RFC 1900 (rfc1900) - Page 2 of 4

Renumbering Needs Work

RFC 1900                 Renumbering Needs Work            February 1996


   Increasingly, renumbering will be needed for organizations that
   require Internet-wide IP connectivity, but do not themselves provide
   a sufficient degree of address information aggregation.  Unless and
   until viable alternatives are developed, extended deployment of
   Classless Inter-Domain Routing (CIDR) is vital to keep the Internet
   routing system alive and to maintain continuous uninterrupted growth
   of the Internet.  With current IP technology, this requires such
   organizations to use addresses belonging to a single large block of
   address space, allocated to their current service provider which acts
   as an aggregator for these addresses.  To contain the growth of
   routing information, whenever such an organization changes to a new
   service provider, the organization's addresses will have to change.
   Occasionally, service providers themselves may have to change to a
   new and larger block of address space. In either of these cases, to
   contain the growth of routing information, the organizations
   concerned would need to renumber their subnet(s) and host(s). If the
   organization does not renumber, then some of the potential
   consequences may include (a) limited (less than Internet-wide) IP
   connectivity, or (b) extra cost to offset the overhead associated
   with the organization's routing information that Internet Service
   Providers have to maintain, or both.

   Currently, renumbering is usually a costly, tedious and error-prone
   process.  It normally requires the services of experts in the area
   and considerable advance planning.  Tools to facilitate renumbering
   are few, not widely available, and not widely deployed. While a
   variety of ad hoc approaches to renumbering have been developed and
   used, the overall situation is far from satisfactory.  There is
   little or no documentation that describes renumbering procedures.
   While renumbering occurs in various parts of the Internet, there is
   little or no documented experience sharing.

2. DNS versus IP Addresses

   Within the Internet architecture an individual host can be identified
   by the IP address(es) assigned to the network interface(s) on that
   host.  The Domain Name System (DNS) provides a convenient way to
   associate legible names with IP addresses.  The DNS name space is
   independent of the IP address space.  DNS names are usually related
   to the ownership and function of the hosts, not to the mechanisms of
   addressing and routing.  A change in DNS name may be a sign of a real
   change in function or ownership, whereas a change in IP address is a
   purely technical event.

   Expressing information in terms of Domain Names allows one to defer
   binding between a particular network entity and its IP address until
   run time. Domain Names for enterprises, and Fully Qualified Domain
   Names (FQDNs, see RFC 1594) for servers and many user systems, are



Carpenter & Rekhter          Informational