Are you talking about EoMPLS VC Type? If Yes so
VC Type 4 is used for Ethernet VLAN mode.
VC Type 5 is used for Ethernet Port mode.
In the Ethernet VLAN mode (VC-Type4), a VLAN header that has some meaning to
the PE routers is always present. In other words, the PE routers look at the VLAN header.
In Ethernet Port mode (VC-TPE 5), the VLAN header might or not be present on the frame.
if a VLAN header does exist, the PE router does not inspect it; rather, it carries the frame transparently.
Running EoMPLS in Ethernet Port mode allows a complete Ethernet trunk to be transported over
one pseudowire, for example if the customer wanna to carry all VLANs from one side to the other side within one VC, and this is happen in case if the customer CE Is ethernet switches.
Best Regards,
Mounir Mohamed
