OSPF vs ISIS - Which do you prefer & why?

Josh Reynolds josh at kyneticwifi.com
Thu Nov 10 22:03:18 UTC 2016

I didn't "trash talk" a vendor. If I did, it would be a multi-thousand line
hate fueled rant with examples and enough colorful language to make
submarine crews blush.

Cisco has been pushing EIGRP and IS-IS as part of their "showing" for
decades. During that same time frame, the majority of the other vendors and
the open source daemons have been using OSPF as their IGP offering. In the
mean time, Cisco found a need to introduce more and more vendor specific
features into their IS-IS offering - no different than any other vendor
would do in their situation to promote the business case (better scaling,
vendor lock-in, other bits).

If you go looking for cross vendor compatibility with as many devices
(routers, switches, servers, etc) as possible, you're going to end up with
OSPF [or BGP, for the data center types that run it to edge nodes]. You
will find a handful, as some have mentioned, of vendors that have adopted
the open version of the protocol and have tried to add
comparable/compatible features to close the gap.

Since the last time I looked, I could not get the same feature sets running
IS-IS in a multi-vendor environment as I could running OSPF. This was my
experience at the time, based on my research and discussions with the

On Nov 10, 2016 3:49 PM, "Nick Hilliard" <nick at foobar.org> wrote:

> Josh Reynolds wrote:
> > I'm sure a lot has changed with Juniper as of 2011 in regard to IS-IS
> > support, which was the last time *I* looked.
> >
> > No, I do not have a list sitting ready, that catalogs in details
> > between product lines and specific firmware versions and subversions
> > between multiple vendors what one supports and what one does not as of
> > Nov 11, 2016.
> >
> > What I can do is point you at the vendor list where you can make a
> > comparison of that vendor to others, for the features that you need in
> > your environment - as I'm not getting paid to maintain such lists, and
> > they are.
> So what you're saying is that you can't even provide a single missing
> feature to justify trash-talking a vendor the way you did?  Not even one??
> Nick

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