[50458] in North American Network Operators' Group
Re: redundancy [was: something about arrogance]
daemon@ATHENA.MIT.EDU (David Schwartz)
Tue Jul 30 06:03:44 2002
From: David Schwartz <davids@webmaster.com>
To: <roque@sbcglobal.net>, <brad.knowles@skynet.be>
Cc: <nanog@merit.edu>
Date: Tue, 30 Jul 2002 03:02:12 -0700
In-Reply-To: <3D46691C.3090200@sbcglobal.net>
Errors-To: owner-nanog-outgoing@merit.edu
On Tue, 30 Jul 2002 03:23:24 -0700, Pedro R Marques wrote:
>All of those are much more frequent than the failure of an=
entire ISP (a
>transit provider). It is expected, i believe, of a competent ISP=
to
>provide redudancy both within a POP and intra-POP=
links/equipment and
>its connections to upstreams/peers.
=09Yes, but when the ISP that all your redundant links go to and=
that you got
all your IPs from goes out of business, what's the mean time to=
repair? 30
days?
>So, my question to the list is, why is multi-homing to 2=
different
>providers such a desirable thing ? What is the motivation and=
why is it
>prefered over multiple connections to the same upstream ?
=09You cannot as easily be held hostage. I have consulted for a few=
ISPs and
have my share of war stories.
=09Here's a (true!) example. One day, a certain head of a fairly=
large ISP
decided that he wouldn't route traffic to or from IPs he had=
assigned that
didn't reverse resolve because he felt it was imperative that=
people be able
to find network contacts in this way (I think he got sick of=
being the one to
get the abuse emails). He told my client three days before=
implementing a
sweep and filter. He had the equivalent of about 38 /24s from=
this ISP
distributed over about 180 customers, they were his sole uplink.
=09Here's another good one. A client needed a /22 immediately for a=
major
customer about to come online, set it up fast or lost the=
account. We made
sure to met all the IP assignment guidelines and our=
justification was
impeccable, we had >90% utilization of a /18. The only problem=
was, the
client's provider had a screw up in their allocations and=
justifications and
their applications were being refused by ARIN until they fixed=
their
problems. Now what?
=09One more just for kicks. Client had a 100Mbps circuit from their=
sole
provider (100Mbps to colocated router, DS3 from this router to=
their
premises). The circuit had been in place for several years and=
the contract
had long since expired. One day, they got a call -- they had 5=
days to agree
to a new (and MUCH higher) pricing scheme with a much higher=
minimum paid
bandwidth amount or their circuit would be turned off. The kicker=
-- they had
to agree to a two year term!
=09The other issue is provider misconfigurations/meltdowns. They're=
not common,
but if you're multihomed, you can just shut down the circuit to=
the
misconfigured providers. There have been a few cases of these=
that I've seem
where the repair time was several hours.
=09If you add cases where just one POP was out, the number goes way=
up. If
you're only in one location yourself and only use one provider,=
all of your
redundant links will likely go to the same POP.
=09DS
