While working at a customer site, I overheard some technicians complaining about an upcoming cutover. Their main concern was that many of the cables connected to the switch were not documented. At one point a tech remarked, "I wonder how many of those connections are even in use?".
They did not want to blindly move the cables and configuration over since they suspected that the majority of the ports were not in use. They suspected could get away with less equipment resulting in less space, etc. I asked how much time we had before the cutover and was surprised to hear that we had 1 month, but that included ordering new equipment.
Of course, we started with the basics;
- We noted which ports did not have link lights. I found out that This proved unreliable since many of the staff are nomadic and are not permanently at their desks. To complicate things further, many of them who were at their desks, used their wireless connection, since it was more convienant.
- we traced the cables that terminated at a punch-down block or patch panel. Unfortunately, the majority of the cables went up into the ceiling tiles, or under the raised floor.
- lastly, many of the office cubicles and desks were blocking the wall jacks.
I suggested that they take their current methodology a step further;
- Use the port description field within the switch config to "label" all known ports.
- Clear the port counters
- Then we can check the interface statistics to see if any of these ports had any traffic, and check the 'cam' table to get the mac address. Then we check the DHCP database to get the users information. Finally, we fill in the switch port description field and clear the port counters again.
- Then I told them that I could easily write a small perl program that will do this every hour and log the findings.
- I recommended that they also send out an email blast to all laptop users to use their wired connection as much as possible for the next few days.
I also had my Fluke Optiview Integrated Analyzer (INA) performing an inventory scan, which identified switch port, MAC address, IP address and machine name to ensure we didn;t miss anything.
I explained that this tool made the manual/perl script process a little easier. I also proved that the manual method was as accurate as the INA since we used some of the same methodologies.
Within a week, we had identified and labeled approx 80% of the connections and physically unplugged all connections that were not in use. At this point, it was easily to determine that we only needed HALF the number of switches, with plenty of extra ports. This saved them a considerable amount of time, money and more importantly - space.
Now the biggest issue remaining was deciding who would come in on the weekend to do the work. Unfortunately the cutover fell on one of our Canadian long weekends, so they were no takers. Since I was the closest to the office, and was confident that the cutover would go quickly, I volunteered to come in. They asked who else I would bring since there was a considerable amount of work to be done.
I explained that since the cables were labeled and the new switch was already configured and mounted, I would bring my neice in with me and we 'should' be done within an hour.
They chucked with the typical, "yeah right".
My neice, Monica came in with me on the Sunday and we noted which ports were active and cut them over first and ensured that the link lights all came on. Then we proceeded with moving over the remaining connections, rerouting the odd cable and tidying things up.
We were done within an hour and were home for dinner with time remaining.
I have concluded that networking is very simliar to home renovation. If you take the time to do your homework and put a plan together, you will spend less time doing the actual work, but will have less surprises along the way.
Author Profile - Tony Fortunato is a Senior Network Specialist with experience in design, implementation, and troubleshooting of LAN/WAN/Wireless networks, desktops and servers since 1989. His background in financial networks includes design and implementation of trading floor networks. Tony has taught at local high schools, Colleges/Universities, Networld/Interop and many onsite private classroom settings to thousands of analysts. Tony is an authorized and certified Fluke Networks and Wireshark Instructor. His Pine Mountain Group CNA Level I and II certification demonstrates his vendor neutral approach to network design, support and implementations. Tony has architected, installed and supported various types of Residential Wireless High Speed as well as hundreds of WIFI hotspots. Tony uses a variety of technologies from Powerline, Wireless and wired technologies to find the most cost-efficient and reliable solution for his customers. Tony combines custom programs, open source and commercial software to ensure a simple support infrastructure.