Paul Brooks pbrooks-link at layer10.com.au
Wed Apr 8 10:02:54 AEST 2009

Jan Whitaker wrote:
> At 11:09 PM 7/04/2009, Paul Brooks wrote:
>> Now try to imagine the backhaul required to service the head-end if
>> 5000-10000 users are hanging off the head-end with 10Gig dedicated links
>> each
> What are the implications for the offshore connectivity?  Or is that 
> what you're referring to?
I was referring to just the local backhaul link feeding data from the 
service provider's core network to the head-end (I hesitate to use the 
word 'exchange', as it might not be at an exchange as we understand the 
term now) of the access network - however the same consideration applies 
to international connectivity, at least while the same ratio of 
local:international data transfer is maintained.

I do however think the apparent 'shortage' of international capacity is 
a misconception at the moment. The issue is generally not any limit on 
capacity - there's plenty of un-utilised bandwidth on some of the 
international cables - the issue currently is the high price, that 
encourages the providers that buy justa little too little capacity to 
run the links into congestion and then some before adding incremental 
capacity, to manage the costs so as to keep the performance just under 
the 'scream point' of their customer base.

ALso, many people do not appreciate the effects of the 
bandwidth-delay-product and the receiver window size that underlies the 
Internet protocols. Even if you were the only person on the planet 
passing traffic along an otherwise empty international cable, you may 
not see any increase in the data transfer rate from a far away site with 
a long round-trip-delay between you and the site. More long-haul 
capacity doesn't necessarily imply faster downloads, it just allows more 
people to transfer data in parallel with you before the system clags up.


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