<s>
The	O
Link	B-Protocol
Layer	I-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
(	O
LLDP	B-Protocol
)	O
is	O
a	O
vendor-neutral	O
link	B-Protocol
layer	I-Protocol
protocol	O
used	O
by	O
network	B-Device
devices	I-Device
for	O
advertising	O
their	O
identity	O
,	O
capabilities	O
,	O
and	O
neighbors	O
on	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
based	O
on	O
IEEE	O
802	O
technology	O
,	O
principally	O
wired	B-Protocol
Ethernet	I-Protocol
.	O
</s>
<s>
The	O
protocol	O
is	O
formally	O
referred	O
to	O
by	O
the	O
IEEE	O
as	O
Station	O
and	O
Media	B-Protocol
Access	I-Protocol
Control	I-Protocol
Connectivity	O
Discovery	O
specified	O
in	O
IEEE	B-Protocol
802.1AB	I-Protocol
with	O
additional	O
support	O
in	O
IEEE	O
802.3	O
section	O
6	O
clause	O
79	O
.	O
</s>
<s>
LLDP	B-Protocol
performs	O
functions	O
similar	O
to	O
several	O
proprietary	O
protocols	O
,	O
such	O
as	O
Cisco	B-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
,	O
Foundry	B-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
,	O
Nortel	B-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
and	O
Link	B-Protocol
Layer	I-Protocol
Topology	I-Protocol
Discovery	I-Protocol
.	O
</s>
<s>
Information	O
gathered	O
with	O
LLDP	B-Protocol
can	O
be	O
stored	O
in	O
the	O
device	O
management	O
information	O
base	O
(	O
MIB	O
)	O
and	O
queried	O
with	O
the	O
Simple	B-Protocol
Network	I-Protocol
Management	I-Protocol
Protocol	I-Protocol
(	O
SNMP	B-Protocol
)	O
as	O
specified	O
in	O
RFC	O
2922	O
.	O
</s>
<s>
The	O
topology	O
of	O
an	O
LLDP-enabled	O
network	O
can	O
be	O
discovered	O
by	O
crawling	O
the	O
hosts	O
and	O
querying	O
this	O
database	O
.	O
</s>
<s>
System	O
capabilities	O
(	O
switching	B-Protocol
,	O
routing	B-Protocol
,	O
etc	O
.	O
)	O
</s>
<s>
The	O
Link	B-Protocol
Layer	I-Protocol
Discovery	I-Protocol
Protocol	I-Protocol
may	O
be	O
used	O
as	O
a	O
component	O
in	O
network	O
management	O
and	O
network	O
monitoring	O
applications	O
.	O
</s>
<s>
One	O
such	O
example	O
is	O
its	O
use	O
in	O
data	B-Protocol
center	I-Protocol
bridging	I-Protocol
requirements	O
.	O
</s>
<s>
LLDP	B-Protocol
is	O
used	O
to	O
advertise	O
power	B-Device
over	I-Device
Ethernet	I-Device
capabilities	O
and	O
requirements	O
and	O
negotiate	O
power	O
delivery	O
.	O
</s>
<s>
Media	O
Endpoint	O
Discovery	O
is	O
an	O
enhancement	O
of	O
LLDP	B-Protocol
,	O
known	O
as	O
LLDP-MED	O
,	O
that	O
provides	O
the	O
following	O
facilities	O
:	O
</s>
<s>
Auto-discovery	O
of	O
LAN	B-General_Concept
policies	O
(	O
such	O
as	O
VLAN	B-General_Concept
,	O
Layer	O
2	O
Priority	O
and	O
Differentiated	O
services	O
(	O
Diffserv	O
)	O
settings	O
)	O
enabling	O
plug	B-Device
and	I-Device
play	I-Device
networking	O
.	O
</s>
<s>
Device	O
location	O
discovery	O
to	O
allow	O
creation	O
of	O
location	O
databases	O
and	O
,	O
in	O
the	O
case	O
of	O
Voice	B-Application
over	I-Application
Internet	I-Application
Protocol	I-Application
(	O
VoIP	B-Application
)	O
,	O
Enhanced	O
911	O
services	O
.	O
</s>
<s>
Extended	O
and	O
automated	O
power	O
management	O
of	O
Power	B-Device
over	I-Device
Ethernet	I-Device
(	O
PoE	B-Device
)	O
end	O
points	O
.	O
</s>
<s>
Inventory	O
management	O
,	O
allowing	O
network	O
administrators	O
to	O
track	O
their	O
network	B-Device
devices	I-Device
,	O
and	O
determine	O
their	O
characteristics	O
(	O
manufacturer	O
,	O
software	O
and	O
hardware	O
versions	O
,	O
serial	O
or	O
asset	O
number	O
)	O
.	O
</s>
<s>
The	O
LLDP-MED	O
protocol	O
extension	O
was	O
formally	O
approved	O
and	O
published	O
as	O
the	O
standard	O
ANSI/TIA	O
-1057	O
by	O
the	O
Telecommunications	O
Industry	O
Association	O
(	O
TIA	O
)	O
in	O
April	O
2006	O
.	O
</s>
<s>
LLDP	B-Protocol
information	O
is	O
sent	O
by	O
devices	O
from	O
each	O
of	O
their	O
interfaces	O
at	O
a	O
fixed	O
interval	O
,	O
in	O
the	O
form	O
of	O
an	O
Ethernet	B-Protocol
frame	I-Protocol
.	O
</s>
<s>
Each	O
frame	O
contains	O
one	O
LLDP	B-Protocol
Data	O
Unit	O
(	O
LLDPDU	O
)	O
.	O
</s>
<s>
Each	O
LLDPDU	O
is	O
a	O
sequence	O
of	O
type	B-Protocol
–	I-Protocol
length	I-Protocol
–	I-Protocol
value	I-Protocol
(	O
TLV	O
)	O
structures	O
.	O
</s>
<s>
The	O
Ethernet	B-Protocol
frame	I-Protocol
used	O
in	O
LLDP	B-Protocol
typically	O
has	O
its	O
destination	O
MAC	B-Protocol
address	O
set	O
to	O
a	O
special	O
multicast	B-Protocol
address	I-Protocol
that	O
802.1D-compliant	O
bridges	O
do	O
not	O
forward	O
.	O
</s>
<s>
The	O
EtherType	B-Protocol
field	O
is	O
set	O
to	O
0x88cc	O
.	O
</s>
<s>
Each	O
LLDP	B-Protocol
frame	O
starts	O
with	O
the	O
following	O
mandatory	O
TLVs	O
:	O
Chassis	O
ID	O
,	O
Port	B-Protocol
ID	O
,	O
and	O
Time-to-Live	O
.	O
</s>
<s>
Accordingly	O
,	O
an	O
Ethernet	B-Protocol
frame	I-Protocol
containing	O
an	O
LLDPDU	O
has	O
the	O
following	O
structure	O
:	O
</s>
<s>
According	O
to	O
IEEE	O
Std	O
802.1AB	B-Protocol
,	O
§	O
9.6.1.3	O
,	O
"	O
The	O
Organizationally	O
Unique	O
Identifier	O
shall	O
contain	O
the	O
organization	O
's	O
OUI	O
as	O
defined	O
in	O
IEEE	O
Std	O
802-2001.	O
"	O
</s>
