I was under the impression that the "rewrite ingress tag pop 1
symmetric" was required in order for the xconnect to work? Removing it
seems to break the xconnect as traffic no longer goes across it.
So is MQC with qos-groups is the only way to preserve the markings with
this platform?
Jose
On 11/6/2012 3:14 PM, Pshem Kowalczyk wrote:
Hi,
On 7 November 2012 08:04, Lobo <loboti...@gmail.com
<mailto:loboti...@gmail.com>> wrote:
Hi everyone. I was hoping I could get some help with an EoMPLS
config I'm working on between an ME3600X and an ME6524 and being
able to preserve the CoS field values.
The xconnect pseudowire it actually up and able to pass traffic so
that's not a problem. The issue is that any CoS values I assign
to the data packets seem to get overwritten on the ME3600X in the
service instance config. This is a rough topology of what I'm using:
Traffic generator --- 3750 --- ME3600X ---pseudowire over mpls
cloud--- ME6524 --- 3750G --- Traffic generator
What I see happening (going from left to right) is that the 3
different CoS values (5,3,0) all get overwritten to zero as soon
as the traffic goes over the xconnect. LDP labels are also sent
as exp zero.
In the opposite direction where the xconnect starts on the ME6524,
the CoS values are copied over to the exp values all the way to
the ME3600X until it passes through the service instance config.
Once I inspect the traffic on the 3750 switch, I see all my
traffic arriving with CoS 0. Note that DSCP is preserved in both
directions.
I'm curious if there is some global command for the ME3600X or
some additional config that I need to do on the service instance
in order to somehow copy the CoS value to EXP bit. Or do I have
to do more inspection and writing of values via MQC?
Here is the config I have for the xconnect on the two platforms.
ME3600X
interface GigabitEthernet0/8
switchport trunk allowed vlan none
switchport mode trunk
load-interval 30
speed 100
duplex full
service instance 3801 ethernet
encapsulation dot1q 3801
rewrite ingress tag pop 1 symmetric
xconnect 172.28.110.2 666 encapsulation mpls
!
ME6524:
interface GigabitEthernet1/1.3801
encapsulation dot1Q 3801
xconnect 172.28.110.2 666 encapsulation mpls
!
Your problem is caused by the following line in 3600x config:
rewrite ingress tag pop 1 symmetric
that line removes the vlan tag and the COS bits with it, so when the
frame hits the PWE3 there is no information about what class the
traffic belonged to originally, just plain ethernet frame. One way to
make it work is to create a set of policies on both 3600x and 6524
that inspect the incoming packets and copy the COS bits into EXP/QoS
bits of the MPLS label and then have a symmetric set of policies on
egress to copy bits from EXP/QoS back to COS (AFAIK 65xx does it
automatically, if not configured otherwise). I believe you have to use
qos-groups on egress, as MPLS markings do not survive till the egress
policy processing.
Between two 3600x you can make it also work if you do not pop the VLAN
tags (then PWE3 carries ethernet frame with VLAN tags).
kind regards
Pshem
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