ing the nonroot port a blocking port. We discussed load balancing only when
we showed you how to set the port priority on a per-VLAN basis. However,
that really wasn't load balancing to the degree that is possible with a Cisco
switched network. In the next section, we'll cover the most efficient ways of
dealing with redundant links in a large, switched internetwork.
links to be treated as though they were one link. Cisco Fast EtherChannel
technology uses the standards-based 802.3 Full-Duplex Fast Ethernet to pro-
vide a reliable high-speed solution for the campus network backbone. Fast
EtherChannel can scale bandwidth within the campus, providing full-duplex
bandwidth at wire speeds of 200Mbps to 800Mbps. It provides high band-
width, load sharing, and redundancy of links in a switched internetwork.
redundancy in the event of a link failure. If a link is lost in a Fast EtherChan-
nel network, traffic is rerouted to one of the other links in just a few milli-
seconds, making the convergence transparent to the user.
which is a group of FastEthernet or Gigabit Ethernet links managed by the
Fast EtherChannel process. Should one link in the bundle fail, the Ethernet
Bundle Controller (EBC) informs the Enhanced Address Recognition Logic
(EARL) ASIC of the failure, and the EARL in turn ages out all addresses
learned on that link. The EBC and the EARL use hardware to recalculate the
source and destination address pair on a different link.
onds. Windowing flow control techniques can make this process a touch