[c-nsp] Providing QoS on Cisco Catalyst Ethernet network

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Mon Feb 25 01:32:48 EST 2008


Robert,

your configuration currently only includes the "marking" part, i.e.
marking CoS on packets and trusting CoS on your trunks. You need to
enable queuing to properly prioritize your voice packets, i.e. wrr-queue
commands.

You might consider using DSCP/precedence marking on your L3 packets and
trusting dscp instead of cos.. This would be a more extensible design.. 

	oli

Robert Hass <> wrote on Thursday, February 21, 2008 2:23 PM:

> Hi
> 
> I have below network:
> 
> VoIP PABX1
>> 
>> FE
>> 
> Cisco Catalyst 2960 (sw1) / Office 1
>> 
>> GE
>> 
> Cisco Catalyst 6503 (sw2)
>> 
>> GE
>> 
> Cisco Catalyst 3560G (sw3)
>> 
>> GE
>> 
> Cisco Catalyst 2960 (sw4) / Office 2
>> 
>> FE
>> 
> VoIP PABX2
> 
> I have to provide QoS for traffic between VoIP PABX1 and VoIP PABX2.
> Computers are in VLAN101, Servers and PABX on VLAN102.
> I have computers and servers on both sides on SW1 and SW4 as well.
> 
> I tried below configuration:
> 
> 1) sw1, 2960
> 
> mls qos
> !
> interface FastEthernet0/6
>  description VoIP_PABX_1
>  switchport access vlan 100
>  switchport mode access
>  load-interval 30
>  mls qos cos 7
>  mls qos trust cos
>  no cdp enable
>  spanning-tree portfast
> !
> interface GigabitEthernet0/1
>  description TRUNK to SW2
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> 
> 2) sw2, 6503/Sup32
> 
> interface GigabitEthernet1/3
>  description TRUNK to SW1
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> !
> interface GigabitEthernet1/6
>  description TRUNK to SW3
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> !
> 
> 3) sw3, 3560G
> 
> interface GigabitEthernet0/11
>  description TRUNK to SW2
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> !
> interface GigabitEthernet0/12
>  description TRUNK to SW4
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> !
> 
> 4) sw4, 2960
> 
> interface FastEthernet0/21
>  description VoIP_PABX_1
>  switchport access vlan 100
>  switchport mode access
>  load-interval 30
>  mls qos cos 7
>  mls qos trust cos
>  no cdp enable
>  spanning-tree portfast
> !
> interface GigabitEthernet0/1
>  description TRUNK to SW3
>  switchport mode trunk
>  load-interval 30
>  no cdp enable
>  mls qos trust cos
> !
> 
> Unfortunately we have problems with communications between both
> PABXes. Suppiler said that there is problem in our Ethernet network
> 
> Is our QoS configuration is correct ? Should be move both IP PABXes
> to separate VLAN instead of using Servers VLAN ?
> 
> Thanks for help
> Robert
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