The MPLS WG Archive

["Hass, Barry" <BHass@ciena.com>]

Hi Geoff,

I agree completely with everything you say here. I think that a policy
server (perhaps located in the LSR, perhaps in a separate box) has to
do the classification. And I imagine that classification policies would be
based on fields in the L3 and higher layer headers.

Barry

> -----Original Message-----
> From:	Geoff Bennett [SMTP:geoff.bennett@marconi.com]
> Sent:	Thursday, April 26, 2001 2:32 AM
> To:	Hass, Barry; Marinzulich, Matias; 'Ashwin Moranganti'; 'MP LS';
> MPLS@UU.NET; mpls-ops@mplsrc.com
> Subject:	RE: MPLS Trafficdriven
> 
> Hi Barry,
> Yes it would make sense.  But who sets the DSCP field?
> 
> The "end user" can't be allowed to do this because DSCP is used to
> prioritise traffic, and everyone would set their traffic to high priority.
> 
> The ideal thing would be to build proxy devices to insert the appropriate
> value according to a policy.  IMHO the obvious location for such a proxy
> is
> the Ingress LSR.  But the problem is how do you recognise the appropriate
> traffic types.
> 
> Cheers,
> Geoff
> 
> 
> 
> 
> At 17:14 25/04/01 -0400, Hass, Barry wrote:
> >Hi Geoff,
> >
> >Would it make sense to use the DSCP field for flow aggregation, perhaps
> >in combination with the IP destination address?
> >
> >Barry
> >
> >> It makes sense to pursue the idea of data driven LSP setup, but it's
> >> essential to combine this approach with a flow aggregation mechanism if
> we
> >> expect to deploy such a technology in "large networks" (eg. a Service
> >> Provider).  In theory the Ingress LSR could be given the capability to
> >> aggregate flows of information into a single LSP, but the details of
> how
> >> this could be done are generally clouded in marketing smoke and mirrors
> >> today.  The issue is that IPv4 lacks either a flow label (which IPv6
> has),
> >> or a session identifier (that ISO TP4 has) to provide an easy
> >> classification mechanism.  The current "edge LSR" implementations are
> >> handicapped by these limitations.  So how can they assign or aggregate
> >> traffic?  They are normally limited to assignment on the basis of
> >> destination IP address (essentially useless in most cases), or by the
> use
> >> of the Port ID, or by some combination of these two.  In other words,
> >> whatever criteria you can use to build a filter or ACL, you can use to
> >> assign individual packets to an existing LSP (or as a trigger mechanism
> to
> >> create a new LSP). 
> >> 
> > 
> ================================================================
> Geoff Bennett
> Tel: (33) 497 21 43 62
> Director of Technology, OCTO
> Fax: (33) 497 21 43 50
> Marconi
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> email: geoff.bennett@marconi.com
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> FRANCE
> ================================================================