NAME
pvctxctl —
display or control ATM PVC
transmitter parameters
SYNOPSIS
pvctxctl |
interface
[[vpi:]vci] |
pvctxctl |
interface
[vpi:]vci
[-n]
[-b
max-bandwidth]
[-j
[vpi:]vci]
[-p
pcr] |
DESCRIPTION
pvctxctl displays or controls the shaper parameters of an ATM
VC. When a shaper value is specified,
pvctxctl sets a shaper
to an ATM VC.
pvctxctl works for a PVC sub interface
pvc(4) as well as a real ATM
interface
en(4).
For a real ATM interface, the specified VC should be assigned beforehand by
route(8).
For a sub interface,
pvctxctl assigns the specified VC to the
sub interface. If another VC is already assigned to the sub interface, the old
VC is invalidated.
Availability of shapers, the number of hardware shaper channels, and accuracy of
shaping are all device dependent. For example, ENI Midway chip has 8 shaper
channels but the driver reserves one for non-shaping VCs.
The options are as follows:
-
-
- interface
- The interface parameter is a string
of the form “name unit”, for example, “en0”.
-
-
- [vpi:]vci
- The VC number to which the shaper is assigned. When the VPI
number is omitted, VPI number 0 is assumed. For example, to assign a
shaper to VPI=0 and VCI=201, the following forms can be used:
"201", "0xc9", "0:201",
"0:0xc9".
-
-
- -b
max-bandwidth
- The PCR parameter can be specified also in “bits per
second”. The rate is the rate of AAL5 frame and the PCR is
calculated by the following form:
PCR = max-bandwidth / 8 / 48
“K” and “M” can be used as a short hand of
“000” and “000000” respectively. For example,
“45M” means “45Mbps” or PCR value
“117187”.
-
-
- -j
[vpi:]vci
- The join parameter is intended for VP shaping. The VC
shaper channel is shared with the existing VC, which means the sum of the
cell rates never exceeds the maximum PCR among the shared VCs. On the
other hand, when the shaper channel is not shared, the sum of the cell
rates could be the sum of the PCRs.
For example, if two VCs (say 201 and 202) share a 45Mbps VP, use:
# pvctxctl en0 201 -b 45M
# pvctxctl en0 202 -b 45M -j
201
-
-
- -n
- This parameter is only for a sub interface. Use NULL
encapsulation instead of LLC/SNAP.
-
-
- -p
pcr
- The PCR (Peak Cell Rate) parameter specifies the peak cell
rate in "cells per second". If PCR value "0" is
specified, no shaper is assigned, which means cells are sent at full-speed
of the link. If PCR value “-1” is specified, the corresponding
VC is invalidated.
SEE ALSO
en(4),
ifconfig(8),
pvcsif(8),
route(8)
BUGS
A real ATM interface and a sub interface require different sequences to set a
shaper. For example, to assign a 45Mbps shaper to VC 201 (0xc9) of en0:
# ifconfig en0 10.0.0.1
# route add -iface 10.0.0.2 -link en0:3.0.0.c9
# pvctxctl en0 0xc9 -b 45M
For a shadow interface,
# pvcsif en0 # creates pvc0
# ifconfig pvc0 10.0.0.1 10.0.0.2
# pvctxctl pvc0 201 -b 45M