<s>
Gateway	B-Protocol
Load	I-Protocol
Balancing	I-Protocol
Protocol	I-Protocol
(	O
GLBP	B-Protocol
)	O
is	O
a	O
Cisco	O
proprietary	O
protocol	O
that	O
attempts	O
to	O
overcome	O
the	O
limitations	O
of	O
existing	O
redundant	O
router	B-Protocol
protocols	O
by	O
adding	O
basic	O
load	B-Application
balancing	I-Application
functionality	O
.	O
</s>
<s>
In	O
addition	O
to	O
being	O
able	O
to	O
set	O
priorities	O
on	O
different	O
gateway	O
routers	B-Protocol
,	O
GLBP	B-Protocol
allows	O
a	O
weighting	O
parameter	O
to	O
be	O
set	O
.	O
</s>
<s>
Based	O
on	O
this	O
weighting	O
(	O
compared	O
to	O
others	O
in	O
the	O
same	O
virtual	O
router	B-Protocol
group	O
)	O
,	O
ARP	O
requests	O
will	O
be	O
answered	O
with	O
MAC	O
addresses	O
pointing	O
to	O
different	O
routers	B-Protocol
.	O
</s>
<s>
Thus	O
,	O
by	O
default	O
,	O
load	B-Application
balancing	I-Application
is	O
not	O
based	O
on	O
traffic	O
load	O
,	O
but	O
rather	O
on	O
the	O
number	O
of	O
hosts	O
that	O
will	O
use	O
each	O
gateway	O
router	B-Protocol
.	O
</s>
<s>
By	O
default	O
,	O
GLBP	B-Protocol
load	O
balances	O
in	O
round-robin	B-Algorithm
fashion	O
.	O
</s>
<s>
GLBP	B-Protocol
elects	O
one	O
AVG	O
(	O
Active	O
Virtual	O
Gateway	O
)	O
for	O
each	O
group	O
.	O
</s>
<s>
The	O
elected	O
AVG	O
then	O
assigns	O
a	O
virtual	O
MAC	O
address	O
to	O
each	O
member	O
of	O
the	O
GLBP	B-Protocol
group	O
,	O
including	O
itself	O
,	O
thus	O
enabling	O
AVFs	O
(	O
Active	O
Virtual	O
Forwarders	O
)	O
.	O
</s>
<s>
By	O
default	O
,	O
GLBP	B-Protocol
routers	B-Protocol
use	O
the	O
local	O
multicast	O
address	O
224.0.0.102	O
to	O
send	O
hello	O
packets	O
to	O
their	O
peers	O
every	O
3	O
seconds	O
over	O
UDP	O
3222	O
(	O
source	O
and	O
destination	O
)	O
.	O
</s>
<s>
Cisco	O
implemented	O
IPv6	B-Protocol
support	O
for	O
GLBP	B-Protocol
in	O
IOS	B-Protocol
release	O
12.2(33 )	O
SXI	O
.	O
</s>
