Not quite a dupe, but there's a similar question here, which has some suggestions about mapping an IP address to a switch port.
In this case, it sounds like the best option is to identify all switch ports that are connected to devices you know about. My suggestions for this (assuming Cisco managed routers/switches):
Identify known devices
From your first hop router(s), do a broadcast ping on each subnet that is trunked to a switch supporting the office space (as opposed to any data centre space you may have). Note, this should be the directed broadcast address of each subnet, rather than the 'all devices' broadcast IP of 255.255.255.255 In Cisco IOS, this can only be done from privileged exec mode. For example, to ping all machines on the subnet 192.168.100.0/25, use:
ping ip 192.168.100.127
This will populate the ARP cache of the router with entries for all machines on each subnet responding to ping.
Again on the first hop routers, extract the list of ARP entries for each subnet:
show ip arp interface vlan 100
This will give you all the IPs and MAC addresses of every device that responded to the ping. You can check the list of IPs against DNS (or another naming service) to identify the names of specific devices. Any IP address that you can't match a name to should be flagged for further investigation.
Map known devices to switch ports
Take the list of MAC addresses and use it to determine which switch port each device is connected to.
show mac-address-table address <mac-address>
Will show you the MAC address table entry for that particular MAC, including which switch port it's connected to. Alternatively:
show mac-address-table vlan <vlan number>
Will show you the MAC address table for all ports in that VLAN. Note, the default time out for MAC address tables on Cisco devices is 5 minutes; you may need to run your broadcast ping again in order to repopulate it.
Map unknown devices to switch ports
For those IPs that you couldn't map to known devices, the commands in the previous section will tell you which port you need to check.
Also, run:
show mac-address-table
with no arguments. Take the output, and remove the lines for any known MAC addresses, as well as any router-router and switch-switch links. The MAC addresses that you will be left with are devices that are connected to your switch, but aren't communicating via IP to your first hop routers. The ports these appear on should also be flagged for investigation.
Map flagged ports to outlets
For all the ports you have flagged (i.e. devices you can't identify), you'll need to do a physical trace from the switch port to the access port on the office floor. If you're lucky, your landlord will use managed cabling infrastructure; if not, be prepared to lift floor tiles and trace cables the old fashioned way. Best of luck.
It will take some time, but the results will be worth it...
Step 1: Document the mess so you know what is connected to every switch port and patch panel (Switch, port, patch, VLAN).
Step 2: Start with one switch and clear the deck:
- configure a port on another switch with the appropriate VLAN
- move the patch to the newly-configured switch port
- verify the connected equipment is working properly
...and repeat until you've cleared the first switch. Make sure the switch is flashed with the lastest firmware and that all the ports are functional.
Step 3: Methodically move patches back to the empty switch, consolidating things as you go so you don't have to cross-patch between racks. Take care to update your documentation as you go.
This would also be an excellent opportunity to establish some cabling standards; you can use color-coded cables to identify critical equipment or individual VLANs, for example.
One thing you should certainly do is label both ends of every cable with a serial number so it will be easier to chase things down in the future (you'll find several good suggestions here). It's good to have documentation, but even better to be able to easily verify that the implementation matches the documentation before you need to move a cable...without having to painstakingly trace the path of the cable from one end to the other!
Once you have your first switch populated with newly-labeled cables, you can pat yourself on the back, take a picture of your neatly-cabled switch, and use it as motivation to come in the next weekend and knock out another switch or two!
The important thing is to keep at it--the first switch will take some time, but as you work though the process you will get more efficient at it and be able to complete more work the next weekend you come in. You won't get it all done in one weekend, but within a couple of months you should have everything cleaned up, have all your patch cables serialized, and your documentation complete.
The hard part is having the discipline to update the documentation as changes and additions are made.
Search ServerFault for questions tagged cable-management for some excellent ideas!
Best Answer
Yes - if I understand you correctly.
Nothing stopping you purchasing a patch-panel then running 48 CAT5's out of the back of the panel (punched in to the panel of course) in a bundle. You then just crimp RJ45 on the end of each of the 48 cables.
If you want to keep the job to a minimum you could purchase 48 patch cables and hack the ends off of them, then just buy a punch-down tool. Crimping RJ45 connectors (in my opinion) is not to be tackled by someone inexperienced as a marginal cable plugged in to a server = disaster. You have less change of getting a punch-down wrong.