Monthly Archives: April 2013

Mininet – Software Defined Networking

Mininet

Mininet is a network emulator written in Python. With it you can create a test network consisting of many devices, for example inside your laptop.
It’s a lot more light-weight compared to emulating switches/routers in GSN3. Initially Mininet appears to be more about easily getting working network rather than tinkering with all the features of devices, but OpenFlow has a lot of nifty capabilities that Mininet makes it a lot easier to explore.
Anyway I think it’s great that there are free software tools to learn how to setup the network.
Check out the link below, there are some assignments that are used at Stanford about how to create your own link state routing protocol. Cool!

It’s easy to set up a network with many switches, routers and hosts. You can specify packet loss, queue size and delays on links.

They did some tests between ssh and mosh, to see how much better mush was when there were packet loss or delays.

You could deploy a setup similar to what you’ve tested inmininet, with real products. OpenFlow is used in both mininet and in the real products :)

Install the mininet VM and test it!

There are many ways to install mininet. They provide a VM that you can boot or you can install it in your OS, but it requires root access.

They got a walkthrough that is quite a nice intro to how to set things up mininet.

A note when using the VM image: If you’re already running Linux, for example I run Ubuntu on my machine all I had to do was to “ssh -X mininet@ip-to-vm” to be able to run wireshark in the vm. That’s a capital X.

 

SDN –  software defined networking

Some sources of information:

http://mininet.org/ – The network emulator

https://github.com/mininet/mininet/wiki/Documentation – On the github there are assignments that you can use to learn more about mininet.

https://www.coursera.org/course/sdn – On Coursera there is a free introduction course to SDN starting May 27! I’m joining it, are you?

http://www.opennetsummit.org/archives-april2013/ Free presentations about SDN inside.

http://tech.slashdot.org/story/13/04/29/2324200/inventor-of-openflow-sdn-admits-most-sdn-today-is-hype SDN is just a hype?

Command View P6000 EVA Simulator 10.0

Due to somewhat popular demand here’s another post detailing the steps for somewhat successfully installing HP P6000 Command View Simulator on Windows 7 x64. It can be a bitch.

The older post is from 2011 with CV 9.4, this one also has PA – performance advisory bundled.

  • Download: http://software.hp.com
  • Two files: EVA Simulator 10.0 (Z7550-00252_EvasimInstaller_100fr_v1.exe) and a readme
  • There is an e-mail listed in the readme!
    • But if you want to, you can put in a comment below saying how sexy I am :p
  • The readme is quite long but most of it is about how to use the PA (performance analyzer), Appendix B is a required read. It describes how to add the Groups so you can log on to CV.
    • A previous blog post by myself truly also goes through how to add a user group :)

For lazy hounds:

  1. (optional) Disable UAC in Windows and make yourself admin.
  2. Put an account in the Windows Group called “HP Storage Admins”.
  3. Launch the downloaded file (it extracts a setup.exe and .msi file)
  4. Launch setup.exe – it’s located in the same directory where you launched the Z7550-00252_EvasimInstaller_100fr_v1.exe
  5. Next, next, next, next, yes, yes, Wait, yes, Installed!
  6. Try out the “Start HP P6000 EVA Simulator” new icon on your desktop, does it work? Profit!

“XF application has stopped working” – some friendly error I got and CV simulator did not start.. Most likely permission issue. Peaking through one of the command-prompts it repeats access denied.

It’s amazing that the CV simulator still relies on .bat scripts. Guess it’s for backwards compatibility with XP and Vista? Only one file necessary for all those Windows OS variants.

With default Windows security, the Simulator runs into a problem when it tries to write to files under c:\program files (x86)\ . There are probably many ways to remedy that, one might be step 1 above. This worked:

  1. Go to C:\Program Files (x86)\Hewlett-Packard\HP P6000 EVA Simulator\evasim
  2. Right-click on ‘start_bundle.bat’ and run it as an administrator. This should start the simulator.
  3. Open up a command prompt with Admin Privileges, cd your way into evasim directory and type: “start startcv.bat”
  4. That should launch the Command View process and also IE pointing to CV.
  5. If not, point your web-browser to: https://localhost:2374/SPoG/ or https://localhost:2374/
  6. Log in with the user/password you added into the “HP Storage Admins” group earlier.

Some tips:

In one of the “DOS” windows, there might be more clues as to what’s going on.

Open a command prompt with admin privilieges by typing “cmd” in the search bar then right-clicking and starting as administrator.

Inside the Simulator DOS prompt you can hit enter and if you see some commands (save, stop, exit, start) then that’s the simulator window.

If you want your changes to be kept, type “save” in the simulator window before quitting.

Some thoughts:

It feels a bit ruggish. I bet this whole mess could be improved quite easily with some decent scripts. Here’s one I’d like to see:

if $os == Win7:
    if $write_read_permissions_in_program_files != "allowed":
        print_in_big_letter("You need more axx! Do $THIS")
        exit_everything_and_die

 

Studying for BCNE – Brocade Certified Network Engineer

In early April of 2013 Brocade had a great offer – ask for it and you’ll get a voucher to an exam – for free!

I took them up on their offer and scored a voucher for the BCNE – Brocade Certified Network Engineer.

After that I noticed that Brocade also has a limited offer for BCNE http://www.brocade.com/education/CNE_250.page , you can take them up on it if you already have a CCNA. By doing that you also get a free voucher to the BCNE exam..

I chose to try it without the recommended course. A bit risky but a long time ago I took the CCNA and passed. For me this exam was probably more about remembering and looking at improvements to all the things in CCNA back in 2005. This post is about my study technique or perhaps more of a record of how I did things. To find places for improvement.

Do you have any study tips you would like to share?

Some really useful links:

  • BCNE in a Nutshell guide – It’s also available on their saba/education page. But it’s out of date in there.
  • Brocade IP Primer – this is a great refresher on most Ethernet things if you’ve been out of touch.
  • Go through the manuals – but read the material in the newer released manuals.
  • IP Quick Reference – CLI Quick and quite comprehensive overview not only of commands but also of technologies.

http://community.brocade.com/docs/DOC-2613 has the list of pages and manuals and guides, but to get the newest documents you have to look elsewhere.
One place to get them is on each Product’s page on brocade.com, at the bottom there is a place to get some manuals.

First thing I did before diving into the materials was to take the BCNE Knowledge Assessment test. Get some sort of idea of what kind of topic the exam is about.

Then I read the nutshell guide and marked the things I needed to learn more about (basically all). Last time I took an exam with Brocade I only read the nutshell in the beginning of my study time, this time I’m re-reading it every now and then to see if I catch something that is not clear and I want to focus extra on. I’m also keeping a focus on the objectives of the exam. Reading the objectives and trying to answer them with as much detail as I can.-The objectives are general so there’s quite a lot of room for freedom there. As a bonus, if you can’t describe something in the objectives well, you just found something you do not know well  enough.

After going through the nutshell guide and checking up on a few acronyms and technologies I hadn’t heard about I read through the IP Primer and did the same things there: Mark the things that I thought would be of interest and what I would need to dig deeper into.

Then went through the NetIron and FastIron configuration guides. Not only did I have a peak at all the pages that were listed as relevant, but also read chapters that was not listed. Either because I found them interesting or perhaps because the subject in those chapters are touched upon in Nutshell. To me that just means the more you know about the subject the better.

Rehash objectives/previous notes and dig deeper. Perhaps first time you read it you glanced over some part. By digging deeper I mean finding the chapters in all the manuals that touch on this subject and reading them, making more notes. Could also be surfing the Internets or Wikipedia for basic overview of how a technology operates. Eventually all of this crystallizes into a view that describes things in your own words.

To me there are parts of IT exams that you just can’t know even if you’ve been working with it for a long time. For example license options or feature differences between all the products. To learn things like these (also other types of questions I thought would come on the exam) I made flashcards in a spreadsheet and printed it on normal A4 so that the question is on one side and the answer is on the back. This was no easy feat.

After going through all these documents you should be able to figure out yourself which areas are being focused on – which you should be making sure that you know.

Some good articles/blog posts:

P.s. I passed :)