5. This frame is delivered to B-component Q as an I-tagged frame (Figure 13.9d).
I-component C may deliver the frame to either (or both) of its virtual ports; each
corresponds to a different virtual port on B-component Q.
6. B-component Q associates the received frame with a B-VLAN appropriate to the
virtual port on which it was received and distributes the multicast or broadcast
throughout the backbone network in the fully tagged format of Figure 13.9f.
7. The frame reaches all of the other I-components shown in the diagram. Only those
I-components that serve the EVC specified in the frame??™s I-SID pay attention to
the frame; the others discard it. Ideally, the combination of B-tag and/or multicast
MAC address chosen by I-component C results in the frame reaching only those
I-components that serve this EVC.
8. I-component E receives the frame. You can assume the Spanning Tree Protocols
have resolved the loops inherent in the connections shown and, in particular, that
the link between I-component B and S-cloud 1B has been severed by the spanning
tree blocking one port or the other of the link.
9. I-component E de-encapsulates the frame.
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