eth_type_trans(9) centos man page | unix.com

ETH_TYPE_TRANS(9)					      Network device support						 ETH_TYPE_TRANS(9)

NAME
       eth_type_trans - determine the packet's protocol ID.

SYNOPSIS
       __be16 eth_type_trans(struct sk_buff * skb, struct net_device * dev);

ARGUMENTS
       skb
	   received socket data

       dev
	   receiving network device

DESCRIPTION
       The rule here is that we assume 802.3 if the type field is short enough to be a length. This is normal practice and works for any 'now in
       use' protocol.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							 ETH_TYPE_TRANS(9)