Is there a typical size for the link between a small, rural exchange out to the wider world? 155 Mbit? 1Gbit? 10Gbit? More, less or something in between or is there no hard and fast rule? The exchange I'm thinking about is Goudhurst (NDGOU) so if anybody knows about that exchange in particular even better!
Depends - you can rarely tell because the exchange could be used to house backhauls from other smaller exchanges in the area.
Your DSLAM will likely have a 155Mbit link to the backhaul because it's still a plain old ADSL Max DSLAM.
Bearing in mind there's no LLU at your exchange and seeing as there are around 1100 lines in total, I'd imagine it has a 155Mbps backhaul which may or may not all be in use.
If it was 21CN enabled (Which it isn't at the moment), I'd have said 1Gbps.
Re: your first question - Very small exchanges which haven't been upgraded to 21CN will mostly have ~30Mbps backhauls to the closest bigger exchange in a town for example like is highlighted on the Kitz website:
http://www.kitz.co.uk/adsl/equip2.htm#cloud
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Telewest (2004-2006): 256Kbps -> 512Kbps
University of Portsmouth's Horrible Network (2013 - 2014) - Supposedly 100/100Mbps
BT (2006 - Present): 8128/448 -> 22494/1211 -> 79987/20000Kbps (BT Infinity 2 on Huawei Cab)
Edited by chris6273 (Mon 04-Aug-14 17:51:52)