DC Fabric Segment Routing Use Case (4)

22 August 2016 | 5 Comments

In the last post in this series, I discussed using SR labels to direct traffic from one flow onto, and from other flows off of, a particular path through a DC fabric. Throughout this series, though, I’ve been using node (or prefix) SIDs to direct the traffic. There is another kind of SID in SR…

DC Fabric Segment Routing Use Case (3)

10 August 2016 | Comments Off on DC Fabric Segment Routing Use Case (3)

In the second post in this series, we considered the use of IGP-Prefix segments to carry a flow along a specific path in a data center fabric. Specifically, we looked at pulling the green flow in this diagram— —along the path [A,F,G,D,E]. Let’s assume this single flow is an elephant flow that we’re trying to…

Layer 2 Routing—Haven’t we been here before?

2 August 2016 | Comments Off on Layer 2 Routing—Haven’t we been here before?

We often think the entire Internet, as we know it, just popped out of “thin air,” somehow complete and whole, with all the pieces in place. In reality, there have been many side roads taken, and many attempts to solve the problem of pushing the maximum amount of data across a wire along the way.…

DC Fabric Segment Routing Use Case (2)

28 July 2016 | 6 Comments

In the first post we covered a bit of the basics around segment routing in the data center. Let’s return to the first use case to see if we can figure out how we’d actually implement the type of traffic steering needed to segregate mouse and elephant flows. Let’s return to our fabric and traffic…

On the ‘net: What does a control plane do?

21 July 2016 | Comments Off on On the ‘net: What does a control plane do?

To really understand Software Defined Networks (SDNs), we need to start from a place far different than the top of the current hype cycle. Instead, where we need to start is thinking about what a control plane actually does in a packet switched network. There seem to be just a few specific things involved in…

DC Fabric Segment Routing Use Case (1)

11 July 2016 | 3 Comments

A couple of weeks ago, I attended a special segment routing Networking Field Day. This set me to thinking about how I would actually use segment routing in a live data center. As always, I’m not so concerned about the configuration aspects, but rather with what bits and pieces I would (or could) put together…

CAP Theorem and Routing

25 March 2016 | 2 Comments

In 2000, Eric Brewer was observing and discussing the various characteristics of database systems. Through this work, he observed that a database generally has three characteristics— Consistency, which means the database will produce the same result for any two readers who happen to read a value at the same moment in time. Availability, which means…