Gigabit Network Problems

Associate
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Hey all,

I am having some slight issues with my network. This is how it is currently setup; I have my Desktop and HTPC connected to a gigabit switch in the same room. The gigabit switch is then connected via powerline to the router which is connected at 100Mbps.

I can access the internet fine through all the connected devices. However, when I start transferring files between the Desktop and HTPC (Big files 20GB+), I only get transfer speeds of around 2MB/s. I assumed that with a gigabit switch, it should be faster. I then did some troubleshooting starting with removing the powerline connection from the switch. I then transferred the same file and I achieved speeds of over 50MB/s which is great.

Why should the powerline/router be restricting the speed when it is essentially on its own network?

and

What can I do about it apart from removing the powerline/router cable just to transfer some files?

Cheers all :)
 
Soldato
Joined
20 Oct 2008
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The speed reduction makes no sense. As you say, local traffic shouldn't be going anyway near the Powerline connection.

I'd suspect that there's faulty kit involved.

Start a large transfer and after a while unplug the router end Powerline adapter from the mains.

Does the speed increase?

If not wait for the switch end Powerline adapter to go to sleep.

Does the speed increase?

Do you have a different switch you could try (10/100 would do)?
 
Associate
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This could also be symptomatic of a dupex missmatch.

Test and verify all your cables.

Check your devices are actually reporting a 1Gbps link speed, tell tale sign of a duplex mismatch is one of the devices reporting half duplex, almost all devices support 100mbit full duplex through auto negotiation, gigabit only operates in full duplex.

Even at 100/full you should see transfer of 10MB/s easily.
 
Associate
OP
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Right guys. Thanks for the recommendations. I have tried copying a file and then disconnecting the powerline connection and the speed increased almost straight away. I don't have any other switch to try.

I changed both computers link speeds to full duplex 1Gbps. It is very strange. It is almost as if the powerline connection is slowing the network down.
 
Soldato
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It sounds like the powerline connection linking the two machines in question to the router is being used when it is live and plugged in, rather than the two machines transfer locally to each other via the gigabit switch. i.e. Even with the gigabit switch they go down the link to the router and then get routed out again via the router. So the router is just doing its job. Have you tried turning DHCP off on the router and setting manual static IP addresses on the two machines and then rerunning the transfer even with the powerline still live. Perhaps that will force them to route locally straight via the switch?
 
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OP
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I removed the DHCP option from the router and rebooted everything and gave everything its own static address, connected everything up and tried and it is still very slow. If you need to know, the switch is a TP-Link 5 Port Gigabit Desktop Switch (TL-SG1005D).
 
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Soldato
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10 Jul 2008
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7,684
What router is it in the setup? Is it possible you have some arp cache problem here and the router sees the MACs of the machines and tries tot ake over the routing and/or broadcasts stuff on the network causing issues?
 
Associate
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South London
Right guys. Thanks for the recommendations. I have tried copying a file and then disconnecting the powerline connection and the speed increased almost straight away. I don't have any other switch to try.

I changed both computers link speeds to full duplex 1Gbps. It is very strange. It is almost as if the powerline connection is slowing the network down.

Connecting a device on a completely different port on a switch will not affect throughput between two ports on a switch. That is the very definition of what a switch does. Is this definately a swich and not a hub. A hub WILL slow down to the speed of the slowest connected device.
 
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