Subject: RE: ATM-LSR

From: Hans Sjoestrand <[email-masked]>
Date: Mon, 22 Nov 1999 10:07:56 +0100 (MET)

Scott, Peter or whoever got the answer, 

I think this is more than a Nortel internal question since it deals
with interoperability. Section 7 of draft-ietf-mpls-atm-02.txt defines
extra VCI as a SHOULD. It is however vague of use and encap.

Given the conflicting requirements and the importance of prioritizing
control traffic in an overload situation, the best interpretation of
this would be to handle routing and signalling on 0/32 and the other
unlabeled trafic on another one.  Authers of mpls-atm, is this a fair
interpretation? and implementors, is this the way it is done?

With this solution I would also propose to set nrt-vbr on 0/32 and ubr 
on the unlabelled channel. 

Regards
/// Hasse 

Scott W Brim wrote:
> 
> Albert, talk to your colleagues inside Nortel, for example Riad Hartani, 
> who are helping with these problems.
> 
> At 15:29 11/20/1999 +0000, Albert Pang wrote:
> >Peter Ashwood-smith wrote:    The ATM-LSRs must be running IP/TCP/UDP or 
> >you cannot run MPLS on them.  Normally one of the VCCs on a port is 
> >configured to run classical IP on  ATM. It is over this VCC that all 
> >normal IP traffic flows and it is over  this VCC that OSPF/RIP etc. will 
> >operate to establish connectivity. TCP  then operates over this VCC also 
> >and is used by MPLS for label requests  and mappings.  [Pang, Albert 
> >[HAHN:2870:EXCH]]   Now the hard question is, is there any 
> >recommendation on what ATM Service Category one should use for this 
> >VCC.  'cbr', 'nrt-vbr', 'rt-vbr', 'ubr', 'abr'?
> >
> >In 'draft-ietf-mpls-atm-02' (seciont 7.1) it is mentioned that:
> >
> >    "The default VPI/VCI value for the non-MPLS connection is VPI 0, 
> > VCI     32.  Other values can be configured, as long as both parties 
> > are     aware of the configured value."
> >
> >But there is no recommendation on what ATM service category it should.
> >
> >The use of this IP/1483/ATM connection seems to have conflicting 
> >requirements:  1) LDP and other routing protocols runs on top of 
> >it.  The priority should be high.  2) Normal IP traffic (destinations 
> >that do not have a FEC) also goes through     this VCC (not as important 
> >as LDP/OSPF).
> >
> >How should we resolve this?  Is there a way to setup yet another 
> >separate  channel (vpi.vci) for signaling (e.g. LDP/OSPF) and not for 
> >normal traffic.
> >
> >Thanks.
> >
> >Albert Pang  Nortel Networks Germany
> >
> >
> >
> >
> 
>

---

From: "Peter Ashwood-Smith" <[email-masked]>
Date: Mon, 22 Nov 1999 11:49:06 -0500

> > >separate  channel (vpi.vci) for signaling (e.g. LDP/OSPF) and not for

  It is possible to establish a separate VCC for LDP control. In the
presence of sustained congestion this may be prudent. We have run LDP 
both ways in various trials and apart from the minor annoyance of adding
another VCC there is no real problem having the parallel VCC.

  Cheers,

  Peter Ashwood-Smith