[PLUG] Very Slow Downloads

Russell Senior russell at personaltelco.net
Tue Oct 25 22:42:09 UTC 2011


>>>>> "Matt" == Matt McKenzie <lnxknight at gmail.com> writes:

Matt> That is logical and could be accurate.  I do not have first hand
Matt> knowledge of this, I am not a cable subscriber myself.  My boss
Matt> for my secondary job, which is tech support, suggested that
Matt> during an issue where a customer had a similar problem, that the
Matt> router being too old might be causing problems.  The customer
Matt> replaced the router and it worked better- granted that does not
Matt> necessarily mean the DOCSIS incompatibility was the issue, but
Matt> he said it was related.  It could have also been an all-in-one
Matt> cable modem + router type of situation, in which case replacing
Matt> the "router" would also replace the modem, thus upgrading to one
Matt> that supported DOCSIS 3.0.

DOCSIS is all on the cable infrastructure and the cable CPE device.
Beyond that, it's all ethernet. Your router doesn't need to know squat
about DOCSIS.

Matt> But it does tend to fit the data, when plugged in directly to
Matt> cable modem he gets 19MBs, when through the router he gets
Matt> around 9MBs- in any case trying the WRT routers should help
Matt> narrow this down.

Routing requires a little CPU to look at each packet, modify it,
figure out which direction it should go and send it on its merry way.
The slowness probably has more to do with the routers CPU, often a
200MHz or slower MIPS core, than anything else.  

Consumer grade routers like this are often incapable of maintaining
wirespeed.  Manufacturers could get away with this because upstream
bandwidth has been pretty limited, and in the case of wireless, the
wireless layer was much slower than wired speeds.  With 802.11n,
that's becoming less true.  Newer routers have been tending to use
faster CPUs.  You don't notice it so much on your local network
because for local traffic your packets are hitting a relatively fast
switch chip and don't have to ever talk to the underpowered CPU.


-- 
Russell Senior, President
russell at personaltelco.net



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