Networking Primer – Part 5.1: Network Layer – IP Addressing

Image of 3D IP Address

Previous: Networking Primer – Part 4: Transport Layer, TCP and UDP

The clue might be in the title, but the Network Layer is one of the more important layers in the network stack. So far we have defined high-level identities, application services and data formats. We have also established our protocols, chopped up data into smaller more manageable pieces and tagged them with a sequence number. It is at this point we need to start defining more details on where we will be sending the data and moving closer to establishing a unique address for both source and destination. We also need network components to be in place to allow us to transmit and route the data appropriately.

The two core concepts at work in this layer are addressing and routing.

Addressing: Internet Protocol (IP)

The most ubiquitous protocol used for network […]

Networking Primer – Part 4: Transport Layer, TCP and UDP

Previous: Networking Primer – Part 3: Application, Presentation and Session Layers

The transport layer is responsible for providing reliable data transfer services to the upper layers of the OSI stack. It is at this stage that we start to consider actually sending the data. This layer also involves the segmentation/desegmentation of data into smaller chunks. It is very rare that a network will be configured to take a large payload from one source node to a destination node. This is why we will segment the overall data payload into smaller pieces. This is also the first place in the stack where we start to apply some addressing so the destination node understands which listening receiver the data is intended to reach. This address comes in the form of a port number. The destination node may be simultaneously listening for (or have the ability to connect to) different network services and the […]

Networking Primer – Part 3: Application, Presentation and Session Layers

Previous: Networking Primer – Part 2: Defining Networking with OSI and TCP/IP Suite

I’ve decided to group the top three layers together into one post. This is because these are more related to the data to be transmitted across the network, rather than the underlying transport mechanisms themselves. These three layers deal with the semantics of the communication, such as who the data will be sent to, the format of the data and the etiquette to be adhered too between the communicating nodes.

Lego Pirate Ship

The Pirate Ship: As with most technical concepts, analogies can help us understand the underpinning processes which are happening as part of the communication. For this series, I’m going to use the following analogy: I work in an office in Manchester and I’d like to send a pirate ship made of Lego to a friend, Rich, who works in an office in […]

Networking Primer – Part 2: Defining Networking with OSI and TCP/IP Suite

Previous: Networking Primer – Part 1: Introduction

What is a network?

This may sound like a very basic question, but I’ll assume the lowest common denominator here and define this briefly.

A network is set of two or more computing entities (nodes) that are configured to communicate with each other by passing information across an interconnecting media.

Ok, now we got that out of the way, we can talk about how exactly those nodes communicate with each other in a way that makes sense and achieves our objective of passing information between them.

A Little History

It is easy to imagine how the first baby steps of networking which occurred in the mid-20th century. As with all technology we start with the simplest goal and see how we can use what tools we available to use to achieve that goal. I’m not going to go into sending signals down telegraph wires, etc. but […]

Networking Primer – Part 1: Introduction

The world of networking has been fairly static for many years now. It’s been historically characterised by static infrastructures that require infrequent changes. These configuration changes were performed via command line interfaces by network engineers, usually sitting with a laptop and a cable plugged directly into a piece of networking hardware. Activities were manual, repeated for every individual device and extremely error prone due to the non-human readable nature of network configuration information.

The workloads running in the modern datacenter have most definitely changed in recent years. It has become apparent that the capabilities of current networking devices and operational approaches simply cannot keep up with the pace of change. In the modern datacenter, the rapid and overwhelming success of server virtualisation has fundamentally changed the way applications consume resources and the network has become somewhat of a bottleneck in providing agile, reliable and cost effective means of […]

Software Defined X – Automation: Job Stealer or Job Enabler?

I’ve had many conversations in recent weeks about the commoditization of the data center with many being concerned about the effect of the diminishing need for specialist hardware and greater automation through software. More specifically, how that might affect the job prospects of administrators and other technical roles in the modern IT environment.

We are in an era of rapid evolutionary change and this can be unsettling for many as change often is. There seems to be a wide variety of reactions to these changes. At one end there is the complete denial and a desire to retain the status quo, with an expectation that these industry changes may never occur. In the middle, we have those that tip their hat in recognition of the general direction of the trends, but expect things to happen more gradually and then there are those that embrace it with an expectation of gaining some […]

Whitepaper: Virtual Backup Strategies: Using Storage Snapshots for Backups

Introduction Effective data protection is a mandatory element in the modern IT environment. Historically, backup strategies were confined to the last few chapters in an administrator’s manual and treated like an afterthought. Now they sit firmly at the forefront of every CIO’s mind. The ability to continue business operations after a system failure and the need to fulfil stringent compliance requirements have made backup a necessity—not only for business continuity, but also for business survival. The question organizations need to ask about data protection is not whether to backup their data, but how to backup their data.

IT systems are prone to rapid evolution and present a constantly shifting landscape and the techniques used to protect those systems need to evolve as well. Perhaps one of the most significant changes in recent years has been the advent of virtualization. In the virtual world, legacy backup systems have become unfit for their […]

PernixData Unbuttons Trench Coat at SFD3 and Reveals..

Flash Virtualization Platform.

It seems in Storage circles there is much discussion around using new technologies to cache data in faster more accessible media. Flash is everywhere.. but there are many choices for where and how you can deploy flash technology in order to alleviate strain on storage systems, whose current SAS/SATA based disk drives are struggling to keep up with the day to day IOPS requirements of many organisations.

Pernix Data believe they have the solution for VMware environments in the form of their Flash Virtualisation Platform (FVP). They certainly have the credentials to be making such claims with team members coming from many leading companies. This includes, Satyam Vaghani, their CTO who came from VMware and was responsible for the creation of VMware’s VMFS filesystem.

FVP is a hardware agnostic server-side flash virtualization solution. It virtualizes PCIe flash cards and local SSD at the server side. […]

Webinar: Storage Assisted Backups: Best practices for VMs

Veeam Webinar 4th July 2013: Storage Assisted Backups: Best practices for VMs

Associated Whitepaper to be published in near future.

Webinar: Disaster Recovery for Virtual Environments, One Simple Solution for Five Common SAN Replication Challenges

This is a replay of webinar, I ran last year.. the associated Whitepaper is linked below:

Whitepaper Available here:

A new sister webinar/whitepaper focusing on using SAN snapshots in a holistic data protection strategy to be posted shortly.