RFC: Updated ARP Queue patch...

[Rui Paulo]

Hi,

On 1 Nov 2010, at 19:20, George Neville-Neil wrote:

> Howdy,
> 
> 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.
> 
> Please review the following patch against HEAD:
> 
> http://people.freebsd.org/~gnn/head-arpqueue2.diff
> 
> This patch makes two changes to the ARP code:
> 
> 1) It adds a sysctl configurable queue of packets that are held until an ARP reply is received or
> timed out.
> 
> net.link.ether.inet.maxhold
> 
> Having the queue addresses a problem in modern systems where programs that use connectionless 
> protocols for communication will suffer from dropping many packets when they start up or when
> an ARP entry moves.
> 
> 2) Makes the time we wait for an arp reply configurable via another sysctl.
> 
> net.link.ether.inet.wait
> 
> 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:
> 
> "It may be desirable to have table aging and/or timeouts.  The
> implementation of these is outside the scope of this protocol."
> 
> 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.
> 
> 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