OSPF vs IS-IS

Fri Aug 12 12:46:38 UTC 2011

On 8/12/2011 8:40 AM, James Jones wrote:
> I would not say ISIS is the prefered protocol. Most service providers I have worked with use OSPF. Most networks outside of the US use it from what I have seen and the larger SPs in the US do too. There must be a reason for that.

Actually, i strongly disagree with this statement.  A good majority of 
the Tier-1 Service Providers that I have worked with in the past used 
IS-IS, I think in large part due to the points mentioned earlier.  I 
know for a fact that in the late 90s, when we were transitioning from an 
ATM core to an MPLS core at UUnet, we selected IS-IS largely due to the 
fact that it supported MPLS Traffic Engineering extensions before 
comparable support was available in OSPF, and the main reason for this 
was due to the fact that IS-IS was TLV based.

Stefan Fouant
JNCIE-ER, JNCIE-M, JNCIE-SEC, JNCI
Technical Trainer, Juniper Networks
http://www.shortestpathfirst.net
http://www.twitter.com/sfouant