[c-nsp] ME3400 DSCP EF bits stripped.

Lee Starnes lee.t.starnes at gmail.com
Fri May 4 19:07:26 EDT 2012


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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