North American Network Operators Group
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Re: IP address space management

  • From: Phillip Vandry
  • Date: Tue Oct 20 13:44:56 1998 
> This also means when the customer needs more space, they either have to
> renumber (and this is the number one customer complaint), or have to set
> up their network with overlayed subnets (and not all the stuff out there
> can successfully do that).

You bet! (Not to mention that the overlayed subnet solution requires that
all traffic between the two subnets must bounce off the router, which means
that the router may need a 100Mbps port in some cases instead of the
10Mbps port the average custoemr router provides).

> We serve primarily business customers with dedicated LAN access, and have
> relatively little dialup business (as measured by address space and revenue).
> This is one of our biggest costs since part of our service is to manage the
> internet access for our customers, including on-site configuration.  So that
> means we actually go renumber the customer for them.  That's good for the
> customer, but it also means we are sorely aware of the costs involved.  We

Ditto for us.

While we have been known to make sparse allocations on occasion, we
usually don't. The overwhelming majority of our customers do not
upgrade their address space. If we made all allocations sparsely, I
can assure you that we would have found ourselves at the bottom of
a hole of our own digging soon enough when some customer needed a
big block and all we had was a multitude of small blocks left.

> try to balance things the best we can by working with customers to determine
> what their needs are with respect to their expanding networking needs over
> the coming year.  I try to allocate what they reasonably expect to need in
> the next 12 months, giving them the smallest subnet that fits that projected
> need if it is not more than 2 or 4 times the current need.   But I have had
> customers who hooked up 3 machines to begin with and knew that they would
> have 100 machines within 6-9 months, and they really did.

We deal with these on a case by case basis, and the usage predictions
made by the customers do indeed come true much of the time. I think the
problem is that tree is claimed to systematically use the sparse
approach, and that is when you can get into trouble.

-Phil