AutoQoS - on which port-types?

adamparanoidadamparanoid Member Posts: 1 ■□□□□□□□□□
Hello,

I'm going to configure AutoQos for about 40 Switches (2960,3560 and 6500) in a LAN to support Cisco VoIP telephony. On trunk-ports, I'm going to use the "auto qos voip trust" and on access-ports, where a Cisco IP phone (and a PC) are attached, I'll use "auto qos voip cisco-phone".
But what should I do with the other access-ports, where no Phone is attached? Maybe ports for printers or other types of clients... Should I configure nothing there? Or should I just issue "mls qos cos 0" or something like that..?

Thanks in advance.

Comments

  • PStefanovPStefanov Member Posts: 79 ■■□□□□□□□□
    When mls qos is enabled, by default all ports are untrusted. So leave the ports as they are. All markings will be automatically set to 0.

    Pavel
  • kpjunglekpjungle Member Posts: 426
    Ofcourse, the access port where you are attached you want to set to CoS 7 or DSCP EF :)
    Studying for CCNP (All done)
  • networker050184networker050184 Mod Posts: 11,962 Mod
    kpjungle wrote: »
    Ofcourse, the access port where you are attached you want to set to CoS 7 or DSCP EF :)

    That goes without saying icon_wink.gif
    An expert is a man who has made all the mistakes which can be made.
  • Paul BozPaul Boz Member Posts: 2,620 ■■■■■■■■□□
    I typically do simple switch QoS as you described, and do "real" QoS on access layer routers. I'm a proponent of L3 in the access layer for this reason.
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  • cowood2676cowood2676 Member Posts: 27 ■□□□□□□□□□
    Paul Boz wrote: »
    I typically do simple switch QoS as you described, and do "real" QoS on access layer routers. I'm a proponent of L3 in the access layer for this reason.

    Doing auto qos is fine and dandy but you have got to remember that you still may face congestion problems between your access layer, distribution, and core layers. In addition to using Cisco's Awsome QOS I also use a class map for all "uplinks" to avoide congestion. It looks like this.

    Create the class:
    Class-map VOICE
    match rtp audio

    Create the policy:
    Policy-map MYVOICE
    class VOICE
    priority 150
    class class-default
    fair-queue

    Apply the policy---on the interface
    service-policy output MYVOICE


    In short this gives voice a guarenteed 150K it will use more if it is available but it will never have less than 150...In times of congestion this will save you....apply it to every uplink out of the access and distribution layers.

    this gives
  • _maurice_maurice Member Posts: 142
    I am fairly new to QoS so please correct me if I'm wrong, but doesn't applying Auto QoS at all layers (access, distro, and core) degrade CPU performance since NBAR is used everywhere. Is it better to have NBAR used at the access layer, and trust markings at the distribution and core layers?
  • ilcram19-2ilcram19-2 Banned Posts: 436
    cowood2676 wrote: »
    Doing auto qos is fine and dandy but you have got to remember that you still may face congestion problems between your access layer, distribution, and core layers. In addition to using Cisco's Awsome QOS I also use a class map for all "uplinks" to avoide congestion. It looks like this.

    Create the class:
    Class-map VOICE
    match rtp audio

    Create the policy:
    Policy-map MYVOICE
    class VOICE
    priority 150
    class class-default
    fair-queue

    Apply the policy---on the interface
    service-policy output MYVOICE



    this gives

    in this config i will modify the follwing stuff

    Create the class:
    Class-map VOICE
    match dscp ef
    ***i will also add this***
    class-map SIGNALING
    match dscp af31
    match dscp cs3

    Create the policy:
    Policy-map VoIP
    class VOICE
    priority 135 *****depending on G711 (64k)or G729(8K)******Also make sure you add VPN overhead*****
    class SIGNALING
    priority 15

    ***but if the line is clable or DSL it is most commonly add a shaper otherwise there can still be some packet dropping****

    class class-default
    shape average 384000
    service-policy VOICE
    service-policy SIGNALING
    fair-queue

    Apply the policy---on the interface
    service-policy output VoIP ****this is usually a WAN Link*****


    Now when you talk about QOS there is different types of qos depending on the layer that we are talking about and the purpuse of it. example layer 2 TOS,COS layer 3 dscp and ip prec there are also some out there like the one above call LLQ, CBWFQ, WRR so you need to really do a research and testing and find out where to mark, classify and apply QOS policies
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