3Com Router 3033 User manual

3Com Router
Configuration Guide for V1.20
http://www.3com.com/
Part No. 10014303
Published January 2004

1.1. Introduction
1.1.1. Scope
This manual provides configuration information for new software features found in V1.20 of the
3Com Router operating system. Use this addendum to supplement configuration information found
in the 3Com Router Configuration Guide.
1.1.2. Online Resources
Download the Router 3000 Installation Guide from:
http://support.3com.com/infodeli/tools/routers/R3000Install.pdf
Download the Router 5000 Installation Guide from:
http://support.3com.com/infodeli/tools/routers/5000Install.pdf
Download the 3Com Router Command Reference Guide from:
http://support.3com.com/infodeli/tools/routers/3ComRouterComRef.pdf
Download the 3Com Router Configuration Guide from:
http://support.3com.com/infodeli/tools/routers/3com_configuration_guide.pdf
Download other current software updates and release notes from:
http://www.3com.com/
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Chapter 1 Configuring Class-Based Queuing
As an extension of WFQ, class based queuing (CBQ) provides users with class
definition support. CBQ assigns individual FIFO reservation queues to the classes
defined by each user to buffer data of the same class. When there is network
congestion, CBQ matches outbound packets according to the classification rule
defined by users to make them enter relevant queues. Before queue entry of packets,
the congestion avoidance mechanism (tail-drop or weighted random early detection
[WRED]) and bandwidth limit must first be checked. When packets leave the queues,
weighted fair scheduling of packets in the queues corresponding to each class should
be performed.
IP Packets
LLQ
BQ1
Classifying
Sent packets
BQ64
Sent queue
¡¡
Scheduling
BQ2
Outgoing first
Figure 1-1 CBQ diagram
If CBQ performs weighted fair treatment to queues of all classes, voice packets, the
delay-sensitive data flow may not be sent out in time. Therefore, PQ is introduced to
CBQ to create low latency queuing (LLQ), which provides strictly preferred sending
service for such delay-sensitive data flow as voice packets.
LLQ strictly combines PQ with CBQ. When a user defines a class, he can specify it to
accept strict priority service. The class of this type is called priority class. All packets
of the priority class enter the same priority queue. Before they enter a queue, the
bandwidth limit of each class of packets should be checked. When packets go out of
the queues, the packets in the priority queue are forwarded before packets in the
queues corresponding to other classes. But if the maximum reservation bandwidth
configured for LLQ is exceeded, the packets in other queue are sent. Weighted fair
scheduling will be performed to the packets in other queues when they are forwarded.
In order to avoid long time delay of packets in other queues, the maximum available
bandwidth can be specified for each priority class during LLQ application for traffic
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policing upon congestion. If no congestion occurs, the priority class is permitted to
use bandwidth exceeding the assigned value. In case of congestion, packets
exceeding the assigned bandwidth of the priority class will be discarded. Burst size is
also configurable under LLQ.
When the system matches packets with rules, it matches priority classes before other
classes. If there are multiple priority classes, they are matched one by one according
to configuration sequence. The same procedure is used to match packets and rules in
other classes. If there are multiple rules in a class, they are also matched one by one
according to the configuration sequence.
1.2 CBQ Configuration Tasks
CBQ (Class Based Queuing) configuration includes:
 Define a class and enter the class view
 Configure matching rules of a class
 Define the policy and enter the policy view
 Configure class in policy and enter policy-class view
 Configure features of a class
 Apply a policy to an interface
1.2.1 Define a Class and Enter the Class View
Defines a class and enters class view.
Perform the following configurations in the system view.
Table 1-1 Define a class and enter the class view
Operation Command
Define a Class and Enter the Class
View qos class [ logic-and | logic-or ] class-name
Delete a class and enter class view undo qos class [ logic-and | logic-or ] class-name
By default, a class named default-class is defined in the system. The class name
defined by the user “class-name” cannot be default-class.
By default, the defined class is logic-and and the interrelationship between matching
rules in the class view is logical AND.
1.2.2 Configure Matching Rules of a Class
1) Define the rule for matching all packets
Perform the following configurations in class view.
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Table 1-2 Define/delete the rule matching all packets
Operation Command
Define the rule matching all packets if-match [logic-not ]any
Delete the rule matching all packets undo if-match [logic- not ]any
2) Define the class matching rule
Perform the following configurations in class view.
Table 1-3 Define/delete the class matching rule
Operation Command
Define the class matching rule if-match [ logic-not ]class class-name
Delete the class matching rule undo if-match [ logic-not ]class class-name
Note:
This command cannot be used circularly. For example, qos class A defines the rules to match qos class
B, while qos class B cannot define a rule matching qos class A directly or indirectly.
3) Define the ACL matching rule
Perform the following configurations in class view.
Table 1-4 Define/delete ACL matching rule
Operation Command
DefineACL matching rule if-match [ logic-not ] acl acl-number
DeleteACL matching rule undo if-match [ logic-not ] acl acl-number
4) Define the MAC address matching rule
Perform the following configurations in class view.
Table 1-5 Define/delete the matching rule of a MAC address
Operation Command
Define MAC address matching rule if-match [ logic-not ]{destination-mac | source-mac }mac-address
Delete MAC address matching rule undo if-match [logic-not ]{destination-mac | source-mac }
mac-address
Note:
The matching rules of the destination MAC address are only meaningful for the policies in outbound
direction and the interface of Ethernet type.
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The matching rules of the source MAC address are only meaningful for the policies in inbound direction
and the interface of Ethernet type.
5) Define the inbound interface matching rule of a class
Perform the following configurations in class view.
Table 1-6 Define/delete the inbound interface matching rule of a class
Operation Command
Define the inbound interface
matching rule of a class if-match [logic-not ]inbound-interface type number }
Delete the inbound interface
matching rule of a class undo if-match [logic-not ]inbound-interface type number
6) Define the DSCP matching rule
The differentiated services code point (DSCP) is a refined field from the 6 high bits of
ToS bytes in IP header by IETF DiffServ workgroup.In the solution submitted by
DiffServ, services are classified and traffic is controlled according to service
requirements at the network ingress. Simultaneously, DSCP is set. Communication
(including resource allocation, packet discard policy, etc.) is classified and served on
the basis of the grouped DSCP values
You can set classified matching rules according to DSCP values.
Perform the following configurations in class view.
Table 1-7 Define/delete DSCP matching rule
Operation Command
Define DSCP matching rule if-match [logic-not ]ip-dscp value [ value ] …
Delete DSCP matching rule undo if-match [logic-not ]ip-dscp value [ value ] …
7) Define the IP precedence matching rule
Perform the following configurations in class view.
Table 1-8 Define/delete ip precedence matching rule
Operation Command
Define IP precedence matching rule if-match [logic-not ] ip-precedence value [ value ] …
Delete IP precedence matching rule undo if-match [logic-not ] ip-precedence …
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Use the corresponding command to configure the value of ip precedence during the
configuration; otherwise, the configuration of the if-match ip precedence command
will overwrite the previous configurations.
8) Define the RTP port matching rule
Perform the following configurations in class view.
Table 1-9 Define/delete RTP port matching rule
Operation Command
Define RTP port matching rule if-match [logic-not ]rtp start-port starting-port-number end-port
end-port-number
Delete RTP port matching rule undo if-match [logic-not ]rtp start-port starting-port-number
end-port end-port-number
Because the RTP priority queue (RTPQ) has a higher priority than that of CBQ, only
RTPQ will take effect if both RTPQ and the queue based on the class matching RTP
are configured at the same time.
9) Define the protocol matching rule
Perform the following configurations in class view.
Table 1-10 Define/delete IP matching rule
Operation Command
Define IP matching rule if-match [logic-not ] protocol ip
Delete IP matching rule undo if-match [logic-not ] protocol ip
10) Define the rule of all packets that do not satisfy the specified matching
rule.
Perform the following configurations in class view.
Table 1-11 Define/delete the rule of all packets not satisfying the specified matching rule
Operation Command
Define the rule of all packets not satisfying specified
matching rule if-match logic-not
criteria
Delete the rule of all packets not satisfying specified
matching rule undo if-match logic-not
criteria
Match-criteria: Matching rule of the class, including acl, any, class, destination-mac,
inbound-interface, ip-precedence, ip-dscp, protocol, rtp, source-mac.
1.2.3 Define the Policy and Enter the Policy View
Policy definition includes definition to the feature requirement for each class in the
policy, such as queue scheduling, including EF, AF, WFQ, TP, TS, and WRED.
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Perform the following configurations in the system view.
Table 1-12 Define the policy and enter the policy view
Operation Command
Define the policy and enter the policy
view qos policy policy-name
Delete the specified policy undo qos policy policy-name
If an interface applies this policy, this policy is not allowed to be deleted. You must
remove the application of this policy on the interface and then delete the policy with
the undo qos policy command.
1.2.4 Configure Class in Policy and Enter Policy-Class View
Perform the following configurations in the policy view.
Table 1-13 Configure class in policy and enter policy-class view
Operation Command
Configure class in policy qos-class class-name
Remove the class configuration undo qos-class class-name
class-name: Name of a class, of a defined class.
1.2.5 Configure Features of a Class in Policy
1) Configure bandwidth
CBQ can set bandwidth and queuing length for each class.
Bandwidth is the minimum guarantee that the router can provide when congestion
occurs. If there is no congestion, each class can use the bandwidth larger than the
assigned one, but if there is congestion, for each class, all the packets exceeding the
assigned bandwidth will be dropped.
Queuing length is the maximum queue length of the class. When the queue is as long
as the preset length, new packets that want to enter the queue will be dropped.
Policy class configured with expedited-forwarding and bandwidth is a priority class
and will enter low latency queuing (LLQ).
Policy class configured with assured-forwarding and bandwidth is an ordinary class.
The class that does not match any policy is called the default-class, and it can be
configured with assured-forwarding and bandwidth. After the default-class is
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configured with a maximum bandwidth, the system will assign the class an individual
queue, called the default queue.
Theoretically, each class can be configured with bandwidth of any size, but generally,
the priority classes can occupy 70% of the total bandwidth, and other ordinary classes
and the default class occupy less than 10%. It should be noted that the total
bandwidth assigned to each class and the RTP priority queue should not be larger
than the available bandwidth (the maximum bandwidth of the interface multiplied by
the percentage of the reserved bandwidth).
Please perform the following configurations in policy-class view.
Table 1-14 Configure assured-forwarding and the minimum bandwidth
Operation Command
Configure assured-forwarding for an
ordinary class or default class and
configure the minimum bandwidth for them af bandwidth { bandwidth | pct percentage }
Delete the assured-forwarding undo af
Configure expedited-forwarding for priority
class and configure the maximum
bandwidth and CBS for it ef bandwidth bandwidth [ cbs size ]
Delete expedited-forwarding undo ef
This function can only be applied on the outbound direction.
Note:
Priority classes must be configured with absolute bandwidth, while ordinary classes and the default class
can be configured with relative bandwidth (in percentage) or absolute bandwidth.
2) Configure fair queue for the default class
Perform the following configurations in the policy-class view.
Table 1-15 Configure fair queue for the default class
Operation Command
Configure WFQ for the default class wfq [queue-number total-queue-number ]
Remove the configured WFQ of the default
class undo wfq
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3) Configure the maximum queue length of the class
Configure maximum queue length of the class and configure the drop type as tail
drop.
Perform the following configurations in the policy-class view.
Table 1-16 Configure the maximum queue length of the class
Operation Command
Configure the maximum queue length of the
class queue-length queue-length
Delete the configuration of maximum queue
length undo queue-length
This command can be used only after the af command has been configured. Execute
the undo af command then queue-length will be deleted as well.
For the default-class, this command can be used only after the af has been
configured.
4) Configure the discarding mode of the class as random.
Perform the following configurations in the policy-class view.
Table 1-17 Configure the discarding mode of the class as random
Operation Command
Configure the discarding mode of the class
as random wred [ip-dscp value | ip-precedence value ]
Restore the default setting undo wred [ ip-dscp value | ip-precedence value ]
ip-dscp indicates that the DSCP value is used to calculate the drop probability of a
packet.
Ip-precedence: Indicate that the IP precedence value is used to calculate drop
probability of a packet, which is the default setting.
This command cannot be used until the af command has been configured. In the
case of the default class, this command be used only after the af command has been
configured. The wred and queue-length commands are mutually exclusive. Other
configurations under the random drop will be deleted simultaneously when this
command is deleted. When a QoS policy including WRED is applied on an interface,
the original WRED configuration on the interface will be invalid.
The default-class can only be configured with the random discard mode based on IP
precedence.
5) Configure exponential of average queue length calculated by WRED
Perform the following configurations in the policy-class view.
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