Question

Strange Performance Issue on X450-G2

  • 21 October 2020
  • 4 replies
  • 55 views

I have a strange performance Issue on a X450-G2-48p-10GE4, i suggest some kind of interoperability issue, but I’m not sure what causes it. I cannot see any hint of a root cause.

When connecting a (new) computer on some ports, although getting 1000Mbit FD (both sides, Switch and computer), I only get about 60Mbit/s throughput, dropping at least 35% of the packets somewhere. Switch reports about max. 2.5% Port utilization, no tx-/rxerrors, no congestion, good cablediag. Target is on the same switch, being part of a stack.

When using an unmanaged switch between, I get about ~950Mbit, no drops. Some older computers also have no problems connecting.

When using some other ports, we also get nearly the full speed, cables were tested for CAT5E without any issue.

This issue exists on either version tested (15.X - 22.7.2.4). Switch therefore was rebooted several times.

Example iperf3 output:

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks, omitting 0 seconds, 10 second test, tos 0
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 7.09 MBytes 59.5 Mbits/sec 254 29.7 KBytes
[ 5] 1.00-2.00 sec 2.05 MBytes 17.2 Mbits/sec 74 19.8 KBytes
[ 5] 2.00-3.00 sec 954 KBytes 7.82 Mbits/sec 23 7.07 KBytes
[ 5] 3.00-4.00 sec 2.11 MBytes 17.7 Mbits/sec 61 15.6 KBytes
[ 5] 4.00-5.00 sec 2.11 MBytes 17.7 Mbits/sec 63 17.0 KBytes
[ 5] 5.00-6.00 sec 2.05 MBytes 17.2 Mbits/sec 61 65.0 KBytes
[ 5] 6.00-7.00 sec 573 KBytes 4.69 Mbits/sec 64 18.4 KBytes
[ 5] 7.00-8.00 sec 1.49 MBytes 12.5 Mbits/sec 15 91.9 KBytes
[ 5] 8.00-9.00 sec 3.36 MBytes 28.1 Mbits/sec 164 24.0 KBytes
[ 5] 9.00-10.00 sec 2.17 MBytes 18.2 Mbits/sec 50 15.6 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 23.9 MBytes 20.1 Mbits/sec 829 sender
[ 5] 0.00-10.00 sec 23.3 MBytes 19.5 Mbits/sec receiver
CPU Utilization: local/sender 0.2% (0.0%u/0.2%s), remote/receiver 0.1% (0.0%u/0.1%s)

Does anyone has any hint what to check next?


4 replies

Userlevel 3

Hi,

 

Is the switch reporting any pause frames received on the ports in question?


You can use the following command to check:

show ports flow-control rx-pauses

If so, do those numbers increment during a test transfer?

 

Thanks,

Chris Thompson

Hi,

there is neither any pause-frame received on any of the ports nor any congestion.

Thanks,

Christoph

Userlevel 3

Hi Christoph,

I have seen an issue like this a few years ago. Some devices worked just fine at Gigabit speed, others were only barely usable. The solution at that time: Set auto-neg on the switch side to only offer 100 Mbit/s. All of a sudden all devices just worked.

The real issue was bad cabling. Some chipsets could cope with that, others could not. After refreshing the cabling Gigabit worked just fine for all devices.

Hope that helps in some way.

-Robert

Userlevel 3

You can also some cable diags on that as well..

 

Thanks,

Chris Thompson

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