"portability" of IP Addresses

Lee Howard spiff at access.digex.net
Fri Jan 31 18:35:07 UTC 1997

On Fri, 31 Jan 1997, Eric Sobocinski wrote:
> On Thu, 30 Jan 1997 at 21:09 MST, Pete Kruckenberg <pete at 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
> > route.
> 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
> > standpoint:
> >  - 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 at inquo.net
> Eric Sobocinski
> sobo at merit.net

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