What Network Settings for 8Mb Broadband?

Question

What Network Settings for 8Mb Broadband?

Hi,

I recently switched broadband service to 8Mb and I am still in the initial phase where my ISP is determing the maximum stable rate for my line. In order to get the best performance from my connection I was wondering whether I should tweak my network configuration.

My service is PPPoA and I connect my Mac to the Internet via a wireless router (a Netgear DG834G). The router's MTU is set to 1500.

My current network settings are:

net.inet.tcp.sendspace=65536
net.inet.tcp.recvspace=65536
net.inet.udp.recvspace=73728
kern.ipc.maxsockbuf=524288
net.inet.tcp.delayed_ack=0
net.inet.tcp.rfc1323=1

Do I need to alter these values to improve my connection? Do I need to alter any other settings?

Regards,

Stuart

Mac mini (PPC), Mac OS X (10.4.7), Netgear DG834G

Posted on Aug 14, 2006 10:39 AM

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Answer 1

Aug 15, 2006 8:26 AM in response to Stuart Wheeler

I should add that the Round Trip Time for my connection to my ISP is 80ms.

Any help would be greatly appreciated as I've spent the last day or so scratching my head trying to fathom this TCP stuff out yet I seem to be none the wiser.

Stuart

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Answer 2

Aug 15, 2006 6:06 PM in response to Stuart Wheeler

I haven't found that mucking around with those settings makes much difference - have your tried a variety of internet speed tests sites? Internetfrog.com - Speakeasy.net - DSLreports.com - etc?

Also, if you paid for an upgrade - you may have to reboot the modem/router that is connected to that line to make sure it authenticates at the new speed.

Also, if you ahve an older modem/router - you may have to chekc with yrou service provider to see if maybe it needs to be replaced with a neewer model in order to get the speed you are paying for.

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Answer 3

Aug 16, 2006 3:33 AM in response to Matt Wolanski

Hi Matt,

yes, I've been trying various speed test sites and have been getting very variable results.

My router is perfectly acceptable for the service provided (in fact the modem part of it is the same as the one they provide for free if I was a new customer), so I don't need to alter that. I've upgraded the firmware in the router so I know that is fine. The router acknowledges the new 8Mbps speed when I look at the status web page it generates.

I have periodically been rebooting the router (about 2 or 3 times a day) to ensure that my ISP can amend their settings on reconnect if needed. In fact, they claim to drop the line themselves every so often during this initial period to assist in this. They do recommend the occasional reboot during this period.

Since posting my initial question I've been reading up about TCP tuning and I almost understand it. The essential calculations seem to be:

Throughput = buffer size / latency

and

buffer size = RTT * bandwidth

The values that really seem to matter are:

net.inet.tcp.recvspace
net.inet.tcp.sendspace (this is also known as RWIN)
kern.ipc.maxsockbuf (this should be the sum of the recvspace and sendspace values)
MTU size (this is typically 1500 or values just below. My ISP specified 1500 and I have set the MTU in both my router and Mac to this.)

Of course, there are other settings in the TCP stack that can be tweaked, but I wouldn't know where to start with these. It would appear that the default settings in Tiger are pretty good for my situation, but if the machine was on a faster connection or network, then they might need adjusting.

I'm going to mark this question as answered, but if you, or anyone else, has any words of wisdom I'd certainly be interested to hear them.

Regards,

Stuart

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Answer 4

Aug 16, 2006 3:36 AM in response to Stuart Wheeler

Ooops! Made a minor error in that last post.

net.inet.tcp.recvspace is the RWIN, and not net.inet.tcp.sendspace.

Stuart

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