0

The Dell switch model info:

# show version
Dell EMC Networking OS10 Enterprise
Copyright (c) 1999-2021 by Dell Inc. All Rights Reserved.
OS Version: 10.5.2.3
Build Version: 10.5.2.3.316
Build Time: 2021-02-26T20:03:25+0000
System Type: S5296F-ON
Architecture: x86_64
Up Time: 35 weeks 6 days 13:15:47

Some ports reported relatively high number of discarded packets. For example:

# show interface ethernet 1/1/44
Ethernet 1/1/44 is up, line protocol is up
... ...
Output statistics:
     ... ...
     0 throttles, 3119778 discarded, 0 Collisions,  wred drops
                  ^^^^^^^^^^^^^^^^^

Is there any logs on the switch side which can explain why so many packets are dropped?

SF.express
  • 378
  • 1
  • 16

1 Answers1

1

With an uptime of 36 weeks, 3M dropped packets may not be much - but it all depends on your workloads.

With an estimated average load of just 1 Gbit/s (or 4%), the port has transmitted 1.75 trillion frames. 3 million frames dropped is one out of every half million.

Most packets are dropped when the egress capacity of the port is temporarily exceeded ("burst"). Of course, there's a buffer in the switch but it's tiny compared to the speed - 32 MB are filled within 10 ms at 25 Gbit/s. Likely, the available buffer capacity on that port is much less. Buffers are often shared between port groups (of 8, 16, ...).

Depending on your topology, you can try using Ethernet flow control. However, most often that does more damage than good (drop rates will very likely drop but overall throughput might drop even more).

Zac67
  • 10,320
  • 2
  • 12
  • 32