From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Lopes <lopsch@lopsch.com>
Date: Fri, 03 Jun 2005 13:15:01 +0000
Subject: Re: [LARTC] how can I monitor a (dumb) switch ?
Message-Id: <42A057D5.7050201@lopsch.com>
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To: lartc@vger.kernel.org

Radu CUGUT schrieb:
> Hello there,
>=20
> Can anyone help me with a problem i have....
>=20
> I have an ethernet LAN, made over dumb fast-ethernet switches
> (10/100mbit) without management, so there is no IP for the switches.
>=20
> What I want, if possible, is to find out if a switch is down or not.
>=20
> It's like with routers... if you want to find out if a router is OK,
> either you send ICMP directly to the router, or to a host "behind" the
> router.
>=20
> Is there any device, or ANY OTHER possibility that I can find out if a
> switch is unplugged or broken.  Users on my LAN aren't reliable (they
> have firewalls, closed computers, etc.), so pinging users that are
> linked to a switch to find out is out of the question.
>=20
> I have got an ideea that if I take an ehernet card, and somehow manage
> to put power in it, than I would have a device with MAC addres to
> arping ... is this correct ?
>=20
> MANY thanks in advance, and SORRY for being a bit out of topic.
>=20
>=20
> Best regards,
> Radu.
>=20
Ping a client you surely know should be connected to the switch. ARP=20
will take the part to find out the hardware address so the packet can be=20
delivered. If the switch is on it should find a hardware address and ARP=20
should put it in your ARP cache. It=B4s independet from ICMP blocks and=20
similar. So after trying to ping you should have an entry in your ARP=20
table which you can control with "arp" command.

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