On Mon, Nov 07, 2005 at 17:04 , the primordial soup was bombarded
with cosmic radiation and a new life form of genus Gleb Smirnoff
emerged to test its air breathing capabilities and with great
I have a proposition on changing the behavior of ARP retransmitting.
Currently we after sending several ARP requests, sending ARP requests
for given IP is suppressed for some interval (by default 20 seconds).
Probably this feature was designed in early 90th, when sending one
additional broadcast packet was an expensive thing.
The man page says the host is considered down "for a short period
(normally 20 seconds), allowing an error to be returned to
transmission attempts in this interval".
I suggest to keep sending ARP requests while there is a demand for
this (we are trying to transmit packets to this particular IP),
ratelimiting these requests to one per second. This will help in a
quite common case, when some host on net is rebooting, and we are
waiting for him to come up, and notice this only after 1 - 20 seconds
since the time it is reachable.
Is the 20 second limit that much of a problem. And the 20 minute
timeout for caching is certainly far more generous that my old
big Cisco that had a 4 hour cache. A user complained that he put
up new machines and things weren't working. I told him he should
have called me before he put the IPs back the way they were as
cleanring the arp-cache took care of that.