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Document Action: 'L2TP Active Discovery Relay for PPPoE' to Informational RFC



The IESG has approved following document:

- 'L2TP Active Discovery Relay for PPPoE '
   <draft-dasilva-l2tp-relaysvc-08.txt> as an Informational RFC

This document is the product of the Layer Two Tunneling Protocol Extensions 
Working Group. 

Note: it was originally intended was that this document be on
standards track (i.e., it was Last Called as a Proposed Standard). But
the document contains a normative reference to RFC 2516, an
informational document. Per RFC 2026, Standards Track documents cannot
have normative references to informational documents.

One consequence of the discussion of the reference issue that occured
with this document, is that the document draft-ymbk-downref-00.txt was
developed. If and when the downref document (or something like it)
becomes a BCP, it is intended that the l2tp document be moved the
Standards Track.

The IESG contact persons are Thomas Narten and Margaret Wasserman.

Technical Summary
   
PPPoE is often deployed in conjunction with L2TP to carry PPP frames
over a network beyond the reach of the local Ethernet network to
which a PPPoE Host is connected. For example, PPP frames tunneled
within PPPoE may be received by an L2TP Access Concentrator (LAC) and
then tunneled to any L2TP Network Server (LNS) reachable via an IP
network.

In addition to tunneling PPP over Ethernet, PPPoE defines a simple
method for discovering services offered by PPPoE Access Concentrators
(PPPoE AC) reachable via Ethernet from the PPPoE Host. Since the
packets used in this exchange are not carried over PPP, they are not
tunneled with the PPP packets over L2TP, thus the discovery
negotiation cannot extend past the LAC without adding functionality.

This document describes a simple method for relaying PPPoE Access
Discovery (PAD) messages over L2TP by extracting the PAD messages and
sending them over the L2TP control channel. After the completion of
setup through the processing of PAD messages, PPP packets arriving
via PPPoE are then tunneled over L2TP in the usual manner as defined
in L2TP [2]. Thus, there are no data plane changes required at the
LAC or LNS to support this feature. Also, by utilizing the L2TP
control channel, the PPPoE discovery mechanism is transported to the
LNS reliably, before creation of any L2TP sessions, and may take
advantage of any special treatment applied to control messages in
transit or upon receipt.
   
Working Group Summary
   
There was support for this document in the WG.
   
Protocol Quality
  
This document has been reviewed for the IESG by Thomas Narten.