At the risk of posting something on topic..
I have 2 routers (lets call them A and B), talking to different upstream
providers, advertising 202.6.75.0/24 via BGP.
202.6.75.0/24 is subnetted, each subnet is on a different VLAN.
These routers talk to each other with iBGP, giving each other everything
(including 202.6.75.0/24 le 32).
I run HSRP between the 2 routers.
Router B prepends my ASN several times before advertising 202.6.75.0.
Relevant stuff (on both boxes):
router bgp 23729
network 202.6.75.0
no synchronization
!
ip route 202.6.75.0 255.255.255.0 Null0
With this config, reachability for 202.6.75.0/24 hosts alternates on and off
roughly every minute. 47% total loss over 10 minutes (ie 5 'bursts' of loss).
These packets are all hitting my AS at router A.
I've turned HSRP off and on again to see if that was causing problems (it
wasn't).
Several solutions I've found:
- Turning the iBGP session to router B off. (uhh..)
- Turning syncronization on.
My understanding of BGP synchronization, is that BGP will only re-advertise
with eBGP prefixes learned via iBGP after learning them via another IGP if
one is running.
<snip>
ec-br-1(config-router)#do sh run | inc router
router bgp 23729
bgp router-id 202.6.75.1
</snip>
I'm not running any IGPs, so synchronization shouldn't be part of the
equation. In any case, I'm not a transit provider.
And, there seems to be no relation to readvertising routes here, the packets
AFAICT are getting to router A and being dropped.
I've got no problem running running with synchronization on at the moment, but
thats not the point. :-)
Any ideas/thoughts?
--
Nathan Ward
