[mythtv-users] New HD HomeRun problem

[Geoffrey Leach]

On 03/03/2009 06:10:16 PM, R. G. Newbury wrote:
> Yan Seiner wrote:
> > On Tue, March 3, 2009 12:01 pm, R. G. Newbury wrote:
> >> Try recycling the power on your ROUTER.
> >> Then, make sure that the router has not changed the IP address of
> the
> >> hdhr.
> >> Make sure that everything, including the channel standard is
> properly
> >> set on the hdhr....
> >> Most likely reason is that the router changed the IP of the hdhr.
> If you
> >> can, reserve the hdhr's IP address by tying it to the MAC, since
> there
> >> is no easy way to contact the hdhr under linux if the IP address
> keeps
> >> changing.
> > 
> > At least on my system (0.21) myth uses a broadcast to locate the
> HDHR. 
> > Maybe once it's up it uses the IP address, but at least for the
> first
> > detection it uses the 0xFFFFFFFF ID for the HDHR, which I'm 
> assuming
> is
> > some sort of "Hey HDHR, Wake up and tell me where you are" call.
> 
> Hmmm, I would have thought that things would be initiated by the 
> HDHR,
> 
> sending a DHCP broadcast at power-up, to commence a handshake with 
> the
> 
> router/DHCP server. Sometime later, the HDHR ends up with an IP
> address. 
> The early hdhr firmware cannot actually *do* a full static address,
> but 
> we can achieve the same result with IP-MAC reservation.
> That handles the IP side, but not how myth finds the hdhr
> 
> So it makes sense that myth uses the device id or FFFFFFFF to ping 
> the
> hdhr.
> 
> Does the hdhr answer with its IP address??? I don't know.
> 
> But if so that is some decidedly nice programming as it neatly
> sidesteps 
> most of the problems with using a (variable) DHCP-served address.
> 
> But of course that doesn't help you and me if we want to be sure that 
> the hdhr is there and operating properly, which is easier to do if 
> the
> 
> IP is static.

I've just finished debugging this outside of MythTV, so I can offer an 
allegedly informed opinion.

When the HDHR comes on-line it issues a DHCP broadcast. That's the 
blinking LED. It expects a response from the DHCP server with an IP 
address. If it does not get one, it re-issues the request, waiting 
progressively longer between each. When the HDHR gets its IP address, 
its ready to respond to a discovery request, as in hdhomerun_config 
discover, which tells you the IP address that was assigned.