The MPLS WG Archive

["Philip Matthews" <philipma@nortelnetworks.com>]

ATM switches that I know about use the "SVC Encoding" technique.
(In this technique, the top label is carried in the VPI and VCI
field of the ATM header).

However, there are routers with ATM cards that use a fourth
technique: send all packets over a single VC and use the top
label stack entry to carry the label.

- Philip

Vikram Venkataraghavan wrote:
> 
> In the MPLS Architecture document
> (draft-ietf-mpls-arch-06), there are listed three
> encoding techniques for MPLS labels to encoded
> directly into the VPI/VCI fields in an ATM AAL5
> header.
> 1. SVC Encoding
> 2. SVP Encoding
> 3. SVP Multipoint Encoding
> 
> The document also points out that there is no
> interoperability mechanism between ATM LSRs that use
> different kinds of encoding.
> 
> Please tell me which kind of encoding is prefered in
> the industry and why? (concerning the design of ATM
> LSRs)
> 
> Thanks in advance,
> Vikram Venkataraghavan
> NEC America