As calculated in the previous section,
the link between the access- and distribution-layer switches must be
capable of carrying up to 96 Mbps of traffic. The decision for the
type of link depends on the following factors:
- If the link is Fast Ethernet in
full-duplex mode, the link is capable of carrying 100 Mbps of
traffic in each direction. This type of link would indeed support a 96-Mbps
load.
- If the link is standard Ethernet
in full-duplex mode, the link is capable of carrying 10 Mbps of
traffic. This capacity is one-tenth the offered load, and
packets would be dropped after switch and port buffers are
consumed. If this situation is unacceptable, then Fast Ethernet
must be chosen.
- If virtual LANs (VLANs) are
implemented in this network, then it is possible that the link
may have to operate in "trunk" mode. If this were the
case, then Fast Ethernet would be required.
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