1.\" $FreeBSD: head/share/man/man4/natm.4 117011 2003-06-28 23:53:39Z ru $
2.\"
3.Dd December 29, 1997
4.Dt NATM 4
5.Os
6.Sh NAME
7.Nm natm
8.Nd Native Mode ATM protocol layer
9.Sh DESCRIPTION
--- 4 unchanged lines hidden (view full) ---
14which provides socket level access to AAL0 and AAL5 virtual circuits.
15To enable this protocol layer, add
16.Dl options NATM
17to your kernel configuration file and re-make the kernel (don't forget
18to do
19.Dq make clean ) .
20.Sh NATM API
21The NATM layer uses a
22.Vt struct sockaddr_natm
23to specify a virtual circuit:
24.Bd -literal -offset indent
25struct sockaddr_natm {
26 u_int8_t snatm_len; /* length */
27 u_int8_t snatm_family; /* AF_NATM */
28 char snatm_if[IFNAMSIZ]; /* interface name */
29 u_int16_t snatm_vci; /* vci */
30 u_int8_t snatm_vpi; /* vpi */
--- 16 unchanged lines hidden (view full) ---
47 snatm.snatm_vpi = 0;
48 r = connect(s, (struct sockaddr *)&snatm, sizeof(snatm));
49 if (r < 0) { perror("connect"); exit(1); }
50 /* s now connected to ATM! */
51.Ed
52.Pp
53The
54.Fn socket
55call simply creates an unconnected NATM socket.
56The
57.Fn connect
58call associates an unconnected NATM socket with a
59virtual circuit and tells the driver to enable that virtual circuit
60for receiving data.
61After the
62.Fn connect
63call one can
64.Fn read
65or
66.Fn write
67to the socket to perform ATM I/O.
68.Sh Internal NATM operation
69Internally, the NATM protocol layer keeps a list of all active virtual
70circuits on the system in
71.Dv natm_pcbs .
72This includes circuits currently being used for IP to prevent NATM and
73IP from clashing over virtual circuit usage.
74.Pp
75When a virtual circuit is enabled for receiving data, the NATM
76protocol layer passes the address of the protocol control block down
77to the driver as a receive
78.Dq handle .
79When inbound data arrives, the driver passes the data back with the
80appropriate receive handle.
81The NATM layer uses this to avoid the
82overhead of a protocol control block lookup.
83This allows us to take
84advantage of the fact that ATM has already demultiplexed the data for
85us.
86.Sh CAVEAT
87The NATM protocol support is subject to change as
88the ATM protocols develop.
89Users should not depend on details of the current implementation, but rather
90the services exported.
91.Sh SEE ALSO
92.Xr en 4 ,
93.Xr fatm 4 ,
94.Xr hatm 4 ,
95.Xr natmip 4
96.Sh AUTHORS
97.An Chuck Cranor
98of Washington University implemented the NATM protocol layer
99along with the EN ATM driver in 1996 for
100.Nx .
2.\"
3.Dd December 29, 1997
4.Dt NATM 4
5.Os
6.Sh NAME
7.Nm natm
8.Nd Native Mode ATM protocol layer
9.Sh DESCRIPTION
--- 4 unchanged lines hidden (view full) ---
14which provides socket level access to AAL0 and AAL5 virtual circuits.
15To enable this protocol layer, add
16.Dl options NATM
17to your kernel configuration file and re-make the kernel (don't forget
18to do
19.Dq make clean ) .
20.Sh NATM API
21The NATM layer uses a
22.Vt struct sockaddr_natm
23to specify a virtual circuit:
24.Bd -literal -offset indent
25struct sockaddr_natm {
26 u_int8_t snatm_len; /* length */
27 u_int8_t snatm_family; /* AF_NATM */
28 char snatm_if[IFNAMSIZ]; /* interface name */
29 u_int16_t snatm_vci; /* vci */
30 u_int8_t snatm_vpi; /* vpi */
--- 16 unchanged lines hidden (view full) ---
47 snatm.snatm_vpi = 0;
48 r = connect(s, (struct sockaddr *)&snatm, sizeof(snatm));
49 if (r < 0) { perror("connect"); exit(1); }
50 /* s now connected to ATM! */
51.Ed
52.Pp
53The
54.Fn socket
55call simply creates an unconnected NATM socket.
56The
57.Fn connect
58call associates an unconnected NATM socket with a
59virtual circuit and tells the driver to enable that virtual circuit
60for receiving data.
61After the
62.Fn connect
63call one can
64.Fn read
65or
66.Fn write
67to the socket to perform ATM I/O.
68.Sh Internal NATM operation
69Internally, the NATM protocol layer keeps a list of all active virtual
70circuits on the system in
71.Dv natm_pcbs .
72This includes circuits currently being used for IP to prevent NATM and
73IP from clashing over virtual circuit usage.
74.Pp
75When a virtual circuit is enabled for receiving data, the NATM
76protocol layer passes the address of the protocol control block down
77to the driver as a receive
78.Dq handle .
79When inbound data arrives, the driver passes the data back with the
80appropriate receive handle.
81The NATM layer uses this to avoid the
82overhead of a protocol control block lookup.
83This allows us to take
84advantage of the fact that ATM has already demultiplexed the data for
85us.
86.Sh CAVEAT
87The NATM protocol support is subject to change as
88the ATM protocols develop.
89Users should not depend on details of the current implementation, but rather
90the services exported.
91.Sh SEE ALSO
92.Xr en 4 ,
93.Xr fatm 4 ,
94.Xr hatm 4 ,
95.Xr natmip 4
96.Sh AUTHORS
97.An Chuck Cranor
98of Washington University implemented the NATM protocol layer
99along with the EN ATM driver in 1996 for
100.Nx .