Wireless rate limit

Question

Hi,
My network infrastructure as simple as following:
LAN(edge switches 3560).......>Aggregator switch(3750)........>Firewall(ASA 5510)........>Router.......>Internet
I define 3 wireless VLANs with 3 SSIDs on the Aggregator switch(3750):
1. one SSID for company employees.
2. one SSID for wireless IP phones.
3. one SSID for company guest which access only internet.
And the wireless APs connected to the LAN(edge switches) direct with trunks.
My question is how to apply a rate limit for SSID for company guest to access internet with B.W. of 128kbps only.
I tried policy map to be applied on the aggregator switch(3750) on the VLAN interface, but, it is not working.
So, any suggested help, please.

Answer 1

Hi Ahmed:
With autonomous APs, rate limiting isn't possible.  All the autonomous APs support is QoS and that's pretty iffy.  At the core of the issue, you're dealing with radio waves and which ones arrive at the radio first, and who was prevented from talking because someone else was talking.  Dealing with these QoS and traffic shaping/policing issues are really tough with wireless because the transmission medium itself is unreliable.
The "Configuring QoS" chapter of the autonomous AP configuration guide
  http://tools.cisco.com/squish/5aCf1
will show you how you can map priority tagging to an SSID so that in that path from radio receiver to outbound on the fastethernet interface toward the rest of the network, you can control which SSID's packets get up into the network first, but the reverse path is a different story.  Because the wireless medium is half-duplex acknowledged, you can have a high priority packet out there on the radio interface trying to be beamed out to the client, and if the client isn't sending their ACK or what have you, it's going to sit and retry until its 63 retries are done before it gets out of the way to let the next high priority packet have a turn at getting transmitted out.
Once the traffic gets past the edge switch, the fact that it was at one time wireless is irrelevant.  You should look at it as a general "rate limiting one VLAN's traffic over another" and check with the routing protocols or traffic shaping folks.
Sincerely,
Rollin Kibbe
Network Management Systems Team