[Cake] overhead and mpu

Dennis Fedtke dennisfedtke at gmail.com
Mon Sep 4 22:46:09 EDT 2017


what values should be used for an Ethernet connection running over 
docsis modem?

I think cake automatically accounts for the Ethernet header.
But how large is the ethernet header? Some sites say 1514 some other 
sites say 1518.
So we have the mac header (14bytes) + the crc checksum (4 bytes) + max 
payload 1500bytes = 1518 bytes?

I looked at the code and there is hard_header_len used.

After some quick googling i found this info:
The value ofhard_header_lenis14(ETH_HLEN) for Ethernet interfaces.

Which "packets size(1500 or 1514 or 1518)" does cake really see and work 
with when running on an Ethernet interface?
Minimum Ethernet payload size is 46 bytes. So should i use mpu 46, mpu 
60 or mpu 64 setting for an Ethernet interface?


More information about the Cake mailing list