On Mon, Jun 30, 2008 at 7:12 PM, Dean Pemberton
True, but we hear the same thing all over the
place, everytime there is
an outage. The same sort of things were said when a similar provider in
another city had a similar length outage. People always seem to be
caught by surprise with one provider.
The fact remains...
Network resilience is like Backups, UPSs, Virus checkers etc. They are
hard to cost justify because if everything goes well you never need
them. If things go badly, then they are too late to install.
Everyone should know how much an 8 hour outage would cost their
business. This way working out if you need a backup link is a simple
economic issue. That or get penalty clauses written into your ISP contract.
It seems to me (correct me if i'm wrong) that if your main provider
only offers 90% uptime guarantee, your secondary provider only needs
about oh.. 10% uptime guarantee... provided the downtime on the second
provider doesn't occur at the same time as the first. This should be
reasonably easily achieveable if you use two different access
providers who don't have any shared infrastructure, preferably using a
different access medium.. copper vs fibre vs wireless etc as Richard
has mentioned. no use getting two telecom DSL connections and whinging
when they both go down because the exchange exploded. (11kv ground
I think this is reasonably well available in NZ, so there's not really
any excuse for not having a secondary access provider these days.
Perhaps this is why nobody was talking about this here when it
happened, as they just failed over, so no big deal, really.
Well, a small elephant sits quietly in the corner of the room,
namely that if a customer site multi-homes, it has about three choices:
a) have two IP prefixes all to itself
b) NATs everything (i.e. no public IP address whatever)
c) gets its own prefix advertised in BGP4
Right now there is no fourth choice and all of the above three
are somewhat broken.