My EtherealMind» Blessay

Using Underscores, Hyphens or CamelCase in Naming Standards

Greg Ferro — Fri, 27 Jan 2012 17:05:32 +0000

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.

Scaling Virtual Appliances With Embrane

Greg Ferro — Mon, 12 Dec 2011 17:07:43 +0000

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.

Cisco, Culture of Buggy Code and the Failure of the TAC

Greg Ferro — Wed, 16 Nov 2011 13:06:14 +0000

In recent months I seem to have hit a lot of bugs in Cisco software. Across the board on the main software releases of IOS, NX-OS or IOS-SX I seem to be hitting a wide range of bugs, and some of them are pretty stupid. And I've realised that, in recent years, it has become so commonplace, so accepted that we actually plan our projects with time to test, locate and check for bugs. And that’s become an expensive and time-consuming problem. Why do we put up with this ?

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

Greg Ferro — Thu, 03 Nov 2011 20:18:26 +0000

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.

Top Five Things About VXLAN – And Why It’s Full of Fail

Greg Ferro — Fri, 16 Sep 2011 16:31:59 +0000

It's obvious #VXLAN was conjured up by a cloudtard. Simple minds devise simple solutions without seeing the complex problems they missed. Here are five things that VXLAN tells us about the networking industry.

Switch Fabrics: Input and Output Queues and Buffers for a Switch Fabric

Greg Ferro — Tue, 06 Sep 2011 19:14:45 +0000

Now that this has established that a Switch Fabric has buffers, I want to flip back into something practical about this application. Lets use an example of four servers connecting to single switch and sharing an Ethernet Storage Array. The array might be using iSCSI or FCoE to delivery SCSI applications to the Servers. The nature of storage traffic is such that it has transient spikes in traffic that must maintain low latency and should not be dropped.

Soft Switching Fails at Scale

Greg Ferro — Sat, 09 Jul 2011 18:12:05 +0000

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 ?

Greg Ferro — Wed, 29 Jun 2011 23:19:04 +0000

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.

Greg Ferro — Sun, 19 Jun 2011 20:38:51 +0000

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)

Greg Ferro — Thu, 02 Jun 2011 18:35:23 +0000

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

Greg Ferro — Sun, 15 May 2011 13:05:19 +0000

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.

Complex Systems Have Complex Failures. That’s Cloud Computing.

Greg Ferro — Tue, 26 Apr 2011 17:00:48 +0000

Exposing cloud failures The result of the Amazon EC2 failure this week has exposed a number of technology strategies in cloud infrastructure as being less than perfect. Complex systems have complex failures The most vexing problem of Cloud Computing is that these systems are complex, and the more complex system the more complex the failure. [...]

Fate Sharing, Failure Domains and Why VTP Is Awesome

Greg Ferro — Wed, 20 Apr 2011 15:00:10 +0000

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.

Musing: How Many 10Gigabit Ethernet Ports Do You Really Need ?

Greg Ferro — Mon, 18 Apr 2011 22:11:53 +0000

I was doing a Data Centre Design recently and did some numbers around the numbers of 10 Gigabit Ethernet ports that need to be deployed. I got a bit of a realisation shock.

Low Level Design – Think About the Next Step

John McManus — Fri, 18 Mar 2011 21:13:58 +0000

A while back Greg wrote a great article about the “Rules of Design Documentation”†http://etherealmind.com/rules-design-documentation-etherealmind/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 [...]

Checkpoint/Nokia Firewall Clustering. Uh Oh.

Greg Ferro — Thu, 17 Mar 2011 17:00:37 +0000

I've been reviewing a network that has some CheckPoint firewalls that have been unstable, and while this isn't surprising (in my experience, it's common enough for Checkpoint firewalls to be unstable for some reason or the other), this time I've been faced with Checkpoint Clustering. A few years back I tried to make this work, but gave up when CheckPoint couldn't make it work either. A few years later, I find someone brave enough to attempt it. This time it's different, I'm the one who has to justify why it's a bad idea. Now that the manuals are not secret anymore I think I've found out why.

Blessay: Comparing Merchant and Custom Silicon

Greg Ferro — Fri, 11 Mar 2011 12:51:52 +0000

Merchant Silicon is an marketing term used to describe the use of "off the shelf" chip components to create a networking product and commonly used by company that design their own silicon chips when explaining that their process is better and more efficient. The networking industry has two types of silicon: ìcustom or in houseî or ìmerchant or off the shelfî. The 'in house silicon' argument goes something like this : We have our specialist engineers who can custom design an ASIC and supporting chips that are completely focussed on the features needed to deliver Product X. As a result, our designs are purposefully built to be faster, better etc. Our prices are more expensive because our products are faster and more focussed and because our costs are higher. The 'merchant silicon' argument goes something like this: The levels of expertise required to design and build a silicon chip is very high. It requires specific skills, tools, and high levels of expertise. If your core business is producing a networking device, then having your own silicon development is not core business. By relying on companies who specialise in silicon design and manufacture, we can focus on software and integration to deliver new and better features at a cheaper price. .......

Citrix Branch Repeater : WCCP or Not to WCCP That Is the Question?

John McManus — Tue, 08 Mar 2011 21:05:13 +0000

Whether ’tis nobler in the network to suffer un-accelerated traffic during an outage or to take arms in the form of Policy Based Routing. When you decide to†deploy†Citrix Branch Repeaters (CBR) you have to†deploy†at either end of the WAN to accelerate and compress traffic between these endpoints. Therefore it would seem sensible to have some [...]

Cisco ACE – Enterprise Load Balancing on a Stick Using Source NAT – Part 3

Greg Ferro — Mon, 14 Feb 2011 15:15:54 +0000

A detailed look at configuring a Cisco ACE module to do load balancing on a stick. This time with basic configuration for dual VIPs and dual NATs.

Cisco ACE – Enterprise Load Balancing on a Stick Using Source NAT – Part 2

Greg Ferro — Wed, 09 Feb 2011 15:00:59 +0000

A detailed look at configuring a Cisco ACE module to do load balancing on a stick. This time with basic configuration for a single VIP.

Cisco ACE – Enterprise Load Balancing on a Stick Using Source NAT – Part 1

Greg Ferro — Tue, 08 Feb 2011 20:52:00 +0000

A detailed look at configuring a Cisco ACE module to do load balancing on a stick.

Cisco Live London 2011 – Live Blog

Greg Ferro — Tue, 01 Feb 2011 09:31:47 +0000

This is my Live Blog for Cisco Live in London 2011. So far, I’ve had plenty of hassles getting registered, as the previously promised pass didn’t work out. But for now I’m here. So lets pass comment on what’s been happening. I’ll try to post some stuff from time to time but I’m thinking that [...]

Perception Is Reality, Design, and Hacking the Presentation

Greg Ferro — Tue, 18 Jan 2011 10:02:06 +0000

Looking closely at how your 'design' your responses to information request so that you can get better outcomes in problem situations at work.

Cisco Cius Versus iPad Versus HP WebOS – Year of the Tablets

Greg Ferro — Thu, 06 Jan 2011 13:12:52 +0000

Comparing Cisco Cius and the iPad in the Enterprise

Controller Based Networks for Data Centres

Greg Ferro — Mon, 13 Dec 2010 16:18:56 +0000

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.