I am testing WS-C3750G-24TS-S with 12.2.35.SE2 in the lab and I can see the switch is dropping small percentage of packets.
I have done a sniffer capture and the input interface is rececing the packets but the output interfaces is dropping a small number of packets in transit (multicast traffic). Both interfaces are running 1000Full copper.
1. I see no drops/discards on the physical interface.
2. I can see buffer drops/missed - see output bellow.
3. CPU and DRAM utilisation is normal
4. The physical interfaces is under utilised.
5. All routing conditions are stable and no issues.
6. I am hacing the same issue on another switch same model/IOS.
Is this a software bug?
Is there a way of increasing the RXQ buffers? I am unable to find the command. I can change the small/mid/large buffers but not the pools.
Re: 3750-24-TS loosing Multicast packets on buffer
Here is the action plan to solve this issue.
1. Show platform port-asic stats drop port asic will give the drops, if any on the egress for a specific port. For newer codes, you can try 'show platform port-asic stats drop , instead of giving port and asic numbers. Check in this output if you see the egress drop counters incrementing.
If you see drops on egress, it indicates oversubscription. Tuning of buffers is only possible when QoS is enabled
2. To check CPU drops, the command is:
Show controller cpu-interface.
This will give you the number of packets hitting each of the 16 queues in the CPU and if any packets were dropped from any of the queues and if the drops are increasing.
3. And Also check you are hitting bug CSCsd84624 3750 drop Fragment multicast packet drop when (S,G) entry is expired.
4. To reduce fragment multicast packets from server and try.
5. To change threshold values on qos configuration in 3750
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