Introduction Flex link is a Cisco solution which replaces STP in certain network topologies. It works by detecting link down on a primary interface and then bringing up the backup interface that has been defined as backup. It is most
Resilient Ethernet Protocol (REP)
Introduction I’m writing a short summary of REP as part of my CCDE studies. REP is an alternative protocol used in place of STP and is most often run in ring based topologies. It is not limited to these topologies
Detecting Network Failure
Introduction In todays networks, reliability is critical. Reliability needs to be high and convergence needs to be fast. There are several ways of detecting network failure but not all of them scale. This post takes a look at different methods
The history of Ethernet – DIX vs 802.3
I’m planning to do a post on BPDUs sent by Cisco switches and analyze why they are sent. To fully understand the coming post first we need to understand the different versions of Ethernet. There is more than one version?
Ethernet – notes
RJ 45 pinouts 10-BASE-T and 100BASE-TX uses pairs two and three, gigabit Ethernet uses all four pairs. Pinout for straight cable: 1-1;2-2;3-3;6-6 Pinout for crossover cable: 1-3;2-6;3-1;6-2 A standard PC transmits on pair one and two and receives on three
The facts of Ethernet – Round three
The previous post talked about autonegotiation. This time I will talk about cables and pinouts and how auto MDIX works. Although I’m not very old I still like to do it the old school way. I don’t rely on auto
The facts of Ethernet – Round two
Autonegotiation – Either you love it or you hate it but pretty much everyone has an opinion on it. I was going to write something more lengthy at first but decided a blog was the wrong place. Autonegotiation works by
The facts of Ethernet round one
Ethernet is the most used layer 2 protocol today and it’s dominance is not likely to end anytime soon. I decided to make a section with some quick facts about Ethernet. There is a lot to know about Ethernet but