Customer Edge Port (CEP). The Customer Edge Port (CEP)
and each Provider Edge Port are treated as separate Bridge Ports
by the spanning tree protocol. If the C-VLAN component connects
to the S-VLAN component with a single Provider Edge Port, and the
associated service instance supports no more than two customer interfaces,
then all frames (including Spanning Tree BPDUs) addressed to the
Bridge Group Address may be relayed between the two Ports of the
C-VLAN component without modification. Otherwise, the Spanning Tree
Protocol Entity shall execute the Rapid Spanning Tree Protocol (RSTP,
Clause 17 of IEEE Std 802.1D), as modified by the provisions of
this subclause.