From: Pierre-Alex (paguanel@hotmail.com)
Date: Fri Jun 02 2006 - 09:46:30 ART
Here is a proof of concept lab I worked on
I think it may be useful for those studying on the 3550 Qos
=========================
Theory from Cisco CD:
In the 3550 the order of operation for QoS is as follows in the ingress queue:
1- classification occurs based on trust, ACL, of vlan ID
2- A DSCP is created
3- If a policier exist, an action is taken to drop, mark-down or pass-through
the packet
Purpose of lab:
Verify that you can put in the same policy-map a "set" for a particular type
of traffic, then re-class it if it exceed certain values
Diagram :
r2 ------trunk -----Switch 1 -----R3
|
R6
r6 is in vlan 26
r3 is in vlan 23
Task:
From R2 send pings to R3 at line rate.
On switch 1 packets from R2 destined to R3 with ip precedence 5
On switch 1 packets from R2 destined to R6 with ip precedence 1
Traffic from R2 to R3 above 1 Mega should be de-classed and transmited with
dscp 31
Configuration:
sw1#sh policy-map
Policy Map police-in
Class vlan26
set dscp cs1
police 500000 93750 exceed-action drop
Class vlan23
set dscp cs5
police 1000000 187500 exceed-action policed-dscp-transmit
Class Map match-all vlan26 (id 5)
Match vlan 26
Match class-map all_ip_traffic
Class Map match-all vlan23 (id 4)
Match vlan 23
Match class-map all_ip_traffic
sw1#sh mls qos maps policed-dscp
Policed-dscp map:
d1 : d2 0 1 2 3 4 5 6 7 8 9
---------------------------------------
0 : 00 01 02 03 04 05 06 07 08 09
1 : 10 11 12 13 14 15 16 17 18 19
2 : 20 21 22 23 24 25 26 27 28 29
3 : 30 31 32 33 34 35 36 37 38 39
4 : 31 41 42 43 44 45 46 47 48 49
5 : 50 51 52 53 54 55 56 57 58 59
6 : 60 61 62 63
! verification:
r3#sh policy-map interface
Ethernet0/0
Service-policy input: inbound_measure
Class-map: all_traffic (match-all)
927846 packets, 640127685 bytes
30 second offered rate 1217000 bps
Match: access-group 1
Class-map: class-default (match-any)
0 packets, 0 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: any
Notice that there are no more a limit to 1 mega
r3#sh access-list 136 | i matches
310 permit ip any any dscp 31 (17172 matches)
400 permit ip any any dscp cs5 (170148 matches)
Notice that some packets are in original precedence and others in the
re-classed precedence. Thus the Qos works as described.
This archive was generated by hypermail 2.1.4 : Sat Jul 01 2006 - 07:57:31 ART