What is the task TNetTask resonsible for?

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Ive found some articles online, nothing of substance however. Only descriptions offered are very vauge like responsible for "switch ethernet traffic".  And as a follow up, why would that task suddenly jump on devices from <5% to > 90% then locking up a switch.
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Jimmy Sands

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Posted 2 years ago

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Brad Parker, Technical Support Engineer

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in ExtremeWare, if the tNetTask is spiked up, that means that there is a lot of traffic going to the CPU of the switch. Look for loops in the network.
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Jimmy Sands

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Did, no loops. We even disabled all ports on LAN rtr (the device being bad here) except for the WAN uplink, still did it.....I think, we tried so many things.  I know we swapped the device out entirely, same issue. I cant for certain say disabled all ports, a co-worker took over some of the troubleshooting at times.  Here an even better one 

tNetTask is the central clearing house for all network I/O. A packet
comes in, netJobAdd'ed, and tNetTask does everything for the packet for its lifetime.  This is done for all packets, all network interfaces, and the entire TCP/IP stack.

Packet captures are showing nothing of substance.
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Erik Auerswald, Embassador

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Hi Jimmy,

did you take packet captures on the WAN uplink port and look for potentially problematic traffic? E.g. IP packets with IP options set, or a TTL of 1, or UDP data sent to an IP without ARP entry? Anything that would be forwarded in software?

Switches are not designed for software forwarding, thus "normal" amounts of traffic needing software forwarding might be sufficient to overload the CPU.

Erik
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Jason Parker, Employee

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Run the command "top" a few times and check the highest processes