uplink speed to a gigabit switch too very slow

I have a netgear cable modem router with a 4 port switch (FR114P) and a
netgear 8 port 10/100/1000 Mbps switch (GS608). When I hook a computer
up to the router my download speed over the internet is about 10% or 15%
slower than if I hook the machine directly to the cable modem. This is
no surprise, and I find it acceptable. However, when I uplink the
router to the 8 port gigabit switch, my download speed drops in half
(half of the already 10% to 15% reduction). The reason I want the
uplink from the router to the gigabit switch is of course so I can
transfer stuff around the local network faster. Right now 3 of the 4
machines on my network have linksys gigabit NICs in them, the 4th has a
100 Mbps card. Transfers between 2 machines on the gigabit switch are
very fast and transfers between 2 machines on the router are also very
fast, just not as fast as the gigabit switch. There are no
configuration options on the gigabit switch. Also I have confirmed the
uplink switch on the router is set properly. Any ideas on what I can do
to fix this?

--
Chris W

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Chris W <(E-Mail Removed)> wrote in message news:<3pRSc.64829$cv5.22522@lakeread07>...
> I have a netgear cable modem router with a 4 port switch (FR114P) and a
> netgear 8 port 10/100/1000 Mbps switch (GS608). When I hook a computer
> up to the router my download speed over the internet is about 10% or 15%
> slower than if I hook the machine directly to the cable modem. This is
> no surprise, and I find it acceptable. However, when I uplink the
> router to the 8 port gigabit switch, my download speed drops in half
> (half of the already 10% to 15% reduction). The reason I want the
> uplink from the router to the gigabit switch is of course so I can
> transfer stuff around the local network faster. Right now 3 of the 4
> machines on my network have linksys gigabit NICs in them, the 4th has a
> 100 Mbps card. Transfers between 2 machines on the gigabit switch are
> very fast and transfers between 2 machines on the router are also very
> fast, just not as fast as the gigabit switch. There are no
> configuration options on the gigabit switch. Also I have confirmed the
> uplink switch on the router is set properly. Any ideas on what I can do
> to fix this?

Nice description but no command output, no data, no numbers ;-(

The CM modem/switch is 10/100 Mbps as many of them are -- some are
10Mbps only but never seen one at 1000Mbps. Should be a clue there
....

Using mii-tool or ethtool or something similar, you need to confirm
that the interfaces are properly auto-negotiating the link speed -- it
is fairly common for this feature to fail and require manually setting
link speeds. You may have to dig around to find a tool to manipulate
the link speed on the CM or switch (if there is one).

Also check the output of ifconfig for indications of errors.

My initial attempt would be to set everything to 100 Mbps (manually if
need be) and see what I get. Try using different ports on the CM and
switch. Check all cables.

Chances are that neither the CM nor the switch has enough memory to
handle the buffering needed to handle 1000Mbps into a 10 Mbps CM port.
Sounds like the nics directly connected to CM behave OK, but when the
1000Mbps switch is placed between them, the CM and the switch uplink
port are not synching properly, maybe even dropping to half-duplex.

To my mind, the CM/uplink should set to 100Mbps -- perhaps not if you
are capped at the "usual" rates of today. They may be setting at
10Mbps. In any case, the LAN side of the switch may have to be set to
match the CM/uplink speed -- maybe even 10 Mbps :-(

You can tell there is a large amount of guessing here -- not familiar
with the specific use of any of your gear, just the spec sheets I
found. Try to find a diagnostic/config page for the CM and/or switch
-- looking for clues. If the neither the CM nor switch can manually
set the link speed, you may have to try setting the nics' manually to
100 Mbps (or even 10 Mbps) and see if you get consistent/acceptable
results that way.

A sniffer, like ethereal, can help see what's happening on the wire,
so you might compare what you see with nics directly connected to CM
and through the switch and at different link speeds. You may find a
clue to help tweak the nic configuration or TCP settings.

That's about all I can offer at this stage without some hard numbers
and command output to go by. Just can't help thinking that the CM and
switch are not negotiating link speed properly -- or at least not as
well as they should :-(

hth,
prg
email above disabled