Man Linux: Main Page and Category List


       qos - Quality of Service specification


       The  text2qos  and  qos2text 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 QOS specifications,
       they expect them in the same format too.

       The most fundamental parameters are the traffic class and the AAL  (ATM
       Adaption  Layer)  type.  If  the  connection  is  bi-directional,  both
       directions have the same traffic class  and  the  same  AAL  type.  The
       traffic class and the AAL type are the first elements (in any order) in
       a QOS specification. The traffic class is the only required element. If
       the  AAL type is omitted, the application will provide a default value.
       The following traffic classes are recognized:

       ubr    Unassigned Bit Rate

       cbr    Constant Bit Rate

       abr    Available Bit Rate

       The following AAL types are recognized:

       aal0   ("raw ATM")


       If both, the traffic class and the AAL type  are  specified,  they  are
       separated by a comma.

       If more parameters are supplied, the traffic class and AAL type must be
       followed by a colon. Traffic parameters can be specified  independently
       for  the  transmit and the receive direction. Their parameter lists are
       prefixed with tx: and rx:, respectively. If both  parameter  lists  are
       present,  the  tx:  list  must  precede the rx: list. If a parameter is
       equal for both directions, it can be placed in a common parameter  list
       (without prefix). The general format is as follows:


       Each  list  consists  of  elements specifying a parameter. Elements can
       appear in any order and they are separated with commas.  The  following
       elements are recognized:

              is a synonym for max_pcr=rate

              The  upper  limit  for the peak cell rate to assign. If omitted,
              any rate up to link speed may be chosen.

              The lower limit for the peak cell rate to  assign.  If  omitted,
              any rate above zero can be chosen.

              is a synonym for max_sdu=size

              The  size of the largest packet that may be sent or received. If
              omitted, a context-dependent default value is used.

       Values are specified as follows:

       rate   The (decimal) rate, optionally followed by a unit. The unit  may
              be  prefixed  with  one  of  the multipliers k, M, or G, meaning
              1’000, 1’000’000, or 1’000’000’000, respectively. The units  cps
              (cells  per second) and bps (bits per second) are recognized. If
              multiplier and unit are omitted, cells per second  are  assumed.
              Note  that  the rate is always converted to cells per second, so
              rounding errors may occur when specifying the rate in  bits  per
              second.  Rates  measured in bits per second are considered to be
              user data rates, i.e. one cell corresponds to 384 bits. The rate
              can  be  a  fractional  value, e.g.  1.3Mbps.  It is an error to
              specify only a multiplier without a  unit.  Link  speed  can  be
              indicated by using the keyword max as the rate.

       size   The (decimal) number of bytes.

       The  tx:  or  rx:  lists may also just contain the single element none,
       which indicates that the corresponding direction is not used.  It is an
       error to specify none for both direction.

       Note  that  commas  must  never  follow  colons  or other commas. Also,
       whitespace  is  not   allowed   inside   a   QOS   specification.   QOS
       specifications are case-insensitive.


       Each of the following lines contains a valid QOS specification:


       The following specificiations are equivalent:



       Werner Almesberger, EPFL LRC/ICA <>