The MPLS WG Archive

[Curtis Villamizar <curtis@workhorse.fictitious.org>]

In message <39D359D5.40A77038@marconi.com>, David Charlap writes:
> Curtis Villamizar wrote:
> > Kainia Cloutier writes:
> >>
> >> I'm currently in London, attending the MPLS Next Generation
> >> Networking conference. I came to this conference with one objective:
> >> finding out how to map an LSP to specific ATM switching hardware,
> >> while using RSVP-TE. For the last several weeks, I read RFCs 2205,
> >> 2210, 2212 and several IETF drafts and still couldn't find one paper
> >> describing "an edge LSR, sending a path message with these parameters
> >> set in the ADSPEC and FLOWSPEC object, will receive, from a
> >> downstream node, an ATM CBR label mapping". (and so on and so forth
> >> for RT-VBR, NRT-VBR, UBR label mappings).
> 
> Strangely enough, I haven't been able to locate an RFC or draft that
> maps IntServ-style QoS specs onto ATM-style.  Which does strike me as
> odd.
> 
> > QoS is supported with the services defined in the diff-serv WG and to
> > the extent that diff-serv services such as EF, AF, etc can be mapped
> > onto ATM you have compatibility with the legacy ATM devices.
> 
> It is also supported by signalling QoS vis IntServ objects.  Each ATM
> switch that supports IntServ will have to reserve according to these
> parameters.  If the hardware can only make reservations using ATM-style
> parameters, then some form of mapping will be needed.
> 
> Although there are a number of RFCs that mention RSVP and ATM together
> (2379, 2380, 2381 and 2381), a quick scan of their content didn't reveal
> any standard formulae for converting one style of resource
> representation to the other.
> 
> -- David


MPLS maps into diff-serv.  Diff-serv does not specify how to implement
a behavior, just the desired characteristics.  Forget intserv.  The
RSVP tspec in RSPV/TE just carries the reservation amount (a per PSC
usage is defined).  This and the PHB is all diff-serv needs.

If you think intserv is somehow important and if you think there is
good reason to specify mapping of intserv to ATM, write a draft and
take it to the ISSLL WG (intserv over specific link layers).
Apparently there wasn't enough interest in the combination of intserv
and ATM so far.

Curtis