concern over public peering points [WAS: Peering point speed publicly available?]

Mon Jul 5 17:55:42 UTC 2004

On 7/5/04 1:18 AM, "Steve Gibbard" <scg at gibbard.org> wrote:
> 
> 
> The performance arguments are probably more controversial.  The arguments
> are that shortening the path between two networks increases performance,
> and that removing an extra network in the middle increases reliability.
> The first argument holds relatively little water, since it's in many cases
> only the AS Path (not really relevant for packet forwarding performance)
> that gets shortened, rather than the number of routers or even the number
> of fiber miles.  If traffic goes from network A, to network A's router at
> an exchange point, to network C, that shouldn't be different
> performance-wise from the traffic going from network A, to Network B's
> router at the exchange point, to Network C.  Assuming none of the three
> networks are underprovisioning, the ownership of the router in the middle
> shouldn't make much difference.  The reliability argument is probably more
> valid -- one less network means one less set of engineers to screw
> something up, but the big transit networks tend to be pretty reliable
> these days, and buying transit from two of them should be quite safe.
> 

I believe that peering does lead to a more robust network and somewhat
better performance. Being heavily peered means that when one of my transit
providers suffers a network 'event', I am less affected. Also, just because
I'm sitting at a network exchange point (and take my transit there) doesn't
mean that's where my transit networks peer. Quite often, I see traffic going
to Stockton or Sacramento through one of my transit connections to be
delivered to a router just a few cages away at PAIX.

> The pricing issues are simpler.  There's a cost to transit (which is, to
> some degree, paying some other network to do your peering for you), and
> there's a cost to peering.  Without a clear qualitative difference between
> the two, peering needs to be cheaper to make much sense.  The costs of
> transit involve not just what gets paid to the transit provider for the IP
> transit, but also the circuit to the transit provider, the router
> interface connecting to the transit provider, engineering time to maintain
> the connection and deal with the transit provider if they have issues, and
> so forth.  Costs of peering include not just the cost of the exchange
> port, but also the circuit to get to the exchange switch, sometimes colo
> in the exchange facility, engineering time to deal with the connection and
> deal with the switch operator if there are issues, and time spent dealing
> with each individual peer, both in convincing them to turn the session up,
> and dealing with problems affecting the session.  Even if the port on the
> exchange switch were free, there would be some scenarios in which peering
> would not be cheaper than transit.
> 

When we established our connection at PAIX, peering bandwidth was a factor
of 20 cheaper than transit. Now they're at parity. Unfortunately, some *IX
operators  haven't seen fit to become more competitive on pricing to keep
peering more economical than average transit pricing.

$5000 for an ethernet switch port? It makes me long for the days of throwing
ethernet cables over the ceiling to informally peer with other networks in a
building. In the 'bad' old days of public exchanges (even the ad hoc ones),
most of the problems were with the design and traffic capacity of the
equipment itself (not a real problem now), not with actual 'operations'.