Networking Lab Experiments

Today I went out and got a table to get my rack of Cisco gear off the floor. I first went to Lowe's and bought a 5 foot long folding table but it turned out to be a little too long, so I returned it. I wound up getting a Husky portable workbench at Home Depot. It seems quite sturdy and I'll probably get a good amount of use from it, and not just to hold up old networking gear.

(There's a mirror on the wall behind the Cisco gear, courtesy of our house's original owners. It'll be replaced with drywall when we redo the room.)

The power strip that everything is plugged into came from Lowe's this morning. It's their Utilitech house brand and has two USB ports for charging devices. I should be able to power a Raspberry Pi off it.

I was working on switch configuration, including VLANs, so I wanted to have more than one computer so I could verify connectivity between hosts was working (or not working, depending on how things were setup). So, I dragged out my old MSI Wind netbook, running Windows 7.

Well, something is hosed up with the networking on it so I decided to dual boot it with Lubuntu Linux. Nowadays my work with Windows is infrequent enough that fixing issues is more of a PITA than it should be, so I figured that Linux would be less trouble.

All my config work was performed using the MacBook Pro, accessing the switch through ZOC and a console cable.

Some Hands-On Cisco Troubleshooting Today

Today I got to put into practice at work some of the stuff I've been reading up on. I was configuring the integrated lights-out management ports on some HP DL360 servers, but could not access them over the network. The network engineer I work with gave me access to the Cisco 4948 switch that the servers are connected to, and I experimented with port speed and duplex settings to no avail.

I pulled up the running config and noticed that the VLAN trunk port from the switch back to the Juniper MX480 router we're using was misconfigured. The original port config looked like this in part:

interface TenGigabitEthernet1/49
 switchport trunk allowed vlan 100-103
 switchport mode trunk

It should have looked like this:

interface TenGigabitEthernet1/49
 switchport trunk allowed vlan 100-104
 switchport mode trunk

Difference in bold.

In other words, van 104, which carries the iLO traffic, wasn't being trunked back to the router, so it wasn't accessible from anywhere else on the network. As soon as I added vlan 104 to the trunk port I was able to ping the iLO ports from outside that vlan.

I have to say, I feel pretty good about myself for catching that.

Cisco Lab

The equipment I ordered to use in my CCNA studies arrived yesterday. As expected, the switches and routers show some wear but overall, they look to be in good shape. The 12U rack is new and went together without too much trouble. It came with a bag of 8x32 rack screws.

I mounted the three Catalyst 2950 switches at the bottom. Incidentally, the auction description said that they would be 24-port switches, but as you can see from the picture, I was shipped 48-port units. I suspect that's what the seller had handy.

Because of how Cisco designed the 1841 router case, I mounted them backwards in the rack so that I have easy access to the ports. I decided to leave 1U between them for routing the power cords. I still have room for a couple more devices such as a server or a 1U power strip.

ASSuming I get the CCNA, if I go on towards my CCNP I'll probably replace at least one of the 2950s with a Layer 3 switch that can route traffic between VLANs. That's a little while down the road, however.

I plan to fire up everything after work tomorrow.

Teaching An Old Dog New Tricks

One of the challenges of a career in IT is keeping up to date and learning new skills. For the past 14 months or so, I've managed the primary lab/data center at my employer's corporate HQ, but have relied upon a couple other guys to handle the network. I'd like to take over the network, which mostly runs on Cisco equipment. So, I decided it's time to get my CCNA certification as a way to get my feet wet.

For texts, I went with Wendell Odom's CCNA Routing and Switching 200-120 Official Certification Library. Additionally, the Free CCNA Workbook site has a variety of lab exercises to do.

Although I'll be able to work on real equipment I felt it would be prudent to learn on gear completely separate from my lab network. My first step was to download and install the GNS3 router emulator on my laptop. I was able to find some usable Cisco images by exercising my Google-fu.

But I also wanted physical hardware to bang on. eBay is full of used Cisco gear. This post on Reddit was helpful in deciding what to buy (and what to avoid). Using that, I ordered a kit off eBay containing three Catalyst 2950 switches and three 1841 routers, plus various cables and T1 WICs, and a desktop rack.

One thing you need when working on initial device configuration and sometimes for troubleshooting is a console cable. Most laptops no longer have a serial port, so I and my coworkers have been relying on USB-to-RS232 adapters, mostly the Keyspan USA-19HS. However, I recently found FTDI chipset based USB-to console cables and got one of them. So far, it's been working fine in OS X Yosemite and El Capitan.