How to find the whether there network device connected between two servers

[Karthik U R]

We have two servers (windows server 2003 machine) setup in duplexed mode.

There is only a single hop between the duplexed partners if we give a traceroute from one system to the other.

How to find out whether there is any Switch connected in between the duplexed partners. ?

[david.macias]

Your question is way too random for this forum not to give some background information.  What are you trying to accomplish and why does it matter if it's behind a switch or not?

david

[Karthik U R]

Thanks for the response.

I just wanted to check out there is any way to find,

1. two server machines connected directly via cross cable.

2. is there a Switch connected between two windows machine via straight cables.?

[William Bell]

Well, there is very little information here but I would do the following:

1. On one of the servers, identify the default gateway

2. Telnet/SSH to the default gateway

3. If the default gateway is a Cisco device, the attached switches are Cisco devices, and CDP is enabled throughout, then check the CDP neighbor table on the default gateway (show cdp neighbor).

4. While on the default gateway, also find the MAC address of the remote (other) server using the "show ip arp" command (note, you can also find the mac address using the arp cache on the windows server (arp -a I believe)

5. Telnet/SSH to the switch identified in step 3

6. On the switch, use the command "show mac address-table" or "show cam dynamic"  (again, assuming Cisco equipment) (the command used depends on the model/version of switch).  You can typically type in the mac address you recorded in step 4 to filter search results. You may need to run the "show mac"/"show cam" commands without specifying the mac address first to see the format that the switch expects (either aaaa:bbbb:cccc:dddd or aa-aa-bb-bb-cc-cc-dd-dd).

7. The result of step 6 will typically identify a port. If the remote server is attached directly to the switch then it will be an access port. There is a possibility that the port identified in step 6 is another switch. To determine which, use the "show cdp neighbor ". For example, if step 6 identified interface GigabitEthernet 0/1 then "show cdp neigh gigabitethernet 0/1".  If you don't see a neighbor listed then either you have found your server's switch port, there is a non-cisco switch on the port, or the attached port is a cisco switch not running CDP.  Not trying to confuse you, just laying out the possible scenarios (note, I am glossing over details here for brevity).

8. If step 7 indicates that there is another switch attached, then repeat steps 6 and 7 until you find your server.

Now, technically, at step 6 you have answered your question. If you see the mac address of your server in the CAM table then you know the device is using a switched network.

HTH.

Regards,

Bill

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