Gigabit capable network tops out at 11 MB/s

[Mr.Humble]

Hi,

 

I needed to copy files from a Bitlocker secured external SSD to a Windows Server 2012 computer, but I couldn't get the drive to open. I plugged it into another PC on the network that runs Windows 10 and wanted to copy it over the network (the server is mapped as a network drive)

 

The connection was only 11 MB/s.

 

Considering we're talking about some 80GB of backups I was not willing to settle with that. I noticed that the PC and server are plugged into a 100Mb router, so I plugged them to a dumb 1Gb switch that's already a part of the network setup. Both PCs and the switch recognized the connection to be Gigabit so I tried again

 

10,4MB/s.

 

I tried rebooting both machines, using different cables, all with the same results. Another PC on the network also transfers at max. 100Mb speeds so I am led to believe it's a configuration issue.

 

However due to it being a work environment I cannot simply run netcfg -d because it's a small business environment and I am not familiar enough with some of the programs to alter settings they depend on.

 

Both server and the first PC are SSD based so there shouldn't be any bottleneck there.

 

Where and how can I troubleshoot this issue?

[Tadrith]

Network transfers are limited by the slowest link in the chain.  Your devices cannot connect with each other directly over the switch.  They are going device -> switch -> router -> switch -> device.  The router is still the bottleneck in your situation.

[Lurick]

4 minutes ago, Tadrith said:

Network transfers are limited by the slowest link in the chain.  Your devices cannot connect with each other directly over the switch.  They are going device -> switch -> router -> switch -> device.  The router is still the bottleneck in your situation.

No, that's not how a switch works, provided the devices are on the same subnet.

A switch most definitely can switch packets between host ports without going to the router.

 

@Mr.Humble Are the devices on the same subnet?

[Mr.Humble]

12 minutes ago, Lurick said:

No, that's not how a switch works, provided the devices are on the same subnet.

A switch most definitely can switch packets between host ports without going to the router.

 

@Mr.Humble Are the devices on the same subnet?

They are as far as I know. It's not a complex network:

 

• ISP-provided modem/router (100Mbps) (we've had some issues with my ASUS VDSL modem, but I still have it around somewhere and it was Gigabit)
  • -> gigabit dumb switch
    • -> server with static IP (gigabit)
      • <- backup LTE modem
    • -> office NUC (gigabit)
    • -> PC (gigabit)
  • -> 100 Mbps devices (printer, card terminal)

Honestly I don't think that the router is even capable of setting up multiple subnets lol. And the server is mapped as a network drive in all other PCs - it was my understanding that this needs a single subnet to work)

 

I can troubleshoot later in the week by disconnecting the router or even linking the server and the NUC directly, but that seems excessive.

 

I also went do Device Manager on all PCs to make sure that Automatic Negotiation is set up for speed on all NICs, which is the case.

[Lurick]

1 minute ago, Mr.Humble said:

-snip-

Yah, that's definitely a pretty simple topology. If you really wanted to rule out the switch, which I definitely don't see being the issue, then you could try to connect the NUC and PC back to back and run a test with iperf or a file copy test and see. The devices negotiate to gigabit but something seems amiss here =/ You could also just load iperf on the server and a client or two clients and check to make sure but if you're seeing a cap with large file transfers of 100Mbps then I'm not sure. Do you happen to have the model of the switch handy by chance? I'm wondering if perhaps it's old enough that something funky is happening like it's doing all the switching via the CPU or something stupid.

 

As a side note, you definitely can put the PC in another subnet and have it work with a server (it's how I have some machines setup right now) but if that's the case then everything has to go through the router but if it's just a commodity ISP modem/router then I doubt it's got a concept of VLANs or multiple subnets then the server wouldn't be accessible if it were on another subnet.

[Mr.Humble]

On 8/25/2019 at 11:54 PM, Lurick said:

Yah, that's definitely a pretty simple topology. If you really wanted to rule out the switch, which I definitely don't see being the issue, then you could try to connect the NUC and PC back to back and run a test with iperf or a file copy test and see. The devices negotiate to gigabit but something seems amiss here =/ You could also just load iperf on the server and a client or two clients and check to make sure but if you're seeing a cap with large file transfers of 100Mbps then I'm not sure. Do you happen to have the model of the switch handy by chance? I'm wondering if perhaps it's old enough that something funky is happening like it's doing all the switching via the CPU or something stupid.

 

As a side note, you definitely can put the PC in another subnet and have it work with a server (it's how I have some machines setup right now) but if that's the case then everything has to go through the router but if it's just a commodity ISP modem/router then I doubt it's got a concept of VLANs or multiple subnets then the server wouldn't be accessible if it were on another subnet.

well, turns out it was most likely some sort of BTS fuckery, as now the transfer between the NUC and the server works at 1Gbit, but the other PC only does 100Mbit. Tested the transfer with my own laptop and it worked at 1Gbit to server and NUC, which is what I need the most.

 

The router, however, is apparently dying, as it spontaneously factory reset itself 5 times in the last 2 days, so I was more focused on getting internet to work at all  It has been replaced with an ASUS DSL-AC55U