This post is going to provide a very basic introduction to configuring VRFs on Cisco IOS and Juniper's Junos. There's so many configuration combinations and options for virtual routing that it would be impossible to go through everything in great detail. At the end of the post I'll provide links to documentation where you can get detail if you want it.
Folks who think Authentication Header (AH) is a manna from heavens need to read the Bible again. Thankfully you dont find too many such folks these days. But there are still some who thank Him everyday for blessing their lives with AH. I dread getting stuck with such people in the elevators — actually, i dont think i would like getting stuck with anybody in an elevator, but these are definitely the worst kind to get stuck with.
So lets start from the beginning.
IPsec, for reasons that nobody cares to remember now, decided to come out with two protocols – Encapsulating Security Payload (ESP) and AH, as part of the core architecture. ESP did pretty much what AH did, with the addition of providing encryption services. While both provided data integrity protection, AH went a step further and also secured a few fields from the IP header for you.
There are bigots, and i unfortunately met one a few days ago, who like to argue that AH provides greater security than ESP since AH covers the IP header as well. They parrot this since that’s what most textbooks and wannabe CCIE blogs and websites say. Lets see if securing the IP header Continue reading
Often time I hear the term Openflow and Software Defined Networking Networking used in many different context which range from solving something simple and useful to literally solving the world hunger problem (or fixing the world economy for that matter). I often get asked to explain the various aspects of how Openflow is changing our lives. So here goes a explanation of the religion called Openflow (and Software Defined Networking) and various ways its manifesting itself in our day to day life. Again its too much to write in one article so I will make it a series of 3 articles. This one focuses on the protocol itself. The 2nd article will focus on how people are trying to develop it and some end user perspective that I have accumulated in last year or so. The last article in series will discuss the challenges and what are we doing to help.
The basic piece of Openflow is nothing more than a wire protocol that allows a piece of code to talk to another piece of code. The idea is that for a typical network equipment, instead of logging in and configuring Continue reading
Here's a summary of interesting articles/posts that I've come across in the last couple of weeks.
#!/bin/sh
#
# install this as .git/hooks/pre-commit to check Puppet manifests
# for errors before committing changes.
rc=0
[ "$SKIP_PRECOMMIT_HOOK" = 1 ] && exit 0
# Make sure we're at top level of repository.
cd $(git rev-parse --show-toplevel)
trap 'rm -rf $tmpdir $tmpfile1 $tmpfile2' EXIT INT HUP
tmpdir=$(mktemp -d precommitXXXXXX)
tmpfile1=$(mktemp errXXXXXX)
tmpfile2=$(mktemp errXXXXXX)
echo "$(basename $0): Validating changes."
# Here we copy files out of the index into a temporary directory. This
# protects us from a the situation in which we have staged an invalid
# configuration using ``git add`` but corrected the changes in the
# working directory. If we checked the files "in place", we would
# fail to detect the errors.
git diff-index --cached --name-only HEAD |
grep '.pp$' |
git checkout-index --stdin --prefix=$tmpdir/
find $tmpdir -type f -name '*.pp' |
while read manifest; do
puppet Continue readingAll network engineers should be familiar with the method for virtualizing the network at Layer 2: the VLAN. VLANs are used to virtualize the bridging table of Layer 2 switches and create virtual switching topologies that overlay the physical network. Traffic traveling in one topology (ie VLAN) cannot bleed through into another topology. In this way, traffic from one group of users or devices can be kept isolated from other users or devices.
Traffic Isolation Using VLANs
VLANs work great in a Layer 2 switched network, but what happens when you need to maintain this traffic separation across a Layer 3 boundary such as a router or firewall?
There are very few technologies that come along which actually make things easier for IT staff. This is particularly true with new technology introductions. Very often, the introduction of a new technology is problematic from a systems service up time perspective. With networking technologies in particular, new introductions often involve large amounts of intermittent down time and a huge amount of human resources to properly plan the outages and migration processes to assure minimal down time. More so than any other, network core technologies tend to be the most disruptive due to their very nature and function. Technologies like MPLS are a good example. It requires full redesign of the network infrastructure as well very detailed design within the network core itself to provide connectivity. While some argue that things like MPLS-TP helps to alleviate this, it is not without cost – and the distruption remains.
IEEE 802.1aq or Shortest Path Bridging (SPB for short) is one of those very few technologies that can introduced in a very seamless fashion with minimal disruption or down time. It can also be introduced with minimal redesign of the existing network if so desired. A good case point example is a recent Continue reading
The last time I upgraded Net-SNMP it wasn't reporting the hrSystemProcesses OID. I wrote about that here. This time around I've upgraded to v5.7 and discovered two issues so far.
This post is for anyone who administers a Juniper SSL VPN. I saw an issue in our environment recently that was created by an unexpected interaction between two different systems that were working to enforce our computer security policy. Because the way the systems were configured is pretty common and because the issue is not specifically warned against by Juniper, I'm going to share it here.