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I am working with hardware guys and trying to monitor switches.Those guys deployed switches with some connectors,to implement such a logic in which whenever switch A goes down switch B goes down as well, very similar to a tree structure or parent/child.I can login to switch interfaces,problem is how I can find this connection between two switches.The idea is network monitoring needs to implement same tree logic between them.I am an alien to network hardware.

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    show cdp neighbors
    – manish ma
    Oct 6, 2021 at 10:36
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    You are also trying to re-invent the wheel. There are many, many products, freeware, and methods for monitoring equipment.
    – Ron Trunk
    Oct 6, 2021 at 12:05

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Depending in the exact makes and models, very often some kind of discovery protocol is used.

E.g. for Cisco switches show cdp neighbors

For HPE Procurve/Aruba switches show lldp info remote

(Note that CDP [proprietary Cisco] and LLDP [open IEEE] are distinct protocols. On most devices, CDP shows no LLDP devices and vice versa. HPE/Aruba often bunches them all together though.)

For more detailed information you'll need to add the device info to your question. Note that discovery protocols are L2-only, so the switches need to be connected directly or via L2-transparent hardware (e.g. media converters) for them to work.

LLDP and CDP are very similar. Both usually show a neighbor's (management) IP or (base) MAC address, device name, features, ... The available information is generally device-specific and varies considerably. The protocols are very common for switches but much less so for other devices.

Once you've got the neighbor information you should update your documentation and configure port/friendly interface names.

If you already know the MAC addresses of the relevant devices you can also use show mac address-table to find out which port (and possibly VLAN) they are attached to.

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  • I have cisco product brand model image version information, I do not know about that hardware which connects two cisco switches, if I had that information I think I could better define the problem as you said.I can not even walk to switches, due to geo reasons. thnx
    – hakkican
    Oct 6, 2021 at 12:14
  • The may be additional hardware between two switches, but very often they are connected directly. Most switches are configured for remote access, e.g. using SSH.
    – Zac67
    Oct 6, 2021 at 12:20
  • I was told that those guys used separate apparatus, not like using cable from one to another switch and I do not have that apparatus information, kind of connector I guess.
    – hakkican
    Oct 6, 2021 at 12:25
  • There's a vast range of possibilities, so unless you can provide more detailed information we'll likely not be able to help you much further, sorry.
    – Zac67
    Oct 6, 2021 at 12:31
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    A managed switch shows interface states - where something is attached by physical layer - and MAC addresses by port - what is attached where by data link layer. When available, CDP or LLDP are just a bonus info. They're rather common with switches but not so with other devices.
    – Zac67
    Oct 7, 2021 at 6:32

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