Blessay: Is the Data Centre “One Network” or “Connected Smaller Networks”

Most people refer to the “Data Centre Network” as though it was a single network. In practice, data centres have a number of individual networks. Each network is specifically designed for a specific purpose and function. A typical data centre network design has about five individual networks that connect together to form the “data centre network” which many people fail to recognise. I’ll define these networks and then look at the future of data centre networks with overlays. What seems clear, today, is that networking will provide different networks for different use cases and the customer will decide.


◎ Introduction to How Overlay Networking and Tunnel Fabrics Work

In this blog post I’ll make an attempt to summarise Overlay Networking in a couple of paragraphs to act as reference for upcoming blog posts that discuss the nature of Tunnel Fabrics in Physical Network environments. It also has pictures.

Tech Notes: What is Shortest Path Bridging IEEE 802.1aq – Brief

Summary of the key elements of the Shortest Path Bridging Protocol IEEE 802.1aq.


Basics: What’s the Difference between STP BPDU Guard and Root Guard

BPDU Guard and Root Guard are enhancements to Spanning Tree Protocol (STP) enhancements that improve the reliability of the protocol to unexpected events ad are primarily to ensure design enforcement ( integrity / security). There they must configured in specific locations in the networks.

Sponsored: Brocade Virtual Symposium – Storage Convergence

Continuing the series from the Brocade Virtual Symposium. In a special video session that was sponsored by Brocade, we got Chip Copper in the room with Stephen Foskett to talk about storage convergence.

Over the last few years, I’ve been very critical of Ethernet storage protocols like [FCoE]( and the fact that storage protocols are unlikely to work well. There are few times here where Chip was able to give me answers and a different viewpoint that gave me a different take on the solutions.


Does SDN represent the evolution of Network Management ? Yes but No It Doesn’t

SDN/OpenFlow is about Network Management, at least, in part. But the rich tools for software control dont’ exist. I also think don’t think that todays management _platforms_ (such as Tivoli, OpenView and BMC) are suitable for network orchestration in the future.


Tech Notes: Juniper QFabric – A Perspective on Scaling Up

Juniper QFabric is a new approach to Ethernet Switch Fabrics. When it was announced last year,it was noted that the underlying physical design is a completely different approach to building Switch Fabrics. Here I’m taking a loosely research based approach to understand how Juniper QFabric is different from all other approaches to the problem, and also a look at some of the challenges ahead.

Comparing Embrane and Nicira is Pointless – They Are Different

Had a few conversations, and some articles, where comparisons are being made between Embrane and Nicira and wanted to point out that there are few similarities between these companies.

Predicting What Will Not Be Big in 2012

I’ve been working on making some predictions about 2012 and networking. I like to do this in the year of 2012 (not 2011 like everyone else) and I like to go further than anyone else and predict what WILL NOT be big in 2012.

Using Underscores, Hyphens or CamelCase in Naming Standards

I’ve been considering a small but vital problem in naming conventions in Networking. Namely, the use of underscores and hyphens in object names and devices. It’s a hot topic for argument when the time comes for corporate standards (and when Network Engineers have beverages in a public house). Now, I figure that there are three possible grammar options for making names – hyphens, underscore and CamelCase.

Responding: On optimizing traffic for network virtualization

I’m responding to Brad Hedlund’s post “On optimizing traffic for network virtualization” where he seems to missed a key point. It’s about cost of ownership in terms of ability to troubleshoot.

Scaling Virtual Appliances with Embrane

Embrane uses concepts of IP Flows to scale virtual appliances. Embrane does this by managing IP flows and then directing to other appliances, in effect creating what I would call a two tier load balancing.

Should I use BFD in my Network ?

Wherein I consider using BFD in Network Designs.

Switch Fabrics: Fabric Arbitration and Buffers

In the article, “What Is the Definition of a Switch Fabric ?” on Switch Fabrics I looked at how a Crossbar switching fabric allow for concurrent circuit forwarding and how this is used to build a fabric. In most cases, frames would be received and forwarded from an input to an output, as show in […]

Cisco C6500 Service Modules – Not My Choice, Now.

These all suggest that the time for planning and designing Service Modules is over. There are no suggestions that service modules for the Nexus 7000 will be developed that I can see. I can prognosticate that it would slow down the development of the core switch / route / performance functions, and it will be some years before those core capabilities is complete enough that service modules would become viable product development tasks — they might be in development, but not much chance of going into production. [^1]

Do I sound bitter about Service Modules ? A bit. I’ve had a number of hard to solve problems that lasted months before code fixes arrived. I’ve been fan of the NAM but the price is now far removed from it’s practical value. USD$30K List is way over priced for its capabilities and even with a 30% discount, you can buy a lot of network management systems that deliver much better functions and features for that price.

Which Network Topology?

Recently Iíve come across some interesting terms for variants of common network topologies, so I decided I’d try to list as many of them as I can for reference. Please suggest others to add.

Low Level Design – Think about the next step

A while back Greg wrote a great article about the “Rules of Design Documentation” these are really valuable rules when it comes to writing a design document and in my opinion is particularly relevant to a Low Level Design AKA Detailed Design Document.   Ask yourself Before you can apply these rules of design you must […]

So you want to use a 3750-X as a Router?

Easy peasy lemon squeezy This seems a straightforward question! Just load up with advanced IP services license, install the license file and reboot the switch and you should be good to go. Well that’s what I thought until recently when I done the very steps above and on the surface seemed okay but I wanted […]

Controller Based Networks for Data Centres

The current technologies of data centre networks don’t address the fundamental scaling issues. You can’t scale to hundreds of independent switches, we need to have less control planes for more coherent functions. Here is my take on next wave of networking in the data centre beyond DCB and TRILL.

FCoE and standards: this is what really matters

In the recent weeks, J. Michael Metz from Cisco entered a ****ing contest with my friend Greg and decided to prove that the FCoE standards are done.

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