Subject: [NSIS] RE: QoS NSLP open issue on region scoping

From: "McDonald, Andrew" <[email-masked]>
Date: Thu, 26 Feb 2004 14:41:01 -0000

[email-masked] wrote:
> The question is: should  the QoS NSLP specification define and
> support a more generic notion of region (e.g. to implement region
> policies independent from aggregation regions,...)?

A few additional thoughts (not actually attempting to answer the question
yet!):

One example might be where the node at the ingress to an administrative
domain wants to query the available resources in the 'local' network as part
of its local admission control decision.

If it is useful/needed, how should it be done?
One possibility is for a marker that indicates that the message should not
be forwarded outside the local domain, and so is terminated by edge nodes.
However, it can also be argued that this is too fragile, and that there
isn't a safe way to do such scoping.
(The trivial case of 'whole path' vs 'next node' doesn't have this problem.
If you get a message with 'next node only' set then you know you shouldn't
send it any further.)

Should the NSLP do this itself? Or should the NTLP provide some generic
functionality to do this?

Regards,
Andrew

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---

From: "Cheng Hong" <[email-masked]>
Date: Fri, 27 Feb 2004 10:14:11 +0800

Hi all,

<Snip>
> > The question is: should  the QoS NSLP specification define 
> and support 
> > a more generic notion of region (e.g. to implement region policies 
> > independent from aggregation regions,...)?
> 
> One example might be where the node at the ingress to an 
> administrative domain wants to query the available resources 
> in the 'local' network as part of its local admission control 
> decision.
> 
> One possibility is for a marker that indicates that the 
> message should not be forwarded outside the local domain, and 
> so is terminated by edge nodes. However, it can also be 
> argued that this is too fragile, and that there isn't a safe 
> way to do such scoping. (The trivial case of 'whole path' vs 
> 'next node' doesn't have this problem. If you get a message 
> with 'next node only' set then you know you shouldn't send it 
> any further.)

I think another issue is how the node verify the region scope in case of a
generic notion. Considering the error case, if the edge node fail to
terminate the scoped message, can a node find out the message violates the
scope? (Different from the Qspec case, this message could be perfectly
recognizable) One possible solution is to assign each region a unique
identifier and carry the identifier with scope "marker". 

> Should the NSLP do this itself? Or should the NTLP provide 
> some generic functionality to do this?

NSLP has to be involved in a certain way. A simple example, for the "next
node" scope, the actual next NSLP node could be several NTLP hops away.
Also, the scope of the region only has meaning at each NSLP layer. (e.g. the
region for a QoS NSLP would be different for a NAT NSLP at the same NTLP
node.)

Cheers

Cheng Hong