Significant Reduction in DSL Throughput

mybrainat3am

Distinguished
Feb 21, 2009
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18,510
Hi folks!

This community has been incredible for research into my IP issues. Thank you!

TLDR:

Verizon ADSL (PPPoE) 10mbit service. Original (11 year-old) Westel 327W started getting flaky at around 9 years of use. Replaced with newer 7500 that a friend gave me. Two years later, the 7500 became just as flaky as the 327W.

Purchased a DM200 to pair with an already owned (but brand new, in box) WGR614v6. Successfully installed the DM200 in bridge (modem only) mode and paired with the WGR614v6. Flakiness fixed but throughput is way off. Both Westells were averaging 11mbit throughput (1.3 MB/s). The new Netgear combo is operating in the 5-6mbit range (700ish KB/s). Pings seem to remain unchanged. The Netgear units are running their latest firmware.

Are there any optimizations that can be done to actually attain the 10mbit service that I'm paying (far too much) for? All the "optimization guides" I've found online address TCP/IP in each computer connected to the network. I can't find any insight to the network hardware itself.


Thanks!
 

kanewolf

Titan
Moderator
With DSL you may have to shink the MTU on the WAN port of the router. Standard ping won't change because ping packets are small. But data transfer could be impacted. You should ping 8.8.8.8 with different sized packets "-l" from 1440 to 1500 using the no-fragment "-f" option on ping. When the MTU is too large, you will get an error. Reduce the size of the packet until you are at maximum with no errors. Then check the settings in your router to verify that the MTU is set correctly on the WAN.
 

mybrainat3am

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Feb 21, 2009
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18,510
Thanks, kanewolf. My normal procedure for optimizing MTU size is to ping (ping 8.8.8.8 -f -l xxxx) google or yahoo, starting at 1492 and reducing until I get no loss in packets. I then add 28 (IP/ICMP header size) and plug the result into the router's MTU setting in WAN configuration. Is this not correct? For this setup, I came up with 1492, which was the default setting in the router. I'll play a bit with MTU settings and see how it effects measured throughput.

Thanks again!