QoS Marking in L2TP

Routing & Switching Quality of Service
1

I have a pseudowire configured in a VLAN over xconnect to connect 2 terminals over a WAN link, please see the configurations below of both routers (C1841 Advanced Enterprise with 4-port FastEthernet HWIC card).

R1:
 
pseudowire-class 2G
encapsulation l2tpv3
protocol none
ip local interface FastEthernet0/0
!
!
!
!
interface FastEthernet0/0
 ip address 10.123.1.3 255.255.255.0 secondary
ip address 10.123.1.2 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
load-interval 30
duplex auto
speed auto
no cdp enable
!
interface Vlan2010
no ip address
no ip proxy-arp
xconnect 10.123.4.2 1 encapsulation l2tpv3 manual pw-class 2G
  l2tp id 2 1

R2:

R2:
 
pseudowire-class 2G
encapsulation l2tpv3
protocol none
ip local interface FastEthernet0/0
!
!
!
!
interface FastEthernet0/0
ip address 10.123.4.3 255.255.255.0 secondary
ip address 10.123.4.2 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
duplex auto
speed auto
no cdp enable
!
interface Vlan2010
no ip address
no ip proxy-arp
xconnect 10.123.1.2 1 encapsulation l2tpv3 manual pw-class 2G
  l2tp id 1 2
!

The traffic going inside VLAN 2010 is already classified and tagged with DSCP values, please see the screenshot below of the captured packets from the VLAN interface.

But on the exit interface, the L2TP header seems to have the TOS field always set to 0x00, please see the screenshot below of the captured packets from interface FastEthernet 0/0

How do I make the router copy the TOS field from the original packet and include it in the IP header of the L2TP packet?

2

Hi Sivakumar,

I don’t have a router that lets me configure VLAN interfaces right now so I used a host device to set the VLAN tag. I didn’t have any issues getting the DSCP value to the other side with your config. Is there anything else that might strip it?

l2tvp3-dscp