Redundant DSL Questions?!

Re: Redundant DSL Questions?!

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>Another good option is to colocate your server somewhere that does
>use BGP. This way, you get all the benefits of redundant connections,
>without the hassle of setting it up and maintaining it yourself.

Agreed, <shameless plug>find yourself a top-notch multi-homed provider to
host your web server, or at least your DNS server, or even just run DNS for
your domain using QDNS Pro and the Fault-tollerence webserver resonder to
prevent all this downtime from happening.
There are several smaller ISPs with excess bandwidth that like to colocate
smaller servers, for very reasonable rates. </shameless plug>

DSL connections are the cheep version of full T-1s. They're cheep because
they don't build in the reliability that providers strive to provide for
T-1 circuits. They do this because for $49.95, it's not worth the effort
to provide 99.99% uptime. Anyone who runs servers on DSL connections
should expect downtime. It's the old saying "You get what you pay for."

T-1s offer much better uptime (typically, I see a T-1 go down for a few
minutes (2-10) about once every 3 or 4 months on average)
Even with a Cisco 7507, running full BGP (and I've been running it for
several months now) doesn't hold the promise of uninterupted network
computing. If (when) a T-1 goes down, it still takes about 10 secconds to
recompute the entire routing table for outbound packets, and then about
2-5 minutes (depending on time of day, and general load of the routers that
make up the internet) for inbound traffic to find its way arround the
downed T-1. (Convergence)
<brag> I have the seccond fastest Route-Switch procoessor Cisco Systems
makes </brag>, so with the faster model, it might be possible to get the
route recomputation down to 5 secconds, but the 2-5 minutes of convergence
is unavoidable. Even the large hosting centers (UUnet, Exodus, Global
Center, AboveNet) are limited by these same fundamental rules.

You just have to hope that the end user will try to load the web site
again, after a 2 minute waiting period. Most users won't.

-Jerry

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