<s>
In	O
computing	O
,	O
the	O
proposed	O
Internet	B-Architecture
Storage	I-Architecture
Name	I-Architecture
Service	I-Architecture
(	O
iSNS	B-Architecture
)	O
protocol	O
allows	O
automated	O
discovery	O
,	O
management	O
and	O
configuration	O
of	O
iSCSI	B-Protocol
and	O
Fibre	B-Architecture
Channel	I-Architecture
devices	O
(	O
using	O
iFCP	B-Protocol
gateways	O
)	O
on	O
a	O
TCP/IP	B-Protocol
network	I-Protocol
.	O
</s>
<s>
iSNS	B-Architecture
provides	O
management	O
services	O
similar	O
to	O
those	O
found	O
in	O
Fibre	B-Architecture
Channel	I-Architecture
networks	O
,	O
allowing	O
a	O
standard	O
IP	B-Protocol
network	I-Protocol
to	O
operate	O
in	O
much	O
the	O
same	O
way	O
that	O
a	O
Fibre	B-Architecture
Channel	I-Architecture
storage	O
area	O
network	O
does	O
.	O
</s>
<s>
Because	O
iSNS	B-Architecture
is	O
able	O
to	O
emulate	O
Fibre	B-Architecture
Channel	I-Architecture
fabric	O
services	O
and	O
manage	O
both	O
iSCSI	B-Protocol
and	O
Fibre	B-Architecture
Channel	I-Architecture
devices	O
,	O
an	O
iSNS	B-Architecture
server	O
can	O
be	O
used	O
as	O
a	O
consolidated	O
configuration	O
point	O
for	O
an	O
entire	O
storage	O
network	O
.	O
</s>
<s>
However	O
,	O
the	O
use	O
of	O
iSNS	B-Architecture
is	O
optional	O
for	O
iSCSI	B-Protocol
while	O
it	O
is	O
required	O
for	O
iFCP	B-Protocol
.	O
</s>
<s>
Additionally	O
,	O
an	O
iSNS	B-Architecture
implementation	O
is	O
not	O
required	O
by	O
the	O
standard	O
to	O
provide	O
support	O
for	O
both	O
of	O
these	O
protocols	O
.	O
</s>
<s>
The	O
iSNS	B-Architecture
standard	O
defines	O
four	O
components	O
:	O
</s>
<s>
The	O
iSNS	B-Architecture
Protocol	O
iSNSP	O
is	O
a	O
protocol	O
that	O
specifies	O
how	O
iSNS	B-Architecture
clients	O
and	O
servers	O
communicate	O
.	O
</s>
<s>
iSNS	B-Architecture
Clients	O
iSNS	B-Architecture
clients	O
are	O
part	O
of	O
iSNSP	O
aware	O
storage	O
devices	O
.	O
</s>
<s>
iSNS	B-Architecture
clients	O
initiate	O
transactions	O
with	O
iSNS	B-Architecture
servers	O
using	O
the	O
iSNSP	O
,	O
register	O
device	O
attribute	O
information	O
in	O
a	O
common	O
Discovery	O
Domain	O
(	O
DD	O
)	O
,	O
download	O
information	O
about	O
other	O
registered	O
clients	O
and	O
receive	O
asynchronous	O
notification	O
of	O
events	O
that	O
occur	O
in	O
their	O
DD(s )	O
.	O
</s>
<s>
iSNS	B-Architecture
Servers	O
iSNS	B-Architecture
servers	O
respond	O
to	O
iSNS	B-Architecture
protocol	O
queries	O
and	O
requests	O
made	O
by	O
iSNS	B-Architecture
clients	O
using	O
the	O
iSNSP	O
.	O
</s>
<s>
iSNS	B-Architecture
servers	O
initiate	O
iSNSP	O
State	O
Change	O
Notifications	O
and	O
store	O
properly	O
authenticated	O
information	O
submitted	O
by	O
a	O
registration	O
request	O
in	O
an	O
iSNS	B-Architecture
database	O
.	O
</s>
<s>
iSNS	B-Architecture
Databases	O
iSNS	B-Architecture
databases	O
are	O
the	O
information	O
repositories	O
for	O
iSNS	B-Architecture
server(s )	O
.	O
</s>
<s>
They	O
maintain	O
information	O
about	O
iSNS	B-Architecture
client	O
attributes	O
;	O
while	O
implementations	O
will	O
vary	O
,	O
a	O
directory-enabled	O
implementation	O
of	O
iSNS	B-Architecture
,	O
for	O
example	O
,	O
might	O
store	O
client	O
attributes	O
in	O
an	O
LDAP	O
directory	O
.	O
</s>
<s>
An	O
iSNS	B-Architecture
implementation	O
provides	O
four	O
primary	O
services	O
:	O
</s>
<s>
iSNS	B-Architecture
implementations	O
allow	O
all	O
entities	O
in	O
a	O
storage	O
network	O
to	O
register	O
and	O
query	O
an	O
iSNS	B-Architecture
database	O
.	O
</s>
<s>
Both	O
targets	O
and	O
initiators	O
can	O
register	O
with	O
the	O
iSNS	B-Architecture
database	O
,	O
and	O
each	O
entity	O
can	O
inquire	O
about	O
other	O
initiators	O
and	O
targets	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
client	O
initiator	O
can	O
obtain	O
information	O
about	O
target	O
devices	O
from	O
an	O
iSNS	B-Architecture
server	O
.	O
</s>
<s>
By	O
grouping	O
storage	O
nodes	O
,	O
administrators	O
are	O
able	O
to	O
limit	O
the	O
login	O
process	O
of	O
each	O
host	O
to	O
the	O
most	O
appropriate	O
subset	O
of	O
targets	O
registered	O
with	O
the	O
iSNS	B-Architecture
,	O
which	O
allows	O
the	O
storage	O
network	O
to	O
scale	O
by	O
reducing	O
the	O
number	O
of	O
unnecessary	O
logins	O
and	O
by	O
limiting	O
the	O
amount	O
of	O
time	O
each	O
host	O
spends	O
establishing	O
login	O
relationships	O
.	O
</s>
<s>
Each	O
target	O
is	O
able	O
to	O
use	O
login	O
control	O
to	O
delegate	O
their	O
access	O
control	O
and	O
authorization	O
policies	O
to	O
an	O
iSNS	B-Architecture
server	O
.	O
</s>
<s>
The	O
state-change	O
notification	O
(	O
SCN	O
)	O
service	O
allows	O
an	O
iSNS	B-Architecture
server	O
to	O
issue	O
notifications	O
about	O
each	O
event	O
that	O
affects	O
storage	O
nodes	O
on	O
the	O
managed	O
network	O
.	O
</s>
<s>
Each	O
iSNS	B-Architecture
client	O
may	O
register	O
for	O
notifications	O
on	O
behalf	O
of	O
its	O
storage	O
nodes	O
,	O
and	O
each	O
client	O
is	O
expected	O
to	O
respond	O
according	O
to	O
its	O
own	O
requirements	O
and	O
implementation	O
.	O
</s>
<s>
Because	O
the	O
iSNS	B-Architecture
database	O
stores	O
naming	O
and	O
discovery	O
information	O
about	O
both	O
Fibre	B-Architecture
Channel	I-Architecture
and	O
iSCSI	B-Protocol
devices	O
,	O
iSNS	B-Architecture
servers	O
are	O
able	O
to	O
store	O
mappings	O
of	O
Fibre	B-Architecture
Channel	I-Architecture
devices	O
to	O
proxy	O
iSCSI	B-Protocol
device	O
images	O
on	O
the	O
IP	B-Protocol
network	I-Protocol
.	O
</s>
<s>
These	O
mappings	O
may	O
also	O
be	O
made	O
in	O
the	O
opposite	O
direction	O
,	O
allowing	O
iSNS	B-Architecture
servers	O
to	O
store	O
mappings	O
from	O
iSCSI	B-Protocol
devices	O
to	O
proxy	O
World	O
Wide	O
Names	O
(	O
WWNs	O
)	O
.	O
</s>
