Got a cam server at a remote site (ExtremeSurfCam.DynDNS.org).

One of the cams went offline, IP addr = 10.0.0.150 (assigned the cam's
setup).

I removed that cam and took it home, connecting it to my home LAN.

But I had forgotten that were was already a cam on my home LAN with IP
addr = 10.0.0.150.

The problem cam came right up and my cam server recognized/rendered it
and it's stream.

OK... that cam's OK and something's goofy at the remote site.

But after removing the problem cam from my home LAN, the "legitimate" 10.0.0.150 cam is no longer recognized: cam server does not see it,
NetScan does not see it, and it is not pingable.

Tried re-booting all my switches, but no joy.

Can anybody postulate what might be going on?

--
Pete Cresswell
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Wed, 17 May 2017 20:29:38 -0400, "(PeteCresswell)" <x@y.Invalid>
wrote:

Got a cam server at a remote site (ExtremeSurfCam.DynDNS.org).

One of the cams went offline, IP addr = 10.0.0.150 (assigned the cam's >setup).

I removed that cam and took it home, connecting it to my home LAN.

But I had forgotten that were was already a cam on my home LAN with IP
addr = 10.0.0.150.

The problem cam came right up and my cam server recognized/rendered it
and it's stream.

OK... that cam's OK and something's goofy at the remote site.

But after removing the problem cam from my home LAN, the "legitimate" >10.0.0.150 cam is no longer recognized: cam server does not see it,
NetScan does not see it, and it is not pingable.

Tried re-booting all my switches, but no joy.

Can anybody postulate what might be going on?

Switches have ARP tables so rebooting the relevant switch(es) or
otherwise clearing their ARP tables so that the new (old/original) MAC
could be learned was a good thing, but your PC has an ARP table, too.

ARP tables are essentially a mapping of IP address to MAC address, so
when you tried to access a device at 10.0.0.150, your PC checked whether
that IP already had an entry in its ARP table, and it did, so it used
the corresponding MAC address, which no longer existed because you
unplugged that cam. If you clear the ARP table and then try to access
that IP, ARP will broadcast a request for whoever owns that IP to
respond, and the response will include the device's MAC address. That
info is then populated in the ARP table. ARP entries should eventually
time out, so your issue should have cleared up automatically after a
certain period of time.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Per Char Jackson:

your PC checked whether
that IP already had an entry in its ARP table, and it did, so it used
the corresponding MAC address, which no longer existed because you
unplugged that cam. If you clear the ARP table and then try to access
that IP, ARP will broadcast a request for whoever owns that IP to
respond, and the response will include the device's MAC address. That
info is then populated in the ARP table. ARP entries should eventually
time out, so your issue should have cleared up automatically after a
certain period of time.

That is what happened....

Now that you have explained it, it's looking to me like I could have
done an

ARP -d,

followed by something like

ARP -s 10.0.0.150 00-aa-00-62-c6-09
--
Pete Cresswell
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Tue, 13 Jun 2017 19:37:03 -0400, "(PeteCresswell)" <x@y.Invalid>
wrote:

Per Char Jackson:

your PC checked whether
that IP already had an entry in its ARP table, and it did, so it used
the corresponding MAC address, which no longer existed because you >>unplugged that cam. If you clear the ARP table and then try to access
that IP, ARP will broadcast a request for whoever owns that IP to
respond, and the response will include the device's MAC address. That
info is then populated in the ARP table. ARP entries should eventually
time out, so your issue should have cleared up automatically after a >>certain period of time.

That is what happened....

Now that you have explained it, it's looking to me like I could have
done an

ARP -d,

followed by something like

ARP -s 10.0.0.150 00-aa-00-62-c6-09

Normally, the 'delete' is good enough by itself, because then ARP will
find the current IP<>MAC mapping and use it. Setting a static entry is
normally not required, or to put it another way, setting a static entry
is usually done with equipment that is known to not work with ARP for
some reason. Your cams seem to work fine in that regard, so "arp -d *"
or "arp -d 10.0.0.150" should have quickly cleared things up. Rebooting
the relevant switch(es) was probably still helpful, as well.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Per Char Jackson:

Normally, the 'delete' is good enough by itself, because then ARP will
find the current IP<>MAC mapping and use it. Setting a static entry is >normally not required, or to put it another way, setting a static entry
is usually done with equipment that is known to not work with ARP for
some reason. Your cams seem to work fine in that regard, so "arp -d *"
or "arp -d 10.0.0.150" should have quickly cleared things up. Rebooting
the relevant switch(es) was probably still helpful, as well.

Thanks again... I've really learned something new with this one.
--
Pete Cresswell
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)