Subject: Re: [mpls-tp] Interworking

From: [email-masked]
Date: Thu, 30 Apr 2009 08:36:35 +0200

Hi Maarten,

Please see inline. 

-----Original Message-----
From: Maarten Vissers [mailto:[email-masked]] 
Sent: Thursday, April 30, 2009 12:55 PM
To: [email-masked]; [email-masked]
Subject: RE: [mpls-tp] Interworking

Hi Jing,

The difference between (3) and (4) is the following:

(3) all services are supported via the EVC layer; i.e. the EVC layer is the 
service/channel layer and starts/ends at the UNI-N ports. The PW is a SS-PW 
layer and monitors p2p EVC link connections.

PE nodes switch/bridge only EVC signals (as all customer service signals are 
supported via EVCs).

------

(4) the p2p and p2mp services are supported via the PW layer (MS-PW) and the 
rmp and mp2mp services are supported via the EVC layer; i.e. the PW layer is 
the service/channel layer for p2p/p2mp services and for those services 
start/end at the UNI-N ports, while the EVC layer is the service/channel layer 
for rmp/mp2mp services and for those services start/end at the UNI-N ports.

Jingrq->So you mean for  the rmp and mp2mp services, we don't need PW layers. I 
think there are two problems with this approach. Firstly, this is different 
from the practice of VPLS in MPLS network. Secondly, I think there are 
scalability problem in core network without PW layers.

Rmp/mp2mp customer services (Ethernet) are either clients of the EVC layer, or 
peer with the EVC layer.

P2p/p2mp customer services (PDH, SDH, ATM, Ethernet, ..) are clients fo the PW 
layer (and may in future also peer with the PW layer).

PE nodes will be able to switch/bridge both PW and EVC signals. Switch fabrics 
must support as such PW switching and Ethernet bridging/switching.

PW connections terminate on the UNI-N ports for the case of p2p/p2mp services. 
PW connections terminate on the NNI ports for the case of rmp/mp2mp services. 

------

Interconnecting a MPLS-TP domain according to layer stack (4) with an Ethernet 
domain with layer stack (5) via an 802.3 interface results in the following for 
rmp/mp2mp services (Ethernet E-Tree, E-LAN):

    (5)                         (4)
-----------------------------------
|   EVC           EVC       EVC   |
----------------------------------------
|   EVP    |   | 802.3 |    |    PW    |
------------   ---------    ------------
| T.Media  |                |   LSP    |
------------                ------------
                            |  T.Media |
                            ------------

Jingrq-> I think above layer stack should be the common one for all the 
services, not only for EVC, but for all the services  (PDH CES, ATM, SDH 
CES, ..)

Best Regards
 
Jing Ruiquan