PPP runs bad

["A.J. Werkman" <werkman digifarma nl>]

I have two rh7.0 boxes connected over a serial PPP line.

When I ping from one to the other I see a packet loss of about 15-20%.
The packet loss is very consistent in the sense that more or less exact 
every thenth and eleventh packet is lost.

The boxes run over a leased line. But the packets are also lost when I do a 
direct modem-modem connection and even whith a direct serial cable 
connecting the two.

I have already changed mtu's and mru's but this does not make any difference.

The fact that the packet loss is so regular seems to me a clue for the 
sollution of this problem, but I don't know where to look for it.

Can anyone direct me to where I could find the cause of this problem.

For your info here is the startup script for the ppp-deamon.
---------------------------
#!/bin/sh
/usr/sbin/pppd \
	/dev/ttyS2 115200 crtscts noipdefault \
	mtu 1500 noauth persist holdoff 5 \
	passive debug \
	172.17.21.125:192.168.71.1
----------------------------------------------
The thing that looks odd to me (but I can't place it into perspective) in 
the log file is this:
----------------------------------------------
Mar 29 19:08:30 agw pppd[7083]: rcvd [Compressed data] 00 0f 82 18 5a 0f 36 
f4 ...
Mar 29 19:08:30 agw pppd[7083]: sent [CCP ResetReq id=0x25]
Mar 29 19:08:30 agw pppd[7083]: rcvd [CCP ResetAck id=0x25]
Mar 29 19:08:41 agw pppd[7083]: rcvd [Compressed data] 00 0a 82 18 da 05 36 
f4 ...
Mar 29 19:08:41 agw pppd[7083]: sent [CCP ResetReq id=0x26]
Mar 29 19:08:41 agw pppd[7083]: rcvd [CCP ResetAck id=0x26]
Mar 29 19:08:51 agw pppd[7083]: rcvd [Compressed data] 00 09 82 18 3a 05 6c 
e8 ...
Mar 29 19:08:51 agw pppd[7083]: sent [CCP ResetReq id=0x27]
Mar 29 19:08:51 agw pppd[7083]: rcvd [CCP ResetAck id=0x27]
Mar 29 19:08:57 agw pppd[7083]: rcvd [Compressed data] 00 05 82 18 3a 0b 6c 
e8 ...
Mar 29 19:08:57 agw pppd[7083]: sent [CCP ResetReq id=0x28]
Mar 29 19:08:57 agw pppd[7083]: rcvd [CCP ResetAck id=0x28]
Mar 29 19:09:03 agw pppd[7083]: rcvd [Compressed data] 00 05 82 18 ba 00 6c 
e8 ...
Mar 29 19:09:03 agw pppd[7083]: sent [CCP ResetReq id=0x29]
Mar 29 19:09:03 agw pppd[7083]: rcvd [CCP ResetAck id=0x29]


Thanks for any help.

Koos.