Discover a non IP element (ex: HUB)

Petals28

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Network management software

In Network management i want to discover a HUB. How is it possiable if the hub is not a snmp enabled element. Situation: A normal HUB is connected to a switch and through that hub 6 Windows and Linux server's are connected. To get them in Map module i want discover the HUB along with the servers. I am geting the servers but it shows that with one port of the switch 6 servers are connect. This may confuse the operator. Note: The connected hub is not a snmp enabled ip element. I hav one more quary. Do all the HUB hav MAC address? Thanks in advance Dipyaman Baral

Asked: December 19, 2005 8:50 AM Last updated: December 20, 2005 7:12 PM

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Last updated: December 19, 2005 5:02 PM GMT

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Thanks. We'll let you know when a new response is added.

Hubs do not have MAC addresses unless they are a managed device. If it doesn’t have SNMP but has telnet or ping you could probably get your monitoring system to show it but this is pretty rare for a hub. Hubs simply take a packet in one port and repeat it out all of the other ports and don’t normally have a need to be managed.

There is no way to discover a hub in a network monitoring program unless it is manageable somehow.

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Atomas Dec 20, 2005 8:52 AM GMT

Hi. A HUB is a HUB and is one of the most basic networked devices. It has it's limitations and before installing servers on a HUB you should be aware of those limitations. Why don't you just put your servers on a switch? NOTE: HUB do not "have" MAC addresses, hosts&servers do. Daniel Jutras CISSP, CISA, CCSA, CCNA

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Bobkberg Dec 20, 2005 7:12 PM GMT

This might take a little work, but since a hub repeats all traffic, and a switch doesn't (Bear in mind that many switches these days aren't manageable either), you might try something like this: 1) Ping everything in your subnet 2) Dump the ARP cache, and save it 3) Make note of your own MAC address 4) Run TCPDump/WinDump to capture level 2 packet headers using the -e (to print link-level addresses), and -s 16 to only capture the first 16 bytes, and save this data. Let it run for a while - like a day or whatever 5) Filter out any lines which contain your own MAC address, or broadcast addresses (FFFFFFFFFFFF). 6) Look for the default gateway's MAC address. The number of different MAC addresses which are paired with the default gateway's MAC address is likely close to the number of hosts on your local collision-domain (hub). Bob

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