follows BSD/OS practice and ucd-snmp code (FreeBSD does it for specific
interfaces only).
was: if_lastchange get updated on every packet transmission/receipt.
now: if_lastchange get updated when IFF_UP is changed.
based on the existing net/if_spppsubr.c stuff.
While there are completely userland (bpf based) implementations available,
those have a vastly larger per packet overhead thus causing major CPU
overhead and higher latency. On an i386 base router, running a 486DX at 50MHz
my line (768kBit/s downstream) was limited to something (varying) between 10
and 20 kByte/s effective download rate. With this implementation I get full
bandwidth (~85kByte/s).
This is client side only. Arguably the right way to add full PPPoE support
(including server side) would be a variation of the ppp line discipline and
appropriate modifications to pppd. I promise every help I can give to anyone
doing that - but I needed this realy fast. Besids, on low memory NAT boxes
with typically a single PPPoE connection, this implementation is more
lightweight than a pppd based one, which nicely fits my needs.
