Subject: [Capwap] Change Request 9.1.3.1. Support for Local MAC User Data Tunneling

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Wed, 28 Sep 2005 14:32:16 -0700

This change request is to allow for 802.3 tunneling of user data in
local bridging mode. I believe that the changes should be relatively
straightforward, but do introduce an interesting set of complications
that need to be evaluated and agreed upon as a group.
 
The LWAPP protocol currently allows for 802.11 tunneling in Split-MAC
mode, allowing for such things as centralized encryption of user data
frames. However, the current definition of the protocol is that when
running in Local-MAC mode, no traffic is tunneled to the controller.
 
If we were to introduce this change, the LWAPP protocol would have three
modes of operation:
1. Split-MAC: Tunnel native MAC frames in UDP (e.g., 802.11)
2. Local-MAC w/ Local Bridge: Do not tunnel 802.3 frames
3. Local-MAC w/ Tunnel: Tunnel 802.3 frames in UDP
 
The issue that we need to decide as a group is whether we really want a
protocol that has three modes of operation, and if so, which one is
mandatory. The evaluation draft states that option 3 is useful for
support of non 802.11 technologies, but this introduces a set of
restrictions. For instance, today the LWAPP protocol allows for
centralized control of various 802.11 functions, including encryption
and 802.11e. This function is not possible with option 3, and therefore
any new technology that assumes this option would not be able to provide
centralization of data frame functions.
 
There is a comment in the recommendation that LWAPP could retain the
RSSI/SNR fields, and then perform 802.3 encapsulation, allowing the AC
to have more visibility. However, I have had some requests to expand
these fields to also include the data rate. Further, there are possible
fields in the header (of technologies we know nothing about) that the
WTP may want to extract and expose to the AC - and how could this be
done with 802.3?

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems