ISP VLAN Tagging

[chad.parish]

If my ISP is logically routing between a routed interface on their end with an IP in the same subnet as my end's Layer 3 router SVI interface for VLAN 10, but the ckt terminates on a layer 2 switched interface on my end using vlan 10, does my ISP need to enable VLAN tagging on their end for VLAN 10?

[MHM Cisco World]

No need if the port connect to ISP is access port.

MHM

[Richard Burts]

I believe that MHM is correct that vlan tagging is not needed if the connection is an access port. But let me provide a bit more detail in the answer. vlan tagging is used when the connection is a trunk. If the connection is on access ports (and the OP certainly suggests that this is the case) then tagging is not needed. If your switch port connecting to the ISP were configured as a trunk, then tagging would become invalid. But not for an access port.