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Contents
Packet flow on a network can be regulated using a traffic shaping mechanism. One such traffic shaping mechanism is a Cisco feature called Generic Traffic Shaping (GTS). Generic Traffic Shaping allows you to regulate the flow of packets going out an interface or subinterface, matching the packet flow to the speed of the interface. This module describes the concepts and tasks related to configuring Generic Traffic Shaping.
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
GTS is a traffic shaping mechanism (also known as a "traffic shaper"). A traffic shaper typically delays excess traffic using a buffer, or queueing mechanism, to hold packets and shape the flow when the data rate of the source is higher than expected. It holds and shapes traffic to a particular bit rate by using the token bucket mechanism. See the "Regulating Packet Flow Using Traffic Shaping" module.
Note | GTS is similar to Class-Based Traffic Shaping. Although Class-Based Traffic Shaping is the Cisco-recommended mechanism, GTS is still supported. |
GTS supports traffic shaping on most media and encapsulation types on the router.
GTS works with a variety of Layer 2 technologies, including Frame Relay, ATM, Switched Multimegabit Data Service (SMDS), and Ethernet.
GTS performs the following tasks:
If adaptive GTS is configured on a Frame Relay network using the traffic-shape rate command, you can also use the traffic-shape adaptive command to specify the minimum bit rate to which the traffic is shaped.
With adaptive GTS, the router uses backward explicit congestion notifications (BECNs) to estimate the available bandwidth and adjust the transmission rate accordingly. The actual maximum transmission rate will be between the rate specified in the traffic-shape adaptive command and the rate specified in the traffic-shape rate command.
Configure these two commands on both ends of the network link, enabling the router at the high-speed end to detect and adapt to congestion even when traffic is flowing primarily in one direction.
For more information about configuring adaptive GTS, see the Configuring Adaptive Generic Traffic Shaping for Frame Relay Networks.
Access control lists filter network traffic by controlling whether routed packets are forwarded or blocked at the router interface. When configured with GTS, the router examines each packet to determine how to shape the traffic on the basis of the criteria you specified for the access control list.
Access control list criteria could be the source address of the traffic, the destination address of the traffic, the upper-layer protocol, or other information. Note that sophisticated users can sometimes successfully evade or fool basic access control lists because no authentication is required.
All of the benefits associated with traffic shaping also apply to GTS. For information about the benefits of traffic shaping, see the "Regulating Packet Flow Using Traffic Shaping" module.
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
traffic-shape
rate
bit-rate
[burst-size] [excess-burst-size] [buffer-limit]
5.
end
6.
show
traffic-shape
[interface-type interface-number]
7.
show
traffic-shape
statistics
[interface-type interface-number]
8.
exit
1.
enable
2.
configure
terminal
3.
access-list
access-list-number
{deny | permit} source [source-wildcard]
4.
interface
type
number
5.
traffic-shape
group
access-list
bit-rate
[burst-size [excess-burst-size]]
6.
end
7.
show
traffic-shape
[interface-type interface-number]
8.
show
traffic-shape
statistics
[interface-type interface-number]
9.
exit
Repeat the above procedure for each additional type of traffic you want to shape.
Note
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
traffic-shape
rate
bit-rate
[burst-size] [excess-burst-size] [buffer-limit]
5.
traffic-shape
adaptive
bit-rate
6.
traffic-shape
fecn-adapt
7.
end
8.
show
traffic-shape
[interface-type interface-number]
9.
show
traffic-shape
statistics
[interface-type interface-number]
10.
exit
The following is an example of GTS configured on serial interface s4/0:
enable
configure terminal
interface s4/0
traffic-shape rate 128000
end
The following is an example of GTS configured using an ACL. In this example, GTS is configured for the outbound traffic on ACL 1.
enable
configure terminal
access-list 1 permit 192.5.34.0 0.0.0.255
interface s4/0
traffic-shape group 101 128000
end
The following is an example of adaptive GTS configured on Frame Relay network. In this example, adaptive GTS is configured using the traffic-shaperate command. The traffic-shapeadaptive command specifies the minimum bit rate to which the traffic is shaped. The actual maximum transmission rate will be between the rate specified in the traffic-shapeadaptive command and the rate specified in the traffic-shaperate command.
enable
configure terminal
interface s4/0
traffic-shape rate 128000
traffic-shape adaptive 64000
traffic-shape fecn-adapt
end
To configure Class-Based Traffic Shaping, see the "Regulating Packet Flow on a Per-Class Basis Using Class-Based Traffic Shaping" module.
To configure Frame Relay Traffic Shaping (FRTS), see the "MQC-Based Frame Relay Traffic Shaping" module.
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
|
Overview information about using traffic shaping to regulate packet flow on a network |
"Regulating Packet Flow Using Traffic Shaping" module |
Class-Based Traffic Shaping |
"Regulating Packet Flow on a Per-Class Basis Using Class-Based Traffic Shaping" module |
FRTS |
"MQC-Based Frame Relay Traffic Shaping" module |
Standard |
Title |
---|---|
No new or modified standards are supported, and support for existing standards has not been modified. |
-- |
MIB |
MIBs Link |
---|---|
No new or modified MIBs are supported, and support for existing MIBs has not been modified.
|
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFC |
Title |
---|---|
No new or modified RFCs are supported, and support for existing RFCs has not been modified. |
-- |
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Software Releases |
Feature Configuration Information |
---|---|---|
Generic Traffic Shaping |
12.2(1) 15.0(1)S Cisco IOS XE 3.1.0 SG |
This feature was introduced. This feature was integrated into the Cisco IOS Release 15.0(1)S. In Cisco IOS XE 3.1.0 SG, this feature was integrated. |