• 20 users on 24Mb ADSL sharing just 1Mb of bandwidth.
• All other users sharing 30Mb of bandwidth on old 20CN 8Mb ADSL.
• Added in enhanced care for all users at £8 a go.
• Forgot monthly broadband line rental charges at £7.90 a go.
• Will charge us for bandwidth across the 21CN network, plus charges for 3km of fibre across the London Docklands and we have to provide the BRAS – but yet they still have the balls to charge us £24k a year just for the privilege of doing business with the almighty BT Wholesale. Seriously, noone can explain what this charge is for given that they have separate charges for both bandwidth and fibre.

When I entered the correct figures into their shitty little price sheet, added in all the things they forgot, it came to a whopping £26 per user before any profit margin is added.

By comparison, Be/Fluidata is charging a non-recurring £3k to setup a simple crossconnect in any London Telehouse, and then all we pay are simple line charges depending on the product used, the average one of which is £16 per month.

It’s quite clear that BT Wholesale is not interested in providing any sort of service to other service providers. The ridiculous ordering/faults system, the outright denial of clear area-wide faults and now these ridiculous and quite arbitrary charges for access to their so-called 21st Century Network that still doesn’t properly support IPv6 are all very telling.

Simply use the Linux traffic control tools as follows. First enter:

tc qdisc add dev eth0 root handle 1: cbq avpkt 1000 bandwidth 100mbit

Now enter the following line. This line sets the bandwidth rate; note the “256kbit”. This will limit our server to 256Kbps.

tc class add dev eth0 parent 1: classid 1:1 cbq rate 256kbit allot 1500 prio 5 bounded isolated

And lastly:

tc filter add dev eth0 parent 1: protocol ip prio 16 u32 match ip dst 0/0 flowid 1:1

For more informtation on how this works, type ‘man tc’ at your console.

• When measuring bandwidth, attempt to use a site or tool that is close to your ISP. If you’re in the UK and you try to test your connection using a site hosted in the US it’s never going to give you a decent idea of your speed. I recommend Speedtest.net, as it’s a single tool that can test to a multitude of different locations and will give you a much better idea of exactly how your line is performing.
• Remember to allow around 10% for overheads. An 8Mb ADSL line will top out at 7.2Mbps. This is due to overheads for the ADSL line itself: a certain amount of bandwidth is required to manage your packets that will not be visible on any web-based bandwidth test.
• Any download requires a certain amount of packets to be sent in the opposite direction. Usually these are acknowledgement packets to assure the server you are downloading from that everything is being received okay (or not, as the case may be). Again, that magic 10% figure is the one to watch out for. A 1Mbps download will roughly need a 100Kbps upload. If you are using up all your upload bandwidth, your download bandwidth will be poor.

Data is traditionally measured in Bytes. A CD contains 650MBytes of data. Bandwidth is measured in bits however, and this is what most customers misunderstand. A CD measured in terms of bandwidth, is 5,200Mbits (there are 8 bits per byte). Note that in writing, you use a capital ‘B’ to denote Bytes, and a lower-case ‘b’ to denote bits.

The issue is that bandwidth is traditionally measured in bits, not bytes. A 1Mbit circuit lets you download at 100KBytes/second. A lot of people make the mistake of thinking that a 1Mbit circuit is the same as downloading at 1MBytes/second.

This becomes a problem when a customer – as has happened today – complains of a slow speed problem. The systems (which I built and maintain) show this customer as downloading up to 32Gbits per day. They dispute this via the phone, proclaiming that they only downloaded “4 gig” (in a 5 hour window, I’ll add). If you do the math: 4*8 = 32. 32Gbits. On a standard ADSL line, that’s a crazy amount of usage – averaging around 1.8Mbit/s for that 5 hour window. During peak hours, an ADSL Max line (due to contention) may only be able to achieve 2Mb/s. It’s a classic case of someone mistaking Bytes for bits… of course, explaining that to them is another matter.