SRR-Queue and traffic prioritization

phoffswell · ‎07-13-2011

Hi -

I have two goals on my Cisco 3750E -

* Limit bandwidth to match carrier provided bandwidth (10M ethernet port, but only 6M provisioned)

* Prioritize some traffic over others through the use of a priority queue.

I have come up with this design:

access-list 100 remark priority traffic

access-list 100 permit ip 10.1.1.0 0.0.3.255 any

access-list 100 permit ip any 10.1.1.0 0.0.3.255

class-map match-all priority-traffic

description Priority Traffic

match access-group 100

!

policy-map traffic-policy

description Traffic Policy

class priority-traffic

! Set priority traffic to dscp 46 EF

set ip dscp ef

interface GigabitEthernet1/0/1

description WAN link

switchport access vlan 2

bandwidth 6000

speed 10

duplex full

! Limit link to 6M

srr-queue bandwidth limit 60

priority-queue out

mls qos trust dscp

spanning-tree portfast

interface Vlan6

description User Network

ip address 192.168.16.1 255.255.255.0

service-policy input traffic-policy

Is this right?

How do I know? Is there a show command to show priority packets?

Am I right in assigning dscp 46 to this interesting traffic? That way it goes to queue 2?

Am I right in applying the priority-queue out command to the interface?

We also have voice traffic. But I think i can trust it to queue up into the router with trusted dscp

Thanks for any suggestions you may have!

Marwan ALshawi · ‎07-14-2011

Hi

- the bandwidth allocation on th eoutbound interface looks ok

however i noticed that you trying to marking using a policy on the vlan interface

if this is the case then you need to change the qos behaivor on the ingress switch interfaces where vlan 6 used either access vlan or trunk

mls qos

!

interface FastEthernet0/x

mls qos vlan-based

now you are using the proirity queue using DSCP

so you need to make sure that COS to DSCP cos 5 tp dscp 46

and make sure that both cos 5 and dscp 46 are alocated to the PQ

mls qos map cos-dscp 0 8 16 24 32 46 48 56

 ! Modifies CoS-to-DSCP mapping to map CoS 5 to DSCP EF

mls qos srr-queue output dscp-map queue 1 threshold 3 46

 ! Maps DSCP EF (VoIP) to Egress Queue 1 (PQ)

now make sur eyou trust DSCP not COS as you using DSCP all the way if you trust COS then the PQ wil linto COS value not the DSCP

for show commnads in the siwtches this is very limted if you are using Presendence vlaue not DSCP you might use the bellow for testing

policy-map VLAN

class TCP

set ip precedence 5

#sho int precedence

Ethernet0/0.100

Input

Precedence 3: 50 packets, 5900 bytes

Precedence 5: 46 packets, 2953 bytes

or you can use sow mls qos interface fax/x statistics

Good luck

if helpful Rate