SIP Message Size Restriction Causes Calls to Drop

Introduction

This document describes how to resolve the problem of calls that fail to establish due to the Cisco TelePresence Server's Session Initiation Protocol (SIP) message size that is too large for the default maximum incoming size configured on Cisco Unified Communications Manager (UCM).

Prerequisites

Requirements

Cisco recommends that you have knowledge of Cisco Unified Communications Manager Release 8.6.1 and earlier, when deployed with these Cisco TelePresence infrastructure products:

• Cisco TelePresence Server MSE 8710
• Cisco TelePresence Server 7010
• Cisco TelePresence Server on Virtual Machine
• Cisco TelePresence Server on Multiparty Media 310/320

Components Used

The information in this document is based on Cisco Unified Communications Manager Release 8.6.1 and earlier, when deployed with the these Cisco TelePresence infrastructure products:

• Cisco TelePresence Server MSE 8710
• Cisco TelePresence Server 7010
• Cisco TelePresence Server on Virtual Machine
• Cisco TelePresence Server on Multiparty Media 310/320

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Background Information

• Calls that fail to establish due to the TelePresence Server's SIP messages that are too large for the default maximum incoming size configured on Cisco UCM.

• The default maximum SIP message size on Cisco UCM Release 8.6.1 and earlier versions is 5000 bytes. The default on Cisco UCM Release 8.6.2 and later versions is 11000 bytes.

Note: Cisco recommends that you do not set the UCM's maximum incoming SIP message size below 11000 bytes when it interoperates with the Cisco TelePresence Server.

Problem

• SIP calls that route between Cisco UCM and TelePresence Server drop during establishment of the call.

• The TelePresence Server's protocols log does not contain either the SIP INVITE or the HTTP 200 OK response (this depends on the call direction).

• Cisco UCM's Simple DirectMedia Layer (SDL) trace has an APPInfo message similar to SIPTcp - Ignoring large message from <ipaddress[port]>. Only allow up to 5000 bytes. Resetting connection.

Solution

The best way to resolve this issue is to upgrade Cisco UCM to Release 9.1.2 (latest version at time of publication of this document) - which has a default maximum incoming SIP message size of 11000 bytes. This resolution supports the most recent features of the TelePresence Server that are used with Cisco UCM.

Alternatively, you can adjust the "SIP Max Incoming Message Size" on your current version of Cisco UCM as shown here:

1. On the Cisco UCM administration interface, choose System > Service Parameters.
2. Choose the active server from the Server drop-down list.
3. Choose Cisco CallManager (Active) from the Service drop-down list.
4. Click Advanced in the toolbar, since the message size is not shown in the Condensed (default) view.
5. Scroll until you find the Clusterwide Parameters (Device - SIP) section.
6. Locate the SIP Max Incoming Message Size parameter.
7. Change the value from 5000 to 11000 (bytes).
8. Click Save.