Phylop
Premium
join:2002-11-17
Reston, VA
|  Upstream channel bonding!
I've been hearing about this delayed upstream channel bonding for quite a while now, I guess it's good to at least get the downstream speeds up, but what "power users" really want is much faster upstream speeds, especially if Cable is going to compete with Verizon FiOS, currently offering 20mbit/s upstream speeds in some tiers.
Otherwise, more technically, how can they manage that downstream speed of something around 100mbit/s with an upstream of merely 2mbit/s? I thought because of the "token bucket" QoS system that most cable companies used the downstream was somewhat dependent on the upstream. Can someone clarify this for me? |
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TKJunkMail
Enjoy the sun
Premium
join:2002-03-03
Avalon, NJ
 ·Sprint Mobile Broa..
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| said by Phylop  :Otherwise, more technically, how can they manage that downstream speed of something around 100mbit/s with an upstream of merely 2mbit/s? I thought because of the "token bucket" QoS system that most cable companies used the downstream was somewhat dependent on the upstream. Can someone clarify this for me? You are right expecting an upload limit having an effect on how fast you can download. But 2 mbps upload(if no other traffic using the upload like a P2P app) would allow an FTP download for example to reach the full download capacity.
But most users would be running multiple connections and apps utilizing upload bandwidth that could ultimately make downloads not be able to use the full download capacity.
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RARPSL
join:1999-12-08
Suffern, NY
| said by TKJunkMail :You are right expecting an upload limit having an effect on how fast you can download. But 2 mbps upload(if no other traffic using the upload like a P2P app) would allow an FTP download for example to reach the full download capacity. TCP/IP is a 2-way communications protocol. To be able to download, you have to upload acknowledgements of the successful receipt of the downloaded packets. There are ways to reduce the need for the upload bandwidth load but even that has a limit (at least until IPv6 is used which allows larger [AKA Jumbo] packets and larger/sliding transmit windows). Each 1500 packet with download data needs a upload packet to say that the downloaded packet has arrived. That uploaded packet controls how fast you can download since you will not be eligible for more downloaded data until you acknowledge the receipt of the "in flight"/prior packets. The ACK packets tend up be small and the major part is the Headers/Overhead not the actual payload content. Thus if you saturate your upload session with the small ACK packets, you can not download any faster. There is also the case where YOU are doing the uploading (such as SENDING not RECEIVING Email) where you are being lock-stepped by maxing out the upload channel. |
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DaveNJ
No Fear
join:1999-09-01
New Jersey | reply to Phylop
I totally agree upstream is becoming more important. Without equal or, close to equal upstream. Any machine doing any activity will lock up, and get timeouts. What good is 20M if you have 2M upload. It prevents the usage. |
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