wet-behind-the-ears whippersnapper seeking advice on building a nationwide network

Tue Sep 20 15:33:31 UTC 2011

On Tue, Sep 20, 2011 at 10:22 AM, Jon Lewis <jlewis at lewis.org> wrote:

> On Tue, 20 Sep 2011, Dorn Hetzel wrote:
>
>  If what you have is LEC frame relay service over which you have PVCs to
>> two
>> providers of IP transit service, then, IMO, you are multihomed.  Are you
>> protected against every single failure mode?  No, but then neither are
>> many
>> folks with more traditional methods of multihoming.  You are certainly
>> afforded reasonable protection against routing issues on each of your two
>> providers.
>>
>
> I'd agree in that case that you do have connectivity to two providers and
> are multihomed, though in a very foolish way.
>
> Past experience has taught me that while Layer 2 LEC frame certainly fails,
it may do so quite a bit less often than the rate of routing flaps, peering
spats, and everything else that can go wrong at Layers 3..9 ...  So while
it's not physically diverse, it may still yield a significant reduction in
downtime compared to that same T1 direct to a single Layer 3 provider...

>
>  How about a hard T1 to provider A and a GRE tunnel over a 3G router for a
>> backup?  That's certainly physically diverse...
>>
>
> If I was the ARIN auditor, I'd say that's borderline acceptable as
> multihomed.  It's not much different from one of your connections being
> "wireless", as long as that 3G connection is of sufficient bandwidth to of
> meaningful utility if the T1 is down.  If your primary connection is
> T1/T3/ethernet/etc. and your second is a v.90 modem, then I'd probably call
> BS on the claim of being multihomed.
>
> So now you think ARIN should be judging how much bandwidth is enough, and
how much is not?  Perhaps I just have a corporate ASN, and my backup
 connection is the most I can afford to make sure at least email gets
through when the primary is down.

It's a slippery slope from "v.90 not good enough" to "less than 2xOCn not
good enough" where n can be adjusted to suitably limit competition...

-dorn