[Dnsmasq-discuss] Slow response to DHCPDISCOVER
adrian.may at oregan.net
Tue Apr 24 04:21:39 BST 2012
In the meantime I installed ClearOS, which uses dnsmasq. Now the PCs get
served fast but my embedded boards are still not getting IPs. If I plug
these embedded boards into my 10 dollar domestic router, they get an IP
instantly. I already tried setting bootp-dynamic and dhcp-broadcast in
the config. If I grep everything under /var/log for dnsmasq, there's no
evidence that requests were even received from these boards. So I still
suspect the networking layer.
As for the boards themselves, I'm not entirely sure what they do.
They've got some kind of embedded linux. One boots into yamon where I
can only say "net init", the other into something of its own invention
where I start udhcpc.
I tried no-ping but it had no effect. I can't get my brain around your
tag system. I've just been writing things like bootp-dynamic with no
tags right in the main config file, or in the case of ClearOS, in the
dhcp config file which is referenced from the main config file. Could it
be that these settings have no effect unless I attach some tags, or put
them inside a subnet declaration?
On 04/23/2012 08:01 PM, Simon Kelley wrote:
> On 23/04/12 12:02, Adrian May wrote:
>> Hi all,
>> I get the same result with dnsmasq, dhcp3-server and isc, namely, that
>> the client has to send several DHCPDISCOVER packets before the server
>> finally responds after about 30 seconds. This is breaking a couple of
>> embedded platforms because they aren't that patient, and I have no way
>> of configuring that.
>> Why don't DHCP servers just respond to the first DHCPDISCOVER?
>> Especially when I made them authoritative?#
> Servers allocate an address and then ping it for a few seconds just to
> be sure it's not in use. That's the main delay. In dnsmasq --no-ping
> will stop this behaviour. Also the client is entitled to wait around
> collecting answers from more than one server before deciding which one
> to use; they rarely do this and it doesn't sound like yours are.
>> I think I might have seen in the logs that the dhcp processes aren't
>> even getting the earlier packets, even though the machine is. It's as if
>> they get discarded by the networking layer. This is a ubuntu server
>> 10.04 machine.
> Firewall rules can affect things, but the result is rarely
> intermittent. Is your network heavily loaded and dropping packets?
>> Any ideas?
>> Dnsmasq-discuss mailing list
>> Dnsmasq-discuss at lists.thekelleys.org.uk
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss at lists.thekelleys.org.uk
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