Subject: RE: [NSIS] RE: Independence of signalling and data path (was RE: [NSIS] Two kindsof requirements)

From: "Glenn Morrow"<[email-masked]>
Date: Mon, 28 Jan 2002 11:09:38 -0600

Marcus,

Here is my opinion on the path-directed or separation question.

It seems to me that some parts of the network will benefit from separate
paths for signaling and bearer data; whereas other parts will not benefit
and will actually be complicated by such a separation. 

The parts that could benefit from a separation are expensive shared media
hops such as cellular and perhaps cable.  

The parts that will not benefit in my opinion is everything else. If
signaling does not follow the path then the signaling nodes will have to
know a great deal of information about routes and routing policies. They
will have to be disclosed either via configuration or cross signaling, the
routing tables, LSPs, VCs, policies and updates. This seems to create a
rather large mess in terms of administrative costs, race conditions,
mismatches in policy and routes between routers and these controllers etc.. 

Mandatory separation would also eliminate the ability to bundle or piggyback
signaling with bearer data.

Sometimes it is beneficial to separate and sometimes it is not. The
architecture could allow for both at different parts of the network;
however, I think the separation is a specific layer 2 optimization issue;
whereas path-directed would be more geared to a general solution for the
connectionless network problem space. 

Glenn

---

From: Marcus Brunner <[email-masked]>
Date: Tue, 29 Jan 2002 11:49:29 +0100

> and will actually be complicated by such a separation.

Glenn, I am not argueing to seperate it always, but for the freedom to 
seperate, depending on the circumstances. As you said a network might 
profit. There also scenarios especially in mobile environamnts and for fast 
re-routing to backup path (with QoS) which some technologies do.

> will have to be disclosed either via configuration or cross signaling,
> the routing tables, LSPs, VCs, policies and updates. This seems to create
> a rather large mess in terms of administrative costs, race conditions,

Knowing about the network in needed anyway thats way we have routing 
protocols running etc.

> Mandatory separation would also eliminate the ability to bundle or
> piggyback signaling with bearer data.
>

I think I am more saying unifying in niot mandatory.

> connectionless network problem space.

Exactly, I would like to be open for different solutions.

Marcus

> Glenn

--------------------------------------
Dr. Marcus Brunner
Network Laboratories
NEC Europe Ltd.

E-Mail: [email-masked]
WWW:    http://www.ccrle.nec.de/
personal home page: http://www.brubers.org/marcus

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