[Disclaimer: I work for MFN/Above.net, that that for what you will.]
C&W did indeed shutdown their peering connections to PSINet
this weekend. While there are many potential explanations
for their actions, I have no visibility into their decision
process. I am disappointed with their decision to disconnect.
PSINet continues to seek a resolution with C&W to restore normal
connectivity in order to avoid further negative impact to both
companies and the Internet. Their decision is hard to understand
based on the following:
I find this quite ironic, as PSINet decided to terminate peering
with AboveNet in November of 2000. AboveNet was disappointed with
PSI's decision, and had worked hard to avoid the disconnection.
To this day, AboveNet is still unsure why PSI took that action,
with the damage that resulted.
The really interesting part, is the claims made below, which I will
address one by one.
- C&W and PSINet upgraded circuits used for peering between
the two networks earlier this year. C&W's recent action
seems inconsistent with the strategy that led to these
upgrades.
The same was true for PSINet and AboveNet. AboveNet ordered multiple
OC-3 peering circuits to PSI. The first was turned up under our
agreement. It was not until we tried to turn up the second that
PSI decided to reevaluate AboveNet as a peer. We were very much
caught by surprise when PSINet abruptly reverse course.
- PSINet's recent addition of direct private peering with several
of C&W's transit customers relieved the peering connections
between the networks of a couple hundred Mbps of traffic
(improving connectivity overall and, undoubtedly, lowering costs
for those transit customers). This is significant only because
C&W claims PSINet no longer has sufficient traffic to justify
the connections according to their published standards. In
fact, PSINet's overall traffic continues to grow.
This one one of the reasons mentioned by PSINet in the disconnection
proceedings for AboveNet. Clearly AboveNet could not be an important
peer due to the lack of traffic. AboveNet has maintained since
day one of its existance a very open peering policy, and the low
traffic to PSI was very much in part due to the robust peering that
AboveNet had with many of PSI's downstreams.
In all fairness, the issue of traffic ratio also came up with PSINet
(so they don't come back and claim they never cared about traffic
levels, just ratio). The ratio is equally funny though, due to
the next point.
- Most of the PSINet traffic previously destined for sites
behind C&W has alternative paths through other providers.
While this sounds like a generally good thing, especially given
the actions C&W has taken, it does make it difficult for those
that require certain traffic levels to be maintained consistently
for peering. Specifically, C&W's customers (or C&W itself) could
alter "natural" traffic flow to favor (or not) various connections
to meet their published standards (or not). PSINet demonstrated
to C&W that if naturally less favorable announcements were
preferred, PSINet could make an almost arbitrarily large (or
small) amount of traffic flow between the peers. Even so, in
C&W's opinion, PSINet will not be able to comply with their
peering policy's traffic standards. It is gratifying to note
that even without C&W peering, substantially all of the
traffic previously flowing between PSINet and C&W continues to
be delivered.
This is true for any provider with a reasonable amount of traffic.
With the number of multi-homed customers behind {Sprint, C&W, UUnet,
AT&T, Genuity, Level 3, Qwest} (and possibly others) it is easy to
move hundreds of megabits of traffic between those providers while
still honoring peering agreements. It is something PSINet ignored,
as well as C&W.
The fact is, most large ISP's can set the ration on any given
peering interface to be whatever they want, of course at the expense
of altering a ratio somewhere else. It's like a baloon, the total
volume (ratio) is fixed, but by squeezing or pulling it you can
make it into limitless shapes.
- At this time PSINet has not disabled the C&W peering interfaces
nor decommissioned any facilities. If C&W chooses to, they can
re-enable interfaces on their side and bring back the connectivity
lost between their non-transit customers and PSINet. PSINet
remains open to discuss with them a new bilateral peering
agreement if they so choose.
How lovely. 
Let me try from our side "At this time AboveNet
has not disabled PSINet's peering interfaces nor decommissioned
any facilities, if PSI chooses to, they can re-enable interfaces
on their side and bring back the connectivity lost..." AboveNet
is of course always open to discussing peering with PSINet, we hold
no grudges.
PSINet remains committed to servicing its customers and the Internet
with the best possible infrastructure and policies. PSINet still
maintains hundreds of peering connections with other ISPs throughout
the world. While posting about matters between PSINet and its
peering partners is not typical, the circumstances and questions
arising from C&W's decision required some clarification. Hopefully
this additional clarification helps everyone understand the current
situation.
Now this is clearly not true. As much as we had to swallow or
pride to do it, AboveNet took steps to make sure that even though
PSINet terminated peering, AboveNet customers experienced uninterrupted
(if a bit rocky for a short time) connectivity to PSINet. Our
commitment to our customers included making sure they could connect
to PSINet. PSINet clearly doesn't care if their customers can
reach C&W.
I feel no sympathy for PSINet, as I am personally a firm believer
in "connectivity is its own reward", and I think the fairly open
AboveNet peering policy reflects that as well. No one wins when
connectivity is broken like this, I have to believe both C&W and
PSI customers are feeling some real pain right now. I hope this
lesson makes people think twice about terminating such peering
relationships in the future.
That said, the irony here is amazing. PSINet has been put in the
exact same position by C&W that they decided to put AboveNet (and
possibly others, I'll let them comment on their situation) into
several months ago, and isn't even big enough to work around the
problem. "What goes around comes around" is very often true, the
provider that was big yesterday can be small tomorrow, and could
possibly even come back to be big again.
If PSINet would like to start down the road to recovery, I suggest
they start with mending some of the relationships they chose to
sever in the past. If a PSINet representative would like to talk
about the AboveNet situation in particular, please mail me privately
and I'll make sure you get in touch with the right people.
Also, I would like to suggest that if you are a Cable and Wireless
customer, and disagree with their current action of terminating
peering relationships (we have nasa.gov and psi.net confirmed on
Nanog, and rumors of many others in the works) I suggest you let
them know how you feel, first with your words, and if that doesn't
work with your dollars, by taking them elsewhere. I know a lot of
people think ISP's don't listen to their customers, and sometimes
it may seem that they don't, but by and large they do try to keep
their customer base happy.