QOS on 3560's

[Jake Pratt]

I am replacing some WAN connections: Point to Point T1's (running from 2820's to a 7200).  I am replacing them with metro Ethernet connections with a 3560 layer 3 switch at each end.  We run Cisco Call Manager, and have IP phones at our locations.  I want to set up QOS on my WAN connection to make sure my packets arrive in the correct order.  I have a few remote users complaining of voice problems, crackling, etc.  The 3560's are acting as routers, and don't directly connect to all the phones.  So I won't be using the mls/auto QOS features, I don't think.  I am trying to use service-policies and class-maps to handle qos, as I have done in the past, but I'm not finding the correct commands.  This is the QOS I currently have set up on my 7200/2820:

class-map match-any voip-control

  match ip dscp af31

class-map match-any voip-rtp

  match ip dscp ef

!

!

policy-map my-voice

  class voip-rtp

    priority 512

  class voip-control

   bandwidth percent 5

  class class-default

   fair-queue

I can create the class-maps on my 3560's, but when I start trying to modify the class settings under the policy-maps, the commands like "priority", "bandwidth", and "fair-queue" are not available.  These are the options at the (config-pmap-c)# prompt:

QoS policy-map class configuration commands:

  exit            Exit from QoS class action configuration mode

  no              Negate or set default values of a command

  police          Police

  service-policy  Configure QoS Service Policy

  set             Set QoS values

  trust           Set trust value for the class

  <cr>

Perhaps I am trying to do this the old way, but I'm just looking to set up some QOS on these switches.  These switches are running a mix of

ip base and ip services IOS versions.  Can anyone help me with the right syntax to setup QOS? 

Thanks

[paolo bevilacqua]

QoS on switches work very diffrently than on routers.

However the same concept applies, you don't need QoS unelss your interfaces are congested. And it very unlikey that they are.

You can check "show interface" for drops, but if packets are dropped in the metroE (and that has to be proved), you will need to talk with SP, not mess with the switches.

[Jake Pratt]

Thanks for your reply.  We are definitely not having congestion problems.  The problematic remote office in question has a 10 Mbps connection, and is not using too much of that bandwidth.  I was not worrying about QOS because of the amount of bandwidth.  However, I have heard lots of complaints about voice quality from that office lately.  So I thought I would add QOS to make sure everything arrives in the same order.  Is it possible to set that up?

[Joseph W. Doherty]

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Posting

As Paolo noted, 3560 QoS configuration can be quite different from typical ISR like QoS.  It offers much less QoS support, especially as the 3560 is designed as a LAN switch.  (Cisco's Metro Ethernet switches tend to have slightly better QoS features.)

That noted, you might be able to take advantage of the 3560's QoS, but just enabling it, and allowing it to use its default settings, often results in worst performance.  Is QoS currently enabled or disabled?

The new Metro Ethernet you're using - is it point-to-point or multipoint?  Do you share a physical link (like a trunk)?  Are your physical interfaces "faster" than any logical bandwidth restrictions?

PS:

BTW, policy-maps on a 3560 are used only for ingress, which is why all the egress type commands are missing.  For egress, you use features of the 4 hardware queues.