|
|
|
Each F-chip/PRE (see "Identifying the Ports" later in this chapter for PRE column explanation) reserves space for IP unicast, IP multicast, and IPX. By default, the number of entries are limited to 15,000 for each (45,000 total). If the CPU attempts to add an entry in excess of 15,000, the L3FE will not be stored and that Flow will only be forwarded via the Slow Path. When looking at the Active FE Cache (Cache Contents) page, the Current Entries column indicates how many entries are currently in the L3F cache. Since the L3 forwarding cache is recalculated periodically, you need to monitor the FE Cache Web page on the switch Web Agent found by selecting the following:
Routing > L3 Forwarding Cache > Cache Contents
Layer 3 forwarding entries live for a time that is the maximum of two timers:
The Age interval timer starts when a new forwarding entry is added to the layer 3 forwarding cache. Each forwarding entry has its own timer.
The chassis timer specifies the number of seconds that the CPU takes to rebuild all forwarding caches on all F-chips in the chassis. Each second, the CPU removes expired forwarding entries from one protocol branch (IP-UNI, IP-Multi, or IPX) of the forwarding cache on one F-Chip and then rebuilds the branch.
On a fully populated P882, rebuilding all forwarding caches on all F-chips takes 400 seconds. On a fully populated P580, this task takes 160 seconds.
The FE Cache page displays as shown below.
Figure�140:�Active FE Cache Web page
|
|
|