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New Member

CLNS routing and ISIS


What is the connection between ISIS routing protocol and CLNS? Do I have to enable clns routing to use ISIS?


New Member

Re: CLNS routing and ISIS


You can configure your router to use CLNS Routing to use ISIS. You will need to use the following commands:

globally turn on CLNS Routing with:

clns routing

Assign logical subinterfaces to which ever port you wish to connect to devices using CLNS and assign:

clns router isis TID !where TID is the target id

isis circuit-type level-2-only

isis metric 63

You can decide on what level or routing is needed and what metric you wish to assign to a specific interface.

globally you will need to assign net statements with the NSAP address of each device. For example:

router isis TID

net NSAP

is-type level-1

If you are connecting end systems, such as a management server to your network you replace is with es.

In IS-IS communications routing is allowed where ES-IS communications routing is not allowed to be passed beyond the ES.

Some useful trouble shooting commands;

show clns neighbors detail

show clns route

debug clns packet

ping NSAP

Pay particular attention to the NSAP addresses and their selector as well as the ES-IS and IS-IS settings on external systems. Most systems that are designed for IS-IS have internal configuration parameters that allow you to turn on/off the IS-IS functionality of the system.


Re: CLNS routing and ISIS

You do not need to configure CLNS routing to route IP using IS-IS--just configure the IS-IS process, and configure the interfaces to use IS-IS routing (ip routing is-is).


Re: CLNS routing and ISIS

yeah, don't need it. I believe certain books wrongly state that you do need it, however this is untrue.

New Member

Re: CLNS routing and ISIS

I think Russ covered the configuration portion of your question, in that clns does not have to be enabled to run IS-IS for IP-only operation.

What is the connection between IS-IS and CLNS?

Originally IS-IS was designed to be the routing protocol for CLNS and work in conjunction with ES-IS. IS-IS runs directly over the data link however, so does not require CLNS to operate. The connection is that IS-IS is capable of advertising CLNS NSAPs (Addresses). In RFC 1195, IS-IS was also extended to advertise IP reachability information.

Hope this helps...

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