Subject: [Isis-wg] Basic Question about IS-IS Routing protocol

From: David Wang <[email-masked]>
Date: Sat, 17 Jun 2000 16:04:26 -0500

Dear Friends,

I need to learn some basics of IS-IS routing protocol and how it works in IP
environment. I cannot find a book, a tutorial or a white paper.

1. Can somebody recommend me some book or tutorial or a white papers?
2. Who is running CLNP instead of IP in their network beside SONET network
management software? Can I learn IS-IS with touch CLNP?
3. What is the major difference between IS-IS and OSPF?
4. When use IS-IS to route IP packets the Link State Advertisement packets
are also IP packets.  People don't have to worry about the OSI CLNP protocol
in IP environment. Is this correct? 
5. Any other comment and information about IS-IS protocol.

Thanks for your help
David

_______________________________________________
Isis-wg mailing list  -  [email-masked]
http://external.juniper.net/mailman/listinfo/isis-wg

---

From: Danny McPherson <[email-masked]>
Date: Fri, 23 Jun 2000 18:20:22 -0600

> 1. Can somebody recommend me some book or tutorial or a white papers?

Radia Perlman's "Interconnections, Second Edition" is the most useful book I'm 
aware of.

> management software? Can I learn IS-IS with touch CLNP?

Yes, as CLNS traffic forwarding isn't required (though OSI stack support is 
per IS-IS packet maintain their original format).  IP-only IS-IS is actually 
the most common implementation of IS-IS today in IP routers (most don't 
support CLNS traffic forwarding).

For IP-only IS-IS, the only OSIish thing you need is NSAP, which is used to 
determine the routers area and give it a system ID.

> 3. What is the major difference between IS-IS and OSPF?

The primary difference is that OSPF is an "open standard protocol", was 
designed expressly for IP, and runs on top of IP.  IS-IS was initially 
designed to support CLNP, then extended to support IP as well.  There are lots 
of other differences, though I'd rather not trigger yet another debate on 
them.  Consulting the MPLS WG mailing list archives, and perhaps the NANOG 
archives (www.nanog.org) should yield some useful information.

> in IP environment. Is this correct? 

No.  IS-IS LSPs (somewhat synonymous to OSPF LS Updates) contain TLVs that 
describe IP or CLNP.  The encapsulation remains the same and OSI stack support 
is required.  Though again, forwarding capability necessarily isn't.

> 5. Any other comment and information about IS-IS protocol.

ISO10589 & RFC 1195 may provide some useful information.  The OSPF RFC(s) 
contain a nice "tutorial" on LS routing and the like.

-danny