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Page 711 / 998 Scroll up to view Page 706 - 710
ATM QoS Feature
QOS
7-15
iMG/RG Software Reference Manual (Quality of Service)
The scheduling algorithm type is specified in the command. If the scheduling algorithm is WF2Qplus, then all
traffic gets enqueued to a default queue (queue 0) with a weight allocation of 100% by default. To enable
enqueuing to the other queues (1-7), assign a weight to the queues using the command
SCHEDULER PRO-
FILE SET QUEUE [1-7] WEIGHT
2.
The Algorithmic Dropper (ALD) can be applied to a queue using the following command
SCHEDULER
PROFILE SET QUEUE {DEFAULT | [1-7]} ALD PROFILE <GREENPROFILE> [<YELLOW-
PROFILE> <REDPROFILE>]
Note that
GreenProfile
,
YellowProfile
and
RedProfile
are the names of ALD profiles that are
different from Scheduler profiles. An ALD profile can be created using the command
ALD ADD PROFILE
[<MINTH> <MAXTH> <MAXDROPPROB> <WEIGHTFACTOR>]
3.
Shaping can be configured to throttle the aggregate output rate of the Scheduler to the specified maximum
rate and burst size using the
COMMAND SCHEDULER SET PROFILE SHAPING <MAXRATE>
<MAXBURST>
4.
Apply the Scheduler profile to an existing transport using the command
TRANSPORTS SET SCHEDULER
PROFILE
Note:
Note that the classifier can be assigned only for transports attached to the adsl interface like RFC1483,
PPPoA and PPPoE(oA).
7.1.4
ATM QoS Feature
The following ATM QoS features are provided by the gateway.
7.1.4.1 ATM Packet Prioritization
After packets have been routed or bridged, the ADSL driver provides transmit prioritisation when packets with
different priorities are sent on the same ATM VC.
Page 712 / 998
QOS
ATM QoS Feature
iMG/RG Software Reference Manual (Quality of Service)
7-16
FIGURE 7-6
The ADSL Driver
7.1.4.2 How ATM packet prioritization works
The ADSL device driver is responsible for transmit scheduling when packets of different priorities are sent on
the same channel.
Note:
ADSL driver prioritization support provides a pure prioritization approach, useful for providing Expedited
Forwarding for voice packets, as opposed to the Scheduler/Algorithmic Dropper that can provide fair
sharing of bandwidth for Assured Forwarding.
The driver discovers the priority of the packet by examining the traffic class field of the buffer that was written
by the Classifier.
If a local application, such as the VoIP, originates packets, the IP stack will set the priority of the packet as appro-
priate. The data stream from the Classifier can also be policed using the Meter to control the data rate for each
stream defined by the Classifier. If the data rate of a stream exceeds the rate set in the Meter profile being used
to police the data stream, then the Meter will drop packets from that stream.
Therefore, using the Classifier and the Meter can help to lessen the impact of forwarding incoming packets
from a high-speed interface such as Ethernet to a low-speed interface such as DSL.
But, without prioritization support in the device driver used for transmitting outgoing packets, the following
problems would also occur when packets are forwarded from a high speed interface to a low speed interface:
•
high priority packets would suffer latency because they are queued behind a number of low priority packets
awaiting transmission
Bridge/Router Software
Meter
Classifier
ATM driver
with packet
prioritization
support
HP
Queue
LP
Queue
Page 713 / 998
Classifier command reference
QOS
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iMG/RG Software Reference Manual (Quality of Service)
•
high priority packets would be dropped, because such a large number of buffers are queued from transmis-
sion that system buffering resources are exhausted.
The ADSL driver provides the following features to prevent this:
•
Transmit scheduling
•
Queue depth limiting
7.1.4.2.1 Transmit scheduling
The ADSL driver can be configured to support two transmit queues per VC; a high priority queue, and a low
priority queue. Packets are placed on a queue indicated by the traffic class field of the buffer.
Note:
Whenever a transmit slot becomes available, a packet is sent from the high priority queue. If there are no
high priority packets available, a packet from the low priority queue is sent instead.
7.1.4.3 Configuring priority handling support
To enable support for different priorities on an existing ATM transport, use the following CLI commands:
pppoe set transport mypppoe prilevels 2
pppoa set transport mypppoa prilevels 2
rfc1483 set transport myrfc prilevels 2
These commands set two priority levels, as supported by the adsl driver.
Note:
Note that packets classified as priority 0 will be placed on the default queue, packets classified as priority
1 or higher will all be placed on the high priority queue.
7.1.5
Classifier command reference
7.1.5.1 Classifier CLI commands
The table below lists the
classifier
commands provided by the CLI:
TABLE 7-1
Classifier
commands
Commands
Fiber
A
Fiber
B
Fiber
C
Fiber
D
Fiber
E
Modular
ADSL
A
ADSL
B
ADSL
C
CLASSIFIER ADD PROFILE
X
X
X
X
X
X
X
X
X
CLASSIFIER CLEAR PROFILES
X
X
X
X
X
X
X
X
X
CLASSIFIER DELETE PROFILE
X
X
X
X
X
X
X
X
X
CLASSIFIER LIST PROFILES
X
X
X
X
X
X
X
X
X
Page 714 / 998
QOS
Classifier command reference
iMG/RG Software Reference Manual (Quality of Service)
7-18
CLASSIFIER PROFILE ADD RULE
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE CLEAR RULES
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE DELETE RULE
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE LIST RULES
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE DATALENGTH
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE DROPPRI
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE DSCP
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE DSTADDR
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE DSTPORT
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE IFDOMAIN
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE MARK DSCP
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE MARK TOS
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE MARK VPRI
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE METERID
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE OFFSET
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE PHYPORT
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE PRIORITY
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE PROTOCOL
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE SRCADDR
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE SRCPORT
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE TOS
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE TRAFFICTYPE
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE VLANID
X
X
X
X
X
X
X
X
X
CLASSIFIER PROFILE SET RULE VLANPRI
X
X
X
X
X
X
X
X
X
CLASSIFIER SHOW PROFILE
X
X
X
X
X
X
X
X
X
TABLE 7-1
Classifier
commands
(Continued)
Commands
Fiber
A
Fiber
B
Fiber
C
Fiber
D
Fiber
E
Modular
ADSL
A
ADSL
B
ADSL
C
Page 715 / 998
Classifier command reference
QOS
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iMG/RG Software Reference Manual (Quality of Service)
7.1.5.1.1
CLASSIFIER ADD PROFILE
Syntax
CLASSIFIER ADD PROFILE <name>
Description
This command creates a classifier profile. You can add rules to the profile using the classi-
fier profile add rule command. You can then set the profile to work on an ATM transport
or transports, using the
TRANSPORT SET CLASSIFIER PROFILE
command.
Options
The following table gives the range of values for each option that can be specified with
this command and a default value for each option (if applicable).
Syntax
Example
classifier add profile pr1
See also
CLASSIFIER PROFILE ADD RULE
TRANSPORTS SET CLASSIFIER PROFILE
7.1.5.1.2 CLASSIFIER CLEAR PROFILES
Syntax
classifier clear profiles
Description
This command deletes all classifier profiles that were created using the classifier add pro-
file command. Any rules associated with the profiles are also deleted by this command.
Example
--> classifier clear profiles
See also
CLASSIFIER ADD PROFILE
7.1.5.1.3 CLASSIFIER DELETE PROFILE
Syntax
CLASSIFIER DELETE PROFILE {<name>|<number>}
Description
This command deletes a single profile that was created using the
CLASSIFIER ADD
PROFILE
command. Any rules associated with the profile are also deleted by this com-
mand.
Options
The following table gives the range of values for each option that can be specified with
this command and a default value (if applicable).
Option
Description
Default Value
name
An arbitrary name that identifies the profile. It can be
made up of one or more letters or a combination of let-
ters and digits, but it cannot start with a digit.
N/A

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