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

[Bob O'Hara (boohara) (boohara]

Scott,

[snip]

Let's start with the premises and the comment immediately following
them:

> (1) intermediate network elements between the WTP and AC must 
> be able to re-mark packets
> 
> (2) in particular, they need to ensure that control traffic 
> is treated at a higher priority than data traffic
> 
> (3) some customers will want to send control down a different 
> path than data to achieve this (or some other) objective
> 
> (4) many of these elements can only classify traffic based on 
> 5-tuples; they apparently cannot use VLAN tags or 1:1 
> mappings of DSCP/802.1q/802.1d mappings
> 
> Bob>> The statement has been made by several posters not that 
> the equipment cannot do this, but that it will not do it, 
> because the source of any QoS marking at the WTP may not be 
> trusted.  The reason for this is that the source of this QoS 
> marking is the client, not the WTP and the client is not 
> trusted to mark QoS properly.  Therefore any mapping of that 
> QoS by the WTP cannot be trusted, either.  More on this, below.

I assume this is meant to refute premise (4), based on the supposition
that the only way to mark traffic is by copying WMM/.11e markings. This
is not the case, as we know that WTPs and ACs can be programmed to
classify traffic and mark it accordingly. 

Bob>> This statement is to refute the claim made in premise (4) that the
equipment cannot use VLAN tags or mappings of the DSCP/802.1Q/802.1D
information in the frame/packet received from the 802.11 client device.
The equipment could use it, if the information were trusted.  The
information is not trusted.  Therefore, the information cannot be used.

 -Bob