Attention Network Engineers – Size really does matter!

No.  I wasn’t meaning that!

I have spent the last few days trying to get an ME-3600 to play nicely with an SRX for VPLS.

AFI L2VPN for BGP was set up and the sessions were established and everything looked good….until I created the VPLS on the Cisco switch.

No sooner than the L2 VFI was created with the autodiscovery toggle, all hell broke loose as below:-

*Apr 10 13:28:25.375: %BGP-5-NBR_RESET: Neighbor 172.16.2.2 reset (Peer closed the session)
*Apr 10 13:28:25.375: %BGP-3-NOTIFICATION: received from neighbor 172.16.2.2 3/10 (illegal network) 0 bytes
*Apr 10 13:28:25.375: %BGP_SESSION-5-ADJCHANGE: neighbor 172.16.2.2 L2VPN Vpls topology base removed from session Peer closed the session
*Apr 10 13:28:25.375: %BGP_SESSION-5-ADJCHANGE: neighbor 172.16.2.2 VPNv4 Unicast topology base removed from session Peer closed the session
*Apr 10 13:28:25.375: %BGP_SESSION-5-ADJCHANGE: neighbor 172.16.2.2 IPv4 Unicast topology base removed from session Peer closed the session

As soon as I removed the VPLS config the session came back up and was stable.  After searching for quite some time and with the help of @tlabs on irc I came across the below:-

http://www.cisco.com/en/US/docs/ios/iproute_bgp/command/reference/irg_bgp4.html#wp1154099

So when configuring L2VN AFI towards a Juniper box ( or even from IOS to IOS-XR/XE ) you need to specify ‘prefix-length-size 2’.

So now I have created my VPLS and the session has stayed up!

Hopefully this little nugget will help someone out at some point 🙂

Nick

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