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I have a fiber optic network of one server connected directly to 4 clients(they are not connected to each other)

The network is suppose to support up to 4x10Gbs, so 10Gbs throughput from each client to the server. Given the server connected directly to 4 clients and the network has the proper hardware and is setup properly, am I suppose to expect a nearly full throughput on almost every throughput test?

I have an issue with software/network and I wish to tell that given a test of my network with 3rd party tool such as iPerf, what throughput am I suppose to see? I am not sure what should I expect from fiber network and how stable it's suppose to be?

Edit: This is the server network adapter: http://www.lr-link.com/products/LREC9804BF-4SFP_.html

user504571
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  • Are the clients directly connected to the server, or through a switch? If so, what is the model of the switch? – Ron Trunk Jan 09 '19 at 19:24
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    You may be limited by server backplane/NIC/disk – Ron Trunk Jan 09 '19 at 19:25
  • What results are you seeing? You obviously cannot get 10 Gb/s to each of the 4x clients simultaneously (because that would be 40 Gb/s to the server). – Attie Jan 09 '19 at 19:36
  • The network adapter for the server suppose to support 40Gbs. Each client is connect via it's own fiber cable and has it's own client/server ips – user504571 Jan 09 '19 at 19:40

1 Answers1

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I have a fiber optic network of one server connected directly to 4 clients(they are not connected to each other)

I'm assuming you're not using a switch.

The network is suppose to support up to 4x10Gbs, so 10Gbs throughput from each client to the server. Given the server connected directly to 4 clients and the network has the proper hardware and is setup properly, am I suppose to expect a nearly full throughput on almost every throughput test?

Yes - provided each node can keep up with the speed and whatever you're transmitting can be provided or stored fast enough. If there's storage access (e.g. file server) the storage needs to be able to supply data at that rate.

Additionally, the node needs to be able to process the data rate from/to the NIC. In extreme, the server's X710 NIC requires 5 GB/s slot bandwidth, so the slot would need to be PCIe 3.0 x8. A PCIe 2.0 x8 or a PCIe 3.0 x4 slot limits the bandwidth to 4 GB/s, PCIe 2.0 x4 to 2 GB/s and so on.

Depending on the processing required, the CPU can also be a bottleneck.

I have an issue with software/network

You're not telling us which issue.

and I wish to tell that given a test of my network with 3rd party tool such as iPerf, what throughput am I suppose to see?

Assuming sufficient bandwidth for the NIC slots, iperf should show very close to 10 Gbit/s throughput for each connection and 40 Gbit/s in total. Effective TCP throughput should be close to 1.18 GB/s per link.

I am not sure what should I expect from fiber network and how stable it's suppose to be?

Fiber or twisted-pair doesn't matter as long as the cable is fine. Ethernet usually aims for a bit error rate to 10^-12 or better, so the frame error rate should be lower than 1 in 800 million. If the error rate is higher there's a problem with the cable (type, length, damage, dirt, ...).

Fiber is sensitive to sharp bends, single-mode even more than multi-mode. Make sure you observe minimum bend radius.

Zac67
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  • Thanks, There is development. I was able to get to nearly 40Gbs with iPerf with 4 clients. But in some tests it would start at 9+Gbs per client then all together get down to 7Gbs. Why does that happen? Is there some sort of throttling somewhere? Should I add this to the quesiton or ask a new one? – user504571 Jan 15 '19 at 17:51
  • @user504571 Your setup may have other bottlenecks than the network links. You can e.g. use *iperf* to run synthetic, network-only tests. However, if you access a file share across the network, the disk subsystem might not be able to keep up with 10G. Or the (web, file, ...) server can't keep up due to CPU/RAM/general processing limitations. – Zac67 Mar 05 '19 at 12:28