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- Red Hat Enterprise Linux
I know, I know who still uses pppd regularly, well we do. We do heavy satellite Iridium communications and use RHEL as our ground station server as well as the operating system on our airborne systems.
In version RHEL 5.2 and up to 5.5 pppd and its multilink function works great. When RHEL 6 and up came out pppd and multilink functions do not work great.
When Ubuntu hit version 9.4 and up pppd quit working properly.
I have yet to discover the exact reason, but it appears to be some kind of memory leak or buffer overrun.
In version RHEL 5 we can run pppd connections for hours on end with many disruptions and reconnects (average operations of 6 - 9 hours).
In version RHEL 6+ pppd will work for approximately the first 2 hours then the reconnects become intermittent until it won't allow for reconnects at all (approximately 3 - 4 hours into operations), it will answer the incoming call but refuse connection, no reason given in a log file. After another half hour or so it won't answer the phone at all.
The only way to get the system operational again is to reboot the server.
Using the same hardware, changing the system over to RHEL 5, then it all works just great.
I'm hoping that in version RHEL 7+ pppd will get fixed so it will be as reliable if not more so than in version 5.