Layer2 qos (cos) assistance 6509-E

katerina.dardoufa · ‎06-12-2015

Hello all,

I would like some help regarding setting up mls qos on our infrastructure.

We have two 6509-E connected via Port-channel with vlans configured with HSRP, one 6509-E is acting as active for a number of vlans and the other is active for the rest (typical design). The 6509E both have trunk ports to connected switches.

There is a need to deply qos for one of the vlans, on which a PBX is to be connected. The vlan will be unrouted (no ip address on SVI). How can this be done?

I understand that on the port switch where the PBX is to be connected, the "auto qos trust cos" command must be issued? What happens with the uplinks? Is the command "auto qos trust" sufficient? What configuration is needed on 6509E? How can the vlan have precedence over other vlans on the trunk links?

We are running 12.2(18)SXF17a on our 6509.

Any insight on the matter will be highly appreciated.

Thank you in advance,

Katerina

Mark Malone · ‎06-12-2015

auto qos voip trust on your access pbx port , mls qos trust dscp on your uplink will work if both commands are available depending on sup hardware in 6500

some newer switches trust dscp by default per port ingress on 65s and 38s ,Nexus do the same , you can check with command below depending on blades and sup ,

Default without applying anything

VSS-CORE#sh queueing interface tenGigabitEthernet 1/5/4
Interface TenGigabitEthernet1/5/4 queueing strategy: Weighted Round-Robin

Port QoS is disabled globally
Queueing on Te1/5/4: Tx Enabled Rx Enabled

Trust boundary disabled

Trust state: trust DSCP

katerina.dardoufa · ‎06-12-2015

Thank you Mark for your answer,

so if I understand correctly:

step 1: enable mls qos on 65xx

step 2: auto qos trust cos/dscp on uplinks and downlinks (if supported)

step 3: on switch ports connected to PBX either trust the cos, or set the cos as needed (mls qos cos value).

Do I have to configure anything on the port-channel connecting the two 65xx (no VSS in place)?

What does the command "mls qos vlan-based" on a trunk interface actually do?

Thank you in advance,

Katerina

Mark Malone · ‎06-12-2015

Check first before enabling anything if the ports are trusting by default some 65s are smart enough you dont have to enable it for ingress

mls qos will enable qos for the whole switch , if you have to enable qos just do it for each port , you run it globally it could have a knock on effect for other traffic

cos is for layer 2 and dscp is for layer 3 , we have auto qos voip trust on access ports and mls qos trust dscp on uplinks as it covers for both , you can check with wireshark if your packets are being marked correctly or by extended ping with tos set and watch the queues increase

Is your pbx marking traffic ? if not set the value on the port if its layer 2 to cos 5

make sure your switch has the mls cos-dscp mapping set as well if your using mls so the cos 5 is translated to dscp 46

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

Yes do your portchannel as well qos needs to be marked source -destination as best practice

Theres a few different ways as you probably see to set the ports , main thing is to make sure your voice packets are being marked with EF in wireshark

Mark Malone · ‎06-12-2015

didnt think mls qos vlan-based went on a trunk thought it was for an SVI

check these links explains it a little better of what you need same concept

http://www.cisco.com/c/en/us/support/docs/switches/catalyst-3750-series-switches/91862-cat3750-qos-config.html

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/auto_qos.html

katerina.dardoufa · ‎06-13-2015

Really appreciate your feedback.

I have seen the mls qos vlan-based command on a trunk port in a sample config, but now that you mention it, there were SVIs with qos, so it doesn't seem to apply in my case, where layer2 qos is needed. Still not sure what the command does.

Thank you for your help,

Katerina