Routers & Switches & Connectivity Issues
May 13, 2012 Leave a comment
My help comes from the Lord, the Maker of heaven and earth. He will not let your foot slip—He who watches over you will not slumber (Psalm 121:1-3).
Friday, my workgroup had a 3AM maintenance window to addresss one network problem, and afterward I went to Bossier City, several hours away, to troubleshoot a different problem. The effort in Bossier City did not go smoothly, and I left thinking a problem could still exist. I could then access our equipment from my phone, so I returned to Baton Rouge with the hope of bringing my daughter to Disney on Ice as planned and continue troubleshooting later. I was blessed this morning by revelation of other lessons learned by not so smooth maintenance efforts. Once, 10 years or so ago, I went to the then Governor’s home with his representative who would later be appointed interim CIO of state IT. My network manager warned me to plan well: “You don’t want to have to go twice.” Of course, the trip went badly, and we did have to return the next day to get the problem resolved.
Simply put, for the Bossier City problem, we tested & sent over a network switch to connect our router to customer equipment, but after someone connected the cables and powered it up for us, we still couldn’t log on to it to be sure customer connections would work. We had an alternate plan for a customer moving in on Monday, but I really wanted to get the switch working. I estimated the work would take about 30 minutes, but I sat alone on the floor in front of my laptop for about 3 hours. There might have been a command line missing from the switch, but since I had to take other steps to get the fiber connection on the router to work, I’m not sure that I didn’t just search for the wrong word when looking for the potentially missing command. I could have made a typo or just used the wrong term. Finally, the switch started talking to the router, and I could proceed with testing internet access.
Internet access from the site worked when we finished installing the router weeks ago, but not Friday. I vaguely recalled, while troubleshooting the switch problem from our office, entering some commands to change the way the router talked to the switch. One of the things we do to connect our backbone (or major) devices to the internet is include them in a smaller set of addresses associated with the connection to our internet service provider. If a port on a backbone device is not properly associated, whatever is connected to it can talk to other routers in our network but not get to the internet. When you first start configuring one of these devices, the commands available are “global” meaning they are not specifically for one port or one process; like on a computer, different applications are used for different things, but all require the computer to be turned on (global). From global configuration mode, you can enter a different configuration mode to change the nature of a particular port or process, like opening a browser or game or MS Word. The available commands are generally different. The command to create one of these subsets of addresses is a global command: “ip vrf group-name”. To bring a device into that group, you enter interface configuration mode, and the command is slightly different: “ip vrf forwarding group-name.” Likewise, to remove a device from a group, the command is “no ip vrf forwarding group-name”. If you forget the “forwarding,” you might accidently delete the whole group; in our computer example, instead of just saying, no I don’t want to open Yahoo, you say, No, I don’t need internet, just take out the whole IE browser. So, on my Bossier City router, there was no group set up for internet access anymore, & I vaguely recalled entering the command without the “forwarding” once while troubleshooting the switch problem from the office. It took me quite a few tries to get the internet group set up again, but still I couldn’t get out to the internet. Some things looked right, though, so I tried to connect directly from the router using the same interface that was tested before. Still no. My work day had started very early, & I knew my mother did not want to take my girl to Disney on Ice, so I had to just leave.
On Saturday, after looking at some emails and requesting the additional work hours used, I logged into the Baton Rouge router to look from there – which I couldn’t do from where I was sitting in Bossier City. I saw a statement using the same address I was first attempting to use on Friday; this causes a problem for the router: as if while standing at your door talking to your neighbor, the phone rings, and it’s the same neighbor with no idea that you’re already in conversation. However, there was no statement regarding the 2nd address I’d tried. This morning I recalled that to connect a laptop to the small router we installed at Bossier City, a cross-over adapter is required to swap the transmit and receive signals. Some devices, such as our main router in Baton Rouge, will detect the type of device it is connected to and swap transmit and receive on its own. I’d thought about looking for that cross over adapter the day or so before the trip, but I didn’t. It might be in my laptop bag, but had I found it, I might have missed Disney on Ice instead of packing up, so praise God.
The Bossier City visit & followup work reminds me this morning of how many troublesome troubleshooting experiences I had early in my IT training (with much greater frequency then). My trainers let me walk through some messy installations and upgrades likely knowing the lessons learned alone in a room hours away from the office with limited or no network access might add more to understanding and troubleshooting skills than what is learned from just watching and reading – not that watching and reading aren’t necessary, too. It can be difficult to let someone walk through the process. I’m so glad they did, and I pray for wisdom in encouraging others through a similar process. Ezekiel 45-46 reviews rules for sacrifice for a generation in exile. So many details demonstrate faith in God, and help me perceive His holiness, a quality we can’t wholy attain in this life. I’m reminded the troubleshooting process undertaken by the Israelites from Abraham to the birth of our Lord Jesus took longer than anticipated and had unexpected results. In Hebrews 11, Paul writes of leaders of faith: Moses continued strong as if he could see the God that no one can see (Hebrews 11:27). It’s only reasonable that the birth of our Savior would follow the writings of kings, prophets, wars, captivity, and plagues. I’m so glad for Old Testament scripture, but I know without Jesus, I’d still be lost in sin without hope of being restored to the Father. In all my activities, I have joy knowing the Lord helps me grow in my walk, my training is to praise His Name, and my retirement will be with the angels in His glorious presence.
With the loving mercy of our God, a new day from heaven will dawn upon us.It will shine on those who live in darkness, in the shadow of death. It will guide us into the path of peace (Luke 1:78-79).


Acts 9:24-25 tells how Paul escapes an attempt on his life: “Day and night they kept close watch on the city gates in order to kill him. But his followers took him by night and lowered him in a basket through an opening in the wall.” Sometimes the wall is a hard head or a situation, but separation from God is still an attempt on our lives. Praise God for prayer opportunities, especially those at choice moments when we’re willing to accept a word from believers & be lowered to our escape route whose name is JESUS.