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This feature module describes the distributed Traffic Shaping (DTS) feature. It includes information on the benefits of the new feature, supported platforms, prerequisites, configuration examples and command reference.
This document includes the following sections:
Many enterprise and service provider customers need to shape traffic in their networks and sometimes to shape IP traffic independent of the underlying interface. In other cases, the goal is to perform traffic shaping to ensure adherence to committed information rates on Frame Relay links.
The DTS feature is one element used to manage the bandwidth of an interface to avoid congestion, to meet remote site requirements, and to conform to a service rate that is provided on that interface.
DTS uses queues to buffer traffic surges that can congest a network. Data is buffered and then sent into the network at a regulated rate. This ensures that traffic will behave to the configured descriptor, as defined by command information rate (CIR), Committed Burst (Bc), and Excess Burst (Be). With the defined average bit rate and burst size that is acceptable on that shaped entity, you can derive a time interval value.
The Be allows more than the Bc to be sent during a time interval under certain conditions. Therefore, DTS provides two types of shape commands: average and peak. When shape average is configured, the interface sends no more than the Bc for each interval, achieving an average rate no higher than the CIR. When shape peak is configured, the interface sends Bc plus Be bits in each interval.
In a link layer network such as Frame Relay, the network sends messages with the forward explicit congestion notification (FECN) or backwards explicit congestion notification (BECN) if there is congestion. With the DTS feature, the traffic shaping adaptive mode takes advantage of these signals and adjusts the traffic descriptors. This approximates the rate to the available bandwidth along the path.
DTS provides the following key benefits:
DTS does not support the following:
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Note A VIP2-50 is strongly recommended when the aggregate line rate of the port adapters on the VIP is greater than DS3. A VIP2-50 card is required for OC-3 rates. |
For related information on DTS, refer to the following documents:
This feature runs on Cisco 7500 series routers with VIP2-40, VIP2-50, or higher.
MIBs
RFCs
DCEF Dependent
Distributed Cisco Express Forwarding (DCEF) must be enabled on the interface before DTS can be enabled.
Policy Maps and Class Maps
A policy map and class maps must be created before DTS is enabled. (See "Configuring a Policy with DTS in the Policy Map".)
See the following sections for configuration tasks for the DTS. Each task in the lists indicates if the task is optional or required.
To create a class map containing match criteria, use the class-map command to specify the class map name, and then use one of the following commands in class map configuration mode:
| Command | Purpose |
|---|---|
Router(config)# class-map class-name | Specifies the user-defined name of class map. |
Router(config-cmap)# match access-group access-group | Specifies the name of the class map to be created and the numbered ACL against whose contents packets are checked to determine if they belong to the class. |
Router(config-cmap)# match input-interface interface-name | Specifies the name of the input interface used as match criteria against which packets are checked to determine if they belong to the class. |
Router(config-cmap)# match protocol protocol | Specifies the name of the protocol used as match criteria against which packets are checked to determine if they belong to the class. |
Router(config-cmap)# match qos-group number | Specifies the number of the QoS group index used as match criteria against which packets are checked to determine if they belong to the class. |
Router (config-cmap)# match any | Specifies that all packets will be matched. |
Router (config-cmap)# match ip precedence number | Specifies up to eight IP precedence values used as match criteria. |
Router (config-cmap)# match ip dscp number | Specifies up to 64 DSCP values used as match criteria. |
To enable DTS you must create a policy map. You can configure class policies for as many classes as are defined on the router up to the maximum of 256.
To configure a policy map, use the policy-map command to specify the policy map name, then use the following configuration commands to configure class name, traffic shaping, and class policy.
Traffic is directed to the policy map default class if it does not satisfy the match criteria of any other classes whose policies are defined in the policy map.
| Command | Purpose | |
|---|---|---|
Step 1 | Router(config)# policy-map policy-name | Specifies the name of the policy map to be created. |
Step 2 | Router(config-pmap)# class class-name
| Specifies the name of a predefined class included in the service policy. |
Step 3 | Router(config-pmap-c)# shape <average | peak> <mean rate>[<burst size> [<excess burst size>]] | Specifies the target bits per second (bps) rate. |
To attach a policy map to the interface and enable DTS on the interface, use the following command in configuration mode:
| Command | Purpose |
|---|---|
Router(config)# service-policy output policy-name | Enables DTS and attaches the specified policy map to the interface. |
To change the amount of bandwidth allocated for an existing class, use the following commands:
| Command | Purpose | |
|---|---|---|
Step 1 | Router(config)# policy-map policy-name | Specifies the name of the service-policy map containing the class to be modified. |
Step 2 | Router(config-pmap)# class class-name | Specifies the name of a class whose bandwidth you want to modify. |
Step 3 | Router(config-pmap-c)# | Specifies the new values for the DTS feature. |
To monitor and maintain the DTS feature, use the following commands:
| Command | Purpose |
|---|---|
Router# show interface [interface-name] shape | Displays detail status of the traffic shaping. |
Router# show policy policy-name | Displays the configuration of all classes composing the specified policy map. |
Router# show policy policy-name class class-name | Displays the configuration of the specified class of the specified policy map. |
This section provides the following configuration examples:
In the following example, traffic that goes out on interface pos1/0/0 is shaped at the rate of 10Mbits/sec.
router(config)# class-map class-interface-all router(config-cmap)# match any router(config-cmap)# exit router(config)# policy-map dts-interface-all-action router(config-pmap)# class class-interface-all router(config-pmap-c)# shape average 10000000 router(config-pmap-c)# exit router(config)# interface pos1/0/0 router(config-if)# service-policy output dts-interface-all-action
In the following example, two classes are created and the match criteria is defined based on the access list number. Traffic that goes out on interface fdi4/0/0 and matches the criteria in access list 10 is shaped to 16Mbps. Traffic that matches the criteria in access list 20 is shaped to 8 Mbps.
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Note The following IP addresses are examples only. |
router(config)# access-list 10 permit 171.69.0.0 router(config)# access-list 20 permit 192.168.0.0 router(config)# class-map class1 router(config-cmap)# match access-group 10 router(config-cmap)# exit router(config)# class-map class2 router(config-cmap)# match access-group 20 router(config-cmap)# exit router(config)# policy-map dts-interface-class-action router(config-pmap)# class class1 router(config-pmap-c)# shape average 16000000 router(config-pmap-c)# exit router(config-pmap)# class class2 router(config-pmap-c)# shape average 8000000 router(config-pmap-c)# exit router(config-pmap)# interface fd4/0/0 router(config-if)# service-policy output dts-interface-class-action
In the following example, traffic going out on sub-interface 6/1/0.1 or 6/1/0.2 is shaped to 1 Mbps.
router(config)# class-map class-p2p-all router(config-cmap)# match any router(config-cmap)# exit router(config)# policy-map dts-p2p-all-action router(config-pmap)# class class-p2p-all router(config-pmap-c)# shape average 1000000 router(config-pmap-c)# exit router(config)# interface hssi6/1/0.1 point-to-point router(config-subif)# service-policy output dts-p2p-all-action router(config-subif)# exit router(config)# interface hssi6/1/0.2 point-to-point router(config-subif)# service-policy output dts-p2p-all-action
In the following example, two classes are created with the match criteria defined by QoS number. Traffic goes out on subinterface 6/1/0.5 or 6/1/0.6 with the QoS-group number 30 shaped to 800 kbps and the QoS-group number 40 shaped to 1.6 Mbps. For the incoming Frame Relay packet that has the FECN bit on, a BECN message is sent out from the interface. For the outgoing Frame Relay packets that match the QoS-group number 40, the shape rate could be further reduced to 800 kbps.
router(config)# class-map class3 router(config-cmap)# match qos-group 30 router(config-cmap)# exit router(config)# class-map class4 router(config-cmap)# match qos-group 40 router(config-cmap)# exit router(config)# policy-map dts-p2p-class-action router(config-pmap)# class class3 router(config-pmap-c)# shape average 800000 router(config-pmap-c)# shape fecn-adapt router(config-pmap-c)# exit router(config-pmap)# class class4 router(config-pmap-c)# shape average 1600000 router(config-pmap-c)# shape adaptive 800000 router(config-pmap-c)# exit router(config)# interface serial 6/1/0.5 point-to-point router(config-subif)# service-policy output dts-p2p-class-action router(config-subif)# exit router(config)# interface serial 6/1/0.6 point-to-point router(config-subif)# service-policy output dts-p2p-class-action
This section documents new commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command reference publications.
In Cisco IOS Release 12.0(1)T or later, you can search and filter the output for show commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.
To use this functionality, enter a show command followed by the "pipe" character (|), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:
command |{begin | include | exclude} regular-expressionFollowing is an example of the show interfaces shape command in which you want the command output to begin with the first line where the expression "Peak Rate" appears:
show interfaces shape| begin PeakRateFor more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T feature module titled CLI String Search.
Sample command reference pages follow. Refer to these samples for standard wording, syntax conventions, and format.
To create a class map to be used for matching packets to the class whose name you specify, use the class-map command. To remove an existing class map from the router, use the no form of this command.
class-map class-name
Syntax Description
class-name Name of the class for the class map. The class name is used for both the class map and policy configuration for the class in the policy map.
No default behavior or values.
Command Modes
Configuration
Command History
12.0(5)XE This command was introduced.
Release
Modification
Use the class-map command to specify the name of the class for which you want to create or modify class map match criteria. The class-map command enables class map configuration mode in which you can enter one of the match commands to configure the match criteria for a class. Packets arriving at the output interface are checked against the match criteria configured for a class map to determine if the packet belongs to that class.
Examples
The following example specifies access101 as the name of a class. The match access-group command is entered following the class-map command to configure the match criteria for the class map based on 101, the specified ACL number:
class-map access101 match access-group 101
Related Commands
class Specifies a class belonging to a service policy map. class class-default Specifies the default class for a service policy map. match access-group Configures the match criteria for a class map based on the specified ACL number. match input-interface Configures the match criteria for a class map based on the specified input interface. match protocol Configures the match criteria for a class map based on the specified protocol. match qos-group Configures the match criteria for a class map based on the specified QoS group. match any Specifies that all packets be matched. match ip precedence Specifies up to eight IP precedence values used as match criteria. match ip dscp Specifies up to 64 DSCP values used as match criteria. policy-map Specifies the policy map to which the class belongs. Command Description class Specifies a class belonging to a service policy map. class class-default Specifies the default class for a service policy map. match access-group Configures the match criteria for a class map based on the specified ACL number. match input-interface Configures the match criteria for a class map based on the specified input interface. match protocol Configures the match criteria for a class map based on the specified protocol. match qos-group Configures the match criteria for a class map based on the specified QoS group.
Command
Description
Use the policy-map configuration command to create or modify a policy map that can be attached to one or more interfaces. To delete a policy map, use the no form of this command.
policy-map policy-name
Syntax Description
policy User defined name
Defaults
No default behavior or values.
Command Modes
Configuration
Command History
12.0(5)XE This command was introduced.
Release
Modification
Usage Guidelines
Before you can configure policies for classes whose match criteria are defined in a class map, you must use the policy-map command to specify the name of the policy map to be created, added to, or modified. Entering the policy-map command enables policy map configuration mode in which you can configure or modify the class policies for that policy map.
You can configure class policies in a policy map only if the classes have previously defined match criteria. Use the class-map and match commands to configure the match criteria for a class. No policy map can contain more than 256 classes.
Examples
The following example shows a policy map called dts-interface-all-action and a class policy that matches any packets:
class-map class-interface-all match any policy-map dts-interface-all-action class class-interface-all shape average 10000000
Related Commands
class Specifies the class whose bandwidth is to be shaped. service-policy output Enables the DTS feature and attaches the specified service policy map to the interface.
Command
Description
Use the shape configuration command to shape traffic to the indicated bit rate according to the algorithm specified. The no form of this command removes shaping and leaves the traffic unshaped.
shape <average | peak> <mean rate>[<burst size>[<excess burst size>]]
Syntax Description
average Bc is the maximum number of bits sent out in each interval. peak Bc+Be is the maximum number of bits sent out in each interval. mean rate Also called CIR, indicates the bit rate used to shape the traffic, in bps (bits per second). When this command is used with BECN approximation, the bit rate is the upper bound of the range of bit rates that will be permitted. burst size The number of bits in a measurement interval (Bc). (optional) excess burst size The acceptable number of bits permitted to go over the burst size (Be). (optional)
Defaults
See Usage Guidelines for burst size.
Command Modes
Policy map class configuration
Command History
12.0(5)XE This command was introduced.
Release
Modification
Usage Guidelines
The measurement interval is Bc/CIR. Bc cannot be set to 0. If this is too large (greater than 128 ms), the system subdivides it into smaller intervals.
If you do not specify Bc and Be, the algorithm decides the default values for the shape entity. The algorithm uses a 4 ms measurement interval, so Bc will be CIR * 4/1000.
Burst sizes larger than the default Bc need to be explicitly specified. The larger the Bc, the longer the measurement interval. This may affect voice traffic latency, if applicable.
When Be is not configured, the default value is equal to Bc.
Examples
The following example configures a shape entity with CIR 1 Mbps and attaches the policy map called dts-interface-all-action to pos1/0/0:
policy-map dts-interface-all-action
class class-interface-all
shape average 10000000
interface pos1/0/0
service-policy output dts-interface-all-action
Related Commands
shape adaptive Causes the traffic shaping feature to recognize BECN signals from the Frame Relay network and adjust its shape rate as a result. shape fecn-adapt Configures a Frame Relay PVC1 to reflect received FECN bits as BECN in Q.922 TEST RESPONSE message.
Command
Description
1permanent virtual circuit
Use the shape adaptive command to configure a Frame Relay interface or a point-to-point subinterface to estimate the available bandwidth by BECN integration while traffic shaping is enabled. If traffic shaping is not enabled, this command has no effect. The no form of this command no longer estimates the available bit rate.
shape adaptive <mean-rate-lower-bound >
Syntax Description
mean-rate-lower-bound To react to Frame Relay BECN the lower bound of the range of bit rates that is permitted.
Defaults
No default behavior or values.
Command Modes
Policy map class configuration
Command History
12.0(5)XE This command was introduced.
Release
Modification
Usage Guidelines
When continuous BECN messages are received, the shape entity immediately decreases its maximum shape rate by 1/4 for each BECN message received until it reaches the lower bound CIR. If, after several intervals, the interface has not received another BECN and there is traffic waiting in the shape queue, it increases back to the maximum rate by 1/16 for each interval. A shape entity with "shape adaptive <lower CIR>" configured will always be shaped between the mean rate upper bound and the mean rate lower bound.
Examples
The following example configures a shape entity with CIR 128 Kbps and sets the lower bound CIR to 64 Kbps when BECN is received:
policy-map dts-p2p-all-action class class-p2p-all shape average 128000 shape adaptive 64000
Use the shape fecn-adapt configuration command to configure a Frame Relay interface to reflect received FECN bits as BECN in Q.922 TEST RESPONSE messages. The no form of this command configures the Frame Relay to no longer reflect FECN as BECN.
shape fecn-adaptSyntax Description
None
Defaults
No default behavior or values.
Command Modes
Policy-map class configuration
Usage Guidelines
When the downstream Frame Relay switch is congested, a Frame Relay interface or point-to-point interface receives a Frame Relay message with FECN bit on. This may be an indication that there is no traffic waiting to carry a BECN to the far end (voice/multimedia traffic is one-way). When shape fecn-adapt is configured a small buffer is allocated, and a Frame Relay Test Response is built on behalf of the Frame Relay switch. The Frame Relay Test Response is equipped with the triggering message's data-link connection identifier (DLCI). It also sets the BECN bit and sends it out to the wire.
Command History
12.0(5)XE This command was introduced.
Release
Modification
Examples
The following example configures a shape entity with CIR 1 Mbps and adapts the Frame Relay message with FECN to BECN:
policy-map dts-p2p-all-action class class-p2p-all shape average 1000000 shape fecn-adapt
Related Commands
shape Configures an interface to shape traffic to an indicated bit rate. shape adaptive Configures a Frame Relay PVC to estimate the available bandwidth by BECN integration while traffic shaping is enabled.
Command
Description
Use the service-policy output command to attach a policy map to an interface in the output direction and enable DTS on that interface. To remove a service policy from an output interface, use the no form of this command.
service-policy output policy-map
Syntax Description
policy-map The name of a service policy map created using the policy-map command.
Defaults
The DTS feature is disabled.
Command Modes
Configuration
Command History
12.0(5)XE This command was introduced.
Release
Modification
Usage Guidelines
You can attach a single policy map to one or more interfaces to specify the service policy for those interfaces. The class policies composing the policy map are then applied to packets that satisfy the class map match criteria for the class.
To successfully attach a policy map to an interface, it must have already been configured.
A service-policy can be attached to a subinterface.
Examples
The following example attaches the policy map called "dts-interface-all-action" to pos1/0/0 to specify the service policy for the interface and enable DTS on it.
interface pos1/0/0
service-policy output dts-interface-all-action
Related Commands
policy-map policy-map Specifies a policy map to be assigned to an interface.
Command
Description
Use the show interfaces shape EXEC command, to display information about traffic shaping for an interface.
show interfaces [interface-type interface-number] shape
Syntax Description
interface-type (Optional) The name of the interface. interface-number (Optional) The number of the interface.
Defaults
No default behavior or values.
Command Modes
EXEC
Command History
12.0(5)XE This command was introduced.
Release
Modification
Examples
The following example shows traffic shaping data: POS1/0/0 nobuffer drop 0 POS1/0/0(class 2):cir 140000000, Bc 4480000, Be 0 packets output 15926185, bytes output 6578M queue limit 10000, queue size 9987, drops 2292096 last clear = 00:06:16 ago, shape rate = 139499000 bps
Fddi4/0/0 nobuffer drop 0 Fddi4/0/0(class 20):cir 64000, Bc 8192, Be 0 packets output 0, bytes output 0 queue limit 0, queue size 0, drops 0 last clear = 00:03:51 ago, shape rate = 0 bps
Serial6/1/0 nobuffer drop 0 Serial6/1/0.1(class 2):cir 128000, Bc 8192, Be 0 lower bound cir 0, adapt to fecn 0 packets output 0, bytes output 0 queue limit 0, queue size 0, drops 0 last clear = 00:01:15 ago, shape rate = 0 bps
| Field | Description |
|---|---|
nobuffers | Number of packet drops due to no available buffer |
POS1/0/0, Fddi4/0/0, Ethernet6/0/4, etc. | Interface/sub-interface name |
(class 10),(class 20), etc. | Class ID |
cir | Mean rate being shaped (bps) |
Bc | Sustained burst size (in bits) |
Be | Excess burst size (in bits) |
lower bound cir | Mean rate lower bound (if the encapsulation is Frame Relay) |
adapt to fecn | Adapt to FECN message (if the encapsulation is Frame Relay) |
packets output | Number of packets sent out from this shape entity |
bytes output | Number of bytes sent out from this shape entity |
queue limit | Shape queue limit |
queue size | Current shape queue size |
drops | Number of packet drops due to full shape queue |
last clear | Time difference since last "clear counters" issued |
shape rate | Bits output divided by the time difference since last "clear counter" issued (in bps) |
Use the show policy-map EXEC command to display information about the policy-map for an interface.
show policy-map [policy name [class name]]
Syntax Description
policy name (Optional) Policy-map name. class name (Optional) Class interface. interface type number (Optional) The name of the interface.
Defaults
No default behavior or values.
Command Modes
EXEC
Command History
| Release | Modification |
|---|---|
12.0(5)XE | This command was introduced. |
Examples
The following example shows the currently configured policy maps:
router(config) # show policy-map Policy Map dts-p2p-all-action class-p2p-all shape average 1000000 32000 0 Policy Map dts-p2p-class-action class3 shape average 800000 51200 0 shape fecn-adapt class4 shape average 1600000 51200 0 shape adaptive 800000 Policy Map dts-interface-all-action class-interface-all shape average 10000000 320000 0 Policy Map dts-interface-class-action class1 shape average 16000000 512000 0 class2 shape average 8000000 256000 0
Related Commands
policy-map Specifies a policy map to be assigned to an interface.
Command
Description
This section provides a comparison between the distributed Traffic Shaping (DTS), Frame Relay Traffic Shaping (FRTS), and Generic Traffic Shaping (GTS) configurations. For more information on DTS Configuration Commands refer to the "Command Reference" section.
To shape all traffic on an interface, subinterface, or PVC use the configurations in the following table:
| Feature | Configuration |
|---|---|
GTS | Router(config)# interface hssi 3/0/0.1 point-to-point Router(config-if)# traffic-shape rate CIR1 [Bc[Be]] |
FRTS | Router(config)# map-class frame-relay slow_vc2 Router(config-cmap)# frame-relay traffic-rate CIR [CIR+EIR]3 Router(config)# interface hssi 3/0/0 Router(config-if)# frame-relay traffic-shaping Router(config)# interface hssi 3/0/0.1 point-to-point Router(config-if)# class slow_vc |
DTS | Router(config)# class-map all-traffic4 Router(config-cmap)# match any Router(config)# policy-map shape-all-traffic5 Router(config-pmap)# class all-traffic6 Router(config-pmap-c)# shape <average | peak>7CIR [Bc [Be]] Router(config)# interface hssi 3/0/0.1 Router(config-if)# service-policy output shape-all-traffic |
| 1CIR=Bc bits per second (bps) 2map-class-name 3CIR+EIR=(Bc+Be) bps 4class-name 5policy-name 6class-name 7<average>=Bc bps <peak>=(Bc+Be) bps |
To shape a specific class of traffic on an interface use the configurations in the following table:
:
| Feature | Configuration |
GTS | Router(config)# access-list 10 permit {type-code wild-mask|address mask}
Router(config)# access-list 20 permit {type-code wild-mask|address mask}
Router(config)# interface hssi 3/0/0.1 point-to-point
Router(config-if)# traffic-shape group 10 CIR [Bc[Be]]
Router(config-if)# traffic-shape group 20 CIR [Bc[Be]]
|
FRTS | Router(config)# access-list 10 {type-code wild-mask|address mask}
Router(config)# queue-list 1 protocol ip 11 list2 103
Router(config)# priority-list 2 protocol ip high
Router(config)# map-class frame-relay slow_vc4
Router(config-cmap)# frame-relay custom-queue list 1
Router(config-cmap)# frame-relay traffic-rate CIR[CIR+EIR]
Router(config)# map-class frame-relay fast_vc5
Router(config-cmap)# frame-relay priority-group 2
Router(config-cmap)# frame-relay traffic-rate CIR [CIR+EIR]
Router(config)# interface hssi 3/0/0
Router(config-if)# frame-relay traffic-shaping
Router(config)# interface hssi 3/0/0.1 point-to-point
Router(config-if)# class slow_vc
Router(config)# interface hssi 3/0/0.2 point-to-point
Router(config-if)# class fast_vc
|
DTS | Router(config)# access-list 10 permit{type-code wild-mask|address mask}
Router(config)# access-list 20 permit{type-code wild-mask|address mask}
Router(config)# class-map class 1
Router(config-cmap)# match access-group 106
Router(config)# class-map class 2
Router(config-cmap)# match access-group 20
Router(config)# |
| 1queue-number 2queue-keyword 3keyword-value 4map-class-name 5map-class-name 6access-group |
Posted: Mon Mar 20 12:58:17 PST 2000
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