RE: OSPF LSA type 3 filtering

> IS-IS supports multiple routed protocols, i.e. IPv4 and IPv6, whereas OSPF doesn't.

Interestingly enough, now as of 15.1(3)S and 15.2(1)T, OSPFv3 supports IPv4 address families. This is as per RFC 5838, "Support of Address Families in OSPFv3".

This essentially puts OSPFv3 (but still not OSPFv2) on par with IS-IS as supporting both IPv4 and IPv6 routing. Right now there is a key limiting factor in the deployment though:

"The OSPFv3 address families feature is supported as of Cisco IOS Release 15.1(3)S and Cisco IOS Release 15.2(1)T. Cisco routers that run software older than these releases and third-party routers will not neighbor with routers running the AF feature for the IPv4 AF because they do not set the AF bit. Therefore, those routers will not participate in the IPv4 AF SPF calculations and will not install the IPv4 OSPFv3 routes in the IPv6 RIB."

http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-ospf.html#wp1086084

Eventually down the road once all your devices run OSPFv3 for IGP routing you can then pick redistribution points between OSPFv3 and OSPFv2 for IPv4, and slowly start to migrate OSPFv2 out of the network.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com
B
Internetwork Expert, Inc.
http://www.INE.com

-----Original Message-----
From: Marko Milivojevic [mailto:markom_at_ipexpert.com]
Sent: Friday, January 04, 2013 1:05 PM
To: Imran Ali
Cc: Joseph L. Brunner; Carlos G Mendioroz; Brian McGahan; Narbik Kocharians; Cisco certification
Subject: Re: OSPF LSA type 3 filtering

IS-IS supports multiple routed protocols, i.e. IPv4 and IPv6, whereas OSPF doesn't.

Also, in the time when MPLS-TE was emerging as a technology, IS-IS behavior to flood unknown TLVs instead of resetting adjacencies when it receives them (OSPF does that when it receives an unknown LSA).
meant a very controlled deployment of new technologies. The fact it's not IP, also has some security benefits (cannot be remotely attacked).
Etc.

What Joseph said is... not quite the reason, since IS-IS also has a requirement for a contiguous L2 area.

--
Marko Milivojevic - CCIE #18427 (SP R&S) Senior CCIE Instructor - IPexpert
Blogs and organic groups at http://www.ccie.net