IPv6 for future CCNAs (+), Final Part.

Unicast Addresses: Unique-Local.
Before we talk about Unique-Local Addresses (ULA), let me tell you about Site-Local addresses; it was deprecated in favor of the ULA back in 2004 because the term “site” was too ambiguous, no body agreed upon a clear definition of the term “site”; what was considered a “Site”?
Also, the provability of Site-Local address being globally unique were no that high, as opposed to ULAs.
ULAs are meant to be routed within an organization’s LAN or even WAN, but they are not routable over the public network (Internet), hence, you can think of ULAs very much as IPv4’s Private addresses.

Continue reading IPv6 for future CCNAs (+), Final Part.


IPv6 for future CCNAs – Part II

In IPv6 for future CCNAs – Part I, we ended the article talking, very lightly, about IPv6 address types. Let´s go ahead and dig deeper into the concepts.

To recap, the IPv6 address types are:

One-to-one communication. Unique address assigned to an interface, a packet sent to a Unicast address will be received by one single interface. There are several types of Unicast addresses:


IPv6 – for future CCNAs – Part I

The History:
So we are running out (have ran out?) of IPv4 addresses. They have been with us since the very beginning, they were there during the 1980`s when everything was calm, and they stuck by us during the chaotic growth of the Internet during the 1990`s. There were some rumors, during the 2000`s, that they were going to run out soon, but something called Classless Inter-Domain Routing (CIDR) and Network Address Translation/Port Address Translation (NAT/PAT) saved our butts… for a while.
These 4 little sets of numbers, called Octets, separated by dots were very mysterious, we used to look at them from the corner of our eyes asking our selves; What are they for?… What do they do?… How do they do it?
We were intimidated just by looking at them, and they were just 4 little sets of decimal numbers, numbers that we recognize, that we use every day in our daily lives.

Continue reading IPv6 – for future CCNAs – Part I

Spanning Tree Protocol, from a future CCNA`s perspective.

Hi guys, this post got awarded “Best Publication” at the Cisco Support Community”!  Thanks a lot.

community spot light

A little bit of history:
Before we talk about Spanning Tree Protocol, let’s organize the different variants of STP. The original STP was developed by Radia Perlman while working for DCE back in 1990. At this time there were no switches yet, only bridges, but because bridges and switches technically do the same job -only switches do it more efficiently and have more features- they suffer from the same issues. Also, because STP was developed during a time when therewere only bridges, the terminology used in STP, even today, makes reference to bridges a lot (Root Bridge, Bridge-ID, etc.). So, when you read about STP from different sources, remember that the terms Switch and Bridge might be used interchangeably.

Continue reading Spanning Tree Protocol, from a future CCNA`s perspective.