Cable Forum - View Single Post - [Merged] NTL Increasing BB Speeds Late Summer 2004

BBKing · 06-05-2004, 23:03

Oo pem...

Lecture on the difference between data storage and data transmission. Storage is always measured in bytes (=8 bits). Multiple bytes are measure up in exact powers of two (kByte is 1024 for instance).

Transmission is always always always measured in bits. Just because IE reports your transfer speed in bytes doesn't mean you should listen to it, it's measuring transfer of a file, rather than a transmission of data.

Network professionals measure everything in bits, and a kilo is a kilo, as in 1000, as in a kilometer. Properly, in other words :P

Thus when TW set the downstream parameter in their new CM file to 768000 bits per second, 768000 bits per second is what you'll get. Or 768 kilobits per second in other words.

Transmission speeds don't have to be exact powers of two to work properly, hence why ntl can base their speeds on multiples of 150k. All of which does lead to the rather odd statistic that TW 512k users are getting a 50% free speed upgrade while ntl 600k users are only getting 25% free.

The probable reason for everyone using 512k etc. is historical, apart from anything else the original Cisco cable modem system examples use the same speeds and terminology as most cable providers subsequently adopted.

06-05-2004, 23:03	#379
BBKing R.I.P. Join Date: Jun 2003 Location: London Services: 20Mb VM CM, Virgin TV Posts: 5,983	Re: [Merged] NTL Increasing BB Speeds Oo pem... Lecture on the difference between data storage and data transmission. Storage is always measured in bytes (=8 bits). Multiple bytes are measure up in exact powers of two (kByte is 1024 for instance). Transmission is always always always measured in bits. Just because IE reports your transfer speed in bytes doesn't mean you should listen to it, it's measuring transfer of a file, rather than a transmission of data. Network professionals measure everything in bits, and a kilo is a kilo, as in 1000, as in a kilometer. Properly, in other words :P Thus when TW set the downstream parameter in their new CM file to 768000 bits per second, 768000 bits per second is what you'll get. Or 768 kilobits per second in other words. Transmission speeds don't have to be exact powers of two to work properly, hence why ntl can base their speeds on multiples of 150k. All of which does lead to the rather odd statistic that TW 512k users are getting a 50% free speed upgrade while ntl 600k users are only getting 25% free. The probable reason for everyone using 512k etc. is historical, apart from anything else the original Cisco cable modem system examples use the same speeds and terminology as most cable providers subsequently adopted.