Re: Strange result while ping serial interface

[Valdis.Kletnieks () vt edu]

> to the remote side of the serial interrface ! When I trace to my local
> serial interface, I got the first hop to the remote end, then second
> hop back to my local interface ! 

IBM AIX 4.3.3 on an RS/6000 does the same thing.  I'm told it has to
do with the inability of some PPP stacks to recognize a chance to
short-circuit packets for its own address - If it comes down from
the stack, it's going out the serial interface, and isn't checked if
the IP address is our own and should just hand it back up the stack
as a "received" packet..  I'm sure the protocol police will write
me a citation if I botched this. ;)

The annoying part is when some program binds to the interface, and
you watch all the packet traffic take a loop out and back.  It's
*amazing* how slow an X11 program can be if it's invoked as
'xfoo -display myhostname:0', if it loops all the X traffic over
the 14.4 modem - twice ;)

The "fix" that I used was '/etc/route add ip.of.interface 127.0.0.1'.
Ugly, but it worked.  Just remember that you did it if you start
adding packet filters (as packets to yourself will be on the loopback
interface, with non 127.0.0.1 addresses)....

                                Valdis Kletnieks
                                Operating Systems Analyst
                                Virginia Tech