Fibre speeds on E0 lines

This is going to sound stupid but a search with google didn't come up with any good reasons for me.

FTTC works with kit in a cab connected to a standard PCP, why cant the kit be installed in the exchange then connected to the copper in a simmiler way?

For example the wires from the main bit of the exchange then go to a (for want of a better word) mini PCP in a corner of the exchange where the signal could be combined as it is with a standard PCP

VDSL in exchange is not allowed due to worries about crosstalk, i.e. not part of the ANFP.

mini PCP as in a hybrid FTTC cabinet or full FTTP is the way EO lines are going to be dealt with, covered this in news yesterday

Ofcom have a sub-committee ( NICC - Network Interoperability Consultative Committee) that determines the rules on connection to BT Openreach's copper (aka the Access Network).

The rules are set in a document known as the ANFP (Access Network Frequency Plan) which determines what is - and is not - allowed to happen within the exchanges, cabinets and over the copper. The aim is to prevent any form of interference between any of the companies that interconnect equipment.

It is the ANFP that allows VDSL2 to happen at all within the cabinets, and was a new version of the ANFP that allowed BT to switch from the 7MHz 8c profile to the 17MHz 17a profile at the end of last year - and so open up the 80/20 products.

However, the rules therein prohibit the use of these frequencies within the exchange building itself.

As I understand it, the ANFP doesn't explicitly say "No VDSL2 in the exchange", but the rules on frequencies and power-masks are the things that end up prohibiting it.

I see, thank you both

Didnt know about yesterday mrstaffron been in Portugal for a week and a bit with no internet when i suddenly thought about it over ice cold beer on the beach in 30 degree heat.

Edited by omnius (Wed 03-Oct-12 21:32:48)

In reply to a post by omnius:

I see, thank you both

Didnt know about yesterday mrstaffron been in Portugal for a week and a bit with no internet when i suddenly thought about it over ice cold beer on the beach in 30 degree heat.

Yer crackers !

I wouldn't have been thinking about broadband. Just the broads in the "sea"nery.

In reply to a post by RobertoS:

I wouldn't have been thinking about broadband. Just the broads in the "sea"nery.

yea its amazing what scantly clad women, booze and the hot sun can do to ya

totally random thoughts!!!!!!

The ANFP is here: ANFP, version 5
The extra document on DSL: here.

Section 6 says:

In reference to www.niccstandards.org.uk/files/current/ND1405V3.1.2.pdf?type=pdf:

The ANFP does not exclude specific systems; it excludes by implication: one may not install a system that
does not conform to the appropriate masks at each of its ends. For example the ANFP would exclude the
following standardised systems from use on any BT access network line (‘ultra short’, ‘extra short’, ‘short’,
‘medium’ or ‘long’):

• ISDN basic access using MMS43/4B3T line code - see Section 6.2.2.
• A 1-pair 2.3 Mbit/s HDSL system using 2B1Q or CAP
• ADSL over ISDN
• Reverse ADSL (i.e. with the high bandwidth implemented in the customer to exchange direction).
  This means that ADSL is precluded from use on private circuits.
• VDSL deployed at an MDF site.

MDF is the main distribution frame in the exchange building - the place where every copper pair comes in.

That would explain why the VDSL test circuit in a local exchange has had it's own 5pr cable pulled back in from the cab, rather than just pushed back up a spare E ....

there is a part of the ANFP (as yet unused) for lines that don't pass through PCPs to have their own mask. ie where there is no risk of a competing VDSL or ADSL signal being added at a cabinet.

The ANFP exchange mask is also the original and I'm not sure anyone has considered updating it for VDSL from the exchange. VDSL from the exchange is used elsewhere, there are masks and frequency plans that should address most issues.

EO lines fall into two camps - short ones close to the exchange that could benefit from VDSL in the exchange and long ones that wouldn't.