I have about 1000 branches in my network. Each of these branch has more than 50 users. Unfortunately, all of them have layer 2 D-Link switches to connect them to the router. We have had many issues dealing with these switches.
Every now and then we receive calls from users of the branches complaining that they are not able to connect to LAN. 90 out of 100 times the issue is with the switch. Sometimes, a reboot helps, sometimes not.
What we do is we ask the local engineer to manually remove the cables one by one. Simultaneously, we check the arp entries on the router.
Initially, it show some users (sometimes no users except router itself) connected. It happens that one of these many number of cables when removed from switch, the arp entries are instantly filled up on the router. We have been itching our knees to find the root cause of these type of issues.
I'm not sure whether it is because of loops,broadcasts, viruses etc. The server rooms are not visited by anyone at the branches except our permission so there is less chance of cables causing the loops.
Kindly help me out on this issue.