Re: l2vpn framework issue

[Ali Sajassi <[e-mail]>]

Hi Eric,

By defining the three models for VPLS-PE, it makes it more clear than what 
it was before. However, it seems you use the term VPLS instance to refer to 
a group of PWs as their associated forwarders, right ? Previously, the term 
VPLS instance was used to refer to a service instance (uni-to-uni) 
including the portion over IP/MPLS. The figure 2 in framework includes a CE 
connected to a VPLS-PE over an access network (e.g., QinQ) and the CE is 
marked to be included in that service instance. And that is consistent with 
my understanding. In other words, I consider a VPLS instance as a service 
instance that is between uni to uni and spans across access networks as 
wells as core MPLS/IP network.

We can call, the group of PWs and their associated forwarder an emulated 
LAN that can correspond to one or more VPLS instances. If it corresponds to 
a single VPLS instance, then we also refer to it as emulated VLAN because 
it looks like a VLAN to a bridge module.

Besides indicating which of these models a given solution uses, it should 
also indicated if the bridged module that it uses, is the standard IEEE 
802.1 bridged module or not.

-Ali

At 01:08 PM 7/29/2003 -0400, Eric Rosen wrote:
>Awhile back  we had a  discussion of  the VPLS model  in this doc,  but that
>discussion is not reflected in draft-ietf-l2vpn-l2-framework-00.txt which is
>now being last called.
>
>My proposal  is to add the  following text at  the end of section  2.2 (just
>before  section  2.2.1).  I  think  this  text does  the  proper  job for  a
>framework document,  i.e., places the  controversial issue in  context while
>leaving the resolution of the controversy to the solutions work.
>-------------------------------------------------------------------------------
>
>    This framework specifies that each "bridge module" has a single
>    "Emulated LAN interface".  It does not specify the number of bridge
>    modules that a VPLS-PE may contain, nor does it specify the number of
>    VPLS instances which may attach to a bridge module over a single
>    "Emulated LAN interface".
>
>    Thus the framework is compatible with at least the following three
>    models:
>
>      - Model 1
>
>        A VPLS-PE contains a single bridge module, and supports a single
>        VPLS instance.  The VPLS instance is an Emulated LAN; if that
>        Emulated LAN contains VLANs, 802.1Q tagging must be used to
>        indicate which packets are in which VLANs.
>
>      - Model 2
>
>        A VPLS-PE contains a single bridge module, but supports multiple
>        VPLS instances.  Each VPLS instance is thought of as a VLAN (in
>        effect, an "Emulated VLAN"), and the set of VPLS instances are
>        treated as a set of VLANs on a common LAN.
>
>      - Model 3
>
>        A VPLS-PE contains an arbitrary number of bridge modules, each of
>        which attaches to a single VPLS instance.
>
>    There may be other models as well, some of which are combinations of
>    the 3 models above.  Different models may have different
>    characteristics, and different scopes of applicability.
>
>    Each VPLS solution should specify the model or models that it is
>    supporting.
>
>    This framework does not specify the way in which bridge control
>    protocols are used on the Emulated LANs.