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Re: "portability" of IP Addresses
From: Lee Howard <spiff () access digex net>
Date: Fri, 31 Jan 1997 13:35:07 -0500 (EST)

On Fri, 31 Jan 1997, Eric Sobocinski wrote:
On Thu, 30 Jan 1997 at 21:09 MST, Pete Kruckenberg <pete () inquo net> wrote:
On Thu, 30 Jan 1997, Alan Hannan wrote:

I would think that ISP A would be all for it, since as soon as ISP B
starts announcing the /20, all in-bound traffic will come through ISP B
and relieve some of ISP A's bandwidth.  Since ISP A is announcing a /16,
the /20 announced by ISP B would take precedence, being a more specific

Why exactly do you think this makes ISP A happy?  Most likely the link
to ISP B is a link that ISP A would have preferred to sell themselves.
And to "relieve some of ISP A's bandwidth" doesn't make ISP A any happier
since they have to engineer for that bandwidth anyway for those cases
where ISP B fails.

Sure A would prefer to sell it, but most professionals would (I think)
admit that greater robustness is achieved with greater distinction
between circuits.  
And, while the engineering must occur to allow for full usage, as you
state, I would argue that lower averages allow more "thorough" 
provisioning.  If five customers multihoming only use the bandwidth
of three singly-connected customers, I can more efficiently plan my

I would think that ISP A would not have much to stand on from a legal
 - your contract does not prevent you from buying service from another
   provider (I'm assuming this),

Probably true, but not necessarily so.  There's nothing illegal about
an exclusive contract.

ANd, in fact, they probably exist.  Is MSNBC contractually free to use
any ISP?

                                 and (I further assume) it does not
   prohibit you from letting another ISP announce those routes

This is a stretch.  Chances are that your contract does not specify
anything about announcing routes to third parties, but since the larger
block was initially assigned to ISP A, it reasonably follows that ISP A
can regulate those blocks through separate policy so long as your
contract does not say otherwise.  Even so, many (most?) contracts these
days make sure by proclaiming that addresses assigned by the ISP are
not the property of the customer and that the ISP retains some level
of control.

ISP A can regulate IP addresses allocated, yes, but it can only
regulate internal policy.  I would think ISP A's position for regulating
address announcement would be particularly weak if assignment had been
publicly made to a customer, such as with SWIP.

I also don't know that it's ISP B's responsibility to follow the 
wishes/policy of ISP A, although I suspect it probably would, since
inter-provider relations are generally more important than any single
customer (insofar as keeping the net up).

Please note that I do not speak on behalf of ANYBODY, except myself.
Although even I disclaim.

Pete Kruckenberg
pete () inquo net

Eric Sobocinski
sobo () merit net

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