Re: [ECOS] RedBoot DHCP broken?

["Chris Garry" <cgarry at sweeneydesign dot co dot uk>]

> > > > When I build RedBoot with the latest sources, DHCP is not working.
> > > > I get the following output from RedBoot:
> > > > 
> > > > ... waiting for BOOTP information
> > > > Invalid DHCP state: 1
> > > > Can't get BOOTP info, using default IP address
> > > > 
> > > > All other network operations are working okay.
> > > > 
> > > > When I use Ethereal to check the packets sent at boot time, no packets
> > > > are seen from RedBoot at all.
> > > > 
> > > > After a quick bit of debugging it seems that in the file
> > > > redboot\current\src\net\bootp.c in the function
> > > > __bootp_find_local_ip()
> > > > 
> > > > the function call:
> > > > __udp_send((char *)&b, txSize, &r, IPPORT_BOOTPS, IPPORT_BOOTPC);
> > > > at line 250 is called and returns a value 0, but no packets make it out onto the
> > > > wire.  Thus when the subsequent code is waiting for a response, it does not
> > > > get one.
> > > > 
> > > > Has anybody else built RedBoot with the latest code and seen/not seen
> > > > this problem?
> > > 
> > > No, I've not seen this problem, but I am interested since I [obviously]
> > > broke it for you.  A few questions:
> > >   * Did it work before?
> > 
> > Yes, it did work before.
> > 
> > >   * Is your server set up for DHCP, or BOOTP only?
> > 
> > DHCP only.
> > 
> > >   * Have you seen the traffic before these changes?  [This might just be
> > >     a network snoop issue]
> > 
> > I had not seen the traffic before - never bothered looking.  However, I can see
> > the traffic for operations that currently work (ping and so on).
> > 
> 
> Is this on the same machine as the DHCP server?  If not, you might not 
> be able to see that traffic, depending on your network hardware.  If you
> are using a network switch, then there may be much traffic that you 
> can't actually snoop.

The DHCP server is not the same machine that is running ethereal, and I am
using a switch.  But the packet I was expecting was the DHCP discover packet
to IP address to 255.255.255.255 - which should be (and indeed now is) seen.

But I agree that using a switch rather than a hub is not great for debugging
networks.


> > >   * Try forcing the network debug code on. 
> > > Can you try things with the attached patch?  Let me know what you find.
> > > 
> > 
> > Tried the patch, and it is now working!
> 
> Good, but I'm a little confused by it.  It may be the case that
> your DHCP server is a bit slow.  The change makes the RedBoot
> code more resilient when it has to retry.

FYI, this is the Network traffic I see now it is working:
(Obviously packets are missing because of the switch)

Time    Source    Dest    Type
4.004824    0.0.0.0    255.255.255.255    DHCP_Discover
4.006231    DHCP_Server    Broadcast    ARP_Who_has_192.168.11.91
5.006438    DHCP_Server    255.255.255.255    DHCP_Offer
5.558438    0.0.0.0    255.255.255.255    DHCP_Request
5.559806    DHCP_Server    Broadcast    ARP_Who_has_192.168.11.91
6.556531    DHCP_Server    255.255.255.255    DHCP_ACK

It looks to me as if the DHCP server is doing an ARP lookup before
responding to the request - which is taking a long time.


> 
> In any case, since it helps I'll commit the changes.
> 

That's great, thanks.


> > The output is now:
> > 
> > ... waiting for BOOTP information
> > Ethernet eth0: MAC address de:ad:be:ef:00:01
> > IP: 192.168.11.91/255.255.255.0, Gateway: 192.168.11.1
> > Default server: 0.0.0.0, DNS server IP: 0.0.0.0
> > 
> > I assume the 'Default server' and 'DNS server IP' values are
> > taken from the config area in FLASH rather than the DHCP
> > server.
> 
> The server IP *can* come from the DHCP server, but it may not.
> Some servers don't provide this, others do.
> Currently the DNS IP only comes from 'fconfig'
> 

I see.

Cheers,
Chris


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