Daryl may still be correct. Linux's bridge module also implements the learning phase (for detection of loops) before it begins forwarding packets.
On Tue, Apr 24, 2012 at 10:38 PM, Adrian May <adrian....@oregan.net> wrote: > Hi Daryl, > > There is no switch. I'm trying to build a router and I'm plugging clients > directly into it. It's actually a little fanless thing with 8 ethernet > ports, 7 of which I bridge to make the private LAN, and the other of which > dials pppoe. I installed ubuntu server 10.04, followed by the bridge, and > then dnsmasq. > > In the meantime, I got another result. With IPFire, I found dhcp very > fast, and it turned out that some of the home made cables around here can't > connect the embedded boards to the little box I'm making the router out of. > But they can connect any PC to my router or the 10 dollar router, and they > can connect any PC or embedded board to the 10 dollar router, and the > proper cables can connect anything to anything. In other words, the only > combination that doesn't work is the home-made cable connecting the > embedded boards to my new router. What's more, it doesn't matter whether I > use a 100Mb or 1Gb socket on the new router. Very strange. That's all under > IPFire, so now I'm reinstalling ubuntu to see if I get the same result. > > Adrian. > > > > > On 04/24/2012 10:51 PM, Daryl Richards wrote: > >> Actually, the "10 dollar domestic router" fix points to the probable >> solution. You likely have spanning tree turned on on your usual switch, >> which will block all traffic on that port for the first 50 seconds after >> a link state change. Either switch to rapid spanning tree, or look into >> your switch's version of "portfast".. >> >> On 12-04-23 11:21 PM, Adrian May wrote: >> >>> Hi Simon, >>> >>> 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? >>> >>> Adrian. >>> >>> >>> >>> 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? >>>> >>>> >>>> Cheers, >>>> >>>> Simon. >>>> >>>> Any ideas? >>>>> >>>>> Adrian. >>>>> >>>>> >>>>> >>>>> >>>>> ______________________________**_________________ >>>>> Dnsmasq-discuss mailing list >>>>> Dnsmasq-discuss@lists.**thekelleys.org.uk<Dnsmasq-discuss@lists.thekelleys.org.uk> >>>>> http://lists.thekelleys.org.**uk/mailman/listinfo/dnsmasq-**discuss<http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss> >>>>> >>>>> >>>> ______________________________**_________________ >>>> Dnsmasq-discuss mailing list >>>> Dnsmasq-discuss@lists.**thekelleys.org.uk<Dnsmasq-discuss@lists.thekelleys.org.uk> >>>> http://lists.thekelleys.org.**uk/mailman/listinfo/dnsmasq-**discuss<http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss> >>>> >>> >>> ______________________________**_________________ >>> Dnsmasq-discuss mailing list >>> Dnsmasq-discuss@lists.**thekelleys.org.uk<Dnsmasq-discuss@lists.thekelleys.org.uk> >>> http://lists.thekelleys.org.**uk/mailman/listinfo/dnsmasq-**discuss<http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss> >>> >> > > ______________________________**_________________ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.**thekelleys.org.uk<Dnsmasq-discuss@lists.thekelleys.org.uk> > http://lists.thekelleys.org.**uk/mailman/listinfo/dnsmasq-**discuss<http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss> >
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