Capwap Mailing List: Re: capwap transport analysis: QoS vs multiport

[Bob O'Hara (boohara) (boohara]

Scott wrote:

>So if the AC and WTP were to mark control packets 
>so as to make them distinguishable from data packets 
>(using one of the marking methods suggested above, 
>and without relying on client truthfulness), what 
>problems remain? 

As Pat points out in a separate email, the problem of controlling how
the WTP marks those packets remains to be solved.  But, that discussion
can continue in Pat's thread.

Another problem is that the WTP, itself, is not trusted by the network
to which it is attached.  A widespread example is a network of WLAN
hotspots.  The WTPs at the hotspot are connected to the AC over a third
party's network.  

In some of those hotspots, the WTP will be local-MAC.  A hotspot user's
packets from a local-MAC WTP will be able to be inspected at ingress to
the third party's network, since the 5-tuple is clearly available in
those packets.  QoS can be applied to those user data packets, without
requiring any changes to the third party's network equipment.

However, if those same packets are sent to the AC by a split-MAC WTP,
the third party network will not be able to distinguish control packets
from data packets, unless they are sent on separate ports.  In the
CAPWAP packet, the 5-tuple is the same for both control and data.

 -Bob