Watch the cloud get bigger and change its shape

What are the key trends we can discern in cloud networking?

For a start it will take place at scale, with networks that are much bigger than we are used to and growing bigger by the day.

Traffic in cloud networks will be very heavy and will display some unique characteristics due to the on-demand nature of cloud computing and storage.

For example: consider the need to set up virtual machines in large numbers, to monitor and manage them, to move them as loads on different servers get balanced, and then to remove them when demand dies down.

It is as if the volume of traffic on a motorway jumps suddenly by 30 per cent but cars already on the road continue to move at the same speed. There are no traffic jams, pile-ups or drivers getting lost.

The way to manage that kind of traffic on a computer network is to build lots of headroom and to ensure that resources are used as little as possible by data packets transiting the network.

Living on the edge

The rapidly growing population of edge devices accessing the cloud network is another notable trend. People are using more and more internet devices, from smartphones to tablet computers, ultrabooks, notebooks and desktop PCs.

Also, as smarter TVs and TV peripherals come to market users will download more high-definition content, including video clips of suppliers' products or services.

Networks become more complex as the number of devices or nodes in the network grows from thousands to tens of thousands and beyond. Traffic soars.

One response is to simplify the network by converging on core protocols. You are keeping pace with growth demands if you can enhance network staff productivity by 20 per cent while growing your network traffic and node count by 20 per cent.

These trends suggest that higher-speed network links using fewer protocols will be a feature of cloud networking.

New improved Ethernet

In the Ethernet area this suggests that 10GbE will become standard as an access or edge bandwidth requirement and 40GbE will become commonly used in the core. A move to 100GbE in the core is quite feasible, with the gradual dispersal of 40Gb out from the core towards the edge as a result.

A cloud network that is all-Ethernet is, in principle, simpler to provision, monitor and manage than one using a mixture of Fibre Channel, InfiniBand and Ethernet.

Each protocol needs its own specialists, supplier contracts, support, and managing arrangements. How much better to converge on just one protocol.

The convergence of Fibre Channel onto Ethernet is becoming feasible because Data Center Ethernet (DCE) is a great advance on the Ethernet LAN we know and love.

It is deterministic, in that portions of its bandwidth can be designated for particular classes of traffic, with high-priority traffic unaffected by spikes in loads. The less important traffic has to bear delays in that case while the high-priority traffic sails across the wires unaffected.

Of course Fibre Channel will be around for many years

Equally important, packets don't get lost. Our everyday LAN tolerates packet loss, sending repeat transmission if one packet is mislaid.

Making Ethernet deterministic and lossless means that with the Fibre Channel over Ethernet (FCoE) protocol running on it, DCE can support Fibre Channel networking and can be used to link servers to databases in storage area network arrays.

These servers use the same Fibre Channel protocol as before, but now it runs on top of Ethernet instead of physical Fibre Channel cables, switches and director-class core switches.

Of course, Fibre Channel will be around for many years: people are simply not swapping out their Fibre Channel deployments for pure FCoE deployments. Uptake continues to lag and currently the vast majority of FCoE use cases occur in the first five feet of the data centre in terms of server I/O.

Need for speed

Faster Ethernet using 40Gbps and 100Gbps links provides speeds that InfiniBand users are accustomed to and opens the way to converging InfiniBand traffic onto Ethernet.

There are many other aspects of networking in the cloud, such as the need for simpler and multiple paths and lower latencies, and resolving these issues requires faster, converged networks. For example, traditional Ethernet relies on single paths to endpoints using the so-called Spanning Tree Protocol.

Suppliers such as Brocade, Cisco and others are flattening Ethernet networks by encouraging traffic to flow more directly across Ethernet using multiple paths. Brocade, for example, has its VCS Fabric technology to do this.

Cloud networking will encourage moves to a reduced number of wire protocols and to faster networking. Both are essential to realise the cost benefits of on-demand cloud IT.

Without these building blocks, the ability to scale is severely limited and the cloud is not all that it could be. ®