designing a modern campus LAN

Автор: | 21.06.2018

Campus local area networks (LANs) come in all shapes and sizes, but let’s keep it simple and say these are enterprise networks with hundreds or thousands of users and LANs in one or more buildings.


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Everything is geographically close so Ethernet and wireless deliver the connectivity and the LAN hardware – switch ports, switches, cabling and the rest – is all owned and maintained by the organisation.

If this description is familiar enough, what’s been changing in campus LANs, compared with years gone by, is the growing demands and expectations of users, in terms of devices connected, across-the-board campus connectivity (no wireless dead spots, please) and required speeds.

And, of course, to deliver on this heightened expectation, there are choices to be made about the hardware investments, the LAN design and whether a software control layer is a worthwhile step.

A software-defined shift

Mike Bushong is vice-president of cloud and enterprise at networks business Juniper, and is one of many suppliers who singles out software-defined networking (SDN) as the big play that promises to transform campus LANs.

“In a way, the campus LAN is the laggard here,” he says. “Datacentres have long been transformed by virtualisation, while WANs and the public cloud are also virtualised, but the software-defined campus LAN is only now moving centre stage.

“What I think is striking, however, is the need for agility is driving SDN in the campus LAN far more than any basic total-cost-of-ownership arguments,” says Bushong.

In other words, Bushong and others reckon it’s the wider forces driving the shift to a cloud-managed enterprise that are taking campus LANs down the same virtualised and cloud-controlled route.

“Networking has always been treated as a necessary capital cost, but now that digital is increasingly everywhere in the enterprise it cannot be treated separately.

“Once operational transformation is the name of the game – and it is, in a context of a digital transformation agenda for enterprises globally – the campus ends up needing to be reimagined. Very quickly, a centrally managed, software-defined campus becomes an imperative.”

The evolution of campus LAN

A similar use case is also made by David Goff, head of enterprise networks for UK and Ireland at Juniper’s rival Cisco.

“The campus LAN has evolved, for sure,” he says. “Fuelled by the increased demand for capacity, a plethora of devices on the network and a need for simplicity, scale and agility, networks then need to be software-defined.

“Once you move away from a more siloed and granular approach down in the hardware and switches, campus LANs, WANs and wireless networks become part of a single infrastructure centralising the network control.”

If this is the vision, what’s the supporting story? Goff argues that a single intuitive network lets businesses cut complexity and share intelligence across the network, implement security policies, troubleshoot problems and configuring changes all at once, from a single view.

Machine learning, AI and data analytics will also enhance campus services, and SDN can deliver all this,” says Goff. “Focusing on the need for greater scale, simplicity and agility, automation and an intent-based network allows organisations to deliver something seamless.”

Operationally open

If Goff and Bushong sound a little like SDN evangelists with an agenda, let’s remind ourselves what a shift to a software-defined campus LAN means for organisations.

In part, it should be noted that this would-be operational shift is also one towards openness and open architecture. It is not just about buying an upgraded product – Cisco’s, Juniper’s or anyone else’s.

Campus LANs built on SDN will be supported by multiple technologies and suppliers, and be set up to be open, simple and agile and developed for the needs of users.

With SDN, indeed, you cannot take your recommendations from a single supplier. You have to shift away from any reliance on exotic or niche hardware and think about the broad, open and simple architecture the campus network needs.

“These are natural progressions and transitions,” says Bushong. “It’s a move from legacy architecture to a multi-cloud environment that lets you manage infrastructure as one cohesive resource. But you need to maintain your options along the way.

“Having an open setup is operationally good, but every step needs to have been analysed and thought through to avoid any unintended consequences,” he says. “This means trying to avoid taking any decisions that are too narrowly scoped; you need to think about the broader migration picture to take the best decisions long-term.”

Leaf-spine networks

Alongside SDN, some argue that the other big change coming through in campus LANs is structural, with leaf-spine networks replacing traditional three-tier networks.

Matt Crawford, technical architect at IT consultancy ComputerWorld, says sometimes a structural rethink is just what’s needed when a campus LAN is under review.

“With leaf-spine configurations, all devices are exactly the same number of segments away and contain a predictable and consistent amount of delay or latency for travelling information,” he says. “That’s because the topology design has only two layers – the leaf layer and spine layer.

“It can make a big difference, too. The leaf layer has access switches that connect to devices like servers, firewalls, load balancers and edge routers,” says Crawford. “The spine layer – made up of switches that perform routing – is the backbone of the network, where every leaf switch is interconnected with each and every spine switch.”

Much faster Ethernet or fibre connectivity also needs pondering. “An upgrade to a 10 Gigabit or even 25 Gigabit network could be what’s needed in some contexts to future-proof a campus LAN,” he says. “Even wireless access is giving 2 Gigabits now, so you need to upgrade a 1 Gigabit Ethernet even to feel the full benefit of that. If a company wants to ensure a LAN upgrade is going to last the course, faster Ethernet definitely needs to be explored.”

What’s the opportunity cost?

Crawford notes that every campus LAN will have its particular dynamics, even if there are some broader, macro changes in the wider world.

“I have worked with manufacturers with robots in factories that need super-reliable high-speed wireless to work, for example, and LANs that need to be reconfigured to give enough reliability.”

In hotels, hospitality and conferencing the landscape has also shifted fast, with many events now expecting to simultaneously host hundreds of mobile devices streaming video content, for example, where once a connection that enabled a few dozen people to check emails would have been enough.

“What matters in relation to many campus LAN investments is simply the opportunity cost of not acting,” says Crawford.

“What could your ageing network cost you if it falls over or flops? What’s the reputational risk? Can a networks manager easily convince the board of the business case for making a long-term investment in the campus LAN? There’s an education piece that boardrooms embracing digital transformation need to fully embrace.”

KLM Engineering’s resilient network

The reasons why campus LANs need attention vary from organisation to organisation and context to context, but one less obvious driver is regulations.

For the Norwich-based aircraft maintenance repair outfit KLM UK Engineering, however, it was a crucial part of the picture when it came to assessing its disaster-recovery capabilities. That’s because a Civil Aviation Authority audit had flagged the need for network improvements that would reduce risks.

Alongside the regulator, the company’s own safety and compliance department also conducted its own audit of KLM Engineering’s network infrastructure in 2015, and raised concerns that there was little provision for network redundancy or outage – both of which posed a serious threat to business continuity and the maintenance of service.

Mark Walker is IT manager at KLM Engineering and says: “In addition to the Civil Aviation Authority audit, KLM Engineering’s network connection had always been provided from the parent company’s head office in Amsterdam. The result was a heavily restricted internet connection that was holding back work on both the shop floor and the back office.”

With close to 400 employees in total spread across linked buildings, KLM Engineering decided the only way to address the problem was to separate from the head office’s connection and upgrade to a standalone campus LAN.

Network specialist LAN3 worked with KLM Engineering on the project and recommended Extreme Networks core switches after comparing them with an equivalent Hewlett Packard Enterprise (HPE) product. Having worked with Extreme Networks for its edge switching, this solution was easy for KLM Engineering to get behind.

The new campus LAN was set up with a 40Gbps backbone, drastically improving the speed of data transfer across the network, and especially when replicating servers and data stores between computer rooms.

“From our perspective, the best thing about the network is that it is largely maintenance- and administration-free,” says Walker. “We’ve not had to do anything since go-live, and as we’re not a big team this is very important. It allows us to focus on more strategic projects rather than worrying about network administration.”

After installation, KLM Engineering was audited internally and the boosted network was found to be disaster recovery-compliant.

Josh Blakey, head of pre-sales at LAN3, says the KLM Engineering project is typical of LAN3’s approach in that it was tightly specified to be commercially fit for purpose and come in on budget.

“Lots of companies have that need to deliver against a very specific set of criteria when it comes to the campus LAN – in this case the disaster recovery specification – and we understand that. Cost counts, after all, and it is rare that price does not matter, even if technologies like software-defined networks are investments worth making for the longer term.”

The other area of evolution Blakey highlights, working, as LAN3 does, with Extreme Networks’ switches and network technologies, is the rise of fully automated end-to-end campus LANs.

“It’s the next step for some, and zero-touch services will sound enticing to many network managers.”


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