They are also used for certain sync channels (at least on isdn they are used).
IMHO the ppp RFC's are not really clean here. They refer to hdlc encapsulation
for the lower layer frame format but also treat the hdlc encapsulation
as part of the ppp protocol proper. The reason is probably the header
compression stuff. With hdlc really separated from the ppp protocol,
header compression negotiation would affect protocols outside the
ppp layer.
> usually compressed out anyway). On balance I thought it was cleaner
> and neater not to have to worry about those 2 bytes in the generic ppp
> code.
If the hdlc header is treated by the sync device and we want to support
header compression, we'll also need to support dynamically changing the
hdlc device's encapsulator.
Henner
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/