Selfish routing

alex at alex at
Sun Apr 27 22:05:16 UTC 2003

> > So, the brilliant technology costs money but does not provide excellent
> > results under all circumstances? Simply not making stupid mistakes
> > designing the network *already* achieves exactly the same result for no
> > additional cost.
> > 
> And what, pray tell, governs stupid mistakes designing the network? 

Let see.... This would be from a company that used to say "we are basically
former baby bell, so you can count on us".

The data center has OC-3 in.

The data center has 4 customers.

Sales people pitch the business to a webfarm that, based on the mrtg graphs
that the owner shows to the sales people does 170Mbit/sec average and
320Mbit/sec peak over last 5 month, with growth of about 10% a month.

The sales people take the order, the customer gets moved from a different
location to the data center. The customer who moved and the existing
customers are going ballistic trying to figure out why they have packet
loss. The company's engineering claims to the customer that there is no
congestion what so ever, since the data center has 2xOC-12 coming into it.

Customer discovers the lie when someone shows him a 7206 that is carrying
the data center.

Shall I continue? A company that went into chapter 11 and now is trying to
really rebrand itself has this great Fujitsu made gear that
they use to handoff DS1s to collo customers, a lot of which are callback
companies. The techs of the carrier joke that every two month, no matter
what they are supposed to do in that collo, they always bring with them a
spare power supply for that gear since at least once a month, a power supply
on the box blows up. 

How about this one? There are very few companies that exercise nearly
complete control over the rights of way for the fiber that leaves island of
manhattan. Of those, just a couple sells dark fiber. Those companies are
known. Majority of the rest would do everything possible not to sell the
fiber or even lambda, preferring, instead to sell you lit circuit. The
buyers for the clients ( most of which are large companies as well ) know
that. They also know that buying the lit circuit would cost them a lot more
in $/mbit then buying the fiber or lambda and lighting it up themselves.
However, they are so pleased with the tickets to SuperBowl that they get
from the sales people of the non-fiber-selling-companies, they would not
ever consider buying from the others.

> For that matter, which network? I've run traffic through some networks for
> years without a problem. Then one day, that network makes a mistake and
> clobbers the traffic I send through it. Naturally, I redirect traffic via
> other networks, but the spare capacity via the other networks does not
> equate to the traffic I'm shifting, so while improving QoS for my
> customers, I have still shorted them.

Do you have more than one exit right now? Do you push around 100Mbit/sec to
each of those providers? Since you aparently have the money, did you
negotiate dials around $50 Mbit/sec exit on giges and OC-12 with 100Mbit

If the answer to this question is "yes" I do not see how you should be
worried about that.

> It could be argued that more spare capacity should have been allotted 
> for the other networks, yet then if the first network hadn't had a 
> problem, money would have been wasted on capacity that wasn't needed. It 
> is an art to establish enough bandwidth to handle redirects from 
> networks having problems and yet keep costs at a reasonable level.

I dont know which world do you live in, but today the sales people will beg
for 100Mbit/sec CIRs on OC-12 links just to meet the quotas. So, why dont
you get those 100Mbit/sec CIRs on OC-12c?

> Hypothetical: You are interconnected with 3 networks pushing 100Mb/s 
> through each. Slammer worm appears and makes 2 networks untrustworthy 
> because of their internal policies. The third network is fine, but your 
> capacity to it probably won't hold 300Mb/s.

Why is your 100Mbit/sec delivered over OC-3s when with 100Mbit/sec CIRs you
can get OC-12 ports from basically everyone?

> Network planning is not just about whether you make a mistake or not. 

Network planning *is* about not making mistakes.

> Performance is dependant upon the networks we interconnect with, issues 
> they may have, and how well we can scale our network to circumvent those 
> issues while remaining cost effective.


Performance does not depend on cost effective interconnects. They are NOT

> My hypothetical is simplistic.  Increase the number of peers, as well as
> the number of peering points to said peers, determine the cost and
> capacity necessary during multiple points of failure, plus the cost within
> your own network of redirecting traffic that normally takes more diverse
> routes, apply chaos theory and recalculate.

Rubbish again. The fundamental problem with this entire industry is that
some very clever marketing and sales people managed to convince entire bunch
of rather bright geeks that networks are complicated. The truth is, it is
not, however, since you have been told that it is over a million times, you
want to believe that it is.


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