1QOS(7)                           Miscellaneous                          QOS(7)
2
3
4

NAME

6       qos - Quality of Service specification
7

DESCRIPTION

9       The  text2qos  and  qos2text functions use the format described in this
10       man page. Because all standard ATM tools on Linux use  those  functions
11       to convert to or from the textual representation of QOS specifications,
12       they expect them in the same format too.
13
14       The most fundamental parameters are the traffic class and the AAL  (ATM
15       Adaption  Layer) type. If the connection is bi-directional, both direc‐
16       tions have the same traffic class and the same AAL  type.  The  traffic
17       class  and  the AAL type are the first elements (in any order) in a QOS
18       specification. The traffic class is the only required element.  If  the
19       AAL  type is omitted, the application will provide a default value. The
20       following traffic classes are recognized:
21
22       ubr    Unassigned Bit Rate
23
24       cbr    Constant Bit Rate
25
26       abr    Available Bit Rate
27
28       The following AAL types are recognized:
29
30       aal0   ("raw ATM")
31
32       aal5
33
34       If both, the traffic class and the AAL type  are  specified,  they  are
35       separated by a comma.
36
37       If more parameters are supplied, the traffic class and AAL type must be
38       followed by a colon. Traffic parameters can be specified  independently
39       for  the  transmit and the receive direction. Their parameter lists are
40       prefixed with tx: and rx:, respectively. If both  parameter  lists  are
41       present,  the  tx:  list  must  precede the rx: list. If a parameter is
42       equal for both directions, it can be placed in a common parameter  list
43       (without prefix). The general format is as follows:
44
45       class_and_aal:common_list,tx:list,rx:list
46
47       Each  list  consists  of  elements specifying a parameter. Elements can
48       appear in any order and they are separated with commas.  The  following
49       elements are recognized:
50
51       pcr=rate
52              is a synonym for max_pcr=rate
53
54       max_pcr=rate
55              The  upper  limit  for the peak cell rate to assign. If omitted,
56              any rate up to link speed may be chosen.
57
58       min_pcr=rate
59              The lower limit for the peak cell rate to  assign.  If  omitted,
60              any rate above zero can be chosen.
61
62       sdu=size
63              is a synonym for max_sdu=size
64
65       max_sdu=size
66              The  size of the largest packet that may be sent or received. If
67              omitted, a context-dependent default value is used.
68
69       Values are specified as follows:
70
71       rate   The (decimal) rate, optionally followed by a unit. The unit  may
72              be  prefixed  with  one  of  the multipliers k, M, or G, meaning
73              1'000, 1'000'000, or 1'000'000'000, respectively. The units  cps
74              (cells  per second) and bps (bits per second) are recognized. If
75              multiplier and unit are omitted, cells per second  are  assumed.
76              Note  that  the rate is always converted to cells per second, so
77              rounding errors may occur when specifying the rate in  bits  per
78              second.  Rates  measured in bits per second are considered to be
79              user data rates, i.e. one cell corresponds to 384 bits. The rate
80              can  be  a  fractional  value, e.g.  1.3Mbps.  It is an error to
81              specify only a multiplier without a  unit.  Link  speed  can  be
82              indicated by using the keyword max as the rate.
83
84       size   The (decimal) number of bytes.
85
86       The  tx:  or  rx:  lists may also just contain the single element none,
87       which indicates that the corresponding direction is not used.  It is an
88       error to specify none for both direction.
89
90       Note that commas must never follow colons or other commas. Also, white‐
91       space is not allowed inside a QOS specification. QOS specifications are
92       case-insensitive.
93

EXAMPLES

95       Each of the following lines contains a valid QOS specification:
96
97         ubr
98         ubr:pcr=100kbps
99         cbr,aal0:pcr=64kbps
100         CBR:max_pcr=11Mbps,min_pcr=10mbps,sdu=8192
101         aal5,ubr:tx:none
102         cbr:tx:pcr=30000,rx:none
103
104       The following specificiations are equivalent:
105
106         CBR,AAL5:PCR=48Mbps
107         cbr,aal5:max_pcr=125000
108         cbr,aal5:tx:pcr=125kcps,rx:pcr=125kcps
109
110

AUTHOR

112       Werner Almesberger, EPFL LRC/ICA <werner.almesberger@epfl.ch>
113
114
115
116Linux                           April 20, 2000                          QOS(7)
Impressum