<s>
Cisco	B-Protocol
Express	I-Protocol
Forwarding	I-Protocol
(	O
CEF	O
)	O
is	O
an	O
advanced	O
layer	O
3	O
switching	O
technology	O
used	O
mainly	O
in	O
large	O
core	B-General_Concept
networks	I-General_Concept
or	O
the	O
Internet	O
to	O
enhance	O
the	O
overall	O
network	O
performance	O
.	O
</s>
<s>
Although	O
CEF	O
is	O
a	O
Cisco	O
proprietary	O
protocol	O
other	O
vendors	O
of	O
multi-layer	O
switches	O
or	O
high-capacity	O
routers	O
offer	O
a	O
similar	O
functionality	O
where	O
layer-3	O
switching	O
or	O
routing	B-Protocol
is	O
done	O
in	O
hardware	O
(	O
in	O
an	O
ASIC	O
)	O
instead	O
of	O
by	O
software	O
and	O
the	O
(	O
central	O
)	O
CPU	B-Device
.	O
</s>
<s>
CEF	O
is	O
mainly	O
used	O
to	O
increase	O
packet	B-Protocol
switching	I-Protocol
speed	O
by	O
reducing	O
the	O
overhead	O
and	O
delays	O
introduced	O
by	O
other	O
routing	B-Protocol
techniques	O
.	O
</s>
<s>
CEF	O
consists	O
of	O
two	O
key	O
components	O
:	O
The	O
Forwarding	B-Protocol
Information	I-Protocol
Base	I-Protocol
(	O
FIB	O
)	O
and	O
adjacencies	O
.	O
</s>
<s>
The	O
FIB	O
is	O
similar	O
to	O
the	O
routing	B-Protocol
table	O
generated	O
by	O
multiple	O
routing	B-Protocol
protocols	I-Protocol
,	O
maintaining	O
only	O
the	O
next-hop	O
address	O
for	O
a	O
particular	O
IP-route	O
.	O
</s>
<s>
Cache	O
adjacency	O
:	O
This	O
type	O
of	O
entry	O
contains	O
the	O
correct	O
outbound	O
interface	O
and	O
the	O
correct	O
Medium	B-Protocol
Access	I-Protocol
Control	I-Protocol
(	O
MAC	O
)	O
address	O
for	O
its	O
FIB	O
entry	O
.	O
</s>
<s>
This	O
avoids	O
the	O
need	O
for	O
querying	O
the	O
main	O
processor	O
or	O
routing	B-Protocol
table	O
in	O
order	O
to	O
get	O
the	O
next-hop	O
information	O
.	O
</s>
<s>
CEF	O
currently	O
supports	O
Ethernet	O
,	O
Frame	B-Protocol
Relay	I-Protocol
,	O
ATM	O
,	O
PPP	B-Protocol
,	O
FDDI	B-Protocol
,	O
tunnels	B-Protocol
,	O
and	O
Cisco	B-Protocol
HDLC	I-Protocol
.	O
</s>
