CEF (Cisco Express Forwarding)

Lessons Discussion
46

  1. The ARP table is stored in RAM, and not in either CAM or TCAM

  2. Here is the Cisco definition of Epoch and how it is used:

The term "epoch" refers to a period of time. A new epoch for a Cisco Express Forwarding table begins when a table rebuild is initiated. The time after this instant is in an epoch different from the time before, and the different epochs are numbered between 0 and 255. Through the use of epochs, the software can distinguish between old and new forwarding information in the same database structure and can retain the old Cisco Express Forwarding database table while the software builds a new table. This is called epoch tracking and it allows Cisco Express Forwarding forwarding to continue uninterrupted while new Cisco Express Forwarding tables are being constructed, and it makes possible a seamless switchover when the new table becomes active

When you issue a show ip cef <route>, the dependencies output means how many other routes depend (are resolvable through) the <route> you looked up via the CEF command.

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