On Link in IPv6
As an avid reader of RFCs and RFC drafts, I’m always running across little bits of knowledge I either already knew and forgot (I forget a lot of things), or things I didn’t know and wouldn’t have expected. RFC5942, published way back in 2010 (a long time in network engineering terms), discusses a topic I […]
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How Does QoS Work?
This sponsored blog post was written by Clark Zoeller, CCIE #13760, Sales Engineer with ActionPacked Networks. Quality of Service (QoS) is a suite of technologies used to manage bandwidth usage as data crosses computer networks. Its most common use is for protection of real-time and high priority data applications. QoS technologies, or tools, each have […]
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The post How Does QoS Work? appeared first on Packet Pushers Podcast and was written by Sponsored Blog Posts.
Configuring SNMPv3 On NX-OS
We’re currently trying to allow a client to perform an operation using SNMP set commands on a Cisco NX-OS switch (namely a 5548).
It’s possible using SNMPv2c and community strings, but this does not generate a log message, making it completely unaccountable. SNMPv3 seems to have the answer. According to the documentation, it provides:
- Integrity
- Encryption
- Authentication
I’ve tested using a set operation to change a MIB using the following command:
snmpset -v 3 -u test -l authpriv -a MD5 -A Testpass01 -x DES -X Testpass01 hostname system.sysLocation.0 s TESTLOCATION
Which works fine.
However, the problem arises when trying to back off the authentication of the SNMP operation to TACACS/RADIUS. My interpretation of the documentation suggests this is possible. My Cisco SE has not denied it either. However, I reckon some changes need to be made to the authentication server. According to what I’ve read:
You can use the VSA cisco-av-pair on AAA servers to specify user role mapping for the Nexus 5000 Series switch using this format:
shell:roles="roleA roleB ..."
If you do not specify the role option in the cisco-av-pair attribute, the default user role is network-operator.
You can also specify your SNMPv3 authentication and privacy Continue reading
IPv6 at the OECD – A Public Policy Perspective on IPv6
The Organisation for Economic Co-operation and Development, the OECD, is a widely referenced and respected source of objective economic data and comparative studies of national economies and economic performance. The organization has a very impressive track record of high quality research and a justified reputation of excellence in its publications, even with its evident preference for advocating economic reform through open markets and their associated competitive rigors. OECD activities in the past have proved to be instrumental in facilitating change in governmental approaches to common issues that have broad economic and social dimensions. So how does IPv6 fit into this picture of OECD activities?Converging Skillsets With Technology
I saw this Engineers Unplugged video today and was reminded of a viewpoint I’ve been slowly developing over the last two years or so: Essentially the discussion is about convergence technologies like FCoE, where we rid ourselves of a completely separate network, and converge FC storage traffic onto our standard Ethernet network. With this technology shift, how does this impact the administration of the technology? Do the teams have to converge as well?Converging Skillsets With Technology
I saw this Engineers Unplugged video today and was reminded of a viewpoint I’ve been slowly developing over the last two years or so: Essentially the discussion is about convergence technologies like FCoE, where we rid ourselves of a completely separate network, and converge FC storage traffic onto our standard Ethernet network. With this technology shift, how does this impact the administration of the technology? Do the teams have to converge as well?Hardware – Clock and Data Recovery
Clock and data recovery is an essential physical-layer function of modern switch and router hardware. Digging deep into the electronics of a router may not be your thing, but clock recovery is a fundamental building block for other network hardware … Continue reading
The post Hardware – Clock and Data Recovery appeared first on The Network Sherpa.
IOS and NX-OS Platform Identifiers
I was preparing a presentation the other day about the high level differences between IOS, IOS-XE and NX-OS and one of the things I included in the presentation was the various platform and branch identifiers that’s used in each OS. It’s just a bit of trivia that I thought would be interesting and might come in handy one day. I’m posting the information I collected below so everyone can reference it.
IOS
For IOS, you can see the platform identifier in the filename and the “show version” output. If we take an example version string, 15.1(2)SG2, and break it down, here’s what each digit in the string signifies:
| 15 | .1 | (2) | SG | 2 |
| Major release number | Minor release number | New feature release number | Branch/train/platform identifier | Maintenance rebuild number |
The branch/platform identifier can also be seen in the IOS filename:
cat4500e-entservicesk9-mz.151-2.SG2.bin
Here’s a summary of the branch identifiers in IOS 15:
- M/T – 800 Series ISR, ISRg2 (1900, 2900, 3900), Connected Grid Router 2000
- S – 7600 Series Router, ME 3600X, ME 3800X
- GC – 5900 Series Embedded Router
- SE – Catalyst 2960, 3560, 3750, IE 3000 Switches
- SG – Catalyst 4500E (Sup 6E and earlier)
- Continue reading
Show 171 – Cisco FabricPath Deep Dive Part 2
Cisco FabricPath is a TRILL-based layer 2 forwarding technology that can take the place of spanning-tree. Allowing a fully-meshed layer 2 network to forward traffic across all links, FabricPath helps customers to make the most of their expensive 10GbE and 40GbE interconnects. In this show, Jamie Caesar, Colby Glass, and Ed Diaz discuss real-world FabricPath […]
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The post Show 171 – Cisco FabricPath Deep Dive Part 2 appeared first on Packet Pushers Podcast and was written by Ethan Banks.
IOS and NX-OS Platform Identifiers
I was preparing a presentation the other day about the high level differences between IOS, IOS-XE and NX-OS and one of the things I included in the presentation was the various platform and branch identifiers that's used in each OS. It's just a bit of trivia that I thought would be interesting and might come in handy one day. I'm posting the information I collected below so everyone can reference it.
Installing Pyenv on Mac OSX
When I’m writing code, I’m usually in OSX. When I want to try things out, or check for compatibility between certain versions of Python, it’s handy to have them all accessible… enter Pyenv. Pyenv is based on Rbenv, which for you non-Rubyists is a tools that allows you to set up Ruby environments that are scoped either globally, per-shell or per-folder!
If you aren’t using Homebrew already, which I highly recommend you should, then install it.
ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go/install)"
Before you start brewing you should run “brew doctor”. This will check that everything is ok with your installation.
brew doctor
Hopefully you will get a message “Your system is ready to brew”, otherwise doctor brew will oftentimes tell you what to do.
brew install python
brew install pyenv
The above commands will, install homebrew’s Python 2.7 (to replace the system pyhton) and install pyenv. Replacing the system Pyhton fixes issues with needing “sudo” for easy_install and others documented here
Now Pyenv is installed, you should edit your “~/.bash_profile” and add the following:
export PYENV_ROOT=/usr/local/opt/pyenv
eval "$(pyenv init -)"
This changes the Pyenv root path and makes sure pyenv is initialized.
$SHELL -l
Installing Pyenv on Mac OSX
When I’m writing code, I’m usually in OSX. When I want to try things out, or check for compatibility between certain versions of Python, it’s handy to have them all accessible… enter Pyenv. Pyenv is based on Rbenv, which for you non-Rubyists is a tools that allows you to set up Ruby environments that are scoped either globally, per-shell or per-folder!
Bypassing the memory check on a VMware ESXi 5
When my new HP ML10 arrived I was ready to install ESXi… until I realised that my 32GB of RAM wouldn’t be on its way for a week! To get around the memory check in ESXi 5.5, I found the awesome instructions here and with a few tweaks was able to get this working. Here are the 20 steps that I followed…
- Boot the system from USB Stick with ESXi installer on it.
- Once the installer welcome screen shows up, press ALT+F1
- Login as “root”, no password.
- cd /usr/lib/vmware/weasel/util
- Delete upgrade_precheck .pyc (compiled version)
- Move precheck.py to precheck.py.old
- cp upgrade_precheck.py.old upgrade_precheck.py
- chmod 666 upgrade_precheck.py
- vi upgrade_precheck.py
- Type “/MEM_MIN” and press ENTER
- Press “i” for insert
- Edit the line to read “MEM_MIN_SIZE= (1*1024–32)”
- Press ESC and then type “:w” and ENTER
- Press ESC and then type “:q!” and ENTER
- ps -c | grep weasel
- Note the process id for “python”
- kill –9 /<process_id/>
- This put me back at the main screen, but you can jump back pressing ALT+F2 if necessary
- Continue the install process
- Fin
Bypassing the memory check on a VMware ESXi 5
When my new HP ML10 arrived I was ready to install ESXi… until I realised that my 32GB of RAM wouldn’t be on its way for a week! To get around the memory check in ESXi 5.5, I found the awesome instructions here and with a few tweaks was able to get this working. Here are the 20 steps that I followed…
Installing Pyenv on Mac OSX
When I’m writing code, I’m usually in OSX. When I want to try things out, or check for compatibility between certain versions of Python, it’s handy to have them all accessible… enter Pyenv. Pyenv is based on Rbenv, which for you non-Rubyists is a tools that allows you to set up Ruby environments that are scoped either globally, per-shell or per-folder!
Bypassing the memory check on a VMware ESXi 5
When my new HP ML10 arrived I was ready to install ESXi… until I realised that my 32GB of RAM wouldn’t be on its way for a week! To get around the memory check in ESXi 5.5, I found the awesome instructions here and with a few tweaks was able to get this working. Here are the 20 steps that I followed…
Install Open vSwitch v2.0 from RPM on RedHat Fedora
This post is for installing OVS from RedHat RPM binaries. If you want to build Open vSwitch from source please see this post. Open vSwitch v2.0 introduces some really important features, at the top of the list is multi-threaded support in vswitchd. This will increase flow instantiation rates significantly into the upstream kernel module. A rough guess would be from ......
About Promotion
There is no such thing as career path.I wrote this several years ago. And I believe it's still true. For those who don't understand why I wrote such thing, please spend few minutes to read that blog post before leaving nasty comment. (This means: you still can leave nasty comment after reading that post :))
Allow me to share my secret: patience is not my virtue.
Every time I want to change to new position, or to new job title, I move to new company. Some of my previous employers offered me promotion the moment I gave them my resignation letter. Some of them simply didn't care and just let me go. For those who offered me promotion, I never accepted the offer. I thought they should have offered that while I was still with them, not at my last moment in the company when I usually had decided to leave.
There was a time I even worked as independent contractor. Had to deal with the customer directly, defined the scope by myself, set the performance index, and delivered end-to-end solution to customer. No job title. No career. Hmm, good old days. Even it was only for several months Continue reading
Hadoop for network engineers part 2 – adding more nodes
In the first article here, I walked through importing netflow data into a single Hadoop instance (pseudonode) and mentioned a progression of the project to add multiple nodes. The ability to do distributed storage and distributed processing of data is ultimately the benefit of using Hadoop/HDFS. So, let’s expand on the project and add one or […]
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The post Hadoop for network engineers part 2 – adding more nodes appeared first on Packet Pushers Podcast and was written by JR Mayberry.
Show 170 – The Spanning Tree Story and More SDN Analysis
This week it’s Greg was configuring spanning tree in the data centre and had a problem with a switch cluster that didn’t work proper. How much networking do you need in a data centre ? Lets say you purchases 2 x 32 port 40GbE switches (common Trident2 configuration) for USD$30K and you use QSFP breakouts […]
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The post Show 170 – The Spanning Tree Story and More SDN Analysis appeared first on Packet Pushers Podcast and was written by Greg Ferro.