Date: Thu, 4 Nov 2010 07:42:24 +0000 From: Rui Paulo <rpaulo@FreeBSD.org> To: George Neville-Neil <gnn@freebsd.org> Cc: arch@freebsd.org, net@freebsd.org Subject: Re: RFC: Updated ARP Queue patch... Message-ID: <FDEEEF3F-E651-4BBC-B09F-0CB92705B6B7@FreeBSD.org> In-Reply-To: <8C96F018-EA61-4C38-AC9A-148D1DC06193@freebsd.org> References: <8C96F018-EA61-4C38-AC9A-148D1DC06193@freebsd.org>
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Hi, On 1 Nov 2010, at 19:20, George Neville-Neil wrote: > Howdy, >=20 > This is marked as "Updated" because I first proposed this on arch@ but = am now sending it to > a wider audience as I'm hoping to commit it in the near future. >=20 > Please review the following patch against HEAD: >=20 > http://people.freebsd.org/~gnn/head-arpqueue2.diff >=20 > This patch makes two changes to the ARP code: >=20 > 1) It adds a sysctl configurable queue of packets that are held until = an ARP reply is received or > timed out. >=20 > net.link.ether.inet.maxhold >=20 > Having the queue addresses a problem in modern systems where programs = that use connectionless=20 > protocols for communication will suffer from dropping many packets = when they start up or when > an ARP entry moves. >=20 > 2) Makes the time we wait for an arp reply configurable via another = sysctl. >=20 > net.link.ether.inet.wait >=20 > The old, pre 8.0, ARP code would run the timer once per second. The = new > ARP code sets a timeout of 20 seconds on each entry. Neither value = was specified > in RFC 826. As a matter of fact, RFC 826 had this to say about = timeouts: >=20 > "It may be desirable to have table aging and/or timeouts. The > implementation of these is outside the scope of this protocol." >=20 > This new code does not change the default value of either the arpqueue = (which was > always 1 packet) nor does it change the new value of the ARP down = timeout. >=20 > I have a different patch for 7, which I will propose after I can get = this in to > HEAD and MFC'd to 8. This looks good to me. Regards, -- Rui Paulo
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