Plusnet currently have 5 x 622Mb BT Central Pipes giving a total available bandwidth of 3110 Mb. All available segments are lit although I have been advised another central is also on order.
Each of these central pipes are split into 4 x 155Mb segments.
They also have a separate LLU feed for customers who are on the LLU products, and are currently transferring some users over to the RIN network.

Segments can be activated fairly quickly and Plusnet normally activate one segment at a time if more bandwidth is required. To see what segments and bandwidth is currently in use see the table below.

Each of the 622 pipes terminate on a high capacity Juniper ERX-1440 .
Juniper 1 terminates 1 x 622 Mb pipe and is located at Telehouse North.
Juniper 2 terminates 1 x 622 Mb pipe and is located at Telehouse North.
Juniper 3 terminates 1 x 622 Mb pipe and is located at Telehouse East.
Juniper 4 terminates 1 x 622 Mb pipe and is located at Telehouse East.
Juniper 5 terminates 1 x 622 Mb pipe and is located at Telehouse North.

Plusnet 7, 8 and 9 are Juniper E320s.
thn-ag2 is a new generation E320 which terminates the flexible LLU pipe.

Generic information about BT Central pipes can be found on my page about how adsl works 2 and more information about the Junipers on how adsl works 3

Overview of pipes and segments in use

You can view the current bandwidth in use by Plusnet's customers from their utilisation graphs on the portal here.

To find out which pipe you are connected do a tracert and by comparing the results with the table below you should be able to see which aggregator you are connected to.

Current IP Addresses

Update Nov 2004 - UserTools have created a gateway checker which will quickly tell you which gateway you are connected to http://users.plus.net/@gateway

Current and Historical pipes and their segments in service are:
There is also one Tiscali LLU central which has flexible bandwith.

May 08

All segments on PlusNet 8 are lit, 2 1/3rd of the segments are allocated to PlusNet customers (and new MAAF signups) and 1 2/3rd segments are allocated to existing (rather than new) MAAF customers and the other MAAF-related realms.

** There are several differences between the 622Mbps and 155Mbps pipes, which means that throughput on a single 622Mb pipe is more or less equivalent to 5 x 155Mb pipe. For more information see my page on the BT Centrals.

Pipe Selection.

BT use the "round robin" method of selecting which pipe you will be connected to when you log onto their network. That means each user is connected to a particular pipe in rotation.
Unfortunately, this method has recently caused some problems as some pipes have been more loaded than others.

The reason being is that each 155Mb pipe has 2 tunnel end points... whilst each 155Mb segment of a 622Mb pipe has 3 end points, therefore the Redbacks have been occasionally more loaded than the Junipers.
The problem can easily be resolved by disconnecting and reconnecting on another pipe.

There are talks that a resolution may be to transferring to all 622Mb pipes, and Plusnet are currently in discussion with BTw to resolve this issue.

UpDate Dec 2004

BTw's method of load balancing the various pipes has meant that some users on certain pipes have seen slight slow-downs.
This issue is being looked at by PN and BT and a solution proposed that the Redbacks will be made redundant and all 622's and Junipers will be installed.
The upgrade progress will take approximately 6 to 12 weeks to be completed.

UpDate Feb 2005

The process of installing 2 more 622Mb pipes and a Juniper at Telehouse East commenced.
14th of Feb saw the pipes go live and the users on Redback 1 moved over to the new pipes.
Redback 1 is to be set up as a fall-over unit for the new Juniper.

The ERX's have subscriber session limits and Juniper are releasing new firmware which will support a greater number later in the year. Until then the the SMS10ks will terminate some sessions on behalf of the ERX's until the firmware is updated.

The 155Mb pipes were decommissioned on the 18th of Feb.

Update Jun 2005

Work in Progress to decommission Redback 2 as an overspill device for Juniper 3 which currently has 2 x 622 pipes. Juniper 4 will take over one of the 622's from Juniper 3.

It is thought that the 2 Redbacks will be utilised as backup devices for the Junipers.

Historical Peak Utilisation Figures.

For about a year I kept an eye on Plusnets Utilisation figures and recorded peak time capacity.
Unfortunately in September 2005 Plusnet withdrew the old style utilisation graphs from which I gained peak capacity, therefore I am no longer able to monitor these figures.

However, Ive kept the tables for historical information and these can be viewed from here.

Contention Ratio

In Feb 2005 I performed the following calculation based on information to hand that time:-

4 x 622Mbps = 2488 available bandwidth

65.97% of users on 512k
24.33% of users on 1024k
9.69% of users on 2048k

65,970 = 512k
24,330 = 1024k
9,690 = 2048k

Total possible peak bandwidth

32,985 (512s)
24,330 (1Mbs)
19,380 (2Mbs)
76,695 Mbps (total)
/ 2488

= 30.83:1

Old Addresses

Historically, the 155 pipes terminated on two Redback SMS10000 aggregators, commonly known as the Redbacks. Each Redback had 5 central pipes and were located at Telehouse East.

* The ERX's have subscriber session limits and Juniper are releasing code which will support a greater number later in the year. In the meantime the SMS10ks will terminate a fair number of sessions on behalf of the ERX's until PN can deploy the code.

Redback 1 was is use DSLconnect customers but these customers have now been amalgamated onto the Junipers. I have recently seen an instance whereby it is possible that Redback 1 was now also being used as an overspill device.

Traffic

PAYG Traffic

Premier Traffic
(suspect this may now be recording something else wef Jun 06)

BroadBand Plus Traffic

Packets Dropped

Traffic Type

Official Plusnet Utilisation Graphs