[192603] in North American Network Operators' Group
Re: OSPF vs ISIS - Which do you prefer & why?
daemon@ATHENA.MIT.EDU (Josh Reynolds)
Wed Nov 9 21:52:46 2016
X-Original-To: nanog@nanog.org
In-Reply-To: <CAO-ok8Rfq5WDHzLFGfgvmrhE9A14Ztw0waaxhM8Coo_fj=buvg@mail.gmail.com>
From: Josh Reynolds <josh@kyneticwifi.com>
Date: Wed, 9 Nov 2016 20:52:42 -0600
To: RT Parrish <routetarget@gmail.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
Vendor support for IS-IS is quite limited - many options for OSPF.
On Nov 9, 2016 8:47 PM, "RT Parrish" <routetarget@gmail.com> wrote:
> I will definitely be looking up the notes from AOL that John referenced.
> But working for a vendor and getting insight from multiple ISPs, here are=
a
> few of the things that I hear most frequently:
>
> 1) Network Topology support - The differences between a single OSPF
> backbone area and a contiguous set of Level-2 adjacencies will occasional=
ly
> be a deciding factor.
> 2) Feature Support on a per vendor basis - Some vendors will roll new
> features out in one or the other protocols prior to the other. Segment
> Routing and some of its enhancements come to mind as being in ISIS first.
> 3) Layer 2 adjacencies - I think someone already mentioned that you form
> adjacencies at layer 2 which also means that with a single adj you can
> support multiple protocols (v4/v6). OSPF would require two different
> instances to support both. Maybe good, maybe not. Depends on your desired
> level of isolation between the two.
> 4) CPU performance is academic at this point - The SPF calculations in mo=
st
> networks would require next to no difference between the two protocols ev=
en
> if running both IPv4 and v6.
>
> End of the day, use the right tool/vendor/technology for the right job.
>
> Hope this helps,
> RT
>
> On Wed, Nov 9, 2016 at 12:12 PM, Michael Bullut <main@kipsang.com> wrote:
>
> > Greetings Team,
> >
> > =E2=80=8BWhile I haven't worked with IS-IS before but the only disadvan=
tage I've
> > encountered with OSPF is that it is resource intensive on the router it
> is
> > running on which is why only one instance runs on any PE & P device on =
an
> > ISP network. OSPF is pretty good in handling the core network routing
> while
> > BGP & EGP handle the last-mile routing between PE & CE devices. BGP & E=
GP
> > can run on top of OSPF. I came across this *article*
> > <https://routingfreak.wordpress.com/2011/03/05/why-
> > providers-still-prefer-is-is-over-ospf-when-designing-
> > large-flat-topologies/>
> > when
> > scrolling the web a while back and I still want to find out if am the
> only
> > one who thinks its a matter of choice between the two. Although there
> isn't
> > distinct 1:1 argument, it's good we discuss it here and figure out why
> one
> > prefer one over the other *(consider a huge flat network)**.* What say
> you
> > ladies and gentlemen?
> >
> > Warm regards,
> >
> > Michael Bullut.
> >
> > ---
> >
> > *Cell:*
> > *+254 723 393 114.**Skype Name:* *Michael Bullut.*
> > *Twitter:*
> > * @Kipsang <http://twitter.com/Kipsang/>*
> > *Blog: http://www.kipsang.com/ <http://www.kipsang.com/>*
> > *E-mail:* *main@kipsang.com <main@kipsang.com>*
> >
> > *---*
> >
>
