Reason 94: External Server Addresses List

Technical Note 2164

Last Reviewed 02-Jan-2007
Applies To
Mobility client and server, version 6.00 and higher
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Summary

When a client is connecting to a Mobility server through a NAT or firewall address you may have problems connecting and see this error:

[*] In version 6.01 and earlier, this is called the Alternate Server Addresses list.

Explanation

The Mobility servers need to know about any NAT addresses that are used by the clients that connect to them. This allows two features to work properly:

• Load balancing. If you have two or more servers in a pool, the servers will balance the client load among them. If a client connects to one server through a NAT or firewall and the server decides to load balance the client to the other server, the server must be able to send the client to an IP address that the client can reach, for example, a different external address.

• Roaming between public and private networks. When a client connects to a Mobility server, the server pushes a list of its known IP addresses, both public and private, down to the client. This allows the client to roam to a different network and still be able to reach the server.

Resolution

To configure the server so that clients can connect to it via its NAT address, follow these steps:

1. Open the Mobility Server Console and go to the Server Settings page.

2. Select your server name in the left-hand column.

3. Select the setting External Server Addresses and enter any NAT addresses that clients will use to reach that server. (In version 6.01 and earlier, this setting is called Alternate Server Addresses.)

   Important: Do not enter any of the server's real (physical) IP addresses. Use the ipconfig utility (run it from a Command Prompt) to get a detailed description of the server's IP networking configuration: if an address shows up in the ipconfig results, the server already knows about it, so it should not be added to this list.

4. Repeat steps 2 and 3 for the other servers in your pool. Note: Do not enter an external address for Server A into the list for Server B. Each server should only list its own external addresses.

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