RFC 1900 (rfc1900) - Page 3 of 4
Renumbering Needs Work
Alternative Format: Original Text Document
RFC 1900 Renumbering Needs Work February 1996
expected to be fairly long-lived, and more stable than IP addresses.
Deferring the binding avoids the risk of changed mapping between IP
addresses and specific network entities (due to changing addressing
information). Moreover, reliance on FQDNs (rather than IP addresses)
also localizes to the DNS the changes needed to deal with changing
addressing information due to renumbering.
In some cases, both the addresses and FQDNs of desk top or portable
systems are allocated dynamically. It is only a highly responsive
dynamic DNS update mechanism that can cope with this.
3. Recommendations
To make renumbering more feasible, the IAB strongly recommends that
all designs and implementations should minimise the cases in which IP
addresses are stored in non-volatile storage maintained by humans,
such as configuration files. Configuration information used by
TCP/IP protocols should be expressed, whenever possible, in terms of
Fully Qualified Domain Names, rather than IP addresses. Hardcoding IP
addresses into applications should be deprecated. Files containing
lists of name to address mappings, other than that used as part of
DNS configuration, should be deprecated, and avoided wherever
possible.
There are times when legacy applications which require configuration
files with IP addresses rather than Domain Names cannot be upgraded
to meet these recommendations. In those cases, it is recommended that
the configuration files be generated automatically from another file
which uses Domain Names, with the substitution of addresses being
done by lookup in the DNS.
Use of licensing technology that is based upon the IP address of a
host system makes renumbering quite difficult. Therefore, the use of
such technology should be strongly discouraged.
The development and deployment of a toolkit to facilitate and
automate host renumbering is essential. The Dynamic Host
Configuration Protocol (DHCP) is clearly an essential part of such a
toolkit. The IAB strongly encourages implementation and wide-scale
deployment of DHCP. Dynamic router discovery (RFC 1256) and service
location (work in progress in the IETF) also belong in this toolkit.
Support for dynamic update capabilities to the Domain Name System
(DNS) that could be done with sufficient authentication would further
facilitate host renumbering. The IAB strongly encourages progression
of work in this area towards standardization within the IETF, with
the goal of integrating DHCP and dynamic update capabilities to
provide truly autoconfigurable TCP/IP hosts.
Carpenter & Rekhter Informational