise the full table to each
other.
RTR_A shows that it received approximately 110,000 routes from both
peers.
RTR_B shows that it received the same number of routes from ISP_B, and
it will BRIEFLY show that it received the same number form RTR_A ('show
ip bgp summary'). If I clear the iBGP neighbors, I can see RTR_B
receive the full table from RTR_A (through repeated 'show ip bgp
summary', but as soon as RTR_B stops receiving, it begins decreasing the
number of routes from RTR_A until it gets down to about 20600 routes. I
can't debug easily because the debug command with a full table just
crushes the router.
If I 'show ip bgp <RTR_B> advertised' on RTR_A, RTR_A shows that it sent
the full table; if it were following up with withdrawal messages, I'd
expect that RTR_A would then recount what it advertized, and 'show ip
bgp <RTR_B> advertised' would not show that the full table was sent.
Therefore I think I can rule out that RTR_B drops the routes due to
withdrawal messages from RTR_A, so I can't figure out what's going on.
I have also triple-checked my route filters, and that's not it.
Any ideas?
Joe
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