North American Network Operators Group

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Re: OSPF -vs- ISIS

  • From: vijay gill
  • Date: Tue Jun 21 10:23:54 2005

Dan Evans wrote:

Can anyone point me to information on what the top N service providers
are using for their IGP? I'm trying to build a case for switching from
OSPF to IS-IS. Those on this list who are currently running IS-IS, do
you find better scalability and stability running IS-IS than OSPF? I
understand that this question is a lot more complex than a simple yes
or no since factors like design and routing policy will certainly
affect the protocols behavior.

Any insights or experiences that you can share would be most helpful.


Daniel Evans
Alltel Communications
Daniel, in short, we've found ISIS to be slightly easier to maintain and run, with slightly more peace of mind in terms of securitiy than OSPF. Performance and stability wise, no major difference that was noticable.

For more information, see the talk by Dave Katz at

Also, AOL's experience in switching from OSPF to ISIS is covered at
the PDF on that page is actually an older version. The full version I used at NANOG is available at