An IT outsourced helpdesk service is working 24/7, which is something good for organizations and offices. I could remember a case where the web portal of the office and VPN went down altogether has every technician alerted on the wee hours regarding the problem. The downside of it is the whole offshore team is helpless as nobody could access the network.
Onsite technical support came during the office hours only to see that there seems massive network traffic. Internet network traffic overloaded due to flooding is a scenario that is catastrophic. That’s exactly what happened to our network infrastructure. Cisco catalyst switch was having 90% high utilization, which makes the whole network unusable.
The task is to isolate the VLAN one by one to identify and detect the source of this huge network traffic. There are several ways to do it, which is through physical pulling of the cables and another much better way is through identifying the rouge port from the switch.
Since, onshore team does not have the technical expertise on CISCO Catalyst Switch it was tried to contact some local network admin consultant. The approach was unsuccessful and nobody really has a choice, but to use the physical way of disconnecting the fiber-optic cable connection to the switch. This took a whole day to do due to the numerous mix of UTP and fiber optic cable connections.
Finally, at the end of the day, the rouge VLAN and the specific device which caused the network flooding was identified. Switch utilization was down to about 45% to 60%. We’re back to work the following day with some isolated area having no access to network and the internet; it’s better than the whole office without email, website, network and internet access.