[Soekris] net4521 Phy Link

[Mike]

Joseph,

    Good work, this is exactly an issue in the situation when a dhcp 
server on a network is not booted yet before the clients come up and 
begin requesting their addresses. Your stations then backoff and retry 
later, resulting in a longer than comfortable period where they have no 
addresses.

    The tool you want is 'mii-tool' and you can use it thusly:

    mii-tool -R eth0

    Which will reset the transceiver on eth0, breaking link, allowing 
the windows station to notice and begin re-acquiring the dhcp address.

    In a larger deployment you may have to deal with this issue 
differently. For example, a cisco switch like the 2924xl will take a 
while to boot and during this time it's ethernets are effectively off, 
so putting this switch in line with your soekris dhcp server would be 
one strategy also.

     Another idea is that 90 seconds to get your board booted and 
serving dhcp is also a very long time. I have mine down to about 30 
seconds - combonation of bios settings (fastboot = enabled and etc), and 
a custom software roll. You may be able to make similar changes for 
yours too.

Mike-


Joseph Barstow wrote:
> Hi all,
>     Short version: Is there a way to make 'ifconfig <dev> down' break 
> phy link on the net4521's onboard Ethernet ports?
>
>     Long version: I'm working with a net4521 for a school project and 
> have a small obstacle.  I have a Windows PC connected to each of the 
> two Ethernet ports which are using DHCP for their IP address 
> configurations.  The demo setup is such that the Windows PCs are fully 
> booted before the net4521 powers on.  Herein lies the problem.
>     My setup of Busybox Linux with kernel 2.6.19 takes approximately 
> 90 seconds to boot from the CF card, but the Windows PCs begin sending 
> DHCP requests as soon as the net4521 powers on and phy link comes up.  
> By the time dnsmasq is running to respond to the DHCP requests, the 
> Windows PCs have given up and backed off to a slow retry.  All-in-all, 
> despite the fact the net4521 only takes 90 seconds to boot, they don't 
> receive usable IP configurations for approximately 5 minutes.
>     The best solution to this problem I can think of is to break phy 
> link on both ports with an 'ifconfig <dev> down' command early in the 
> boot sequence, and then bring it back up after dnsmasq is ready for 
> DHCP requests, thus triggering the Windows PCs to ask for an address 
> config.  However, ifconfig seems unable to break phy link on either 
> Ethernet port.  Is there anything I can do about this?  Should I be 
> using a specific driver module rather than the standard Ethernet 
> support compiled into the 2.6.19 kernel?  Will Capone and his boys 
> rule the streets of Chicago forever?
>
> Other vital information:
> The context of the project is such that client PCs are expected to be 
> varying and random.  I cannot use static configurations or alter the 
> Windows DHCP timer -- I must attempt to fix this from the net4521's 
> side.  Suggestions for accomplishing this without trying to break phy 
> link are welcomed.
>
> Thanks guys,
> Joe
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