Cef Features Enabled By Default - Cisco Catalyst 3850 Configuration Manual

CEF Features Enabled by Default

The line cards perform the express forwarding between port adapters, relieving the RP of involvement in
the switching operation, thus also enhancing system performance.
Distributed Cisco Express Forwarding uses an interprocess communication (IPC) mechanism to ensure
synchronization of FIB tables and adjacency tables on the RP and line cards.
The figure below shows the relationship between the RP and line cards when distributed Cisco Express
Forwarding mode is active.
Figure 3
In the figure above, the line cards perform the switching. In devices where you can mix various types of
cards in the same device, all line cards might not support distributed Cisco Express Forwarding. When a
line card that does not support distributed Cisco Express Forwarding receives a packet from one of these
other devices, the line card forwards the packet to the next higher switching layer (the RP). This structure
allows legacy interface processors to exist in the device with newer interface processors.
CEF Features Enabled by Default
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Distributed Cisco Express Forwarding Mode Operation
Routing
table
Line card
Adjacency
FIB
table
OC-12 OC-3
Per-destination load balancing and the universal load sharing algorithm
Distributed tunnel switching
Multipoint generic routing encapsulation (GRE) tunnels
CEF distributed tunnel switching
CEF Distributed Tunnel Switching, page 8
IP Switching Cisco Express Forwarding Configuration Guide, Cisco IOS XE Release 3SE (Catalyst 3850 Switches)
Cisco device
running distributed CEF
Route Processor
Adjacency
FIB table
table
IPC
Line card
Adjacency
FIB
table
FE Serial
Unresolved Adjacency
Line card
Adjacency
FIB
table
T3 FDDI
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