Subject: [PWE3] One clarification needed on Multi-segment PW with FEC 128

From: "Dutta, Pranjal" <[email-masked]>
Date: Mon, 7 Aug 2006 13:26:46 +0530

Hi All,

                  I am looking for one clarification on the solutions
proposed in draft "Segmented Pseudo Wire" applying to the following
scenario:

        A-------------B---------------C        

             T-PE                       S-PE
T-PE

                   I need two Ethernet PWs from A - 1) one SS-PW1 from A
to B and 

                                                                      2)
one MS-PW2 from A to C via B (so B is PW switching point) 

                   Native traffic sent from A over PW1 should reach only
B.

                   Native traffic sent from A over PW2 should reach only
C.

                Now I want to create VPLS like full-mesh between A, B
and C with LDP FEC 128 in the above way. 

                The following is from the draft -

   6.1.3. LDP using FEC 128 to LDP using the generalized FEC 129
 
   When a PE is using the generalized FEC 129, there are two distinct
   roles that a PE can assume: active and passive. A PE that assumes the
   active role will send the LDP PW setup message, while a passive role
   PE will simply reply to an incoming LDP PW setup message. The PW
   switching point PE, will always remain passive until a PWID FEC 128
   LDP message is received, which will cause the corresponding
   generalized PW FEC LDP message to be formed and sent. If a
   generalized FEC PW LDP message is received while the switching point
   PE is in a passive role, the corresponding PW FEC 128 LDP message
   will be formed and sent.
 
   PWIDs need to be mapped to the corresponding AGI/TAI/SAI and vice
   versa.  This can be accomplished by local PW switching point
   configuration, or by some other means, such as some form of auto
   discovery. Such other means are outside the scope of this document.
 
                So, First the SS-PWs will be formed between A-B and B-C
by usual procedures in PWE3-CTRL. Then B (S-PE) advertises its binding 
                and performs the switching. Now for VPLS like service
with FEC 128 we have to signal the same vc-id from A to B for both PW1
and PW2.
                So what would be the differentiator a B between the
mappings for PW1 and PW2 received? 
        How the switching would be done for PW2?
        
    The draft doesn't specify exact procedures for PW switching though
LDP in this kind of scenario. Is there any work going on in PWE3 WG to
address it?
        Any clarification would be greatly appreciated.
 
Thanks,
Pranjal    

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---

From: "Dutta, Pranjal" <[email-masked]>
Date: Mon, 7 Aug 2006 13:51:24 +0530

I have found my answer in draft "Dynamic Placement of Multi Segment
Pseudo Wires". Sorry for the previous mail.
 
Thanks,
Pranjal

________________________________

From: Dutta, Pranjal 
Sent: Monday, 07 August, 2006 1:27 PM
To: [email-masked]
Subject: One clarification needed on Multi-segment PW with FEC 128

Hi All,

             T-PE                       S-PE
T-PE

                                                                      2)

 

        
 
Thanks,
Pranjal