[U-Boot] [PATCH] net: BOOTP retry timeout improvements

[Thierry Reding <thierry.reding@gmail.com>]

On Fri, Aug 15, 2014 at 11:39:08PM +0200, Thierry Reding wrote:
> On Fri, Aug 15, 2014 at 10:02:40AM -0600, Stephen Warren wrote:
[...]
> > (and as an aside, how on earth is your DHCP server taking >500ms to respond,
> > yet still actually responding?)
> 
> It's a black box mostly but it seems to be doing the same for any of the
> other devices (tcpdump on the machine that I'm typing this from gives me
> roughly 430 ms in one session and 580 ms in another between the DISCOVER
> message and the server's reply) on the network.
> 
> This seems absurdly long, but it's consumer network equipment (I'd even
> say high-end by the price-tag) and there's not a lot I can configure to
> make it faster. I also suspect that other people may have hardware with
> similar latency.

Oh, looking further at tcpdump output it seems like the DHCP server is
sending out an ARP request for the IP address that it's about to OFFER
to make sure nobody is using it yet. Waiting for an ARP reply probably
accounts for most of the delay.

Looking at various websites this seems to be a common practice in DHCP
servers.

Thierry
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