How to Identify Connected Ports Using Testers like Fluke

ciscoethernetinterfacetesting

At work I've been tasked to create a program that acts similar to Fluke testing devices (such as LinkRunners) but will be much more extensive and specific to our needs. One of the capabilities that has been requested is determining the interface port that the testing device is currently connected to.

So before I run off into detail, does Cisco deploy a standard or proprietary protocol that handles all this? Somehow a Fluke LinkRunner is retrieving the information without logging in administratively, an operation that I would like to mimic.

To put this in perspective, a laptop with the loaded software will either connect directly to an Ethernet port on the switch or through permalink by testing on the jack-end where it is terminated for the customer. Like Fluke testing devices they would like for it to display the switch name, interface, port, VLAN, etc. so that the technician may verify that everything is working properly.

What I don't know (since I'm only a student engineer being trained on the job) is how Cisco communicates with a testing device and provides this information. I understand that you can determine what a device is connected to on the administrative end by checking for the MAC Address in the ARP table or looking up the client IP but this is to work on the front-end. I could try to use SNMP but with how the college has set up the network the switches are on a different, secure VLAN. The laptop would not be able to jump onto this VLAN to run SNMP and fetch the required information.

Ideas, suggestions, questions, critcism?

EDIT

CDP/LLDP was pointed out and I feel silly for working with these but not having had yet researched them. From this I can get information, however this brings up another question if it must be enabled on the switch to allow retrieving said information.

A comment upon the answer has finished fulfilling my questions. Special thanks to the two who helped!

Best Answer

I'm almost 100% positive that for Cisco switches it would be CDP (Cisco Discovery Protocol) while on other vendors, they would use the industry standard LLDP (Link Layer Discovery Protocol). From CDP, you can get information such as switch port, VLAN, switch name, and link negotiation info (e.g. full vs half duplex) to name a few.

I hope this helps.

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