[j-nsp] MX960 JunOS recommendations

[sthaug at nethelp.no]

From: Tima Maryin <tima at transtelecom.net>
Subject: Re: [j-nsp] MX960 JunOS recommendations
Date: Wed, 11 Nov 2009 17:11:56 +0300

> Uhm, i see your point here.
> We indeed have cisco - cisco - Jun - Jun setup
> 
> 
> My cisco interface mtu = ip mtu = mpls mtu =9000
> But i reeeealy doubt that bgp keepalive packet size can come close to that mtu.
> 
> 
> On Juniper i set interface mtu = cisco mtu +14 and it works fine!
> And! As you say, it reports different mpls mtu value:

Make sure that your IP MTU is the same on both Cisco and Juniper sides.
If you run IS-IS, make sure your CLNS MTU is the same on both Cisco and
Juniper sides.

People have been running interoperable Cisco and Juniper networks for
many years. This is not rocket science.

We have standardized on 4470 byte MTU. This means mtu 4470 on Cisco
IOS physical Ethernet interfaces, and MTU 4484 on Juniper JunOS
physical Ethernet interfaces. No need to explicitly set IP or CLNS
MTU.

(Also no need to specify anything at all for SDH/SONET interfaces...)

Steinar Haug, Nethelp consulting, sthaug at nethelp.no