nanog mailing list archives
Re: OSPF vs IS-IS
From: Jimmy Hess <mysidia () gmail com>
Date: Thu, 11 Aug 2011 19:16:58 -0500
On Thu, Aug 11, 2011 at 5:19 PM, Randy Bush <randy () psg com> wrote:
how about simpler and more stable?
ISIS is also decoupled from IP making it more robust and flexible/future-proof, as in adaptible to new protocols -- IP connectivity is not required for ISIS nodes to discover and associate with L2 connected neighbors. At the fundamental level, there are plenty of reasons to exclude OSPF from running in a SP core; when a technically superior choice is available and usable. The IP decoupling is a good example. As in, ISIS topology is independent from (non-tunneled) IP topology, which is more flexible. There is less complexity, and basic troubleshooting is facilitated favorably to OSPFv2/v3, due to the larger amount of baggage OSPF carries with it. If you need to renumber your network, including IS-IS routers', you will impact the contents of IPv4 routes transmitted and forwarding table contents, but your adjacencies do not rely on the IP protocol, and aren't dependant on neighbor IP addressing. Need to support IPv6 addresses? ISIS was trivially extended to do it. Need to support routing to MAC addresses? Again... just a new type field. OSPF requires... shall we say, more fundamental changes to attempt to extend it. More fundamental changes to a more complex protocol = more opportunities for bugs. I would encourage you to ask the opposite question: " Is there any reason to run OSPF over IS-IS in the SP core?" And the answer would be... probably not. There is not really a good technical reason to run OSPF over IS-IS in the SP core. You might have some aesthetic considerations such as wanting the SP core to run the same protocol as something else, despite its limitations. Then you will have to ask yourself if the aesthetic considerations outweigh the technical benefits. -- -JH
Current thread:
- Re: OSPF vs IS-IS, (continued)
- Re: OSPF vs IS-IS Jeffrey S. Young (Aug 13)
- Re: OSPF vs IS-IS Saku Ytti (Aug 13)
- Re: OSPF vs IS-IS Tom Hill (Aug 12)
- Re: OSPF vs IS-IS Scott Morris (Aug 12)
- Re: OSPF vs IS-IS Scott Morris (Aug 12)
- RE: OSPF vs IS-IS Doug Marschke (Aug 16)
- Re: OSPF vs IS-IS Jeff Wheeler (Aug 12)
- Re: OSPF vs IS-IS Douglas Otis (Aug 12)
- Re: OSPF vs IS-IS Randy Bush (Aug 11)
- Re: OSPF vs IS-IS Stefan Fouant (Aug 11)
- Re: OSPF vs IS-IS Jimmy Hess (Aug 11)
- Re: OSPF vs IS-IS Stefan Fouant (Aug 11)
- Re: OSPF vs IS-IS Joel Jaeggli (Aug 11)
- Re: OSPF vs IS-IS Vinny Abello (Aug 13)
- Re: OSPF vs IS-IS Matt Addison (Aug 13)