<s>
Port	B-Protocol
Aggregation	I-Protocol
Protocol	I-Protocol
(	O
PAgP	B-Protocol
)	O
is	O
a	O
Cisco	O
Systems	O
proprietary	O
networking	O
protocol	O
,	O
which	O
is	O
used	O
for	O
the	O
automated	O
,	O
link	B-Architecture
aggregation	I-Architecture
of	O
Ethernet	O
switch	O
ports	O
,	O
known	O
as	O
an	O
EtherChannel	B-Protocol
.	O
</s>
<s>
PAgP	B-Protocol
is	O
proprietary	O
to	O
Cisco	O
Systems	O
.	O
</s>
<s>
A	O
similar	O
protocol	O
known	O
as	O
Link	B-Architecture
Aggregation	I-Architecture
Control	O
Protocol	O
(	O
LACP	O
)	O
—	O
released	O
by	O
the	O
IEEE	O
—	O
is	O
an	O
industry	O
standard	O
and	O
is	O
not	O
tied	O
to	O
a	O
specific	O
vendor	O
.	O
</s>
<s>
PAgP	B-Protocol
messages	B-Protocol
are	O
always	O
sent	O
to	O
the	O
well-known	O
Cisco	O
multicast	O
address	O
01-00-0C-CC-CC-CC	O
with	O
protocol	O
type	O
code	O
0x0104	O
.	O
</s>
<s>
PAgP	B-Protocol
uses	O
the	O
same	O
multicast	O
group	O
MAC	O
address	O
of	O
CDP	O
.	O
</s>
<s>
PAgP	B-Protocol
can	O
be	O
configured	O
on	O
a	O
Cisco	O
switch	O
to	O
operate	O
in	O
three	O
different	O
modes	O
:	O
</s>
<s>
on	O
-	O
no	O
protocols	O
are	O
used	O
:	O
it	O
assumes	O
the	O
other	O
side	O
has	O
enabled	O
link	B-Architecture
aggregation	I-Architecture
.	O
</s>
<s>
On	O
Cisco	O
network	O
devices	O
running	O
CatOS	B-Operating_System
,	O
a	O
single	O
switch	O
module	O
may	O
only	O
be	O
configured	O
to	O
run	O
in	O
either	O
LACP	O
or	O
PAgP	B-Protocol
modes	O
.	O
</s>
<s>
Cisco	O
devices	O
that	O
run	O
IOS	B-Protocol
(	O
native	O
and/or	O
non-hybrid	O
mode	O
boxes	O
)	O
support	O
individual	O
port	O
configuration	O
for	O
LACP	O
and	O
are	O
not	O
restricted	O
to	O
per-module	O
settings	O
as	O
with	O
CatOS	B-Operating_System
.	O
</s>
<s>
A	O
limitation	O
of	O
Port	B-Protocol
Aggregation	I-Protocol
Protocol	I-Protocol
is	O
that	O
all	O
the	O
physical	O
ports	O
in	O
the	O
aggregation	O
group	O
must	O
reside	O
on	O
the	O
same	O
switch	O
.	O
</s>
<s>
Cisco	O
's	O
6500	O
and	O
the	O
4500E	O
platforms	O
,	O
remove	O
this	O
limitation	O
using	O
Virtual	O
Switching	O
System	O
(	O
VSS	O
)	O
,	O
which	O
allows	O
port	B-Architecture
channels	I-Architecture
to	O
be	O
split	O
between	O
two	O
chassis	O
.	O
</s>
<s>
With	O
Port	B-Protocol
Aggregation	I-Protocol
Protocol	I-Protocol
"	O
the	O
line	O
speed	O
of	O
an	O
agport	O
is	O
the	O
total	O
of	O
the	O
line	O
speeds	O
of	O
each	O
of	O
its	O
physical	O
ports.	O
"	O
</s>
<s>
Plain	O
EtherChannel	B-Protocol
load-balancing	O
works	O
by	O
having	O
the	O
switch	O
assign	O
a	O
hash	O
result	O
from	O
0-7	O
based	O
on	O
the	O
configured	O
hash	O
method	O
(	O
load-balancing	O
algorithm	O
)	O
for	O
the	O
type	O
of	O
traffic	O
.	O
</s>
<s>
However	O
,	O
some	O
PagP-enabled	O
switches	O
can	O
negotiate	O
between	O
a	O
"	O
maximize	O
load	O
balancing	O
"	O
and	O
"	O
preserve	O
ordering	O
"	O
link	O
:	O
the	O
former	O
give	O
maximum	O
aggregated	O
bandwidth	O
at	O
the	O
expense	O
of	O
packet	O
ordering	O
,	O
while	O
the	O
latter	O
assures	O
no	O
packet	O
reordering	O
to	O
occur	O
but	O
limit	O
a	O
single	O
transfer	O
to	O
the	O
bandwidth	O
of	O
a	O
single	O
interface	O
.	O
</s>
