Subject: [Isis-wg] I-D Action:draft-ietf-isis-mi-00.txt

From: [email-masked]
Date: Mon, 18 Feb 2008 09:15:02 -0800 (PST)

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the IS-IS for IP Internets Working Group of the IETF.

	Title           : IS-IS Multi-Instance
	Author(s)       : S. Previdi, et al.
	Filename        : draft-ietf-isis-mi-00.txt
	Pages           : 9
	Date            : 2008-02-18

This draft describes a mechanism that allows a single router to share
one or more links among multiple IS-IS routing protocol instances.

Multiple instances allow the isolation of resources associated with
each instance.  Routers will form instance specific adjacencies,
exchange instance specific routing updates and compute paths
utilizing instance specific LSDB information.  Each PDU will contain
a new TLV identifying the instance to which the PDU belongs.  This
allows a network operator to deploy multiple IS-IS instances in
parallel, using the same set of links when required and still have
the capability of computing instance specific paths.  This draft does
not address the forwarding paradigm that needs to be used in order to
ensure data PDUs are forwarded according to the paths computed by a
specific instance.

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From: Vishwas Manral <[email-masked]>
Date: Mon, 18 Feb 2008 09:41:02 -0800

Hi,

I looked at the idea of the draft. Though we say it will work fine with 
older IS-IS implementations which do not support this functionality. I 
guess we need all instances on a network to support it before we can 
turn on the functionality on a network.

Unlike in OSPF, where a use of the functionality without all routers 
supporting it will result in adjacencies not being formed at all.

Thanks,
Vishwas

[email-masked] wrote:
> ------------------------------------------------------------------------

---

From: "Les Ginsberg (ginsberg)" <[email-masked]>
Date: Mon, 18 Feb 2008 10:16:17 -0800

Vishwas -

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On
Behalf
> Of Vishwas Manral
> Sent: Monday, February 18, 2008 9:41 AM
> Cc: [email-masked]
> Subject: Re: [Isis-wg] I-D Action:draft-ietf-isis-mi-00.txt
> 
> Hi,
> 

I am having trouble understanding the concern behind your comment.

Let's suppose we get to a point where all routers support the MI
extension. They still have to be configured to support a particular
instance (say #10) on a set of interfaces. If all the configuration for
instance #10 is not present, the topology will be less than what is
desired. How does this differ from the case where some routers don't
support MI at all?

This isn't a tool to provide automatic configuration.

So partial deployment of MI may be just fine if the set of links desired
for a particular topology is restricted. It is up to the customer as to
when it is useful to turn on.

   Les

> > This draft is a work item of the IS-IS for IP Internets Working
Group of
> the IETF.
> > You can also visit
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