Federation provides your organization with the ability to communicate with other organizations’ Access Edge Servers to share IM and presence. You can also federate with an audio conferencing provider (ACP) using either of the two methods described in this section. The process of configuring federation with an organization or an audio conferencing provider is identical. For a list of supported ACPs, see Office Communications Server 2007 R2 Audio Conferencing Providers at http://go.microsoft.com/fwlink/?LinkId=145230 .

If you have enabled federation on the Access Edge service, access by federated partners, including ACPs, is controlled using one of the following methods:

How Federated Traffic Is Evaluated When Using Automatic Discovery

If you choose to use automatic discovery of federated partners, the Access Edge service automatically evaluates incoming federated traffic in the following way:

  • If a federated party sends requests to more than 1,000 URIs (valid or invalid) in the local domain, the connection first placed on the Watch list is evaluated first. Any additional requests are blocked by the Access Edge service. If the Access Edge service detects suspicious traffic on a connection, it limits the federation partner to a low message rate of one message per second. The Access Edge service detects suspicious traffic by calculating the ratio of the number of successful responses to the number of failed responses. The Access Edge service also limits legitimate federated partner connections (unless added to the Allowlist) to 20 messages per second. The list of suspicious peer connects is displayed in the Access Edge service Computer Management console.

  • If you know that you will have more than 1,000 requests sent by a legitimate federated partner or a volume of more than 20 messages per second sent to your organization, you must add the federated partner to the Allowtab to allow these volumes.

The following figure shows rate limitations on open federation.

Figure 1. Limiting connections for enhanced federation

After configuring federation, you can use the Office Communications Server 2007 R2 administrative tools to monitor and manage federated partner access on an ongoing basis. For more information, see the Administering Office Communications Server 2007 R2documentation.