On Fri, 19 Mar 2004, Wolfgang S. Rupprecht wrote:
> gdt@ir.bbn.com (Greg Troxel) writes:
> > Linux has a mechanism that marks an arp entry fresh when a TCP packet
> > is received that acks something, as that validates that the arp entry
> > at least caused the packet to get delivered.
> 
> Thats an interesting idea but it has to be done carefully when one is
> dealing with proxy-arps and wireless access points.  A mobile user
> might have moved out of range of one AP and onto another.  The TCP
> stream would still be following them, but "their" MAC address has
> changed.

If you copy the remote MAC address from the incoming packet into the ARP
table, instead of just assuming that the existing ARP table entry was
valid, then you avoid that problem. 

--apb (Alan Barrett)