<s>
InterSwitch	B-Protocol
Trunk	I-Protocol
(	O
IST	O
)	O
is	O
one	O
or	O
more	O
parallel	O
point-to-point	O
links	O
(	O
Link	B-Architecture
aggregation	I-Architecture
)	O
that	O
connect	O
two	O
switches	O
together	O
to	O
create	O
a	O
single	O
logical	O
switch	O
.	O
</s>
<s>
For	O
example	O
,	O
Brocade	O
calls	O
this	O
an	O
Inter-Chassis	B-Protocol
Link	I-Protocol
(	O
ICL	O
)	O
.	O
</s>
<s>
This	O
allows	O
any	O
vendor	O
's	O
equipment	O
configured	O
to	O
use	O
the	O
IEEE	O
802.3ad	O
static	O
link	B-Architecture
aggregation	I-Architecture
protocol	O
to	O
connect	O
to	O
both	O
switches	O
and	O
take	O
advantage	O
of	O
load	O
balancing	O
,	O
redundant	O
connections	O
.	O
</s>
<s>
The	O
IST	O
protocol	O
was	O
developed	O
by	O
Nortel	O
(	O
now	O
acquired	O
by	O
Avaya	O
,	O
which	O
is	O
now	O
acquired	O
by	O
Extreme	O
Networks	O
)	O
to	O
enhance	O
the	O
capabilities	O
of	O
Link	B-Architecture
aggregation	I-Architecture
,	O
and	O
is	O
required	O
to	O
be	O
configured	O
prior	O
to	O
configuring	O
the	O
SMLT	O
,	O
DSMLT	B-Protocol
or	O
R-SMLT	O
functions	O
on	O
the	O
two	O
aggregate	O
(	O
core	O
,	O
distribution	O
,	O
or	O
access	O
)	O
switches	O
.	O
</s>
<s>
The	O
edge	O
equipment	O
can	O
be	O
configured	O
with	O
any	O
of	O
the	O
following	O
;	O
Multi-Link	B-Protocol
Trunking	I-Protocol
(	O
MLT	O
)	O
,	O
DMLT	B-Protocol
,	O
IEEE	O
802.3ad	O
static	O
link	B-Architecture
aggregation	I-Architecture
,	O
IEEE	O
802.3ad	O
Static	O
Gigabit	O
EtherChannel	O
(	O
GEC	O
)	O
,	O
IEEE	O
802.3ad	O
Static	O
Fast	O
EtherChannel	O
(	O
FEC	O
)	O
,	O
SMLT	O
,	O
DSMLT	B-Protocol
,	O
and	O
other	O
static	O
link	B-Architecture
aggregation	I-Architecture
protocols	O
.	O
</s>
<s>
IST	O
is	O
supported	O
on	O
Nortel	O
's	O
Routing	O
Switch	O
1600	O
,	O
5000	O
,	O
8300	O
,	O
ERS	B-Protocol
8600	I-Protocol
,	O
MERS	B-Protocol
8600	I-Protocol
products	O
and	O
also	O
on	O
Avaya	O
's	O
Virtual	O
Services	O
Platform	O
VSP	B-Architecture
7000	I-Architecture
and	O
VSP	B-Architecture
9000	I-Architecture
.	O
</s>
