04-06-2010 06:53 AM
hi All,
i have a setup as below
CE1 -----PE1 ---------PE--- ( Sniffer )-----PE----------PE2--------CE2
PE1 to CE1
==========
service instance 10 ethernet
encapsulation dot1q 10
xconnect 10.192.168.105 100 encapsulation mpls
!
PE2 to CE2
=========
interface TenGigabitEthernet5/0/0
no ip address
mls qos trust dscp
service instance 10 ethernet
encapsulation dot1q 20
xconnect 10.192.168.104 100 encapsulation mpls pw-class Test
!
No rewrites are done.
The VC type used is Type 4 ( i.e ETH VLAN )
Capturing packet at the Sniffer
========================
When i send traffic from CE1 to CE2 i see SD tag added on the packet as 10
When i send traffic from CE2 to CE1 i see SD tag added on the packet as 20.
Can u let me know how the SD Tag is determined in the above setup?
More Info
========
Packet captured looks like
[ L2 Header ] [Two Label MPLS STACK ] [CW] [ Actual Ethernet Frame ]
Actual Ethernet frame lookes like below
============================
[ L2 header ] [SD tag ] [ Vlan TAG from CE ] [ Data]
Thanks in advance
04-06-2010 07:27 AM
04-06-2010 09:49 AM
So the SD Tag Added would be
This leaves me with one basic question
1 : What is the use of adding SD tag for VC type 4 ?
In my setup The SD Tag gets poped when sent out towards CE
04-06-2010 12:42 PM
here are your options
vlanid 10 ===> (mpls) <=== vlanid 20
so you would have to manipulate the vlan tags in order for acceptance at the other end
left to right...translate 10 to 20
right to left ..translate 20 to 10
Router A Router B
interface 1/0/1 interface 1/0/1
vlanid 10 ===> (mpls) <=== vlanid 10
Router A
interface 1/0/1
service instance 10 ethernet
encapsulation dot1q 10
xconnect (router b) 110 encapsulation mpls
Router B
interface 1/0/1
service instance 10 ethernet
encapsulation dot1q 10
xconnect (routera) 110 encapsulation mpls
interface 1/0/2 interface 1/0/1
vlanid 10 ===> (mpls) <=== vlanid 10
Router A
interface 1/0/2
service instance 10 ethernet
encapsulation dot1q 10
xconnect (router b) 110 encapsulation mpls
Router B (this will not work because you already have an encapsulation dot1q 10 defined on this interface)
interface 1/0/1
service instance 10 ethernet
encapsulation dot1q 10
xconnect (routera) 110 encapsulation mpls
so you will have to do this
interface 1/0/1
service instance 20
encapsulation default (any tagged traffic comming in, not looking at the vlan-id, however a vlan-id other than 10 will pass thru this)
rewrite ingress tag translate 1 to 1 dot1q 10 (changing the vlan-id to 10)
xconnect (routera) 120 encapsulation mpls
In summary, vlan tags are significant only to the port. So you can use the same vlan id on another port.
Jude Bryant
Pioneer Telephone
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