Re: comments on requirements draft

[Ramakrishna Gummadi <ramki@cs.berkeley.edu>]

Peter,
	Just a thought on the amount of addressing overhead this would
involve with transport-level multihoming: assuming each of your customers
dual homes with any provider that is triply redundant, this means their
network-level header overhead would be 16*3*2=96 bytes. This is not at all
a pleasant thought if we consider the fact that the average packet size is
about 500 bytes...

thanks,
ramki

> I was at a recent conference in Aus and the issue of Service Level Agreements
> was being discussed in a forum panel.  Each of three very large
> telco's/provider's (by Aus standards anyway) representatives were all highly
> confident that they could promise extremely high levels of redundancy and there
> was no need to have more than one provider.
>
> However by the end of the panel discussion and after several war stories were
> shared by members of the audience and even one member on the panel, it
> was eventually conceded that for an effective SLA, redundancy was crucial, and
> in particular to multiple providers.  The forum concluded with an independent
> consultant's reflection that they always recommended complete redundancy to
> their clients especially at the last mile.
>
> I also find that the further you are away from the core of the internet in your
> region, the higher is the risk of things going bang.  We are multply homed to 3
> providers even though we are a small ISP, and I have had occusion to depend on
> each of them for large outages over the past year.  Some outages were
> configuration problems in networks, while others were meltdowns in the
> providers infrastructure including major cable breaks, and even one
> international fibre break.  Had it not been for our multihoming, our service
> would have been out for a minimum of several hours, and in one worst case
> scenario we suffered, 2-3 days.
>
> This risk of things going wrong being higher at the edge is a curious
> observation as it flies in the face of the conventional wisdom that says that
> the smaller you are, and further from the core, the less need one should have
> for multihoming.  I would suggest the converse may actually be true.  The
> smaller or perhaps more remote a site or network is, the higher is the risk
> that the quality of their service is going to be degraded in one way or
> another.
>
> I guess my point is that to maintain any kind of quality of service, a small
> provider has to go that extra mile (pardon the pun) and provide a better
> service to differentiate their brand from the big providers.  One method of
> differentiation is redundancy by multihoming, even if the perceived cost may be
> high.
>
> Peter
>
> --
> Peter R. Tattam                            peter@trumpet.com
> Managing Director,    Trumpet Software International Pty Ltd
> Hobart, Australia,  Ph. +61-3-6245-0220,  Fax +61-3-62450210
>
>
>