Service: Renumbering

Renumbering is usually required when an enterprise wants to change from one Internet Service Provider to another. The IP addresses from the old provider won't work in the new provider's network. The enterprise needs to move all workstations and servers over to IP address space received from the new provider.

This is a delicate procedure and if it isn't planned carefully beforehand many things can go wrong causing outages. In the worst case scenario these outages can only be corrected by external entities (such as domain name authorities) and it may take days to fix the problems.

Examples of network components and services that require special consideration: domain name service, network file systems, static configuration of addresses, firewalls and authentication methods, email service.

Ways to avoid the problems of renumbering

• Get your very own address space
  as opposed to using addresses given by the service provider
  • RIPE Membership (LIR)
  • RIPE Object Maintenance
  • Advanced BGP Designs
  • RPSL Magic
• Use grey address space internally (not really recommended)
• Use DHCP and SLP extensively (doesn't help externally visible services)
• Use IPv6 autoconfiguration

CASE: Capnova 2003

"The operation was a success", proclaims Mikael Nylund, the Chief Technical Officer of Capnova.

In the autumn of the year 2003 Capnova Oy, a Finnish web hosting provider, wanted to relocate all their servers from one physical location to another and simultaneously renumber them from one block of addresses to another. Capnova hosts thousands of web sites with associated email and DNS services. Some of the sites also have additional tailored services.

Capnova trusted in Axu TM Oy to plan the operation so that there would be minimal problems and customer complaints. There was also a very limited time to plan and execute the change.

"The operation was a success", said Mikael Nylund, the CTO of Capnova. "Given the time frame and resources at our disposal we couldn't have gotten a more perfect result."