Re: [ECOS] Re: DHCP shuts down Ethernet device?

[Hugo Tyson <hmt at redhat dot com>]

Jonathan Larmour <jlarmour@redhat.com> writes:
> Anthony Massa wrote:
> > >> I am running RedBoot on an MBX board and downloading my eCos
> > >application
> > >> with networking support.
> > >>
> > >> I noticed your post about the Ethernet device shutdown and
> > >was wondering if
> > >> I could possibly be running
> > >> into the same problem.
> > >
> > >Only if you don't have a DHCP server on your net and you're
> > >trying to use
> > >the ethernet driver for other purposes than the TCP/IP stack.
> > 
> > I have a DHCP server on my net.  However, my confusion comes with the fact
> > that I have RedBoot coming up using BOOTP, which I have a server for as
> > well.  So, RedBoot gets its IP address.  Is this address then passed onto
> > the application, or is the application layer supposed to get its own, new
> > address?

The latter.  The app gets a separate IP address.

> > I'm a little confused about how the RedBoot and eCos app layer stack coexist
> > on my target.  I am using the RedBoot Ethernet for debugging the
> > application.
> 
> They each get their own *IP* addresses. Or one can be static and the other
> dynamic, or whatever you want. Think of them as completely separate.

...but they share a MAC address (inevitably).  Which means that it is
unlikely to work correctly if you have *both* IP addresses acquired
dynamically, because the BOOTP or DHCP server doesn't know who is asking,
so doesn't know which of the two IP addresses to serve.

I suppose that, since RedBoot uses BOOTP only, and the eCos stack uses DHCP
only, if you tell your DHCP server to ignore BOOTP requests, then they
would be distinguished correctly.  But the servers are quite entitled to
cancel the address they handed out "last time" if they see the same MAC
address asking for (and getting) a different address.

I always configure a static IP address in RedBoot's fconfig world, for use
by RedBoot, and let the eCos app get a dynamic address from DHCP.  That
works fine.

	- Huge