Subject: About Aggregate Tree definition and comments for draft-ietf-l3vpn-2547bis-mcast-03.txt

From: [email-masked]
Date: Fri, 3 Nov 2006 10:52:07 +0800

Hi all
 
   I have two questions about the draft. Thanks.

   First: About definition and my comments
   A P-multicast tree can be used to instantiate a PMSI service for only
   one MVPN or for more than one MVPN. When a P-multicast tree is shared
   across multiple MVPNs it is termed an Aggregate Tree [RAGGARWA-
   MCAST]. 
 
   The above sentence define the concept of Aggregate Tree, which implies
   that Aggregate Tree is shared by more than one MVPNs. This is the case
   for I-PMSI, while for S-PMSI, an ingress PE could assign a unique label
   to each C-(S,G)(described in the end of section 6.3.4), which implies
   that an Aggregate Tree can shared by more than one C-(S,G), and these 
C-(S,G)
   may belong to the same MVPN. Then the definition of Aggregate Tree is
   not clearly for S-PMSI.
   Maybe the definition should be "When a P-multicast tree is shared
   across multiple PMSIs, it is termed an Aggregate Tree". Just a 
suggestion.
 
   What's more, ingress PE still assign a unique label to each MVPN for 
S-PMSI,
   and each S-PMSI belong to the same MVPN use the same demultiplexing 
label.
   In that case, the above definition of Aggregate Tree is correct for 
both
   I-PMSI and S-PMSI.
 
   The two label assignment method described above for S-PMSI require 
different
   forwarding process. We define the method as follows:
   a. A unique demultiplexing label is assigned to each C-(S,G) or S-PMSI
   b. S-PMSIs belonging to the same MVPN are assigned the same 
demultiplexing label
 
   For method a, when egress PE receive the multicast packet, it can 
directly get the
   outgoing interface to lookup the demultiplexing label. And for method 
b, egress
   PE should lookup the demultiplexing label to get MVPN forwarding table, 
and find
   the outgoing interface through MVPN forwarding table.

   Second:
   At the beginning of section 7.4, the sentence "The procedures of 
section 7.3 tell 
   a PE when it must start listening" should be "The procedures of section 
7.2.2.3 
   tell a PE when it must start listening"

   Best Regards
   Jin Lizhong

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