BT Wholesale

BT Central

A BT Central links BT Wholesale"s broadband network and a Service Provider"s premises and is used to aggregate and back-haul End User traffic.

There are six BT Central options to choose from, offering a range of data-rates and number of simultaneous sessions supported:

2 to 34 Mbit/s

  2M/bits 10Mbit/s 34M/bits
Sessions supported 250 1600 1600
Service level TotalCare TotalCare TotalCare
Interface 10baseT 100baseT 100baseT
Physical interface RJ45 RJ45 RJ45
Network Terminating Equipment (NTE) Cisco 3640/3725 Cisco 7204VXR Cisco 7204VXR

155 Mbit/s - 622 Mbit/s

  155Mbit/s 155Mbit/s L2TP 622Mbit/s L2TP/LNSv1
Sessions supported 6400 8000 25600 max
Service Level TotalCare TotalCare TotalCare
Interface Gigabit Ethernet Single Mode Optical Fibre Gigabit Ethernet
Physical Interface STM-1 STM-1 STM-4
NTE Cisco 7204VXR or Cisco 7507 ADM 2 x Cisco 3550

For further information, please see SIN329

Lead Times

The standard lead time for provision of the variants of BT Central are:

  • 2Mbits/s - 35 working days
  • 10Mbit/s, 34Mbit/s, 155Mbit/s and 155Mbit/s (L2TP) - 65 working days
  • 622Mbit/s (L2TP) - 77 working days

Please note that the maximum radial distance reach of BT Central 622Mbit/s is 25km from a BT IPStream PoP site. All other variants of BT Central have a fixed rental price up to a radial distance of 40km from a BT IPstream PoP site but can be extended beyond 40km at an additional per km rental charge. All installations are subject to a site survey.

Layer 2 Tunnelling Protocol (L2TP) pass-through option

The L2TP option offers a tunnelled presentation rather than the standard BT Central routed presentation and is available on the 155Mbit/s and 622Mbit/s service. With L2TP, End User sessions are passed through to the Service Provider’s network, giving greater flexibility to control the termination of PPP sessions. L2TP is ideal for Service Provider central management centres or central IP address allocation. To use the L2TP option, Service Providers must provide the infrastructure to terminate the End User PPP sessions.

Further Information is available in SIN 374

Pricing

Service providers can choose between charging methods for BT Central. Three options are available: standard, usage or capacity based charging. For further pricing information please see the Service Provider Price List.

For further information about these pricing options please contact your BT account manager.

BT Central 622Mbit/s Flexing Bandwidth Rental Charges

For the L2TP and LNSv1 options on the 622Mbit/s service, an Service Provider can order any one of the bandwidth increments to begin with and then flex this up to the maximum at any time during the first 12 months. At the end of this 12 month period, the full BT Central 622Mbit/s charge will apply regardless of the current increments being rented.

Full pricing information is available from the Service Provider Price List.

BT Central Resilience

The level of resilience on the link between the Service Provider’s premises and the BT network varies between BT Central bandwidth options as follows:

  • BT Central 2 Mbit/s - this has a single option of a single fibre through a single duct to the Service Provider’s premises.
  • BT Central 10 Mbit/s and 34 Mbit/s - this has a standard resilience of a single fibre through a single duct between BT's network and the Service Provider’s premises. An additional fibre can be provided in the single duct or it can be routed to your premises through a second duct at an additional cost as detailed in the BT Price List. This additional duct is subject to site survey and can only be ordered in conjunction with a second fibre.
  • BT Central 155 Mbit/s - this has a standard resilience of dual fibres through a single duct between BT"s network and the Service Provider’s premises. A second duct is available at an additional cost, each duct containing a fibre. This is subject to site survey and costs will depend on the work carried out.. Please use a CRF if you wish to order this facility.
  • BT Central 622 Mbit/s - this has a standard resilience of dual fibres through a single duct between BT’s network and the Service Provider’s premises. A separate duct will be provided where possible, subject to survey.

Please note:

  • BT Central products do not support the ability to route the individual fibres of a dual fibre access to your premises from separate broadband PoP sites.
  • BT Central products do not support the ability for you to nominate the specific broadband PoP sites that your BT Centrals are connected to. BT will normally connect BT Centrals to the nearest broadband PoP site.

RADIUS server

The Service Provider is responsible for providing their own RADIUS server, connected to BT’s NTE, to authenticate user logins and allocate IP addresses.

Further Information is available in SIN 329

RADIUS Accounting Data

BT Central supports RADIUS End User accounting data, at no charge, except for the 155Mbit/s L2TP variant and except for BT Central Plus. The accounting data will be available via a data feed to the Service Provider’s RADIUS server. As well as stop and start accounting data, the data will be refreshed every two hours to provide interim accounting messages. Service providers also have the option to ask BT to turn on the extra RADIUS traffic attributes 42, 43, 47 & 48.

Further Information is available in SIN 329.

RADIUS accounting data transfer attributes 42, 43, 47 and 48 have a level of accuracy comparable with typical IP traffic measurement equipment. There are, however, circumstances in which accounting packets and records may be lost. The traffic measurements are therefore an approximate indication of the individual End User traffic.

Please request RADIUS End User accounting data using the BT Central CRF.

Domain Name Options

This is a service enabling Service Providers to map domain names to multiple BT Central connections and provides a simple process for adding new BT Centrals.

There are three options; any combination of them is known as ‘many-to-many’.

One-to-one

The default option maps one domain name to one BT Central link.

Many-to-one

This option maps more than one domain name to a BT Central link. BT IPstream can support up to ten domain names per BT Central, offering Service Providers more flexibility in constructing and tailoring their End User services.

One-to-many

This option maps one domain name to a group of BT Centrals. End user sessions are sequentially distributed over the Home Gateways and LTSs, offering a form of resilience that falls short of true load balancing. If a BT Central is lost, End User sessions will be re-established on one of the other BT Centrals in the group; when service resumes, Service Provider can either force End User sessions to be re-established manually or allow them to rebalance over time. A maximum of 100 Home Gateways or LTSs can be supported in a one-to-many group - for example 25 BT Central 155Mbit/s or 50 BT Central L2TP 155Mbit/s.

Recommendations

;BT strongly recommends that Service Providers create a group of BT Centrals with the same bandwidth and supported simultaneous sessions. There have been issues with throughput and contention where End Users are terminated on a group of BT centrals with different bandwidths - for example BT Central 10Mbit/s and BT Central 34Mbit/s.

BT strongly recommends that Service Providers provide an additional two IP addresses. BT will NAT the proxy RADIUS to those addresses, as this is more efficient with RADIUS Packet Routing

BT will not support one-to-many groups of mixed services - for example ‘Classic’ and L2TP

If the Service Provider does not use dynamic IP addressing and the Address Pool is hosted on the BT Home Gateway, BGP4 Routing must be used

BGP4 Routing Protocol will be part of the standard configuration of BT Home Gateways. The BT Home Gateway router will be configured with a private AS number - AS65400 - to be used with iBGP

BGP4 Routing Protocol is only available on BT Central 10Mbit/s and above products

Only BT hosted dynamic IP address pools are supported with a One-to-many group of BT Central 2Mbit/s links.