Subject: MPLS Label Stack Encoding

From: Mark Stewart <[email-masked]>
Date: Mon, 20 Nov 2000 14:55:42 -0500

Hi All

"draft-ietf-mpls-label-encaps-08.txt"  defines distinct
protocol/ethertype fields for MPLS unicast and MPLS multicast. I find it
strange to add address space information to the protocol type field, and
am curious if someone can clarify why this separation of label spaces
was mandated?

Further I am curious as to what constitutes an MPLS multicast packet in
this case. Does it apply on a specific hop, or must the multicast
property be preserved end to end?

Can a multicast packet be tunneled through a unicast LSP?

ciao

mark

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From: Curtis Villamizar <[email-masked]>
Date: Tue, 21 Nov 2000 13:56:45 -0500

> Can a multicast packet be tunneled through a unicast LSP?

Because a unicast tunnel has one destination and a multicast tunnel
may have replication points and multiple destinations.

The shorter answer is the two don't go to the same place and if you
stuck them in the same LSP you'd have to look under the label at each
IP header to figure out how to forward.  Sort of defeats the purpose
doesn't it.

Curtis