<s>
A	O
network	B-Protocol
service	I-Protocol
access	I-Protocol
point	I-Protocol
address	I-Protocol
(	O
NSAP	B-Protocol
address	I-Protocol
)	O
,	O
defined	O
in	O
ISO/IEC	O
8348	O
,	O
is	O
an	O
identifying	O
label	O
for	O
a	O
service	B-Protocol
access	I-Protocol
point	I-Protocol
(	O
SAP	O
)	O
used	O
in	O
OSI	O
networking	O
.	O
</s>
<s>
These	O
are	O
roughly	O
comparable	O
to	O
IP	B-Protocol
addresses	I-Protocol
used	O
in	O
the	O
Internet	B-Protocol
Protocol	I-Protocol
;	O
they	O
can	O
specify	O
a	O
piece	O
of	O
equipment	O
connected	O
to	O
an	O
Asynchronous	O
Transfer	O
Mode	O
(	O
ATM	O
)	O
network	O
.	O
</s>
<s>
A	O
specific	O
stream	O
,	O
analogous	O
to	O
a	O
TCP/IP	O
port	O
or	O
socket	B-Protocol
,	O
is	O
specified	O
by	O
using	O
a	O
transport	O
service	B-Protocol
access	I-Protocol
point	I-Protocol
(	O
TSAP	B-Protocol
)	O
.	O
</s>
<s>
NSAP	B-Protocol
addresses	O
are	O
allocated	O
by	O
the	O
International	O
Organization	O
for	O
Standardization	O
(	O
ISO	O
)	O
,	O
through	O
a	O
system	O
of	O
delegated	O
authorities	O
,	O
which	O
are	O
generally	O
national	O
standards	O
organizations	O
.	O
</s>
<s>
One	O
of	O
the	O
schemes	O
to	O
generate	O
NSAPs	B-Protocol
uses	O
E.164	O
which	O
is	O
the	O
addressing	O
format	O
describing	O
telephone	O
numbers	O
.	O
</s>
<s>
NSAP	B-Protocol
addresses	O
do	O
not	O
specify	O
where	O
a	O
network	O
terminal	O
is	O
located	O
.	O
</s>
<s>
Routing	B-Protocol
equipment	O
must	O
translate	O
NSAP	B-Protocol
addresses	O
to	O
subnetwork	O
points	O
of	O
attachment	O
(	O
SNPAs	O
)	O
to	O
route	O
OSI	O
packets	O
;	O
virtual	O
circuit	O
identifier	O
(	O
VCI	O
)	O
numbers	O
are	O
an	O
example	O
of	O
a	O
datalink	O
layer	O
SNPAs	O
in	O
ATM	O
;	O
when	O
OSI	O
packets	O
are	O
sent	O
encapsulated	O
in	O
IP	O
packets	O
,	O
the	O
IP	B-Protocol
address	I-Protocol
is	O
considered	O
an	O
SNPA	O
.	O
</s>
<s>
Synchronous	O
Digital	O
Hierarchy/Synchronous	O
Optical	O
Networking	O
networks	O
are	O
a	O
major	O
part	O
of	O
the	O
network	O
infrastructure	O
,	O
and	O
NSAPs	B-Protocol
are	O
used	O
extensively	O
.	O
</s>
<s>
NSAP	B-Protocol
addresses	O
are	O
used	O
in	O
the	O
following	O
OSI-based	O
network	O
technologies	O
:	O
</s>
<s>
Synchronous	B-Protocol
Digital	I-Protocol
Hierarchy	I-Protocol
and	O
Synchronous	B-Protocol
Optical	I-Protocol
Networking	I-Protocol
networks	O
.	O
</s>
<s>
NSAP-style	O
addresses	O
are	O
used	O
in	O
the	O
IS-IS	B-Protocol
routing	B-Protocol
protocol	O
.	O
</s>
<s>
The	O
network	O
selector	O
(	O
NSEL	O
)	O
is	O
a	O
field	O
in	O
the	O
NSAP	B-Protocol
address	I-Protocol
that	O
identifies	O
the	O
network	B-Application
layer	I-Application
service	O
to	O
which	O
a	O
packet	O
should	O
be	O
sent	O
.	O
</s>
<s>
In	O
the	O
IS-IS	B-Protocol
routing	B-Protocol
protocol	O
,	O
the	O
field	O
is	O
sometimes	O
referred	O
to	O
as	O
the	O
SEL	O
field	O
.	O
</s>
