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Support of the Session Initiation Protocol SUBSCRIBE/NOTIFY Methods

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Support of SIP SUBSCRIBE/NOTIFY Methods

Table Of Contents

Support of SIP SUBSCRIBE/NOTIFY Methods

Feature Overview

Benefits

Restrictions

Related Features and Technologies

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Prerequisites

Provisioning Tasks

Planning for Provisioning

Provisioning Procedures

Provisioning Basics

Provisioning SUBSCRIBE/NOTIFY Methods

Enabling SUBSCRIBE/NOTIFY Methods

Disabling SUBSCRIBE/NOTIFY Methods

Provisioning Unsolicited Notifications

Enabling Unsolicited Notifications

Disabling Unsolicited Notifications

Provisioning Subscription Duration

Provisioning Minimum Subscription Duration for Telephony Event

Provisioning Maximum Duration for SUBSCRIBE

Reference Information

Properties

Glossary

Obtaining Documentation and Submitting a Service Request


Support of SIP SUBSCRIBE/NOTIFY Methods


Document Release History

Publication Date
Comments

September 1, 2003

Initial version of the document.

January 31, 2005

Clarification of the implementation of the NOTIFY method.

March 29, 2005

Added note regarding Cisco MGC support of INFO messages.


Feature History

Release
Modification

9.4(1)

This feature was introduced on the Cisco Media Gateway Controller (MGC) software.


The Support of Session Initiated Protocol (SIP) SUBSCRIBE/NOTIFY Methods feature is described in the following sections:

Feature Overview

Supported Platforms

Supported Standards, MIBs, and RFCs

Prerequisites

Provisioning Tasks

Reference Information

Glossary

Obtaining Documentation and Submitting a Service Request

Feature Overview

The Support of SIP SUBSCRIBE/NOTIFY Methods feature enables the Cisco MGC to act as a Notifier in a SIP network. This feature provides the Cisco MGC the ability to receive SUBSCRIBE messages from a SIP user agent and to return NOTIFY messages to that SIP user agent.

If this feature is enabled, and a SUBSCRIBE message is received, the MGC sends an MGCP NOTIFY message requesting the Dual-Tone Multi-Frequency (DTMF) data to the associated Media Gateway Controller Protocol (MGCP) media gateway. If the MGCP media gateway receives DTMF, it sends the DTMF digits to the MGC. The MGC returns these DTMF digits to the subscribing SIP user agent in out-of-band NOTIFY messages (these NOTIFY messages do not use the RTP stream). This is useful for a variety of applications that monitor calls for a specific event and perform an action based upon the received event.

If the Cisco MGC receives an unsolicited SIP NOTIFY message with DTMF, the MGC uses MGCP commands to cause the connected MGCP media gateway to send the specified DTMF tone(s) to the PSTN.

Benefits

This feature has the following benefits:

Support for SIP-Based ITS

This feature enables DTMF to be passed from Skinny phones connected to an ITS over SIP to the Cisco MGC, and then out to the PSTN.

Support of Pre-Paid Card Services

This feature enables the Cisco MGC to support pre-paid card services. Detection of the long pound sign (a DTMF digit) enables some pre-paid card services and IP Centrex.

Mid-Call DTMF Access Support

This feature provides SIP Back-to-Back User Agents (B2BUAs) access to mid-call DTMF to enable support of follow-on card services (long pound sign detection), and feature invocation (for example, changing a call forwarding number).

Support for IP Private Branch Exchanges (PBXs)

Some IP PBXs require access to DTMF to invoke feature commands. This feature enables an increase in efficiency in networks, as these IP PBXs will no longer require an additional piece of hardware in the network to access DTMF.

Restrictions

This feature can only be used in conjunction with SIP user agents that support the standard SIP SUBSCRIBE/NOTIFY methods.

Related Features and Technologies

This feature is related to the following Cisco IOS software features:

Support for SIP SUBSCRIBE/NOTIFY Methods

SIP-SRST and ITS/SRST SIP Enhancements

Related Documents

This document contains information that is related strictly to this feature. The documents that contain additional information related to the Cisco Media Gateway Controller (MGC) are listed below:

Release notes for Cisco Media Gateway Controller Software Release 9.4(1)

Cisco Media Gateway Controller Hardware Installation Guide

Regulatory Compliance and Safety Information for the Cisco Media Gateway Controller

Cisco Media Gateway Controller Software Release 9Installation and Configuration Guide

Cisco Media Gateway Controller Software Release 9 Provisioning Guide

Cisco Media Gateway Controller Software Release 9 Dial Plan Guide

Cisco Media Gateway Controller Software Release 9 MML Command Reference Guide

Cisco Media Gateway Controller Software Release 9 Messages Reference Guide

Cisco Media Gateway Controller Software Release 9 Billing Interface Guide

Cisco Media Gateway Controller Software Release 9 MIB Guide

Cisco Media Gateway Controller Software Release 9 Operations, Maintenance, and Troubleshooting Guide

Cisco Voice Services Provisioning Tool Release 2.3(2) User's Guide

Cisco Media Gateway Controller Node Manager Release 2.3(2) User's Guide

Supported Platforms

The hardware platforms supported for the Cisco MGC software are described in the Release Notes for Cisco Media Gateway Controller Software Release 9.4(1).

Supported Standards, MIBs, and RFCs

This feature supports the following standards, MIBs, and RFCs.

Standards

No new standards are supported by this feature.

MIBs

No new or modified MIBs are supported by this feature. For more information on the MIBs used in the Cisco MGC software, refer to the Cisco Media Gateway Controller Release 9 MIB Guide.

RFCs

This feature supports the following RFCs

RFC-3265—Session Initiation Protocol (SIP) Specific Event Notification

RFC 2976—Session Initiation Protocol (SIP) INFO Method

This feature has the following limitations in support of the above RFCs:

When this feature is enabled, the Cisco MGC acts only as a Notifier of telephony events.

All methods are supported only after the ANSWER/CONNECT state. If any method SUBSCRIBE, or INFO is received before the connect state, a non-200 class response with "Retry-After" header is sent to the subscribing or sending device. The sending device is required to re-send the message again after stipulated time interval. For the Unsolicited NOTIFY, when advertised in the INVITE message in Call-Info header, receives a response in 18x/200 message, which requires the MGC to initiate the subscription with the MGCP Gateway is delayed after till the connect state is achieved.

MGC returns the DTMF digits using the SIP standard NOTIFY method to the SIP user agent only after receiving a SUBSCRIBE message. MGC sends the DTMF digits to the PSTN after receiving the proprietary Unsolicited NOTIFY method from the SIP user agent. The INFO method is used only to receive unsolicited notification from a SIP user agent to pass DTMF to the PSTN.


Note The Cisco MGC does not generate INFO messages. The Cisco MGC supports the INFO method for backward compatibility only.


If the MGCP media gateways do not send any subscription duration data for a telephony event, the Cisco MGC uses the default duration data for that event. The minimum duration data for a telephony event can be configured on the Cisco MGC.

Prerequisites

You must have Cisco MGC software Release 9.4(1). Prerequisites for this release can be found in the Release Notes for the Cisco Media Gateway Controller Software Release 9.4(1).

Information on the prerequisites for the implementation of the related features in Cisco IOS software for the MGCP media gateways can be found in the Support for SIP SUBSCRIBE/NOTIFY Methods and the SIP-SRST and ITS/SRST SIP Enhancements feature module.

Provisioning Tasks

This section provides provisioning information for this feature. Additional examples of provisioning for the Cisco MGC software can be found in the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

The provisioning information appears in the following sections:

Planning for Provisioning

Provisioning Procedures

Provisioning SUBSCRIBE/NOTIFY Methods

Provisioning Unsolicited Notifications

Provisioning Subscription Duration

Planning for Provisioning

Before you provision this feature, determine the minimum and maximum duration for which a SIP device can subscribe to an event.

For more information on planning the provisioning for the rest of the Cisco MGC software, refer to the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

Provisioning Procedures

This section contains the procedures necessary for provisioning this feature. This section covers the following topics:

Provisioning Basics

Provisioning SUBSCRIBE/NOTIFY Methods

Provisioning Unsolicited Notifications

Provisioning Subscription Duration

Provisioning Basics

You can use the four procedures in this section to start a provisioning session, save provisioning data, end a provisioning session, and retrieve current provisioning data. For more detailed information about provisioning your Cisco MGC software, refer to the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

Starting a Provisioning Session

You might need to start a provisioning session as part of your system operations. To do this, log in to the active Cisco MGC, start an MML session, and enter the following command:

mml>prov-sta::srcver="curr_ver",dstver="mod_ver"

Where:

curr_ver—The name of the current configuration version. In place of the name of the current configuration version, you can also enter:


Note If you do not know the name of your current configuration session, you can use the procedure in the "Retrieving Data on the Current Provisioning Session" section.


new—A new default session configuration; no existing source configuration is available.

active—Selects the active configuration as the source for configuration changes.


Note You can use new as the source configuration only when there is no existing, active set of provisioning data in the configuration library. Therefore, new cannot be used as the source configuration once a provisioning session has been saved and activated by using prov-cpy or prov-dply. Once you have saved and activated a set of data, you must use either active or the name of the set of provisioning data as the source configuration.


mod_ver—A new configuration version name that contains your provisioning changes.

For example, to use a configuration version called ver1 as the basis for a version to be called ver2, you would enter the following command:

mml>prov-sta::srcver="ver1",dstver="ver2"

Once a provisioning session is underway, you can use the prov-add, prov-ed, and prov-dlt MML commands to add, modify, and delete components on your system. This document describes how to add, modify, and delete components for this feature. For more information on provisioning other components on your Cisco PGW 2200, refer to the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

There are two ways to close your provisioning session:

Saving and activating your provisioning changes, as described in the "Saving and Activating Your Provisioning Changes" section

Ending your provisioning session without saving and activating your changes, as described in the "Ending a Provisioning Session Without Activating your Changes" section

Saving and Activating Your Provisioning Changes

When you have completed making provisioning changes in your session, you must enter a command to save and activate your changes. There are two different provisioning MML commands that do this: prov-cpy and prov-dply.


Caution Using the prov-cpy or prov-dply MML command can severely impact your system's call processing performance, depending on the extent of your provisioning changes. We recommend that you issue these commands during a maintenance window, when traffic is minimal.

The prov-cpy MML command is used to save and activate your changes on the active Cisco MGC. This command is typically used to save and activate changes on a Cisco MGC in a simplex configuration. However, you can use the prov-cpy MML command on Cisco MGCs in high-availability or continuous-service configurations, to save and activate your changes on the active Cisco MGC. If you choose to do this, you should enter the prov-sync MML command immediately afterwards, to have your changes saved and activated on the standby Cisco MGC.


Note When you enter the prov-cpy command, your provisioning session is also automatically ended. If you want to make additional provisioning changes, you must start a new provisioning session (see the "Starting a Provisioning Session" section).



Caution Using the prov-sync MML command can severely impact your system's call processing performance. We recommend that this command be issued during a maintenance window when traffic is minimal.


Note When the prov-sync MML command is used to synchronize the provisioning settings on the standby MGC host with current settings on the active MGC host, the system does not indicate when the synchronization process has failed.


The prov-dply MML command is used to save and activate your changes on the active and standby
Cisco MGCs. This command is typically used to save and activate changes on Cisco MGCs in high-availability or continuous-service configurations. This command should not be used on a Cisco MGC in a simplex configuration.


Note When you enter the prov-dply command, your provisioning session is also automatically ended, unless an error occurs during execution. If you want to make additional provisioning changes, you must start a new provisioning session as described in the "Starting a Provisioning Session" section.


Ending a Provisioning Session Without Activating your Changes

You may find that you want to end a provisioning session without saving and activating the changes you have entered during your session. To do so, you can enter the prov-stp MML command. This command ends your current provisioning session and your changes are not entered.

Retrieving Provisioning Data

You can use the prov-rtrv MML command to retrieve information about your current provisioning settings. The ways in which you can use this command to retrieve provisioning data are described in the following sections:

Retrieving Data for an Individual Component

Retrieving Data for Select Components

Retrieving Data for All Components of a Particular Type

Retrieving Data on the Current Provisioning Session

Retrieving Data on Supported Signaling Protocols

Retrieving Data for an Individual Component

You can retrieve provisioning data on any individual component on your system. To do this, log in to the active Cisco MGC, start an MML session, and enter the following command:

mml>prov-rtrv:component:name=MML_name

Where:

component—The MML component type. You can find a complete list of MML component types in the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

MML_name—The MML name for the desired component. You can determine the MML names for the various components using the prov-rtrv:all MML command.

For example, to view the provisioning data for an IUA signaling service called iua1, you would enter the following command:

mml>prov-rtrv:sigsvcprop:name="iua1"

Retrieving Data for Select Components

You can retrieve data on select components provisioned on your system. To do this, log in to the active Cisco MGC, start an MML session, and enter the following command:

mml>prov-rtrv:all


Note This command returns data on all signaling components, except for signaling service and linkset properties.


Retrieving Data for All Components of a Particular Type

You can retrieve provisioning data on all components of a particular type on your system. To do this, log in to the active Cisco MGC, start an MML session, and enter the following command:

mml>prov-rtrv:component:"all"

Where: component is the MML component type associated with the desired component group. You can find a complete list of MML component types in the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.


Note Components that are used to retrieve signaling or routing properties (that is sigsvcprop, lnksetprop, and trnkgrpprop) cannot use this command. The properties for only one signaling or routing component can be listed per command instance. Please use the following format:

mml>prov-rtrv:propComp:name="compName" | name="ss7famName"

Where:

propComp—MML component name appropriate to the property type you want to retrieve, as listed below:

sigsvcprop—Provides maintenance access to the properties of signaling services
trnkgrpprop—Provides maintenance access to the properties of trunk groups
lnksetprop—Provides maintenance access to the properties of linksets

compName—MML name of a previously provisioned signaling service or trunk group

ss7famName—MML name of the SS7 family associated with the desired linkset


For example, to view the provisioning data for all signaling services, enter the following command:

mml>prov-rtrv:naspath:"all"

Retrieving Data on the Current Provisioning Session

You can retrieve provisioning data on the current provisioning session. To do this, log in to the active Cisco MGC, start an MML session, and enter the following command:

mml>prov-rtrv:session

The system returns a response similar to the following:

MGC-02 - Media Gateway Controller 2003-01-13 13:39:19
M  RTRV
   "session=jtest:session"
   /*
Session ID = mml1
SRCVER = active
DSTVER = jtest
   */

Retrieving Data on Supported Signaling Protocols

You can retrieve protocol data for the current provisioning session. To do this, log in to the active
Cisco MGC, start an MML session, and enter the following command:

mml>prov-rtrv:variants

Provisioning SUBSCRIBE/NOTIFY Methods

The procedures for provisioning the SUBSCRIBE/NOTIFY methods are in the following sections:

Enabling SUBSCRIBE/NOTIFY Methods

Disabling SUBSCRIBE/NOTIFY Methods

Enabling SUBSCRIBE/NOTIFY Methods

Use the following steps to enable the SUBSCRIBE/NOTIFY methods:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Enable the SUBSCRIBE/NOTIFY methods on a SIP trunk group with the following command:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", SubscribeNotifySupport=1

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

For example, to enable the SUBSCRIBE/NOTIFY methods on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333", custgrpid="1111", SubscribeNotifySupport=1

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Disabling SUBSCRIBE/NOTIFY Methods

Use the following steps to disable the SUBSCRIBE/NOTIFY methods:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Disable the SUBSCRIBE/NOTIFY methods on a SIP trunk group with the following command:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", SubscribeNotifySupport=0

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

For example, to disable the SUBSCRIBE/NOTIFY methods on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333",custgrpid="1111", SubscribeNotifySupport=0

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Provisioning Unsolicited Notifications

The procedures for provisioning unsolicited notifications are in the following sections:

Enabling Unsolicited Notifications

Disabling Unsolicited Notifications

Enabling Unsolicited Notifications

Use the following steps to enable the Unsolicited NOTIFY method for SIP DTMF digits by the Cisco MGC:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Enable unsolicited notifications on a SIP trunk group using the following command:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", UnsolicitedNotifyMethod=1

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

For example, to enable unsolicited notifications on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333",custgrpid="1111", UnsolicitedNotifyMethod=1

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Disabling Unsolicited Notifications

Use the following steps to disable the Unsolicited NOTIFY method for SIP DTMF digits by the Cisco MGC:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Disable unsolicited notifications on a SIP trunk group using the following command:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", UnsolicitedNotifyMethod=0

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

For example, to disable unsolicited notifications on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333",custgrpid="1111", UnsolicitedNotifyMethod=0

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Provisioning Subscription Duration

The procedures for provisioning the duration data for subscriptions are in the following sections:

Provisioning Minimum Subscription Duration for Telephony Event

Provisioning Maximum Duration for SUBSCRIBE

Provisioning Minimum Subscription Duration for Telephony Event

Use the following steps to define the minimum duration for which a telephony event can exist before it can be re-subscribed:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Set the minimum duration of a telephony event on a SIP trunk group:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", 
MinEventSubscribeDuration=minsub

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

minsub—Minimum amount of time in milliseconds a subscription event can last. The valid value is from 40 ms to 3600 ms. The default value is 40 ms.

For example, to provision a telephony event to last a minimum of 200 ms on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333",custgrpid="1111", MinEventSubscribeDuration=200

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Provisioning Maximum Duration for SUBSCRIBE

Use the following steps to define the maximum duration for which the subscription can exist before it needs a re-subscription:


Step 1 Start a provisioning session as described in the "Starting a Provisioning Session" section.

Step 2 Set the maximum duration time for a subscription on a SIP trunk group:

mml> prov-ed:trnkgrpprop:name="trnkgrpnum", custgrpid="grpid", 
MaxSubscriptionDuration=maxsub

Where:

trnkgrpnum—Number identifying a previously provisioned SIP trunk group.

grpid—Associated customer group ID.

maxsub—Maximum amount of time in seconds a subscription can last. The valid value is from 0 to 3600 seconds. The default value is 0 seconds.

For example, to provision a subscription to last a maximum of 3600 seconds on a SIP trunk group called 3333, you would enter the following command:

mml> prov-ed:trnkgrpprop:name="3333",custgrpid="1111", MaxSubscriptionDuration=3600

Step 3 If there are no other components that you need to provision, end your provisioning session as described in the "Saving and Activating Your Provisioning Changes" section.


Reference Information

The "Properties" section contains reference material related to this feature.

Properties

The properties in this section are modified for this feature. For information on other properties for the Cisco MGC software, refer to the Cisco Media Gateway Controller Software Release 9 Provisioning Guide.

The parent objects for the properties involved in this feature are found in Table 8.

Table 8 Software Properties Related to this Feature

Property Name
Parent Object
AVM
DPNSS
EISUP
IOCC
ISDNPRI
MGCP
RLM
SESSION
SGCP
SS7-ANSI
SS7-China
SS7-ITU
SS7-Japan
SS7-UK
TALI-IOCC
TCAPOverIP
TrunkGroup
VSI

SubscribeNotifySupport

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X

 

UnsolicitedNotifyMethod

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X

 

MinEventSubscribeDuration

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X

 

MaxSubscriptionDuration

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X

 


The properties modified for this feature are described in Table 9.

Table 9 Properties 

Property
Definition

SubscribeNotifySupport

Enables or disables SIP SUBSCRIBE/NOTIFY methods for solicited notification of SIP DTMF digits.

Valid Values:
0-SUBSCRIBE/NOTIFY methods disabled
1-SUBSCRIBE/NOTIFY methods enabled.

Default Value: 0 (disabled)

UnsolicitedNotifyMethod

Enables or disables the Unsolicited NOTIFY method for unsolicited notification of SIP DTMF digits.

Valid Values:
0-Unsolicited NOTIFY method disabled
1-Unsolicited NOTIFY method enabled.

Default Value: 0 (disabled)

MinEventSubscribeDuration

Defines the minimum duration for which a telephony event can be subscribed. It is an integer value in milliseconds.

Valid Values: Range from 40 ms to 3600 ms

Default Value: 40 ms

MaxSubscriptionDuration

Defines the maximum duration for which a subscription can be made. It is an integer value in seconds.

Valid Values: Range from 0 seconds to 3600 seconds

Default Value: 0 second


Glossary

Table 10 contains definitions of acronyms and technical terms used in this feature module.

Table 10 Glossary  

Term
Description

B2BUA

Back-to-Back User Agent

DTMF

Dual-Tone Multi-frequency. DTMF dialing consists of simultaneous voice-band tones generated when a button is pressed on a telephone. The use of DTMF signaling for this feature enables support for advanced telephony services. Currently there are a number of application servers and service creation platforms that do not support media connections. To provide value-added services to the network, these servers and platforms need to be aware of signaling events from a specific participant in the call. Once the server or platform is aware of the DTMF events that are being signaled, it can use third-party call control, or other signaling mechanisms, to provide enhanced services.

MGCP

Media Gateway Controller Protocol

MML

Man-Machine Language

NOTIFY

Used to notify a SIP node that an event which has been requested by an earlier SUBSCRIBE method has occurred.

PSTN

Public Switched Telephone Network

SIP

Session Initiation Protocol

SUBSCRIBE

A method used in SIP networks used to request asynchronous notification of an event or set of events at a later time.

Unsolicited NOTIFY

A Cisco-proprietary method for sending the supported requested telephony event data.


Obtaining Documentation and Submitting a Service Request

For information on obtaining documentation, submitting a service request, and gathering additional information, see the monthly What's New in Cisco Product Documentation, which also lists all new and revised Cisco technical documentation, at:

http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html

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