Subject: About draft-kompella-ppvpn-dtls-02.txt

From: lidefeng <[email-masked]>
Date: Tue, 29 Apr 2003 11:44:05 +0800

Hi,all,

In section "5.4. Packet Forwarding" of
draft-kompella-ppvpn-dtls-02.txt,there is a paragraph illustrating an
example,the figure and the forwarding procedure is as follows:

" Figure 1

       {A,0,k} <- +-------+       W  ->      +-------+ -> {A',0,k'}
      ============| PE X  |<****************>| PE X' |=======[L2PE U']
      |           +-------+       W' <-      +-------+
      |  announces {K,0,k} \                /  announces {K',0,k'}
      | for L2PE U, site ID p\              /   for L2PE U', site ID p'
      |                      ..............
   [L2PE U]                  .    core    .
      |                      ..............   announces {L,0,l} for
      | announces {M,0,m}   /              \ L2PE V, site ID q
      | L2PE U, site ID r   /      announces \        -> {B,0,l}
      |           +-------+       {L',0,l'}  +-------+=======[      ]
      ============| PE Z  |       for L2PE V, | PE Y  |       [L2PE V]
       {C,0,m} <- +-------+       site ID q' +-------+=======[      ]
                                                      -> {B',0,l'}
   Say an endpoint "behind" L2PE U decides to send a VPLS T packet to
   some endpoint "behind" L2PE U'.  All L2PE U knows about L2PE U' is
   that its site ID is p', i.e., to send packets to L2PE U', L2PE U must
   use label (A+p') (how it arrives at this is described in the section
   on learning).  The L2PE route at PE X states that the label (A+p') is
   swapped with (K'+p), and the packet is put in tunnel W to PE X'.
   When PE X' gets the packet, it removes the packet from the tunnel,
   and sees label (K'+p).  PE X' swaps the label with (A'+p) per its
   L2PE route, and sends this packet to L2PE U'.  Seeing label (A'+p),
   L2PE U' knows that the packet is a VPLS T packet which originated at
   L2PE U (i.e., the L2PE with site ID p).
"

What I am concerned is when the packet of the subtended customer site arrivs
the local PE and is sent from the PE to L2PE,if the label is carried in the
packet? From the above example,the packet is labeled,if so,then the label
should be assigned and distributed by L2PE to PE,but in the above
example,the label is assigned and distributed by PE to L2PE(the label A'+p
is assigned by PE X' to L2PE U').If this procedure is somewhat incorrect?
Could anyone please clarify this question?

Thanks very much!

Li Defeng