Re: [OPSAWG] Fwd: Alternate Tunnel Encapsulation for Data Frame in CAPWAP

Qiao Fu <> Mon, 24 February 2014 06:16 UTC

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Subject: Re: [OPSAWG] Fwd: Alternate Tunnel Encapsulation for Data Frame in CAPWAP
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Hi, all. I have read through the draft and here are some comment.

This draft addresses on two shortcomings of the current CAPWAP. 
1) the current one does not allow the WTP to tunnel data frames to an
endpoint other than AC;
2) it does not allow the WTP to tunnel data frames using any encapsulation
other than CAPWAP.
This draft presents a case in which the WTP may have the requirement to
tunnel a frame to an AR but not an AC. Moreover, when tunneling to an AR,
the choice of tunnel encapsulation may be extended to other types, such as
L2TP, L2TPv3, IP-in-IP, IP/GRE and etc.. The authors further describe how
the WTP can be configured with this alternate tunnel. The suggested
procedure to establish the alternate tunnel encapsulation is also presented.

The case presented in the draft is quite clear, and the solution of
alternate tunnel encapsulation in the draft is quite straightforward.
Therefore, I support for working group adoption.

Best regards!
Qiao Fu

发件人: OPSAWG [] 代表
发送时间: 2014年2月19日 9:00
主题: OPSAWG Digest, Vol 81, Issue 35

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Today's Topics:

   1.  Fwd: Alternate Tunnel Encapsulation for Data Frames in
      CAPWAP (Melinda Shore)


Message: 1
Date: Tue, 18 Feb 2014 16:00:00 -0900
From: Melinda Shore <>
To: "" <>
Subject: [OPSAWG] Fwd: Alternate Tunnel Encapsulation for Data Frames
Message-ID: <>
Content-Type: text/plain; charset="iso-8859-1"

Please note that Rajesh is planning to ask for working
group adoption of this document.  Please give it a read
and provide feedback on this mailing list.  Particularly
interested in the question of how well it meshes with
CAPWAP documents we've already adopted.


-------- Original Message --------
Subject: 	[OPSAWG] Alternate Tunnel Encapsulation for Data Frames in
Date: 	Tue, 18 Feb 2014 22:10:10 +0000
From: 	Rajesh Pazhyannur (rpazhyan) <>
To: <>


We have a submitted a new version of Alternate Tunnel Encapsulation for
Data Frames in


   In centralized IEEE 802.11 Wireless Local Area Network (WLAN)
   architecture, the Access Controller (AC) isn't intelligent enough
   actually to aggregate all the wireless frames, even the bandwidth
   requirement in the access point is increasing.  Thus it is a general
   case in the existing operator's network that WTPs forward the
   wireless frames directly to Access Router (AR) to avoid overload on
   the AC.  In this scenario, CAPWAP Control Channel and CAPWAP Data
   Channel are separated from each other.  This document extends CAPWAP
   for applicability of CAPWAP Control and Data Channel separation.

We received some questions and suggestions from Dan Romascanu and John
Kaippallimalil on the mailing list on the previous draft. We have
attempted to address them in this draft. Specifically,

 1. How does this draft address signaling, discovery mechanisms related
    to setting up alternate tunnel. (ans. Tunneling protocols like
    L2TPv3, IP/GRE (PMIPv6) already have a signaling mechanism. This
    draft focuses on specifying the tunnel type and provides a container
    to hold message elements)
 2. Need for alternate tunnel encapsulation (given the existence of
    defined mode with local bridging)

We would like to get it adopted as a working group item and would like
feedback on whether we are on track.




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