<s>
Cisco	B-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
(	O
CDP	O
)	O
is	O
a	O
proprietary	O
data	B-Protocol
link	I-Protocol
layer	I-Protocol
protocol	O
developed	O
by	O
Cisco	O
Systems	O
in	O
1994	O
by	O
Keith	O
McCloghrie	O
and	O
Dino	O
Farinacci	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
share	O
information	O
about	O
other	O
directly	O
connected	O
Cisco	O
equipment	O
,	O
such	O
as	O
the	O
operating	B-General_Concept
system	I-General_Concept
version	O
and	O
IP	B-Protocol
address	I-Protocol
.	O
</s>
<s>
CDP	O
can	O
also	O
be	O
used	O
for	O
On-Demand	B-Protocol
Routing	I-Protocol
,	O
which	O
is	O
a	O
method	O
of	O
including	O
routing	O
information	O
in	O
CDP	O
announcements	O
so	O
that	O
dynamic	O
routing	B-Protocol
protocols	I-Protocol
do	O
not	O
need	O
to	O
be	O
used	O
in	O
simple	O
networks	O
.	O
</s>
<s>
Cisco	O
devices	O
send	O
CDP	O
announcements	O
to	O
the	O
destination	O
MAC	O
address	O
,	O
out	O
each	O
connected	O
network	B-Protocol
interface	I-Protocol
.	O
</s>
<s>
These	O
multicast	O
frames	B-Protocol
may	O
be	O
received	O
by	O
Cisco	O
switches	O
and	O
other	O
networking	O
devices	O
that	O
support	O
CDP	O
into	O
their	O
connected	O
network	B-Protocol
interface	I-Protocol
.	O
</s>
<s>
This	O
multicast	O
destination	O
is	O
also	O
used	O
in	O
other	O
Cisco	O
protocols	O
such	O
as	O
Virtual	B-General_Concept
Local	I-General_Concept
Area	I-General_Concept
Network	I-General_Concept
(	O
VLAN	B-General_Concept
)	O
Trunking	O
Protocol	O
(	O
VTP	B-Protocol
)	O
.	O
</s>
<s>
By	O
default	O
,	O
CDP	O
announcements	O
are	O
sent	O
every	O
60	O
seconds	O
on	O
interfaces	O
that	O
support	O
Subnetwork	B-Protocol
Access	I-Protocol
Protocol	I-Protocol
(	O
SNAP	O
)	O
headers	O
,	O
including	O
Ethernet	O
,	O
Frame	B-Protocol
Relay	I-Protocol
and	O
Asynchronous	O
Transfer	O
Mode	O
(	O
ATM	O
)	O
.	O
</s>
<s>
This	O
table	O
is	O
also	O
accessible	O
via	O
Simple	B-Protocol
Network	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
SNMP	B-Protocol
)	O
.	O
</s>
<s>
The	O
information	O
contained	O
in	O
CDP	O
announcements	O
varies	O
by	O
the	O
type	O
of	O
device	O
and	O
the	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
running	O
on	O
it	O
.	O
</s>
<s>
This	O
information	O
may	O
include	O
the	O
operating	B-General_Concept
system	I-General_Concept
version	O
,	O
hostname	B-Protocol
,	O
every	O
address	O
(	O
i.e.	O
</s>
<s>
IP	B-Protocol
address	I-Protocol
)	O
from	O
all	O
protocol(s )	O
configured	O
on	O
the	O
port	O
where	O
CDP	O
frame	B-Protocol
is	O
sent	O
,	O
the	O
port	O
identifier	O
from	O
which	O
the	O
announcement	O
was	O
sent	O
,	O
device	O
type	O
and	O
model	O
,	O
duplex	O
setting	O
,	O
VTP	B-Protocol
domain	O
,	O
native	O
VLAN	B-General_Concept
,	O
power	O
draw	O
(	O
for	O
Power	B-Device
over	I-Device
Ethernet	I-Device
devices	O
)	O
,	O
and	O
other	O
device	O
specific	O
information	O
.	O
</s>
<s>
The	O
details	O
contained	O
in	O
these	O
announcements	O
is	O
easily	O
extended	O
due	O
to	O
the	O
use	O
of	O
the	O
type	B-Protocol
–	I-Protocol
length	I-Protocol
–	I-Protocol
value	I-Protocol
(	O
TLV	O
)	O
frame	B-Protocol
format	O
.	O
</s>
<s>
CDP	O
support	O
was	O
replaced	O
with	O
IEEE	B-Protocol
802.1AB	I-Protocol
Link	B-Protocol
Layer	I-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
(	O
LLDP	B-Protocol
)	O
,	O
an	O
IEEE	O
standard	O
that	O
is	O
implemented	O
by	O
multiple	O
vendors	O
and	O
is	O
functionally	O
similar	O
to	O
CDP	O
.	O
</s>
<s>
Several	O
other	O
manufacturers	O
,	O
including	O
Dell	O
and	O
Netgear	O
have	O
used	O
the	O
brand-neutral	O
name	O
Industry	B-Protocol
Standard	I-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
(	O
ISDP	O
)	O
to	O
refer	O
to	O
their	O
implementations	O
of	O
a	O
CDP-compatible	O
protocol	O
.	O
</s>
