Internet core scale and market-based address allocation
nickless at mcs.anl.gov
Mon May 5 17:50:37 UTC 2003
At 05:18 PM 5/5/2003 +0100, Sean M.Doran wrote:
>More importantly than keeping the "routing brain" underpowered
>compared to run-of-the-mill PeeCees, constraining the amount
>of state in the network gives us some system slack in making
>time-space tradeoffs within a routing system (and parts thereof).
>As an industry, we can cope with memory speed increases
>levelling off, OR with specialized chip production slowing down.
>Increasing the amount of state in the network destroys
>a very important belts-and-braces approach to growth.
Very good point--the issue is one of the amount of core state, whether that
state is created through unicast BGP prefix advertisements or multicast
MSDP Source Active advertisements.
In each of these cases, I believe service providers should charge the
customer for state that is (or could be) created in the core.
Today, service provider costs are generally driven by a combination of
circuit costs (read: recovering monopolist telcos)
equipment costs (packets-per-second)
equipment costs (amount of state the equipment can handle)
real-estate costs (roughly proportionate to number of customers,
and includes things like power and cooling)
people costs (proportionate to quantity of customers and equipment)
Pricing to the customers, however, is generally driven by the customer's
requirements for bandwidth, not the customer's ability or desire to create
state within the core. This leads to the following pernicious distortions
(two of which come off the top of my head; there may be more):
- Service provider sales/marketing has a perverse anti-incentive to
promote multicast. If multicast is promoted, then the immediate
result is a *reduction* in their commissions, because multicast
service reduces the customer's demand for billable bandwidth
- Customers end up charged for provider-specific IP addresses. The
costs to the service provider for managing and allocating IP
addresses need to be covered, of course. But if the *customer*
covers those costs, then the customer has an incentive to acquire
portable address space--which is then independently routed,
increasing the amount of state in the core.
As a customer of the voice telephone industry, I have the option of
accepting a provider-assigned telephone number when I establish
service. Or, I can pay a little more and retain my previously-assigned
telephone number. The choice I make depends on how much the telephone
number change will cost me overall, taking into account the cost of
preserving the prior address versus the costs of communicating my new
telephone number to actual and potential callers.
In the IP world, the cost of advertising the new IP address to actual and
potential communicators is relatively low due to DNS. But the cost of
being able to *accept* those communications may be much higher, since I
have to change state in all the devices (servers, routers, etc) that expect
to receive messages using the old addresses.
Bill Nickless http://www.mcs.anl.gov/people/nickless +1 630 252 7390
PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7 nickless at mcs.anl.gov
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