The MPLS-OPS Archive

["Naidu, Venkata" <Venkata.Naidu@Marconi.com>]

Hi Chris

 

I had this question for a long...

* If IS-IS is not using any L3 (CLNP/IP) then

  those IS-IS routing packets can't be forwarded beyond

  1 hope. For example, OSPF packets can be forwarded

  or flooded more than 1 hope in Virtual neighbor

  environment. Am I correct or missing something?

 

* If IS-IS packets are forwarded directly over L2

  then how does it cope up with fragmentation and

  reassembly services. I am not able to visualize

  how IS-IS packets will be transmitted over different

  L2 technologies like ATM and broadcast/multicast capable

  networks etc. How they get code-points?

 

Thanks & Regards --
http://www.geocities.com/kvsnaidu

-----Original Message-----
From: Chris Flores [mailto:chris.flores@onfiber.com]
Sent: Wednesday, April 25, 2001 10:59 AM
To: 'zheng jiang gu'; mpls-ops@mplsrc.com; juniper-nsp@puck.nether.net; Aviva Garrett
Subject: RE: [j-nsp] isis question

My response is in-line. I hope it helps...

-----Original Message-----
From: zheng jiang gu [mailto:zjgu@ce-air.com]
Sent: Tuesday, April 24, 2001 9:15 PM
To: mpls-ops@mplsrc.com; juniper-nsp@puck.nether.net; Aviva Garrett
Subject: [j-nsp] isis question

hi all:

   When I study isis, I meet the problem:

1  Which network layer use to encapsulation isis-pdu?

Is it clnp or ip? 

 

CF: The OSI packets (or PDUs) are forwarded "as is" or transmitted directly over the underlying link layer without the need for encapsulation - per RFC 1195.

 

2  How many IS-IS adjacency between point-to-point routers?

 

CF: IIH (IS-IS Hello) PDUs are utilized to initialize and maintain adjacencies between neighbors. On a p2p link, one neighbor creates one adjacency. Do you have a more specific question that needs answering?

 

br

shawn