Ports from switch to system

Question

I have rcently joined a company and we want to migrate our network to 10.0.0.0 ip address range from 192.168.0.0.

Also we want to configure few vlan's

But the major challange i am facing is that there is no documentation available for wiring. How can i track which port of which switch is going to which system.

Please help me.

You are lacking some information that can help you solve this problem. 1) Switch/router make and model. 2) How is the network physically set up now (multiple buildings, multiple wiring closets). — Travis, May 13 '15 at 15:24

score 2 · Answer 1 · answered May 13 '15 at 15:03

2

1. Physically

Trace the cables, and mark them off as you go.

2. MAC Address

If your switch infrastructure is managed and intelligent enough, you should be able to see the MAC addresses present on each port. In Cisco-land, the command is show mac-address-table on the switch.

3. CDP/LLDP

Some hosts and switches may be capable of using CDP (Cisco Discovery Protocol) and/or LLDP (Link Layer Discovery Protocol) to determine their place in the network infrastructure. The availability and usefulness of this will vary widely, and is too broad to exhaustively categorize here.

answered May 13 '15 at 15:03

Hyppy

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CDP anf lldp is not providing the ip address of systems on other sides – Mahima Kundu May 13 '15 at 17:34
Switches don't care much about IP addresses now, do they? – Hyppy May 13 '15 at 17:47

score 0 · Answer 2 · answered May 13 '15 at 15:05

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It is possible if your switches support discovery protocol like LLDP

If your switch sends LLDP packets you can capture them on a system with tcpdump: tcpdump -s 1524 -vv -i eth0 -c 1 ether proto 0x88cc

Most likely you will see port identificator on the Port ID field

It may take some time to see such packet depending on switches configuration.

answered May 13 '15 at 15:05

nARN

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but I want to find ports for 300 systems. – Mahima Kundu May 13 '15 at 17:34
This method works well if you have remote access to every system. I assumed that most time you do. In this case you can run a script to capture and parse LLDP packet. I regularly do this on thousands machines. – nARN May 14 '15 at 12:16

score 0 · Answer 3 · answered May 13 '15 at 15:50

Provided you do not have a proper cable detector, or other equipment, and you do not intend to fiddle with some discovery protocols you might want to switch all the network stations, approach each station, detach the LAN cable, and attach it to a laptop or something, and see which light comes on on the switch. Two people are ideal for this. This is the fool-proof way to do this. (Also get yourself a decent label printer).

Ports from switch to system

3 Answers3