[cisco-voip] A simple QOS implementation for VOIP?

[Nick Matthews]

Hi John,

This isn't quite right.  The percent keyword is going to use:
1.  Physical speed of link it is applied to
2.  Shaper or Policer value in the parent policy above it.

In this case your priority percent is applied directly to the interface.

Change it to this, and you'll be better off:


class-map match-any voip1
 match access-group name host-voip1

policy-map policy-qos1
 class class-default
   shape average 650000
   service-policy policy-qos2


policy-map policy-qos2
 class voip1
   priority percent 60

interface FastEthernet4
 service-policy output policy-qos1

As well, your access list seems to make it look like all of your voice
is going to one server.  If you're sure this is the case it works.
Most cases the phones will talk to other phones directly, and you're
better off with something like this:

class-map match-any phone-traffic
match dscp ef
match protocol rtp audio




-nick


On Tue, Jun 9, 2009 at 4:44 PM, John Lange<john at johnlange.ca> wrote:
> I'm trying to create a relatively simplistic QOS implementation that
> simply prioritizes all traffic to and from a voip server.
>
> The device is a Cisco 871 connected to a typical cable modem with a
> theoretical speed limit of 1 mb/s upload but measured at about .65 mb/s.
>
> This is the config I've come up with. I've tested it and it seems to be
> doing something but I'm not 100% convinced this is correct.
>
> Is this the right methodology? And if so, is the shape average in the
> correct place?
>
> -----
>
> class-map match-any voip1
>  match access-group name host-voip1
>
> policy-map policy-qos1
>  class voip1
>    priority percent 60
>  class class-default
>    shape average 650000
>
> interface FastEthernet4
>  service-policy output policy-qos1
>
> ip access-list extended host-voip1
>  permit ip host <voip server IP> any
>  permit ip any host <voip server IP>
>
>
> --
> John Lange
> http://www.johnlange.ca
>
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