Parallel Fast EtherChannel Links

Parallel Fast EtherChannel Links
Fast EtherChannel uses load distribution to share the links in a bundle. A bundle 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.
The convergence time is sometimes referred to as the failover time, which is the time it takes
for the new address to be relearned—about 10 microseconds. Windowing flow control techniques
can make this process a touch longer, but that depends on the particular application in
use. The key is not having the application time out, and the failover time is fast enough to stop
the timeout from happening.