Subject: RE: [Capwap] comment about LWAPP and other wireless technologies

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Wed, 3 Aug 2005 06:15:22 -0700

> Pat,
> As I indicated below, there are cases where local AP is 
> implemented and in addition there is small deployment 
> scenarios, will not really burden the CPU. Also, a packet 
> doesn't need to be sent per each data packet but rather only 
> when a threshold is met

How do you define an RF threshold, and given the wide variations that
can exist between packets in most environments, how do you guarantee
that this doesn't negatively impact the WTP/AC performance?

> 
> But regardless, 802.3 frames seems to me to be the more 
> generic case, while 802.11 is a specific media, not related 
> to the AC technology which is usually Ethernet. And as 
> indicated on a different mail thread, seems that with the 
> 802.11 frame format, LWAPP is not fully compliant with the 
> CAPWAP objectives (supporting all wireless formats) 
Respectfully disagree. We haven't decided how 802.16 is mapped onto the
CAPWAP protocol. Therefore the LWAPP protocol allows it by being
flexible in allow the native frames to be tunneled. So it does in fact
comply with the standard.

Pat Calhoun
CTO, Wireless Networking Business Unit Cisco Systems
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---

From: Tal Anker <[email-masked]>
Date: Wed, 3 Aug 2005 16:33:30 +0300 (IDT)

> comply with the standard.

Indeed semantically this makes the LWAPP is compliant with the standard.
However, it also means that when for instance an 802.16 WTP will
 be introduced, the AC would need to be adapted to process, in the data
plane, the 802.16 native frames...  I would be more concerned by the
implication of this (because in many cases it would imply HW upgrade to
the AC) than any other concern I've heard till now (e.g. the SW image
download in the other email thread...).

As was already suggested - why not supporting both modes? Sending the
fames in the AC native format and not the WTP wireless native format would
mean that in high probability you will only need to upgrade the AC SW and
not the silicon...

- Tal

=====================================================================
Tal Anker, PhD.
DANSS - Distributed Algorithms, Networking and Secure Systems Group.
The School of Engineering and Computer Science,
The hebrew University of Jerusalem,
Israel.