Subject: Comments on draft-ietf-l2vpn-l2tp-radius-vpls-00.txt

From: Sasha Vainshtein <[email-masked]>
Date: Thu, 22 Jan 2004 13:19:29 +0200

Juha, Mark, Stephen and all,
I'd like to raise a couple of issues with 
draft-ietf-l2vpn-l2tp-radius-vpls-00.txt.
These issues both stem from comparison with
draft-ietf-ppvpn-vpls-ldp-01.txt but are, IMO,
orthogonal to "MPLS vs. IP" or "LDP vs. L2TP" plane(s).

1. draft-ietf-ppvpn-vpls-ldp-01.txt explicitly defines that,
in order to achieve loop-free operation without running SPT
across the VPLS, mesh of PE-to-PE Ethermet PWs *and* 
split-horizon forwarding (where frames received from one 
of the PE-to-PE PWs will never be forwarded to another such PW). 
I did not find any reference to split-horizon forwarding in
draft-ietf-l2vpn-l2tp-radius-vpls-00.txt. My understanding is
that this is simply an omission. Is this correct? If yes,
I would suggest at least explicitly stating it in the draft' otherwise
a detailed explanation is clearly required.

2. draft-ietf-ppvpn-vpls-ldp-01.txt defines, in addition to
the "full mesh" VPLS, a hierarchical VPLS formed by two types of
devices:
- PE-rs (which is very much equivalent to the "full mesh" PE)
- MTU-s (which is only connected to one or, possibly two PE-rs 
  in "hub-and-spokes" topology).
My first impression is that such a model is equally applicable
to RADIUS/L2TPv3-based VPLS, but the procedures need to be adapted
accordingly. 

Hopefully these comments will be useful.

With best regards,
                                   Sasha Vainshtein
email:     [email-masked]
tel:       +972-3-7659993 (office)
           +972-8-9254948 (res.)
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