The MPLS WG Archive

[<benjamin.niven-jenkins@bt.com>]

Colleagues,

I have a question on draft-ietf-mpls-multicast-encaps-01.

The draft essentially redfines ethertype 0x8848 to mean "the top label
is an upstream assigned MPLS multicast label", so why in section 5, GRE
if all the encapsulated MPLS packets have an upstream assigned label is
the Ethertype set to 0x8847?

Ben

Internet-Drafts@ietf.org <mailto:Internet-Drafts@ietf.org> wrote:
> A New Internet-Draft is available from the on-line
> Internet-Drafts directories.
> This draft is a work item of the Multiprotocol Label
> Switching Working Group of the IETF.
> 
> 	Title		: MPLS Multicast Encapsulations
> 	Author(s)	: T. Eckert, et al.
> 	Filename	: draft-ietf-mpls-multicast-encaps-01.txt
Pages		: 9
> 	Date		: 2006-9-8
> 
> RFC 3032 established two data link layer codepoints for MPLS:
> one to indicate that the data link layer frame is carrying an
> MPLS unicast packet, and the other to indicate that the data
> link layer frame is carrying an MPLS multicast packet.  This
> specification updates RFC3032 by redefining the meaning of these two
> codepoints. 
> The former "multicast codepoint" is now to be used only on
> multiaccess media, and it is to mean "the top label of the
> following label stack is an upstream-assigned label".  The
> former "unicast codepoint" is to be used in all other cases.
> Whether the data link layer payload is a unicast MPLS packet
> or a multicast MPLS packet is now to be determined by looking
> up the top label, rather than by the codepoint.
> 
> RFC3032 does not specify the destination address to be placed
> in the "MAC DA" field of an ethernet frame which carries an
> MPLS multicast packet.  This document provides that specification.
> 
> This document updates RFC 3032 and RFC 4023.
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-mpls-multicast-
> encaps-01.txt 
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