Cable Forum - Rumour from The Bloke in the Pub

Quote:

Originally Posted by ian@huth

I would take a guess that your range of possible upload speeds is far too optimistic. ;)

If the cap remains a soft cap the upload speeds defenitly wont be that high but if NTL have everything in check stopping people raping it on p2p its quite possible. I would think tho 384kbit would be the lowest needed to allow good performance.
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Quote:

Originally Posted by altis

Erm...

The maximum payload of a TCP/IP packet is around 1500 bytes. I'm not sure of the exact size of an ACK packet (including headers) but let's make it easy and say 15 bytes. That's a 100:1 ratio.

Then note that, if implemented efficiently, each ACK packet can acknowledge more than one data packet. The number it can simultaneously acknowledge is limited by the size of the 'window' - which is, in turn, limited by the buffer space inside the receiver.

Some peeps report that their upload speed limits their download capability. What is usually happening is that they are uploading loads AT THE SAME TIME. When this happens, the ACK packets are held up by the outgoing data packets.

IMHO for normal surfing, 100kbps upload will be entirely adequate for 10Mbps download.

Downloading at 2mbit uses up about 5kB/sec for me so approx 25kB/sec imo is needed, bearing in mind I optimised my connection I think normally it requires more acks so I will say 30-35kB is needed for someone who doesnt need to upload at the same time on stock tcp window settings. Or have I got this wrong and you dont multiply upload the same ratio as download?