[nsp] Traffic shaping with QoS on Cisco 3550

[sthaug at nethelp.no]

> I have been reading up on "Understanding QoS Policing and Marking on the
> Catalyst 3550" (http://www.cisco.com/warp/public/473/153.html), and got
> the part about ingress traffic and policing down traffic. But I have
> trouble grasping how to configure egress traffic (switchport -> server),
> this is limited to Policer Markdown and Match DSCP which isnt described
> properly in the document. Looking for examples of traffic shaping with
> egress traffic..

The key here is that you cannot classify (based on for instance an IP
access list) but need to match an existing DSCP value. Remember that
the switch uses DSCP internally for *all* classification.

So assuming all your traffic going out one particular port has been
classified as DSCP 0 (which it will be by default :-), you can do
something like this to give the customer 6 Mbps:

class-map match-any all_traffic
  match ip dscp 0

policy-map customer_6mbps
  class all_traffic
    police 6000000 750000 exceed-action drop

interface FastEthernet0/5
 switchport access vlan 10
 switchport mode access
 service-policy output customer_6mbps

Steinar Haug, Nethelp consulting, sthaug at nethelp.no