20402 routing entries

Geert Jan de Groot GeertJan.deGroot at ripe.net
Sat Apr 16 15:35:51 UTC 1994

On Fri, 15 Apr 94 16:50:26 MDT  Walt Haas wrote:
> It seems to me that this entire discussion is based on the premise that
> renumbering is extremely slow, difficult, expensive and disruptive.
> This belief is probably justified given current technology.  Our Chemistry
> department reported that they renumbered 20 workstations, and it was a
> week before anybody involved got any useful work done.  One shudders to
> think what this means if extrapolated to the global Internet.
> However, if we could develop a technology which could make renumbering
> of a network (ie. a company, university or similar-sized unit) fast and
> efficient, this premise would break down and it would no longer be unreasonab
> to consider renumbering the organization when switching providers.

I don't believe that renumbering should be this painful, *if done right*.
In a previous occupation, I managed a network of about 150 machines
of various types and kinds. It was intentionally set up in such a way that
network configuration information (IP addresses, netmasks, default routes
etc) was concentrated on one machine and other config info was built
from that automagically (using machine-built config files, RARP, bootp,
rdist and the like).

I have done a number of splits, moves, merges and the like and found that,
if the network is managed this way, renumbering doesn't have to be painful
at all. The last big action (merging three parts that were split one
year beforehand), took only two hours.

The key to this is realizing that this might happen one day and planning
for it. Basically, preparing new master config files and typing 'make'
should do 90% of the work. 
It also does involve doing things *different* than most manufacturers 
want: instead of typing in the (fixed) IP address the first time
a shiny new box boots, think how you can make (re-)configuration
automatic. As an added bonus, you can use the same mechanism to distribute
patches, new security measures and the like.

I know of similar mechanisms at some other places. Like me, they
have done some re-designs of their network over time. It can be done.

Geert Jan

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