VLANs in one VLAN : service tag ?

Dear MK Enthusiasts,

in a scenario, I’ve got 3 routers :

R2 --------------- R1 --------------- R3

I need to transport customer VLANs between R2 and R3 in transparent mode in one of my VLAN ( 1002 ).( I don’t know VLAN tag number of my customer ).

Can you confirm I need to use a service vlan tag on my 1002 VLAN between all this routers ?

Thanks a lot

Armel