randy@psg.COM (Randy Bush) writes:
Most of the large ISPs in the US run IS-IS as their IP IGP.
In europe a number of PTTs have chosen IS-IS as the IGP for their new
IP Internet backbones. That might be an indication if IS-IS is dead.
hypothesis: big isps talk less. except a few loudmouths <g>, and when jhawk
gets pissed off <g^2>.
I know why most of the older large ISPs use IS-IS, because it was the
only option that worked at the time. But now that some router vendors
have come out with workable OSPF implementations, I've been wondering
which road the new ISP competitors would take. So far, they've been
hiring all the engineering staff away from the older ISPs. And then
the engineers set up the new network with the same skills, meaning IS-IS.
But what if you started from a clean slate...
If you didn't have an installed base, and didn't already know one or
the other, which would you choose? Or just punt, and use iBGP....
randy@psg.COM (Randy Bush) writes:
>> Most of the large ISPs in the US run IS-IS as their IP IGP.
>> In europe a number of PTTs have chosen IS-IS as the IGP for their new
>> IP Internet backbones. That might be an indication if IS-IS is dead.
>
>hypothesis: big isps talk less. except a few loudmouths <g>, and when jhawk
>gets pissed off <g^2>.
I know why most of the older large ISPs use IS-IS, because it was the
only option that worked at the time. But now that some router vendors
have come out with workable OSPF implementations, I've been wondering
which road the new ISP competitors would take. So far, they've been
hiring all the engineering staff away from the older ISPs. And then
the engineers set up the new network with the same skills, meaning IS-IS.
But what if you started from a clean slate...
I know of one new network planned by people originally most familiar with
OSPF that is now running IS-IS. It did start out as OSPF allright, but
when you go beyond 200+ routers in area 0 within 6 months (and still
growing) you start wondering whether you shouldn't take a different
approach -- and thats when IS-IS comes in handy.
If you didn't have an installed base, and didn't already know one or
the other, which would you choose? Or just punt, and use iBGP....
I guess it depends on how large you plan to get 
- and yes, I know, that OSPF scales quite well if you design it
carefully WRT areas, but so does IS-IS...
Another way to look at it would be that you could keep on making
sloppy networkdesign far longer in an IS-IS network than you could with
OSPF 
--
Sean Donelan, Data Research Associates, Inc, St. Louis, MO
Affiliation given for identification not representation
/Niels Chr.
SEAN@SDG.DRA.COM (Sean Donelan) writes:
If you didn't have an installed base, and didn't already know one or
the other, which would you choose? Or just punt, and use iBGP....
I'm only slightly biased, but...
Having implemented IS-IS; having listened to a certain former IS-IS
implementor gripe greviously about the fun he was having implementing OSPF;
having watched both successful and unsuccesful OSPF implementations;
knowing what I know about both protocols, and given Murphy's tendency to
veer towards complexity, my decision would take less time than an SPF.
Tony
Or just punt, and use iBGP....
let's not go through this one again if you're interested, there's a
lengthy argument thread on this subject from a few months back...