[lug] PPP question

[Ralf Mattes]

On Sat, 8 Apr 2000, Eric Weber wrote:

> I recently upgraded by Debian box from 2.0 to 2.1.  After the upgrade I
> noticed that my ppp connection would transmit packets every 30 seconds or
> so, even when I wasn't doing anything.  My ppp log reveals:
> 
> Apr  8 21:20:45 pluto pppd[214]: sent [LCP EchoReq id=0x22
> magic=0x1d0187a4]

Plain old PPP echo request frames.
If you don't send any network packages over the line for a certain
time the ppp daemon will send some echo frames to test whether the
line is still up and running.
> 
> etc.  I'm afraid I don't know what this is.  Is it harmless?  Is there a
> way I could turn off this behavior?  Thanks.

Pretty harmless and very helpfull, especially if your peer dies without
closing the line. AFAIK there are two options for pppd to control echo
behaviour (i usually only work with the ISDN-ppp):

       lcp-echo-interval n
              If this option is given,  pppd  will  send  an  LCP
              echo-request  frame  to  the  peer every n seconds.
              Normally the  peer  should  respond  to  the  echo-
              request  by sending an echo-reply.  This option can
              be used with the lcp-echo-failure option to  detect
              that the peer is no longer connected.

     lcp-echo-failure n
              If this option is given, pppd will presume the peer
              to be dead if n LCP echo-requests are sent  without
              receiving a valid LCP echo-reply.  If this happens,
              pppd will terminate the connection.   Use  of  this
              option  requires a non-zero value for the lcp-echo-
              interval parameter.  This option  can  be  used  to
              enable pppd to terminate after the physical connec­
              tion has been broken (e.g., the modem has hung  up)
              in situations where no hardware modem control lines
              are available.


 (from the manpages)

If you are interested in more detailed information i suggest the
O'Reilly PPP book (or send me an email).

 Ralf



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| Ralf Mattes                         | rm at schauinsland.com         |==
| Programming, Administration         | rm at ns.aura.de               |==
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