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  1. #1

    pppd won't re-establish link after one client reboots

    I have a major problem with a system i have. Mind you, I can't discuss it in detail as it's a military application. I need to know if any of you have some ppp experience/expertise!

    This is what I have: (This may not be the clearest diagram )

    Client A-> usb-to-rs422 -> wireless analog radio --->

    Client B-> usb-to-rs422 -> wireless analog radio --->

    Client C->usb-to-rs422 -> wireless analog radio --->

    <----> wireless analog radio -> rs422-to-usb -> Server

    We use a pppd process to connect between the systems. The server runs through a loop to setup ip addresses on the clients.

    Server command: (this is surrounded by a for loop which basically sets $ip_add to 1,2, or 3 and $i to 0,1,2)

    usr/sbin/pppd -detach lock maxfail 0 persist unit $ppp_unit 192.168.$ip_add.101:192.168.$ip_add.100 /dev/ttyUSB$i 19200 &

    client command:

    /usr/sbin/pppd -detach lock maxfail 0 persist defaultroute unit 0 /dev/ttyUSB2 19200 &

    OS = Fedora Core 5
    pppd version 2.4.3

    Here's the problem: Upon initially setting up the 3 clients and server, everything is fine. Client A gets, B gets, C gets as it should. However, if, say, client B gets rebooted, it won't reconnect. Or, if the server gets rebooted, NOTHING works.

    Now, i think I've found an issue, but I'm not sure how to resolve it... IF we bring everything down, boot up the server first, then boot up A, then B, and finally C, they all work. It's a nice workaround, but considering A, B, and C are all a 20 minute drive from each other, it's not very good.

    So it's obviously an issue of the server not re-establishing the ppp link. I don't know enough about ppp to get it working fast enough.

    now, one other thing i've noticed is the "-detach" option. Looking at the man pages for pppd, they have a nodetach and updetach option, but no "-detach" option. I don't get any complaints from running pppd with -detach, but I'm not sure it's supported anymore. This command was originally run on Fedora Core 3 with a currently unknown version of pppd.

    Sooooo.... does anyone have an idea as to why the server won't re-establish a ppp link? Oh, and background: There was an existing, working, setup here which was replaced with new client/server hardware, OS, and software, but basically the same stuff. The old stuff "works" as it should, i.e. can take down any piece of the system and it will re-establish connection without having to be reconnected in any specific order.

    any help will be greatly appreciated and your names will be put into the comments line as a special development supporter by the military unless you don't want the recognition.


  2. #2

    I'm still having this issue.

    I've finally been able to consistently duplicate this issue.

    What I've seen, is that if one of the clients goes down the server side doesn't seem to care and thinks it's still connected. The client can't get it's IP addy reestablished, and thus fails to connect.

    I have tried a number of options and am about to try reverting back to an older version of pppd that I knew for fact was working on different hardware...

    Any thoughts or suggestions would be greatly appreciated!

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