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Just what is LLU?

VileReynard
Seasoned Pro
Posts: 10,999
Thanks: 265
Fixes: 11
Registered: 01-09-2007

Just what is LLU?

I know LLU is a TLA for "Local Loop Unbundling".
But how does this allow higher ADSL speeds?
AFAIK it doesn't reduce the line length - so how can it go faster?

3 REPLIES
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: Just what is LLU?

LLU basically means a third party company installs their own hardware into an exchange, and also (possibly) provides their own backhaul into their network.
Installing their own hardware means they can install kit that is more 'up to date' than BT, and supports ADSL2+ by default.  By managing their own backhaul, it means that they can sometimes provide much larger 'pipes' back into their own network.
ADSL in the UK has a theoretical max of 8mbps.  ADSL2+ has a theoretical max of 24mbps.
This is why companies like BeThere can provide 24Mbps connections to some properties in the UK.
However, ADSL2+ is a bit of a double edged sword.  By all accounts, if your sync speed is generally below 4mpbs you are unlikely to see any improvement, and may even see a decrease in speed due to the signalling protocol in use.  If you sync above 4mbps then you are likely to see a speed increase - although to reach 24mbps you're probably going to have to rent a flat above your telephone exchange!
Once an LLU provider has given you 'up to 24mbps' from your house to the exchange, their next problem is to provide a circuit from the exchange into their network.  This is generally known as 'Backhaul'.  This is the part of the network where BT used to say there would be contention.
Currently, BT provide (most of) Plusnet's backhaul.  They charge a fixed amount for this.  LLU providers have the option of installing their own backhaul (usually in the form of fibre lines) which terminate at one of their regional POPs.  This can be cheaper to maintain in the long run, but more expensive 'up front'.
Ultimately, there is an expense involved:
1.  An up-front expense of buying their own ADSL2+ DSLAMs (I believe the first few DSLAMs that BT put in were purported to cost around £750,000 each.  I have no idea what a current costing for a single ADSL2+ DSLAM would be)
2.  Up-front costs for installation of fibre backhaul
This is compared to the Plusnet method of:
1.  Relying on BT for all points of the network up to the Centrals that deliver the consumer to their network.  This method has a much lower up-front cost, but a higher associated 'running cost'
HTH
B.
Ianwild
Grafter
Posts: 3,835
Registered: 05-04-2007

Re: Just what is LLU?

Quote from: Barry
By managing their own backhaul, it means that they can sometimes provide much larger 'pipes' back into their own network.

Or much smaller ones!
http://news.independent.co.uk/business/news/article3193954.ece
Ian
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: Just what is LLU?

chuckle.
B.