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Broadband: Installation

Some of the important things to do after you've installed a high-speed connection to the Internet - no matter what type of high-speed service - is to install a firewall, and adjust your computer's 'Receive Window' size. In many cases, this adjustment will result in faster speeds - and it's unlikely that your broadband provider will do this for you, or even tell you about it. The adjustment will make changes to your registry - it is a good idea to first backup your registry.

I also suggest first doing some Speedtests to get an idea of your throughput before any changes.
I like to do Speedtests and monitor real-time throughput with a tool like MyVitalAgent.

There are several ways to check and change the Receive Window (RWIN):

DSL Reports - Tweak Tester: Requires Java-browser; will test and recommend tweaks. Suggested registry tweaks
Navas Cable/DSL
: Provides .reg files and entry details you can use with Regedit.

Some of these sites may recommend changes beyond the Receive Window - I recommend making one change at a time, and checking your speed & throughput after each change. Note: You have to re-boot your system after you make a change to your registry in order for the change to take effect.

WHY DO THIS? The default settings in Windows networking may be fine for a local area network, but are inadequate for high-speed Internet connections. The servers you access require an acknowledgement (ACKs)for all packets sent to you, and once your receive window fills, no additional data is sent until the server receives ACKs for these packets. The latency between you and the server can causes a delay is receipt of data from the server, and it's receipt of your ACKs. The default Windows settings are good for dial-up connections, or high-speed networks with low latency (20ms or less).

The "ideal" RWIN will constantly change: the latency to each particular server you access may vary; it will also vary to the same sites at different instants in time. To calculate "ideal" RWIN:

Latency in ms * 1.5 * Line Speed in kbps / 8

"Line Speed" = your downstream DSL line speed, or for cable, the maximum downstream modem speed (often capped at 2mbps).

Since you need to enter a fixed RWIN value, you should use the highest average latency you get to distant servers. I recommend using PingPlotter to check latency.

For example: If your average high latency is 200ms, and your line speed is 2mbs:

RWIN = 200 * 1.5 * 2,000 / 8
RWIN = 75000


A firewall will help protect you from the hackers that can and will try to 'break into' your system.

There are various firewalls available, but one of the best is free for personal use - ZoneLabs' ZoneAlarm. While a firewall isn't a bad idea with even a dial-up internet connection, the 'always on' nature of your broadband connection, combined with either a fixed-IP or seldom-changing IP address makes your broadband connection more inviting to hacker attacks.

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