07-21-2008 06:45 AM - edited 03-06-2019 12:19 AM
Hi,
trying to set up Qos on a 2960. What i want to do : Tagging port Fa0/4 to Cos 5
I've done this with 2950 EI but it doesn't work witch 2960
Here's my configuration
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos
interface FastEthernet0/4
description *** MEDIA GATEWAY RTP ***
switchport access vlan 11
switchport mode access
switchport nonegotiate
speed 100
duplex full
mls qos cos 5
mls qos trust cos
spanning-tree portfast
end
I monitor port Fa0/4 and all trames have dscp 0
What is wrong in my configuration ? same configuration works with 2950.
Thanks
07-21-2008 08:12 AM
You usually use "cos" for non-ip traffic (trunk interfaces) and "dscp" for ip traffic.
What kind of traffic is traversing via this interface?
Is the media gateway server setting its own "cos" value or you want the switch to insert this value on the packets?
If so, you must use "mls qos cos 5 override".
For more information on QoS in Cat2960 see:
HTH,
__
Edison.
07-21-2008 08:52 AM
We have ip traffic. The media gateway is not able to set its own "cos" value.
cmd line Mls qos cos 5 override is not accepted by the switch
07-21-2008 09:31 AM
Configure for DSCP instead.
__
Edison.
07-21-2008 11:19 AM
The "mls qos cos override" is a separate command that you would enter on the interface but its not your problem. If your gateway doesn't mark COS then it isn't needed. I agree just mark the DSCP with EF(46).
07-21-2008 04:34 PM
+1 on DSCP.
Bear in mind that CoS field only exists on Ethernet frame with 802.1Q header. Since your port is configured as access port, there's no 802.1Q header, hence no CoS field. On the contrary, DSCP field is contained within the IP header, so it exists end-to-end. Always configure DSCP/IP Prec when you can, and only fallback to CoS when your hardware is not capable to look past L2 header. Note that most newer Layer-2 switches can look up to layer-4 headers for QoS purposes only.
07-21-2008 10:41 PM
But why the same configuration works on a 2950 switch ? What is wrong for 2960 ?
How can i configure DSCP/ IP Prec on the port to mark all frames incoming on this port with EF ?
07-21-2008 11:57 PM
Good point. Sorry I missed that. I'm not sure why it worked on 2950, but not 2960. But then again, we're talking about change of platform, so I'm not at all surprised that the configs would have to change too, especially in relation to QoS.
Here's a QoS config guide for 2960. There're a few sections about configuring classification and marking using DSCP: http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_37_se/configuration/guide/swqos.pdf
Edit: better yet, start with configuring AutoQoS on the interface before you start with the classification and marking configs. This will ensure all the necessary QoS configs are automatically generated by the switch. Saves you from having to manually configuring everything from scratch. :-)
07-22-2008 04:10 AM
One of the challenges of QOS is almost every platform is different, try the following and I did this from memory so if someone else sees a problem with it chime in:
policy-map your_policy
class class-default
set dscp ef
interface fa0/4
service-policy input your_policy
07-22-2008 04:21 AM
That will work. However, it's better to apply the commands above AFTER issuing AutoQoS. If nothing else, to ensure the CoS-to-DSCP and DSCP-to-CoS mappings are done properly. As has been pointed out, every platform is different, so it's better to let AutoQoS handle this type of platform-specific configurations.
07-22-2008 04:56 AM
sorry but no success. Diffserv is still 0 in my network trace
07-22-2008 05:06 AM
Where are you sniffing the traffic?
07-22-2008 05:22 AM
On the same switch
My sniffer is on fast 0/3 and i monitor fast0/4
07-22-2008 05:58 AM
I believe you are sniffing the traffic before the switch marks it. Try sniffing a port where the traffic is exiting the switch or the the port on the next upstream device where this switch connects too.
07-22-2008 07:00 AM
Sniffing an other port, same pb
Here is my configuration
mls qos
policy-map VOIP_SIEMENS
class class-default
set dscp ef
interface FastEthernet0/4
description *** MEDIA GATEWAY RTP ***
switchport access vlan 11
switchport mode access
switchport nonegotiate
load-interval 30
speed 100
duplex full
spanning-tree portfast
service-policy input VOIP_SIEMENS
end
MAN_SW_TOIP-0_01#sh mls qos interface fastEthernet 0/4
FastEthernet0/4
Attached policy-map for Ingress: VOIP_SIEMENS
trust state: not trusted
trust mode: not trusted
trust enabled flag: ena
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
Trust device: none
qos mode: port-based
MAN_SW_TOIP-0_01#sh policy-map interface fastEthernet 0/4
FastEthernet0/4
Service-policy input: VOIP_SIEMENS
Class-map: class-default (match-any)
0 packets, 0 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: any
0 packets, 0 bytes
30 second rate 0 bps
Policy map seems not working ???
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