OSPF Topology Transparent Zones

17 April 2018 | Comments Off on OSPF Topology Transparent Zones

Anyone who has worked with OSPF for any length of time has at least heard of areas—but perhaps before diving into Topology Transparent Zones (TTZs), a short review is in order. In this diagram, routers A and B are in area 0, routers C and D are Area Border Routers (ABRs), and routers E, F,…

What’s wrong with the IETF. And what’s right

22 March 2018 | 4 Comments

I have not counted the IETF’s I have attended; I only know the first RFC on which I’m listed as a co-author was published in 2000, so this must be close to 20 years of interacting with the IETF community. I’m pretty certain I’ve attended at least two meetings a year in some years, and…

Low Latency Networking

12 March 2018 | Comments Off on Low Latency Networking

Low latency is coming to a network near you. In fact, it’s probably coming to your network, whether or not you realize it. This article was cross posted at APNIC While bandwidth has always been the primary measure of a network, and cross sectional or non-contending bandwidth for data center fabrics, further research and reflection…

DFS and Low Points

6 March 2018 | Comments Off on DFS and Low Points

On a recent history of networking episode, Alia talked a little about Maximally Redundant Trees (MRTs), and the concept of Depth First Search (DFS) numbering, along with the idea of a low point. While low points are quickly explained in my new book in the context of MRTs, I thought it worthwhile to revisit the…

The DNS Negative Cache

13 February 2018 | Comments Off on The DNS Negative Cache

Considering the DNS query chain— A host queries a local recursive server to find out about banana.example The server queries the root server, then recursively the authoritative server, looking for this domain name banana.example does not exist There are two possible responses in this chain of queries, actually. .example might not exist at all. In…

SLAAC and DHCPv6

5 December 2017 | 1 Comment

When deploying IPv6, one of the fundamental questions the network engineer needs to ask is: DHCPv6, or SLAAC? As the argument between these two has reached almost political dimensions, perhaps a quick look at the positive and negative attributes of each solution are. Originally, the idea was that IPv6 addresses would be created using stateless…

Reaction: Enabling Privacy is not Harmful

2 November 2017 | Comments Off on Reaction: Enabling Privacy is not Harmful

The argument for end-to-end encryption is apparently heating up with the work moving forward on TLSv1.3 currently in progress in the IETF. The naysayers, however, are also out in force, arguing that end-to-end encryption is a net negative. What is the line of argument? According to a recent article in CircleID, it seems to be…

BGPsec and Reality

23 October 2017 | 2 Comments

From time to time, someone publishes a new blog post lauding the wonderfulness of BGPsec, such as this one over at the Internet Society. In return, I sometimes feel like I am a broken record discussing the problems with the basic idea of BGPsec—while it can solve some problems, it creates a lot of new…

IS-IS Multi Instance: RFC8202

16 October 2017 | Comments Off on IS-IS Multi Instance: RFC8202

Multi-Instance IS-IS One of the nice things about IS-IS is the ability to run IPv6 and IPv4 in the same protocol, over a single instance. So long as the two topologies are congruent, deploying v6 as dual stack is very simply. But what if your topologies are not congruent? The figure below illustrates the difference.…

Reaction: Networking Vendors are Only Good for the Free Lunch

13 September 2017 | 1 Comment

I ran into an article over at the Register this week which painted the entire networking industry, from vendors to standards bodies, with a rather broad brush. While there are true bits and pieces in the piece, some balance seems to be in order. The article recaps a presentation by Peyton Koran at Electronic Arts…