[RRG] Charging for updates in BGP

[Robin Whittle <rw@firstpr.com.au>]

Hi Michael,

Continuing from:

  Re: [RRG] Separation vs. Elimination
  http://psg.com/lists/rrg/2008/msg02583.html

we were discussing charging for BGP updates, as part of discussing
similarities and differences between Ivip and BGP.

>> In both cases, there is a global system which enables packets
>> addressed to some prefix to be sent to some router.  Ivip only works
>> as an addition to the BGP system.  BGP works on its own.  BGP's
>> handling of changes is slow and expensive - and difficult or
>> impossible to charge end-users for when they make a change.  Ivip's
>
> Why? Say I'm your customer, and we have a configured BGP session. You
> count the number of updates that arrive over that connection per month,
> and then charge me per update once a month.

OK, I am an ISP and you are an edge network with your own PI space, generating
changed advertisements for whatever reasons, such as multihoming service
restoration and/or incoming traffic TE.  I assume you have one or more other
ISPs as well.

I could charge you per update, but it would probably only make business sense if
all the other ISPs did the same, at the same rate.  If they didn't charge, or
charged less, I would be at a competitive disadvantage.

Why would I want to do this, unless I was forced to do so by my upstream providers?

Why would they want to force me to do this, when I could choose some other
upstream provider which didn't force me to do so too?


Let's say I am ISP-1 and you multihome with ISP-2.  If ISP-1 and ISP-2 have very
different connections to the rest of the Net, when you change your advertisement
from one to the other, the effects may ripple through and cause messages to, and
changes of best path in, potentially every router in the DFZ.

If ISP-1 and ISP-2 share the same single upstream provider, or perhaps the same
two upstream providers . . . then no matter how often you change the way you
advertise your prefix with ISP-1 and ISP-2, you are probably only burdening
these two ISPs and a few routers at the edge of the common upstream provider(s).

So there is a wide variability in the impact of your update, depending on the
structure of the interdomain connections and how the routers are configured.  In
that case, how fair is it to charge you the same fee per update, when the impact
it has on the rest of the DFZ depends on things which are largely outside your
control?


I figure charging for each BGP changed advertisement could be done, like this,
via some technical and commercial arrangements.  However, it would only make a
marginal impact on the routing scaling problem.  Another arrangement might be to
have some global registry of ASes and their PI prefixes - where the ASes have
all agreed to pay some fee per update, to some central fund, and there is some
technical arrangement to monitor the changes they make, so the payments can be
seen to be correct.  But how would that work?  Some changes might not be
detectable except very close to the upstream ISPs of each edge network.


  - Robin


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