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Brandon_Cotter
Contributor

Demonstrating pause frames

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Hello!

I am trying to find a mysterious source of packet loss using my R80.10 JHF 225 gateways. The administrator of the access layer is saying their switch is receiving "pause frames" from the firewall and so it's dropping packets it cannot deliver in a timely manner. I am not sure how to evaluate this - from reading, it does not appear that they would necessarily show up in a packet capture. I've also read that those perhaps exclusively originate from an endpoint or a switch. I tried a tcpdump from the gateway and wireshark filter "macc.opcode == pause" - no results.

In the specific scenario I am troubleshooting that I hope is indicative of the larger problem, an attempt to connect to an https server reliably gets SYN-SYN/ACK-ACK-Client Hello ... Client Hello ... RST (from server). We've seen it before with a QoS/CoS issue on our switch hardware.

In searching for similar issues, I found https://community.checkpoint.com/t5/General-Topics/Ifconfig-dropped-explanation/m-p/24447#M4885 but ifconfig does not report any Rx or Tx errors, so our situation does not map well to that scenario.

I'm not getting indications that the gateway is under any meaningful load, though cpview does show 195,627 "Instance High CPU" drops, though on a "Inbound Packets/sec" rate of around 70k.

How can I determine whether the gateway is telling the switch to suspend passing packets?

 

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