I2RS and Remote Triggered Black Holes

24 October 2016 |

In our last post, we looked at how I2RS is useful for managing elephant flows on a data center fabric. In this post, I want to cover a use case for I2RS that is outside the data center, along the network edge—remote triggered black holes (RTBH). Rather than looking directly at the I2RS use case,…

Elephant Flows, Fabrics, and I2RS

3 October 2016 |

The last post in this series on I2RS argues that this interface is designed to augment, rather than replace, the normal, distributed routing protocol. What sort of use case could we construct that would use I2RS in this way? What about elephant flows in data center fabrics? An earlier post considers how to solve the…

Can I2RS Keep Up? (I2RS Performance)

20 September 2016 |

What about I2RS performance? The first post in this series provides a basic overview of I2RS; there I used a simple diagram to illustrate how I2RS interacts with the RIB— One question that comes to mind when looking at a data flow like this (or rather should come to mind!) is what kind of performance…

DC Fabric Segment Routing Use Case (5)

7 September 2016 | Comments Off on DC Fabric Segment Routing Use Case (5)

In this, the last post on DC fabrics as a Segment Routing use case, I mostly want to tie up some final loose ends. I will probably return to SR in the future to discuss other ideas and technical details. Anycast Anyone who keeps up with LinkedIn knows anycast plays a major role in many…

On Definitions: Whatever is Forwarding Information?

5 September 2016 |

After last week’s, a reader left a comment noting “I2RS doesn’t manipulate forwarding data.” If I2RS isn’t “manipulating forwarding data,” then what, precisely, is it doing? I thought it’s worth a post to try and help folks understand the definitions in this space—except, as you’ll soon discover, there are no definitions here. In fact, it’s…

An I2RS Overview

31 August 2016 |

What is the Interface to the Routing System (I2RS), and why do we need it? To get a good I2RS overview, consider the following illustration for a moment— What does the interface between, say, BGP and the routing table (RIB) actually look like? What sort of information is carried over this interface, and why? A…

On the ‘net: I2RS on Packet Pushers

24 August 2016 | Comments Off on On the ‘net: I2RS on Packet Pushers

While Greg was at the IETF in Berlin, Sue Hares and I—the two current co-chairs of the I2RS working group—had a general discussion around what the big idea is and where the working group is headed. You can listen to the recording at Packet Pushers.

DC Fabric Segment Routing Use Case (4)

22 August 2016 |

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.…