Route table growth and hardware to the filter

michael.dillon at michael.dillon at
Sun Sep 23 18:57:07 UTC 2007

>         On Sun, 23 Sep 2007 michael.dillon at wrote:
>     > > having full routes from multiple providers was the only way 
>     > > to be automatically protected.
>     > 
>     > Not so. Anyone who had sufficient transit was also 
> protected from
>     > the games. And they shielded their customers as well.
> Michael, how are these two statements not in agreement?  It 
> looks to me like you're saying the same thing: A network 
> which claims "tier 1" status by failing to buy any transit, 
> subjects its customers to connectivity failures when 
> depeering happens, while a normal multi-homed network does 
> not inflict that failure upon its customers.  Isn't that what 
> you're both saying?

I suppose that if you dig deeper, which most people don't seem to do,
then buying transit is just one form of having full routes from
multiple providers. But on the surface, the comment that I responded
to seemed to be repeating that commonly held belief than only 
transit-free, default-free providers with multiple peers for
any given prefix, can be considered Tier 1. Last century, there
was lots of boasting in the business and people needed rules of
thumb such as "default free" and "transit free" to sift the wheat
from the chaff. But I don't think that is true anymore, especially
not on a global scale (even a partly global scale). There are providers
who provide high levels of service and reliability who have some 
transit and some default routes in the mix.

I'd like to see a lot more focus on how a network deals with single
points of failure, physical separacy of links, and the like. These
are more important than whether they are a pure-play peering network.

> Disclaimer: this is my first posting of the morning, thus 
> it's inevitably dunderheaded or offensive, for which everyone 
> has my apologies in advance.

Not at all. It is inevitable to have misunderstandings when going
a paradigm change. We went through the last one when the telecom
bought up the ISP industry. But now we are going through another one as
businesses higher up the OSI stack, like Google, are getting into
an IP WAN. Also, traditional telecom companies are diversifying into 
other service areas higher up the stack in a similar way to how IBM
out from being a computer hardware manufacturer into a services company.

--Michael Dillon

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