Internet of Interest 20120212 curve

Bumper SDN/OpenFlow Roundup on Links for ONS 2012

  Internets of Interest is a conceit of mine where I collect¬†useful, relevant or just fun places on the Internet and a bit commentary about what I’ve found interesting about them. With the Open Network Summit 2012¬†happening last week, there was an avalanche of hype from the mainstream press. I’ve attempted to pick something off […]

Quote of the Day about Spanning Tree

Quote of the Day about Spanning Tree


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.

Can Fibre Optic Ethernet Cables Be Longer Than The Standard ?

Short Answer is “It depends, but usually yes.” Long answer follows with a discussion of launch power, receiver sensitivity, and cable losses.

ipspace openflow webinar 20111118

Webinar on SDN & OpenFlow – Sponsored by Big Switch – Open Attendance

I’m pleased to announce that Big Switch have agreed to sponsor SDN & OpenFlow Webinar on February 7th, 2012 and that the event will be free and open to anyone to attend.

Are you a Network Architect or Designer ? Are you responsible for strategy, long term vision, or simply keeping track of upcoming technologies ? If so, you will need to know more about OpenFlow and Software Defined Networking and how it impacts the future of Networking in software and hardware.

And now, thanks to sponsorship from BigSwitch Networks, anyone can attend.

Ipspace openflow webinar 20111204

Ethernet Jumbo Frames, Full Duplex and Why Jumbo Frames are 9000 bytes)

I’ve been doing some research into Ethernet and the use of Jumbo frames for some content I’ve been writing and come across something interesting. The documents state that Jumbo frames can only be used on Full Duplex Ethernet connections.

Modular Data Centre – on the highway

Saw this modular data centre rolling down the highway today.

Problems with Cat6A Cables in Data Center

I was reading a white paper by Panduit that claims that 10GBaseT is suitable for use. I’ve been critical of Cat6A cable and believe that it’s not suitable for data centre use.

Cisco Nexus 5000 / 2000 Pricing Bundles and Fabric Extension Transceivers (FETs) vs 10GbaseSR SFPs.

Recently I noticed that Cisco is selling “Fabric Ethernet Transceivers” for the Nexus switch family. Some research shows that these are replacements for 10GBaseSX SFP modules. Importantly, it’s cheaper to install new cabling than to buy 10BaseSR SFP+ modules.

Requirements Terminology – Defining MUST, SHOULD and MAY

One of the problems of working with the PRINCE2 practitioners is that the people tend to get highly focussed on definitions in the Scope of Works. A Scope of Works defines what the deliverables the customer is to received.

The problem with a Scope of Works is that it is usually prepared before the work is started and/or fully understood. maybe you have a Gap Analysis, or a Consulting Reports or a Requirements Document to setup the initial engagement (every company has their own name of the same thing).

What is an Ethernet Fabric ?

Define “Ethernet Fabric”

Fibre Connectors

A short summary of the Fibre Cable Connectors, description and some notes on usage. This is summary notes and intended for reference.

Soft Switching Fails at Scale

There is a significant camp of software developers who are developing software switching solutions for hypervisors. Which is nice, I guess. The use of software switching in the hypervisor has some good points but, in my view they are heavily outweighed by the bad. I present the use case, and show that software

What is the Definition of a Switch Fabric ?

The marketing people in IT tend to be overwhelmed by complexity and deep technology. For many liberal arts graduates, they take the drowning option and latch onto certain terms and then grossly abuse it. The most egregious abuse today is “cloud” but “fabric” comes a close second. In this series of posts I want to look at what is a FABRIC and provide a canonical look at what it does and how it works for us.

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.

VMware: Let’s get logical – the case for OpenFlow network virtualization (and their failed network plans)

VMware has made several strategic moves to implement dynamic networking – vSwitch, vDS, Nexus 1000 (in partnership with Cisco), vCloud External Networks (using MAC in MAC of all things) and have basically failed to deliver overlay technology without implementing technology in the network itself. Equally, VMware hasn’t been willing to engage with the networking vendors to develop technologies that would solve this problem – VNtag / VEPA/ VEP combined with TRILL / SPBB, instead letting them argue amongst themselves. VMware attempt with vCloud networking using MACinMAC encapsulation seems to have failed and stalled and is getting another attempt using MACinIP. VMware/Xen/HyperV are all desperate to have a more dynamic network that can be controlled from their software and this might be where OpenFlow gets a big lift – as a configuration engine.

Review: HP and Optical Backplanes

There were a lot of cool things at InterOp, but not much that was new from the big vendors. For example, Cisco didn’t announce anything, probably waiting announce at Cisco Live in July where they can control the press and message much more tightly. However, HP announced the A10500 switch (action pictures ) which is a new campus switch and Gnodal arrived with new products.

However in the centre of the HP stand there was something very cool – a prototype E8212 ProCurve switch with a fully optical backplane. Hp procurve optical backplane 1

PacketShaper and Flow Directions

I stumbled across an old diagram I made a long time ago about the direction of flows on a BlueCoat PacketShaper. Since I’ve been looking for it for about three years, I’ve diagrammed it quickly so that it is here for future reference when I’m working PacketWise in the future. PacketShaper PacketWise is one of my very favourite tools for managing traffic flows, and much preferable to PHB QoS aka DiffServ for many types of use cases.

An TCP flow has four possible directional attribute related to the use of a inside and outside networks, and whether the flow was initiated from the client to server which sets the “direction” of the flow relative to the Packeteer. The flow is determined by who initiated the three way handshake. For purposes here, the Client always initiates the TCP connection, and the Server terminates the connection.

TCP Session and Direction

Most people understand the three way handshake, but not many consider the direction of the session.
Packet shaper flow directions 0

The connection from the client to the server is outbound, but is inbound on the server. And vice versa, the server outbound session is inbound on the client.

Packet shaper flow directions 0 1
That’s not very useful for being able to define the direction of flows.

Why is direction important ?

Direction of flows is important if you want to configure asymmetric rules. That is, not all protocols require symmetic bandwidth. For example, HTTP traffic is usually a 10:1 ratio for reply to request. That is, a request for this webpage is about 10KB, but the reply with the data, images and javascript is more than 100KB.

Packet shaper flow directions 0 2

For an FTP upload server, you might have the reverse condition where the inbound traffic is far more than the outbound.

To make the most of your Internet connection for this case, you could configure the inbound bandwidth on your Internet connection to be 80% FTP, 20% HTTP and the outbound bandwidth to be 20% FTP and 80% HTTP. This gives a far better utilisation, especially in regards to better TCP Windowing and overall TCP goodput.

HP A10500 FlexiCampus – Action Pics

I wanted take a quick look at the guts of the A10500 switch because its got some interesting features. And since no one else in the press even looked at the box, I feel it’s necessary to do some nerd action photos with the line cards.

Fate Sharing, Failure Domains and why VTP is awesome

A lot of people regard Virtual Trunking Protocol(VTP) as nothing but trouble. Indeed, it’s hard to find many people who will implement it on their network. I find this baffling – it’s a great tool that dramatically reduces time, errors, and troubleshooting is something that we should all embrace and use wherever we can. Naturally, with great power comes great evil. So, lets be clever instead.

Subscribe For Weekly Updates by Email

Get a Weekly Summary of Latest Articles and Posts to your Email Inbox Every Sunday

Thanks for signing up. Look for the email from MailChimp & make sure you confirm your email address. You may need to check your spam or gmail settings to be sure of receiving the email.

Note: You can unsubscribe at any time using the link at the bottom of every email.