HTIRW: Overview


Okay, so we all know some little slice or another of the Internet. But how do all these slices really fit together? How does … [Read more...]

Windows ISATAP Client, Part 1

Last month I had the opportunity to work with a company to perform an IPv6 pilot.  There are a lot of elements to light up … [Read more...]

Cisco Internal VLAN Usage


About a month ago I worked on an old CatOS switch. Working on this switch reminded me about some of the differences between … [Read more...]

Ordered FIB


In a past post, we’ve discussed microloops in link state protocols. If we examine a small ring topology (if you come to my … [Read more...]

Secret CEF Attributes Part 6, The BGP Connection

In the first five parts of this series we covered all the steps necessary to distribute QoS and monitoring to a large … [Read more...]

Using Next Generation MVPN to optimize your MPLS core – Part 1


Like many network engineers I have had difficulties with multicast, the logic is all messed up right!? The only … [Read more...]

Secret CEF Attributes, Part 5

So far we've explored some very cool features of CEF and the attributes we can push into the FIB to identify certain kinds of … [Read more...]

Secret CEF Attributes, Part 4

In Parts 1, Part 2 and Part 3 we saw we can use the CEF table to express all sorts of different QoS policies. In Part 4 we … [Read more...]

Out with the old, in with the new


A few weeks ago I was asked to help a client turn up and move everything over to a new network. I have done this many times … [Read more...]

CEF Secret Attributes, Part 3

In Part 1 we saw we can mark prefixes in CEF with certain attributes that might give us interesting things to play with. In … [Read more...]

FAT or Entropy Label?

FAT Label

In this article we are going to see two features that improve the load-balancing in the MLPS Core. Why? In the networking … [Read more...]

BGP Path Hunting/Exploration


 Only one change or link flap can cause one hour or more traffic drop.  It is weird, right? But this is true. In this … [Read more...]

CEF Secret Attributes, Part 2

In Part 1 we saw there were three markings that can be potentially applied to a prefix in CEF. They are the Precedence, … [Read more...]


2014-01-13 fig01

Don’t look now, but you have microloops. How do I know? Because virtually every network with rings larger than three hops, … [Read more...]

Secret CEF Attributes, Part 1

Welcome to the first in a series of articles that will explore some of the interesting properties we can insert into CEF, … [Read more...]