Allocation of IP Addresses

Jim Browning jfbb at
Thu Mar 14 19:25:27 UTC 1996

It has been suggested that this discussion should be held only on com-priv, 
as it is global in nature.  I am responding to the nanog list only because 
it is the source of the most recent post....

>From:  Andrew Smith[SMTP:awsmith at]
>> >> How many times is it reasonable to ask a customer to renumber?  Once 
>> >> certainly reasonable.  Twice is questionable.  More than that and I 
>> >> suspect the customer would renumber all right, but as part of 
shifting to a
>> >> different ISP.
>Please tell me how this could happen? I would call this poor planning
>on the part of the ISP. Simply request network space from your provider
>until you can justify say a /18-16...(if you get a /18, request that
>the rest of the /16 is reserved for you and BACK IT UP with documentation)
>by noting that you will return ALL of your provider assigned networks
>within X amount of time of recieving the delegation from the NIC.

This (reserving the /16) sounds like wonderful approach.  In our particular 
case, we promised InterNIC that, if they would reserve a /16 to back up our 
/18, we would renumber all our customers into that space, returning a 
directly allocated /19 and two different provider assigned blocks.  We are 
in the process of establishing connections into the NAPs, so having a 
sufficiently large *contiguous* space is of course very important to us if 
we are to successfully peer.  We invested significant effort in providing 
what we feel is very adequate documentation.  So far, InterNIC has only 
said that they 'would consider' reserving additional space.  Should we 
proceed with renumbering our customers into a space which *might* have 
contiguous space reserved???

>This is 1 renumbering. (Not including switching providers if you
>so choose...a cost of doing business that you must accept if
>it's your choice..although I'll stick my neck out and say this should
>happen early when it is least can usually tell if
>you want to leave an provider early on)

We are doing our best to avoid 'poor planning', and that is what has 
created this issue for us.  Multiple renumbering will occur only (1) if 
InterNIC insists on our accepting incremental additions of noncontiguous 
/18s, or (2) if each of our "small steps" is into a different address 
space.  In the case of (1) we would ultimately have to consolidate these to 
enable aggregation of our routes.  In the case of (2), we would have to 
constantly renumber.

Jim Browning

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