Cisco VIRL Experience

I've been using real Cisco equipment in my network labs for a while now and to a certain extent, especially when starting out, I firmly believe there is no substitute, however, over the past couple of years I have started to virtualize a lot of my lab.

A lot of this effort was driven by the need to use servers like LDAP, DNS, DHCP as a part of the lab network. Having a spare PC that I could use to run a number of virtual servers was handy. In fact the first PC I used for this was a Core2Duo machine with 8GB of ram in an SFF case! Not exactly a power house but did exactly what I needed.

So how does this relate to Cisco's VIRL? As I progressed in my studies, I started to need appliances and devices that I could not purchase inexpensively on ebay. Machines like the Cisco Nexus switch were ( and still are) way out of my price range for a lab. Not to mention, I don't really have the space for a 7k chassis!

Which is where VIRL comes in. The application allows the use of real Cisco images, legally, that can run on a PC. I have tried all three versions over the past 12 months. Initially I used the ESXI version on the aforementioned Core2Duo most, under ESXi 5 and 5.5 but that was not satisfactory. This was late 2016 and I found the use of Maestro horrible at best.

I then attempted an install on my i5 desktop under VMWare Workstation 12 and that wasn't much better. In both cases the issues were the NIC configs which seemed extremely picky and often failed, and the communication between Maestro and the VIRL server.

Eventually I settled on a dedicated host with a bare metal install which worked very well. Once I had this working, I found the simulator quite satisfactory.

Fast forward to October 2017 and I am looking at reducing the physical size of my lab. I hadn't used VIRL for a few months and decided to get it up and running again. So first I check to see if there are new versions and there are! Not only are there new versions, but it appears that Cisco have really trimmed the fat a lot. I opted to down load the new 1 NIC VMWare Workstation version and install on my desktop machine. This was much easier than in the past, and the VIRL server appears to use considerably less resource than its previous versions. This has enabled me to eliminate the stand alone VIRL server, eliminating an entire box from the lab.

So far I have only managed to perform one quick simulation but from that I was able to say that it is still slow to start and stop (i5, 32GB RAM and 256GB SSD) but certainly fit for purpose for my needs.

EIGRP Routing on a Cisco 3550

This evening I was trying to get a Cisco 3550 switch (EMI) to form an EIGRP adjacency with a router directly connected to it. However, I kept getting the following syslog message:

%DUAL-5-NBRCHANGE: EIGRP-IPv4 10: Neighbor 172.26.6.9 (GigabitEthernet0/0) is down: retry limit exceeded

... and the ip route command showed nothing. Same with show eigrp neighbor and topology command. So what was going on?

Router neighbors

I ran the debugs on both the router and switch, and that showed me nothing.  I checked all manor of protocol settings, rebooted both devices, checked CPU usage etc.

I could ping the router from the switch and vice versa, so what was I doing wrong?

I had missed one vitally important step when using L3 capability on a switch; I had neglected to enable the routing.

As soon as I issued the command ip routing, my neighbor adjacencies came up and my route tables now held the correct shared routes.

So, what was it that tipped me off? I was checking to see if the switch was enabled to handle multicast traffic. Now this is important because the EIGRP routing updates are multicast. The way to do this is to type:

(config)# ip m?

and you will see the multicast commands listed. I did not see that, in fact I saw nothing. So I backed up a little and typed:

(config)# ip ?

and as I was scrolling through the list of possibilities, I saw, routing ... and my memory was jogged.

Sometimes you just have to remember the basics!

Cisco 1841 Memory Upgrade

If like me, you like to browse eBay for cheap gear, for your Cisco lab, then you have very likely looked at the Cisco 1841 router. Many are advertised as having IOS 15, but beware; they often don't have enough memory to run. IOS12 will run on 128MB but IOS15 requires the full 384MB in order to run correctly.

This is what happens when you don't have enough memory:

Crash caused by lack of memory

This has happened to me twice now; twice I have purchased 1841's with IOS 15, and twice they have not had the required amount of memory to run IOS 15.

My first 1841 came with IOS12 and 15 so I just dropped back to 12. This is currently my home router. My latest purchase needs to run IOS15 for my lab work, so I decided to try a memory upgrade.

Memory prior to upgrade

This is the Cisco page showing how to add the additional memory. It is very straight forward requiring only the removal of one screw to get the box open.

Of course you can't just throw any old memory in there. The 1841 comes with either 128MB or 256MB of DRAM, with a single slot for upgrading to 384MB. In my case I have 128MB so I needed a 256MB ram module, and after a little research, this is the one to get.

Installation took maybe all of 5 minutes, and the router is up and running again:

Memory post upgrade

And that is all there is to it. I've been working with the router most of the day, and so far run into no issues with functionality or with the extra memory.