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.
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.
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:
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 […]
The post Show 171 – Cisco FabricPath Deep Dive Part 2 appeared first on Packet Pushers Podcast and was written by Ethan Banks.
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.
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!
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
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…
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…
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…
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!
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 […]
The post Hadoop for network engineers part 2 – adding more nodes appeared first on Packet Pushers Podcast and was written by JR Mayberry.
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 […]
The post Show 170 – The Spanning Tree Story and More SDN Analysis appeared first on Packet Pushers Podcast and was written by Greg Ferro.
How does the internet work - We know what is networking
EIGRP internals and getting hands dirty in debugging routing adjacency and solving EIGRP neighboring issues. What is sequence TLV and Conditional Receive CR-mode and CR flag Couple of days ago I got a strange network behavior in my CCIE lab. Something was wrong between a router and L3 switch connection and there was EIGRP neighbor […]
It seems appropriate to write a FFF post about Virtual Extensible LAN (VXLAN) now since VXLAN is the new hotness in the data center these days. With VMware’s NSX using VLXAN (among other overlays) as a core part of its overall solution and the recent announcement of Cisco’s Application Centric Infrastructure (ACI) and the accompanying Nexus 9000 switch, both of which leverage VXLAN for delivering a network fabric, it seems inevitable that network engineers will have to use and understand VXLAN in the not too distant future.
As usual, this post is not meant to be an introduction to the technology; I assume you have at least a passing familiarity with VXLAN. Instead, I will jump right into 5 operational/technical/functional aspects of the protocol.
For more information on VXLAN, check out the draft at the IETF.
Despite the apparent ubiquity and fervent hype around VXLAN, it’s actually been designed to solve specific problems. It has not been designed to be “everything to everyone”.
The first, and most often cited, use case is for data center operators that require more than ~4000 logical partitions in the network. These 4000 partitions equate to the maximum number of Continue reading
It seems appropriate to write a FFF post about Virtual Extensible LAN (VXLAN) now since VXLAN is the new hotness in the data center these days. With VMware's NSX using VLXAN (among other overlays) as a core part of its overall solution and the recent announcement of Cisco's Application Centric Infrastructure (ACI) and the accompanying Nexus 9000 switch, both of which leverage VXLAN for delivering a network fabric, it seems inevitable that network engineers will have to use and understand VXLAN in the not too distant future.
As usual, this post is not meant to be an introduction to the technology; I assume you have at least a passing familiarity with VXLAN. Instead, I will jump right into 5 operational/technical/functional aspects of the protocol.
For more information on VXLAN, check out the draft at the IETF.
GNS3 has been a crucial tool used by many network engineers to emulate computer networks. It has proven to be fundamental studying for all network certification levels such as CCNA, CCNP and CCIE. It has been crucial for network design validations within many companies. With the news of Cisco’s VIRL, many said that GNS3 will disappear, but that doesn’t seem to be the case. GNS3 is going through a major redesign and needs the help of all the engineers that it helped over the years.
Recently, Stephen Guppy from GNS3.net contacted me about some of the changes coming to GNS3. He was very excited to share with me the new direction they are heading and the croudfounding campaign going on. These new software improvements incorporate:
Switching has been a major feature preventing network engineer from exclusively using GNS3 for their certification study. The difficulty in supporting switching platforms is that most of their ASCIs were build on proprietary hardware and can’t be easily ported. With the new GNS3, switching will be supported using L2IOU. Some features are not supported Continue reading
In my last blog post I described how to set up SSH with TPM-protected keys. This time I'll try to explain how it works.
The SRK is a public key pair that is the main secret inside the TPM chip. It is always generated by the chip, and the private key cannot be read or migrated.
In order to use the SRK key with any operation, the SRK password must be supplied. The SRK password is just an access password. It's not related to the key itself. The SRK password is usually set to the Well Known Secret (20 null characters), or sometimes the empty string, or something silly like "12345678".
There is not much point in having a good SRK password, since you probably have to store it on disk somewhere anyway, to allow TPM operations by daemons.
If you want a password then you probably want to set that per key, not chip-wide like the SRK password is.
The stpm-keygen binary asks the TPM to generate a key, and the TPM
hands back the public portion of the key, and a "blob" that has no meaning to
anyone except the TPM. The blob is encrypted Continue reading
In my last blog post I described how to set up SSH with TPM-protected keys. This time I'll try to explain how it works.
The SRK is a public key pair that is the main secret inside the TPM chip. It is always generated by the chip, and the private key cannot be read or migrated.
In order to use the SRK key with any operation, the SRK password must be supplied. The SRK password is just an access password. It's not related to the key itself. The SRK password is usually set to the Well Known Secret (20 null characters), or sometimes the empty string, or something silly like "12345678".
There is not much point in having a good SRK password, since you probably have to store it on disk somewhere anyway, to allow TPM operations by daemons.
If you want a password then you probably want to set that per key, not chip-wide like the SRK password is.
The stpm-keygen binary asks the TPM to generate a key, and the TPM
hands back the public portion of the key, and a "blob" that has no meaning to
anyone except the TPM. The blob is encrypted Continue reading
