Re: ARP request retransmitting

From: Bill Vermillion (bv_at_wjv.com)
Date: 11/07/05

  • Next message: Chuck Swiger: "Re: ARP request retransmitting" 
    Date: Mon, 7 Nov 2005 10:19:27 -0500
To: Gleb Smirnoff <glebius@freebsd.org>

    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
    effort gasped:

    > Colleagues,

    > 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.

    > Any objections?

    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.

    How big is your network?

    Bill 

    -- 
Bill Vermillion - bv @ wjv . com
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  • Next message: Chuck Swiger: "Re: ARP request retransmitting"