NAME

       sap - Service Access Point specification

DESCRIPTION

       The  text2sap  and sap2text functions use the format described in this man page. Because all standard ATM
       tools  on  Linux  use  those  functions  to  convert  to  or  from  the  textual  representation  of  SAP
       specifications, they expect them in the same format too.

       The  SAP  is  divided  into  two parts: the broadband high layer information (BHLI) and the broadband low
       layer information (BLLI). A SAP can contain one, both, or none of them. In the latter case,  the  SAP  is
       usually considered as a wildcard SAP, i.e. a SAP that is compatible with any other SAP.

       Each  part begins with its name (bhli or blli), followed by a colon and a (non-empty) list of attributes,
       which are of the form attribute=value. Some attributes have sub-attributes, which follow them. Everything
       that isn't separated by a colon or an equal sign is separated by a comma.

       Values  which  are  a number of bytes are specified as the corresponding sequence of pairs of hex digits.
       The sequence can be optionally prefixed with 0x. Values with  are  integers  in  a  given  range  can  be
       specified in decimal (no prefix), octal (0 prefix), and hexadecimal (0x prefix).

       The  following,  mutually  exclusive  attributes  are allowed in the bhli part (see the corresponding ATM
       Forum and ITU documents for the semantics):

       iso=1-8 bytes
              ISO

       user=1-8 bytes
              User-specific

       hlp=4 bytes
              High layer profile.  Note that this attribute only exists on UNI 3.0. text2sap only recognizes  it
              if your system is configured to accept UNI 3.0 message formats.

       oui=3 bytes,id=4 bytes
              Vendor-specific application identifier

       The  structure  of the bhli part is more complex. It distinguishes three layers, l1, l2, and l3, of which
       the first one is presently unsupported. For layer two, the following (mutually  exclusive)  possibilities
       exist:

       l2=iso1745
              Basic mode ISO 1745

       l2=q291
              ITU-T Q.291 (Rec. I.441)

       l2=lapb
              Extended LAPB, half-duplex (Rec. T.71)

       l2=iso8802
              LAN LLC (ISO/IEC 8802/2)

       l2=x75 ITU-T X.75, SLP

       l2=x25_ll ...
              ITU-T  X.25,  link  layer.  This  attribute  and  the  following attributes through l2=iso7776 can
              optionally be followed by one  or  more  of  the  following  sub-attributes:  mode=mode  (mode  of
              operation, either norm or ext), and window=window size (window size in k, 1-127).

       l2=x25_ml ...
              ITU-T X.25, multilink

       l2=hdlc_arm ...
              HDLC ARM (ISO/IEC 4335)

       l2=hdlc_nrm ...
              HDLC NRM (ISO/IEC 4335)

       l2=hdlc_abm ...
              HDLC ABM (ISO/IEC 4335)

       l2=q992 ...
              ITU-T Q.922

       l2=iso7776 ...
              ISO 7776 DTE-DTE

       l2=user,info=information
              User-specified. information is an integer in the range 0 to 255.

       For layer three, the following (again, mutually exclusive) possibilities exist:

       l3=iso8473
              ITU-T X.233 | ISO/IEC 8473

       l3=t70 ITU-T T.70 minimum network layer

       l3=h321
              ITU-T Recommendation H.321

       l3=x25 ...
              ITU-T  X.25,  packet  layer.  This  attribute  and  the  following  attributes through l3=x223 can
              optionally be followed by one or more of the  following  sub-attributes:  mode=mode  (see  above),
              size=default packet size (4-12, corresponding to 16-4096), window=window size (see above).

       l3=iso8208 ...
              ISO/IEC 8208

       l3=x223 ...
              ITU-T X.223 | ISO/IEC 8878

       l3=tr9577,ipi=identifier ...
              ISO/IEC  TR  9577.  identifier  is  the  initial  protocol identifier in the range 0-255. For SNAP
              (0x80), the keyword snap can be used, and the following sub-attributes have to be specified: oui=3
              bytes, and pid=2 bytes.

       l2=user,info=information
              User-specified, see above.

       l3=h310 ...
              ITU-T  Recommendation  H.310.  The  sub-attribute  term=type  (terminal  type, rx, tx, or rxtx) is
              recognized. If present, it enables the two additional  sub-attributes  fw_mpx=capability  (forward
              multiplexing  capability,  ts,  ts_fec,  ps,  ps_fec,  or  h221)  and  bw_mpx=capability. Both are
              optional.

       Note that commas must never follow colons or other commas. Also, whitespace is not allowed inside  a  SAP
       specification.  SAP  specifications  are case-insensitive. On input, items must be written in exactly the
       order used in this document.

EXAMPLES

       blli:l2=iso8802
              Classical IP over ATM (RFC1577)

       bhli:oui=0x0060D7,id=0x01000001,blli:l2=iso8802
              Arequipa (RFC2170)

       blli:l3=tr9577,ipi=snap,oui=0x00A03E,pid=0x0002
              LAN Emulation

AUTHOR

       Werner Almesberger, EPFL LRC <werner.almesberger@lrc.di.epfl.ch>