Re: Low latency IP direct connection over ISDN

On 11/11/2012 07:20 PM, Matthias-Christian Ott wrote:
> Hi,
>
> I want to connect two sites in Germany with minimal latency under low
> bandwidth requirements. Both sides have numbers with the same area code.
>
> It seems that all data on ADSL2+ lines is routed to a central exchange
> several hundred kilometres away and thus latency is more than 60 ms (one
> site is far away from the DSLAM and only has a 384 Kbit/s connection).
> Can latency be improved via ISDN (I've read contradicting statements
> about this)? My theory is that a direct ISDN connection (with itund)
> would be routed within the same regional area and not sent to a central
> internet exchange.

No idea if ISDN would result in less latency. Never heard of that before.

Eons ago the trick I used with an ISP to avoid going through a far away 
main Central Office (CO) which aggregated traffic from several closer 
CO's was ordering something called a "dry copper pair" which would 
transparently connect between my site and the ISP via the closest 
intermediary Central Office(s) and avoiding the far away Central Office. 
The telco basically created one long copper pair going from my site to 
the ISP's colo without going through any equipment. At the ISP the 
copper pair was hooked up to a port on (iirc) an Ascend MaxTNT and on my 
side a Telindus DSL modem was used. Result: a stable 2Mbit/s link with 
low latency at a cost of €50/month.

Obviously telco's don't like these kind of deals. They would rather sell 
you an expensive fiber link hooking up to some metro SDH/SONET ring. So 
make sure you say it's for an alarm system or some kind of M2M 
monitoring thingy. Don't tell them you need a business DSL link with 
less latency. I'm not even sure if telco's still offer "dry copper 
pairs" so you may want to ask around.

Regards,
Patrick