Troubleshooting XMPP TCP dialback is a bit different than typical server-to-server communication in Communications Server 2007 R2. This article tries to help you troubleshoot XMPP TCP dialback issues if federation with Google Talk or other XMPP domains doesn’t work as expected by using tools such as Communications Server 2007 R2 Logging Tool, Network Monitor, and other methods.

Author: Rob Pittfield

Publication date: February 2010

Product version: Communications Server 2007 R2 XMPP Gateway

In this article we try to give you enough information to troubleshoot XMPP TCP dialback issues if federation with Google Talk or other XMPP domains doesn’t work as expected.

Google and Jabber XCP 5.4 support federation with other XMPP servers by using TCP dialback. To troubleshoot connectivity issues with these servers, an understanding of the connection process is helpful.

For details about how the connection process works at a protocol level, see section 8 of RFC 3920 at http://www.ietf.org/rfc/rfc3920.txt

There are four tasks to ensure that the XMPP Gateway to other XMPP server connections functions correctly (gmail.com is used as an example below):

  • The XMPP Gateway must be able to resolve the DNS SRV record, _xmpp-server._tcp.gmail.com, to an A record (for example, server.gmail.com).
  • The TCP connection and initial negotiation to Gmail.com must be successful.
  • The SRV record, _xmpp-server._tcp.<sip-domain>, must be configured to resolve to an A record that matches the FQDN of your XMPP Gateway.
  • The TCP port 5269 on your external firewalls must be opened to allow inbound connections from the Gmail.com servers to connect to the XMPP Gateway in your perimeter network.

The four tasks just listed will help ensure that dialback connectivity from Gmail.com to your XMPP Gateway on TCP port 5269 is successful. However, if problems occur when trying to establish a connection to Gmail.com, the following three tools are useful to help you troubleshoot the problem.

Read the complete article in the Technical Library.

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