[c-nsp] ME3400 DSCP EF bits stripped.

[ar]

Try to trust dscp/cos value of incoming packets of the access port.


________________________________
 From: ML <ml at kenweb.org>
To: cisco-nsp at puck.nether.net 
Sent: Sunday, May 6, 2012 11:45 AM
Subject: Re: [c-nsp] ME3400 DSCP EF bits stripped.
 
On 5/4/2012 7:07 PM, Lee Starnes wrote:
> Hello all,
>
> I have been banging my head against the wall for some time now trying to
> figure out why the DSCP bits are being stripped and replaced with "0" on
> all packets when coming from a customer connected to one of our ME3400
> switches. The switch is not doing any routing for them. It is just acting
> as a L2 transport between their gear and our network.
>
> Customer is connected to to port FA0/24 with that port being an access
> switchport. The VLAN associated with it is not an interface on the switch.
> The VLAN is simply just trunked via Gig0/1 to a 6509. The customer is
> setting dscp bit EF on their voice traffic and when that traffic enters the
> ME3400, those bits change to 0. Is there something that needs to be set to
> prevent this data from being stripped? We have monitored the traffic with
> an RSPAN port and are not able to see anything other then dscp 0 on all
> traffic for this interface. While I have not looked at other interfaces, I
> suspect this is the same for all of them. Below is the config for this.
>
>
>
> vlan 800
>   remote-span
> !
> vlan 936
> !
> interface FastEthernet0/24
>   description  ETHERNET - Circuit ID: xxxxxxxxxxxxxx
>   switchport access vlan 936
> !
> interface GigabitEthernet0/1
>   description uplink to 6509
>   port-type nni
>   switchport trunk allowed vlan 32,500-520,800,936
>   switchport mode trunk
>   load-interval 30
>   speed nonegotiate
>   !
> monitor session 3 source interface Fa0/24
> monitor session 3 destination remote vlan 800
>
>
> Any ideas would be greatly appreciated.
>
> Thanks,
>
> -Lee
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Is it possible that the 6509 is remarking traffic? Considering you are 
using RSPAN are you capturing traffic upstream?

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