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Connecting multiple customers who use the same internal addresses

Feb 05, 20032 mins
Enterprise Applications

* Dr. Internet columnist Steve Blass offers advice on how to connect multiple customers using NAT

Is there a way to connect customer networks that use the same internal IP address space (10.X.X.X) to a managed service provider’s connection? We want to connect multiple customers who use the same internal addresses. We have Computer Associates’ Unicenter at the network operations center to monitor multiple customer networks.

This problem finally might push IPv6 ubiquity into the Internet backbone. Matching IPv4 addresses can be name-mangled and translated into IPv6 addresses quite nicely. To accomplish the task today one must ensure that static network address translation (NAT) addresses are in use on the customer site so there is a stable one-to-one mapping from private to public addresses. The public addresses are added to the management platform by hand rather than through autodiscovery, and the customer firewall must be configured to let User Datagram Protocol (UDP)-based management traffic such as SNMP traverse the Internet boundary. To manage devices inside the firewall that don’t have public NATs, use a local management ‘console’ inside the customer network (which needs a public NAT) to communicate with the central management facility. More background can be found at previous Dr. Internet columns ( and and in the expert forums.

Blass is a network architect at Change@Work in Houston. He can be reached at dr.internet@