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>