Table Of Contents

H.248 Configurable T-Max

Contents

Information About H.248 Configurable T-Max

How to Configure H.248 Configurable T-Max

Configuring H.248 Configurable T-Max

Additional References

Related Documents

Standards

MIBs

Technical Assistance

H.248 Configurable T-Max

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This release adds a configuration command to modify the value of T-Max. T-Max is a timer used by the H.248 stack on the DBE while sending messages to the media gateway controller (MGC) over an unreliable transport media (for example, UDP). If the MGC sends the same transaction again to the DBE within the T-Max interval, the DBE considers it to be a duplicate request.

Feature History for H.248 Configurable T-Max

Release	Modification
Release 3.5.1	This command was first introduced on the Cisco CRS-1.
Release 3.6.0	No modification.

Contents

This module contains the following sections:

•Information About H.248 Configurable T-Max

•How to Configure H.248 Configurable T-Max

•Additional References

•Additional References

Information About H.248 Configurable T-Max

This release adds a configuration command to modify the value of T-Max. T-Max is a timer used by the H.248 stack on the DBE while sending messages to the media gateway controller (MGC) over an unreliable transport media (for example, UDP). Because of the unreliable nature of the transport, the DBE keeps retransmitting a message until it receives a response from the MGC. However, prior to any retransmission, the DBE checks that the time elapsed since the sending of the initial datagram is no greater than T-Max. If more time than the T-Max time has elapsed, the DBE concludes that the MGC has failed, and that it begins its recovery process.

The new feature enables the user to change the value of T-Max, in order to modify the behavior of the H.248 stack on the DBE (depending on network conditions and customer preferences), while sending messages to the MGC over unreliable transport media. There are two scenarios of the DBE's behavior:

•DBE receives the same transaction request again within the T-Max interval: for example, another ADD request from the MGC. In this case, the DBE does not allocate additional resources and considers the request to be a duplicate.

•DBE does not receive the acknowledgement from the MGC and keeps retransmitting the same message till T-Max times out. The retransmission attempts are made on the average every 4 seconds.

How to Configure H.248 Configurable T-Max

This section contains the steps for configuring H.248 T-Max.

Configuring H.248 Configurable T-Max

SUMMARY STEPS

1. configure

2. sbc service-name

3. dbe

4. vdbe [global]

5. h248-tmax timer-value

6. commit

7. exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables the global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(config)# sbc mysbc	Enters the mode of an SBC service. Use the service-name argument to define the name of the SBC.
Step 3	dbe Example: RP/0/0/CPU0:router(config-sbc)# dbe	Enters the mode of the data border element (DBE) function of the SBC.
Step 4	vdbe [global] Example: RP/0/0/CPU0:router(config-sbc-dbe)# vdbe	Enters the mode for configuring virtual DBE (vDBE) parameters.
Step 5	h248-tmax timer-value Example: RP/0/0/CPU0:router(config-sbc-dbe-vdbe)# h248-tmax 20000	Defines the value of the T-Max timer which the DBE should use after forming associations with an H.248 controller. The no version of this command cancels this configuration option. •timer-value—Defines the duration of the timer in milliseconds. The range is 5000-50000. The default is 10000.
Step 6	commit Example: RP/0/0/CPU0:router(config-sbc-dbe-vdbe)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 7	exit Example: RP/0/0/CPU0:router(config-sbc-dbe-vdbe)# exit	Exits the current mode of the configuration.

Additional References

The following sections provide references related to configuring H.248 Configurable T-Max.

Related Documents

Related Topic	Document Title
Cisco IOS XR master command reference	Cisco IOS XR Master Commands List
Cisco IOS XR SBC interface configuration commands	Cisco IOS XR Session Border Controller Command Reference
Initial system bootup and configuration information for a router using the Cisco IOS XR Software	Cisco IOS XR Getting Started Guide
Cisco IOS XR command modes	Cisco IOS XR Command Mode Reference

Standards

Standards	Title
No new or modified standards are supported by this feature, and support from existing standards has not been modified by this feature.	—

MIBs

MIBs	MIBs Link
—	To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

Technical Assistance

Description	Link
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport