From: Tomi Manninen (lrbkhs@uni-mannheim.de)
Date: Thu Dec 12 2002 - 23:14:36 EET
On Thu, 12 Dec 2002, Michael Willems wrote:
> The first time, instead of a ping (ICMP echo request), my node send a
> packet "from VA3MVW to QST". That results in no replies, so in the shell I
> see "no route to host".
These are ARP packets (Address Resolution Protocol, mapping IP-numbers to
hardware addresses ie. callsigns).
Chances are your ARP timings are too aggressive, they usually are by
default. This causes it to time out and report "no route" to you.
> If I ping again immediately, it DOES send the echo request, and gets back
> an echo ack from the other side, and all is OK< the ping works.
It would seem that the other system does indeed reply to the ARP query
while you are not watching anymore but not in time for the first ping to
succeed. The second time it's cached so everything works.
Two options. First, set up a static ARP entry. This is practical if your
neighbors are very few and static ie. don't change things like their
callsign-ssid's very often. The syntax is something like this:
arp -H ax25 -i <ifname> -s <ipaddr> <callsign>
Second option is to tweak the timings. I prefer this and have this in my
startup script:
# ARP timings
#
PROCPATH=/proc/sys/net/ipv4/neigh/${IFNAME}
echo 5 > ${PROCPATH}/mcast_solicit # 5 retries
echo 500 > ${PROCPATH}/retrans_time # 5 sec intervals
echo 1800 > ${PROCPATH}/base_reachable_time
For further info, see /usr/src/linux/Documentation/filesystems/proc.txt
under "Network Neighbor handling".
-- Tomi Manninen Internet: wpaq.echwwcc@temp.korbs.pl OH2BNS AX.25: gxfzj@schwarzes.net KP20ME04 Amprnet: jtyrut@kerailya.tunkki.fi- To unsubscribe from this list: send the line "unsubscribe linux-hams" in the body of a message to puwjwn@uni-stuttgart.de More majordomo info at http://vger.kernel.org/majordomo-info.html
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