Subject: Re: Draft Minutes From Pittsburgh

From: Kireeti Kompella <[email-masked]>
Date: Tue, 17 Oct 2000 21:58:18 -0700 (PDT)

Hi Yangguang,

> One implication Frank hinted is that:
> 
> For A----B, even there could be many bundles between A and B, there needs only
> one control channel (no need for physical channel, a TCP session is enough)
> between them. Bundle in circuit network is different from "interface" in IP
> network in the sense that a bundle can be included in one LSA, but only send to
> neighbor once.

You have a good point.  In section 3.2 of the bundling document, it
says that a bundle must have a control channel, but is not very
clear that multiple bundles can share a control channel.  We will
make this clearer in the next revision.

Meanwhile, let me say this explicitly: between a pair of GLSRs (i.e.,
LSRs, OXCs, SXCs, ...), the requirement is that there must be at
least one control channel; the requirement is *not* one per bundle.
Corresponding to this control channel, one routing adjacency is
needed.

The routing module can generate LSAs for all the bundle(s) assigned
to a control channel when both the control channel adjacency is up
and the bundles are up (LMP can be used to say when the bundles are
up).  If a bundle changes, the LSA corresponding to that bundle alone
is re-flooded.

This addresses the issue of flood optimization: having multiple
bundles does *not* mean having multiple adjacencies, so flooding
optimization is not a requirement.

Kireeti.

---

From: "Frank Hujber" <[email-masked]>
Date: Wed, 18 Oct 2000 07:11:30 -0400

Kireeti, et al,

Consider three routers as a small segment of a larger optical network, A, B,
and C. A and B areOXCs and are directly connected by a DWDM with some number
of lightpaths. However, their control plane connection is through C, which
is a pure IP router, not an OXC. We've made the (painful) assumption that
the customer/provider has such demand for his lightpaths that he does not
want to sacrifice a wavelength for control. It would seem possible to manage
optical links A-to-B with a LSP A-to-C-to-B as along as A and B knew their
optical connectivity and C knew that it was not part of the optical path.

We do regard this as a degerate case, but one that we must (here in NJ) be
prepared to support.

Frank Hujber
[email-masked]

---

From: Yangguang Xu <[email-masked]>
Date: Wed, 18 Oct 2000 09:35:00 -0400

Kireeti,

> Corresponding to this control channel, one routing adjacency is

The key point is that routing adjacency in circuit switched network data plane
has nothing to do with control channels (the control plane). At least there
shouldn't be any assumption about their co-existence.

For each routing adjacency (in data plane), you only need a TCP session as Frank
hinted. Not necessary a physical control channel.

> up).  If a bundle changes, the LSA corresponding to that bundle alone

I agree your point of flooding control. 

BTW, I had a feeling that LMP suggest control channel for each bundle. (I read
it long time ago, can't remember exactly). If this is the case, it's simply not
right. For example, a OXC has 10 neighbors, between each neighbor there are 2
bundles, then do you need 20 control channels? NO!

Bundle has nothing to do with control channel.

> optimization is not a requirement.

Agree,

---

From: Bala Rajagopalan <[email-masked]>
Date: Wed, 18 Oct 2000 10:55:45 -0400

Kireeti:

I think we're beginning to reach some convergence here.

> make this clearer in the next revision.

I have had private discussions with Jonathan about this in the context of LMP.
Specifically, I wanted to remove the one-to-one association between
control channels and bundles, and make it possible to have a single
control channel for multiple bundles.
LMP presently doesn't support this.

> Corresponding to this control channel, one routing adjacency is

But if you use LMP underneath, you WILL get multiple control
channels (and hence multiple adjacencies). The single adjacency
is the entire rationale
for our proposal (leaving aside more straightforward parameters for
SONET links). If you can incorporate this feature in your proposal,
it'd be close to our proposal. However,  the LMP spec needs to
change. (I had indicated specific changes in LMP messages for this
to Jonathan).

> up).  If a bundle changes, the LSA corresponding to that bundle alone

The details need to be provided for this.

> optimization is not a requirement.

My contention is that this is not at all evident from your present set of
drafts (and LMP).  And, this is the chief contribution of our draft.

If you can incorporate the support for single control channel for multiple
bundles, and provide more details on how adjacencies are maintained,
flooding procedures, etc, we'd be happy to consider the resulting
draft.

regards,

--

Bala Rajagopalan
Tellium, Inc.
2 Crescent Place
P.O. Box 901
Oceanport, NJ 07757-0901
Tel: (732) 923-4237
Fax: (732) 923-9804
Email: [email-masked]