OSPF vs IS-IS

Sun Aug 14 01:49:58 UTC 2011

On Sat, Aug 13, 2011 at 21:11, Vinny Abello <vinny at abellohome.net> wrote:
> One of my favorite features in IS-IS is the ability to set the overload
> bit during maintenance. The effect is the router on which you set it
> isn't seen by any other devices in the topology as a transit path, but
> you can still reach the router itself. I'm not as familiar with OSPF so
> I'm unsure if there is a similar feature, but I thought it was exclusive
> to IS-IS. Being able to easily limit the IGP size via the above
> technique is also a great benefit. You can basically get away with just
> your loopbacks.
>
> -Vinny

Cisco and Juniper both support this (overload) in OSPFv2 using the
process described in RFC 3137. Juniper use the familiar 'overload'
command under the OSPF configuration, Cisco use the 'max-metric
router-lsa' [1] command under the OSPF config. Both should give
similar results to ISIS overload.

~Matt

1: http://www.cisco.com/en/US/products/ps6599/products_white_paper09186a00800ade18.shtml