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       sap - Service Access Point specification


       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

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

       iso=1-8 bytes

       user=1-8 bytes

       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:

              Basic mode ISO 1745

              ITU-T Q.291 (Rec. I.441)

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

              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

              User-specified. information is an integer in the range 0 to 255.

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

              ITU-T X.233 | ISO/IEC 8473

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

              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.

              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.


              Classical IP over ATM (RFC1577)

              Arequipa (RFC2170)

              LAN Emulation


       Werner Almesberger, EPFL LRC <>