QoS on Cat6500

Alberto Seg · ‎03-12-2018

Hi,

I have a problem with a QoS configuration on a catalyst 6513.. This is a campus distribution switch, access layer is a routed access layer.

I'm trying to verify a qos config. This config is configured with a input policy-map on the routed port faced to access layer switch (Cat3750). This input policy-map is based in ACLs to set a specific IP precedence.

In the other side, WAN interface, I have configured an output policy-map based in IPP value to match the traffic (that previosly in LAN port, we have classified)

LAN port = policy-map input for classify based in ACLs to set IPP

WAN port = Policy map output, it used LAN port clasification.

Problem is that this not working, in service policy out I see that all traffic is in class-default (IPP=0).

#sh mls qos
QoS is enabled globally
Policy marking depends on port_trust
QoS ip packet dscp rewrite enabled globally
Input mode for GRE Tunnel is Pipe mode
Input mode for MPLS is Pipe mode

Bridged QoS is enabled on the following interfaces:
    Vl1503
QoS Trust state is DSCP on the following interface
Gi1/15 Gi1/19 Gi2/22 Gi2/24 Gi3/13 Gi11/1 Gi11/2 Gi11/3 Gi11/4 Gi11/5
Gi11/23 Gi11/32 Gi11/46 Gi11/47 Gi12/5 Gi12/8 Te13/1 Te13/2 Te13/3 Po2
Vlan or Portchannel(Multi-Earl) policies supported: Yes
Egress policies supported: Yes

----- Module [7] -----
QoS global counters:
    Total packets: 45967030
    IP shortcut packets: 0
    Packets dropped by policing: 0
    IP packets with TOS changed by policing: 7300243
    IP packets with COS changed by policing: 13872733
    Non-IP packets with COS changed by policing: 97
    MPLS packets with EXP changed by policing: 0

I try to disable dscp rewrite globally but with same behaviour.

#sh module
Mod Ports Card Type                              Model              Serial No.
--- ----- -------------------------------------- ------------------ -----------
1   24 CEF720 24 port 1000mb SFP              WS-X6724-SFP       SAL093271BX
2   24 CEF720 24 port 1000mb SFP              WS-X6724-SFP       SAL09327AZZ
3   24 CEF720 24 port 1000mb SFP              WS-X6724-SFP       SAL093271AY
7    2 Supervisor Engine 720 (Active)         WS-SUP720-3B       SAL09306B0Q
11   48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX     SAL09285LTM
12   48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX     SAL09296425
13    4 CEF720 4 port 10-Gigabit Ethernet      WS-X6704-10GE      SAL09454RZZ

This is LAN port for example.

#sh queueing interface gigabitEthernet 3/3
Interface GigabitEthernet3/3 queueing strategy: Weighted Round-Robin
Port QoS is enabled
Port is untrusted
Extend trust state: not trusted [COS = 0]
Default COS is 0
Queueing Mode In Tx direction: mode-cos

Also, I try to configure marking in Cat3750 a configure mls qos trust in LAN port, but it has not worked either.

I think that 6513 is rewrite IPP/COS internally but I don't correct it.

Any idea??

Thanks in advance

Alberto Seg · ‎03-13-2018

any ideas?

chrihussey · ‎03-13-2018

I'm a bit confused, are the ports that you are having the problem untrusted?

I've never used the global dscp disable on the 6500, but on the interfaces I use the "mls qos trust dscp" and that seems to work fine.

If you could provide the policy map, in and out interface configs, it would be helpful in figuring out what is going on.

Regards

Alberto Seg · ‎03-14-2018

Hi,

sorry, I will try to explain in better. Attached you will find a basic network diagram for this connection and a couple of files:

Policy input.txt -> Config for input policy map (applied on Gi3/3)
Policy Output.txt -> Config for output policy map (applied on Gi1/15)

Policy input classify (in this example) over 1MB in class for IPP2 and in policy output this traffic is going to default class. you will see the show commands attached in "show policy mapa.txt"

Thanks in advanced, if you will have any question, please tell me and I try to resolved it

chrihussey · ‎03-14-2018

It is difficult to say exactly what is happening. I think it would be helpful to determine if the packets are being properly marked or if it is something with the output service policy. Would it be possible to span a port on the 3750 and the 6500? Check for the DSCP markings from the 3750, then the same on the WAN output to see if the packets are appropriately marked. It may help point you in the right direction.

I'll keep looking and if anything else comes to mind I'll let you know.

Alberto Seg · ‎03-14-2018

That would be ideal, but it's complicated.

I think that in some way it is as if the 6500 rewrites the package, I do not know if it is based on the fact that even if it has a service policy input on the LAN port, it considers port as untrusted and rewrite the packet... I do not know ...
I'm not clear about how these packages are handled internally by the Catalyst 6050 regarding QoS

Thanks