The MPLS WG Archive

["Naidu, Venkata" <Venkata.Naidu@Marconi.com>]

Hi Niel
  It is very much possible to negotiate MPLS ATM label when
2 ATM LSRs/LERs are connected (RFC3038 explains) in different 
scenarios:

* If MPLS capable ATM LSRs are connected directly then
  you don't need VCID. Because local significant VPI/VCI are 
  same at both ends of PVC/SVC.

* If MPLS capable ATM LSRs are not connected directly (i.e.,
  to a pure ATM cloud):
   - If VP switching is used, then VCI is used as MPLS label.
     Because intermediate ATM switches won't look at/modify 
     VCI field. 
       - VCID exchange is not required. VCI may be used as VCID.
         This is a common scenario used by most of the current
         implementers. 
       - You can negotiate/configure VPID.

   - If VC switching is used, then VPI/VCI may not be same
     at both ends of LSRs. So you need to map VCID to a VC
     in both LSRs.

Of course, we can use inband/outband notification of VPID/VCID.

Thanks & Regards
Venkata Subbaiah Naidu
--
http://www.geocities.com/kvsnaidu 


> Hello all
> 
> I have some questions about 2 MPLS LSR's between a normal ATM network.
> Is this possible with VCID notification RFC 3038? They 
> describe a mechanism 
> to connect a VC identifier to vci/vpi. With the meaning when 
> that the upper 
> label which normaly is encoded in vpi/vci will arive at the other LSR 
> clearly (without being switched) when there are some other 
> ATM switches 
> between it. Could anyone explain me some more about this??
> 
> Thanks for anwsering my question.
> 
> With kind regards,
> 
> Niels Sitters