QoS on Cisco Aironet 1200

Discussion in 'Cisco' started by Andrea Alfieri, Feb 14, 2005.

  1. I'm trying to apply QoS over an Access Point aironet 1200, because this AP should
    support QoS. The problem is that I would like to make a differentiated
    service based on the port number. For example the traffic destinated to the
    UDP port 3333 should have CoS 6 (interactive voice), and all the traffic to
    the other port CoS Best Effort. On the Internet I read the manual for the
    configuration of Filters an QoS but I didn't understand how to do that.
    The question is: is it possible to do what I described? Or the AP supports
    QoS only for traffic pre-marked from other devices, i.e. the sources have to
    mark packets at level 2 using IEEE 802.1Q tags, or at level 3 using the TOS
    IP packet field?
    Thank you
     
    Andrea Alfieri, Feb 14, 2005
    #1
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  2. Andrea Alfieri

    Ben Guest

    Hi Andrea,

    I am not really familiar with this model, but the standard Cisco way is
    to define your separate classes to match port numbers is using access-lists.

    But, from the configuration guide here:
    http://www.cisco.com/en/US/partner/...figuration_guide_chapter09186a0080147d70.html
    ....it seems that you indeed cannot classiy packets on the aeronet. The
    main restrictions of QoS on the Aeronet I have copied in below:

    QoS for Wireless LANs Versus QoS on Wired LANs

    The QoS implementation for wireless LANs differs from QoS
    implementations on other Cisco devices. With QoS enabled, access points
    perform the following:

    * They do not classify packets; they prioritize packets based on
    DSCP value, client type (such as a wireless phone), or the priority
    value in the 802.1q or 802.1p tag.
    * They do not match packets using ACL; they use only MQC class-map
    for matching clauses.
    * They do not construct internal DSCP values; they only support
    mapping by assigning IP DSCP, Precedence, or Protocol values to Layer 2
    COS values.
    * They do only FIFO queueing on the Ethernet egress port.
    * They support only 802.1Q/P tagged packets. Access points do not
    support ISL.
    * They support only MQC policy-map set cos action.

    The essence of all this is that the packets should be marked prior to
    entering the ethernet port, and you should probably apply the policy to
    the radio interface so you can using a queueing mechanism to enforce it
    (Ethernet interface only supports FIFO).

    However, reading on there may be a workaround if you can get your
    priority traffic to arrive on a separate VLAN. If it's coming in mixed
    up with non-priority traffic this is a no go:

    Precedence of QoS Settings

    When you enable QoS, the access point queues packets based on the Layer
    2 class of service value for each packet. The access point applies QoS
    policies in this order:

    <snip>

    4. Default classification for all packets on VLAN—If you set a default
    classification for all packets on a VLAN, that policy is fourth in the
    precedence list.



    Hope this helps.

    Ben
     
    Ben, Feb 14, 2005
    #2
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