Layer 2 VPN (VPLS) versus Layer 3 VPN (VPRN) -- packet content difference question

Hi All,

  I was hoping someone might know the difference (if there is any) between layer 2 VPN VPLS and layer 3 VPN VPRN when it comes to the contents of the MPLS packet.   I have the need to inspect the contents of the IP packets as they are traversing the MPLS network.  I need to know the format of the ethernet frame to expect and was wondering if there is a difference in the formating in these two cases.

I am currently expecting a format like so:

Dest Mac     (6 bytes)

Src Mac        (6 bytes)

Ethtype 0x8847 (2 bytes)

MPLS Label (4 bytes)

MPLS Label (4 bytes)  (BOS bit set indicating last label)

Dest Mac (6 bytes)

Src Mac (6 bytes)

Ethtype 0x0800  (2 bytes)  

IPV4 packet  (x bytes)

Does anyone know?   

Thanks

Bob