As part of my job as a Senior Network Engineer, I develop procedures for undertakings of varying complexity. In this post I’m describing a technique that greatly simplifies any project where a routing domain is expected to churn (i.e. neighborships going up and down, routes flapping), when such event is undesirable. Motivation I developed this technique for a… Read More »
Apparently, there are several very distinct topics in routing which have the word “demand” in them. First, there is Cisco On-Demand Routing quasi-protocol, and then there are on-demand circuits which routing protocols must treat differently. Last but not least, the on-demand circuits are used for Routing Backup.
Sometimes while you do routing, you want to do it in a destination-based way and also differentiate routing for different sub-autonomous systems in your AS. Well, such behavior can be enforced by PBR, but it is not that scalable and it lacks some of the nicer things dynamic routing protocols bring to the table. Enter Virtual Routing and… Read More »
Policy-based routing allows network administrator to stir traffic in directions different from the one chosen by destination-based routing and its routing protocols. This can be useful in several scenarios, namely in dual-homing to different ISPs, as well as other special cases. Using policy-based routing for dual-homing General notes on dual-homing The term Dual-homing in its most general meaning… Read More »
Policy-based routing for IP networks in Cisco routers is a very powerful and precise tool which allows a network administrator to achieve a great many things. In my opinion it should be considered just as fundamental, as general routing mechanisms. How it is different from general destination-based routing and what we can to with it is the subject… Read More »
Internet Protocol Routing, nowadays commonly known as L3 Switching, is part of the process of forwarding an IP packet from Source to Destination. Interestingly, it happens more often then commonly understood: even on a common subnet we often need to make an IP routing decision.
In continuation of my last post, here I will write down about EIGRP operation a little mote. Packets On the wire, EIGRP is present with five types of packets: Hello and Acknowledgements (ACKs are just Hellos with the relevant bit set). They are the only EIGRP packets sent unreliably – that is, without acknowledgement. Any other packet must… Read More »
I’ve decided to listen to some advice and use blogging as a learning aid. And to begin with, I’d like to tackle on the subject of EIGRP. It’s no secret that EIGRP is Cisco’s beloved proprietary (it is published as an IETF draft, but apparently public version lacks a feature or two) routing protocol, and thus it is… Read More »