Puppy Linux Discussion Forum

[GuestToo]

synchronous pppoe module

this installs the kernel module n_hdlc.o.gz
which allows you to use the synchronous PPP option
when you connect to the internet using Roaring Penguin (adsl)

modules
source

[bombayrockers]

Can you Kindly explain what is synchronous pppoe and its advantages ?

[GuestToo]

http://linux.com.hk/penguin/man/8/pppoe.html
"You are encouraged to use this option if it works, because it greatly reduces the CPU overhead of pppoe. However, it MAY be unreliable on slow machines -- there is a race condition between pppd writing data and pppoe reading it. For this reason, the default setting is asynchronous. If you encounter bugs or crashes with Synchronous PPP, turn it off"

/etc/ppp/pppoe.conf
"Do you want to use synchronous PPP? "yes" or "no". "yes" is much
# easier on CPU usage, but may not work for you. It is safer to use
# "no", but you may want to experiment with "yes". "yes" is generally
# safe on Linux machines with the n_hdlc line discipline; unsafe on others."

http://tinyurl.com/ddeud
"You can immediately see two gross inefficiencies: User-space code is executed for every PPPoE frame, and byte-stuffing and de-stuffing is done twice. For outgoing frames, the kernel carefully performs byte stuffing, which is undone by pppoe. For incoming frames, pppoe stuffs them and the kernel de-stuffs them."

basically, asynchronous PPP is safer, but uses more cpu time

synchronous PPP is less work for the cpu, but might cause problems on a slow machine

you probably wouldn't notice much difference for internet connections ... if you use pppoe on a LAN at higher speeds than an internet connection, you might notice a big difference

the main reason i made this package is because a few people were having trouble connecting to adsl with Roaring Penguin, and i thought that being able to try the synchronous PPP option might help ... i seem to remember reading somewhere that some hardware will only work with synchronous PPP

anyway, it seems to work ... i have synchronous PPP enabled right now

[BarryK]

G2, thanks for that info.
The next test release of Puppy2 will have n_hdlc.o module.