Linux network driver and mtu -


i'm writing network device driver linux. reasons have reduce dynamically mtu network interface while initializing.

when driver calculates , sets mtu example value 892 - kernel trims outgoing frames 310 bytes.

the question is: why outgoing packets 310 bytes long instead of 892 bytes?

edit: (part of code calculating mtu)

bitrate = 250;  // [kbit/s] limit_us = upstream_timeslot = 5000; // [us] mtu = (limit_us - 144) * bitrate * 2 / 15625 - fp->wdev->hard_header_len - sizeof(struct ether_header);

it calculates maximum value of 1 frame fits transmission timeslot slow transmission 250kbps.


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