different BGP session behavior 12.6->15.3?

[EtherNation_Use]

Create Date: Feb 28 2013 8:38PM

Hi all,

I recently tried upgrading one of our core X480 routers from 12.6.3-patch1-8 to 15.3.1 as we're hoping to turn up IPv6 BGP soon. The switch is peered with another X480 inside our AS, running 12.6, and an ISP router, which is a Juniper. The IBGP session came up just fine, but the EBGP session with the Juniper came up, exchanged routes, and was shut down from the Juniper side, with an "optional attributes error." The session gets reset, and eventually the cycle repeats. Traffic flows, but the resets cause our routes to flap through that ISP, causing connectivity issues. The ISP has opened a ticket with Juniper to see what might be causing this, but has anyone seen behavior like this in moving from 12.6 to 15.3? Is there a different set of standard behavior with BGP sessions in 15.3?

Anonymized config follows. Route policy "ISPOut" referenced below restricts our exported routes to our NLRI, matching exactly.

enable bgp address-family ipv4-unicast advertise-inactive-route
configure bgp AS-number 65000
configure bgp routerid 192.168.1.2
configure bgp maximum-paths 4
enable bgp community format AS-number:number
configure bgp restart aware-only
configure bgp add network 192.168.1.0/22
create bgp neighbor 10.10.10.5 remote-AS-number 65001
configure bgp neighbor 10.10.10.5 source-interface ipaddress 10.10.10.6
configure bgp neighbor 10.10.10.5 password encrypted "blahblahblah"
configure bgp neighbor 10.10.10.5 description "ISP BGP Peer"
create bgp neighbor 192.168.1.1 remote-AS-number 65000
configure bgp neighbor 192.168.1.1 source-interface ipaddress 192.168.1.2
configure bgp neighbor 192.168.1.1 password encrypted "blahblahblah"
enable bgp neighbor 192.168.1.1
configure bgp neighbor 10.10.10.5 next-hop-self
configure bgp neighbor 10.10.10.5 route-policy out ISPOut
disable bgp neighbor 10.10.10.5 capability ipv4-multicast
configure bgp neighbor 192.168.1.1 send-community standard
disable bgp neighbor 192.168.1.1 capability ipv4-multicast
(from Ansley_Barnes)

[EtherNation_Use]

Create Date: Mar 3 2013 3:45AM

Ansley, per the RFC, if you receive a malformed BGP update with (in this case I believe it is an aggregator attribute with an AS value of 0), the session is supposed to reset. However, since an update might be sent constantly from an ISP, and as a workaround, a CLI command is introduced in 15.3.2 (or 15.2.3) to address this issue. Also, as a reference point, I recommend checking PD # PD4-3298430801 in 15.2.3 release notes.

In other words, I recommend downloading the 15.2.3 image and running the command configure bgp invalid-message-action drop-attribute aggregator-as-number-0 to address this issue. (from ethernet)

[EtherNation_Use]

Create Date: Mar 1 2013 10:14PM

Hello Ansley

I have not seen this behavior. I would recommend opening a case with Extreme TAC as well so we can try and reproduce.

P (from Paul_Russo)