PPP-layer Echo
Neo-Vortex
root at Neo-Vortex.net
Wed Apr 27 15:38:04 PDT 2005
On Wed, 27 Apr 2005, Crist J. Clark wrote:
> All I want to do is send an echo-request and listen for the
> echo-reply at the PPP layer. Note that I am talking about
> pings _at the link layer,_ not IP layer pings. A quick look
> at the ppp(8) manpage didn't seem to indicate any tools for
> sending or receiving PPP-layer echoes. If ppp(8) doesn't have
> the ability, does anyone have any other _simple_ suggestions
> for doing this (e.g. dunno if it's worth writing a netgrap(4)
> node for this unless its really simple)?
By link layer ping, do you mean lqr stuff?
lqr
Default: Disabled and Accepted. This option decides if Link
Quality Requests will be sent or accepted. LQR is a protocol
that allows ppp to determine that the link is down without rely-
ing on the modems carrier detect. When LQR is enabled, ppp sends
the QUALPROTO option (see ``set lqrperiod'' below) as part of the
LCP request. If the peer agrees, both sides will exchange LQR
packets at the agreed frequency, allowing detailed link quality
monitoring by enabling LQM logging. If the peer doesn't agree,
ppp will send ECHO LQR requests instead. These packets pass no
information of interest, but they MUST be replied to by the peer.
Whether using LQR or ECHO LQR, ppp will abruptly drop the connec-
tion if 5 unacknowledged packets have been sent rather than send-
ing a 6th. A message is logged at the PHASE level, and any
appropriate ``reconnect'' values are honoured as if the peer were
responsible for dropping the connection.
~Neo-Vortex
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