Strange Performance Issue on X450-G2

[CFaber]

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?

[CThompsonEXOS]

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

Thanks,

Chris Thompson

[rbrt]

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

[CFaber]

Hi,

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

Thanks,

Christoph

[CThompsonEXOS]

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