I had the weirdest of a problem. Two computers communicating with each other over ping and TFTP works. When I boot one of them into U-boot (a bootloader that supports TFTP boot) it can’t ping not load tftp of the other machine complaining on ARP timeouts.
I swapped with a dumb switch - all works. Everything else (machines, cables) are the same. The managed switch is a Cisco switch and I have a serial console to it, but I’m not familiar with managing those switches - what feature is potentially blocking u-boot’s arp packets?
I’ve double checked with tcpdump - the other machine never seer u-boot’s arp packets, but does when the same board is booted into Linux.
I’ve also checked Cisco’s monitor event-trace arp continuous and it didn’t print any packets but it did say link status went from up to down to back up when I rebooted.
Is there some sort of Mac filter on Cisco switches?
I think lemmy is messing up. I replied a week ago.
But we did figure it out. Fastport was disabled and uboot resets the electrical lines which caused the managed switch to rebuild its tree which was still happening by the time uboot started sending arp requests
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