VLANs - they won't happen overnight but . . .

VLANs - they won't happen overnight but . . .

The IT industry has a terrible habit of marketing new whiz-bang technologies that never live up to overhyped expectations.

The VLAN, or virtual LAN, is one such "marketechtural" innovation that received much initial fanfare that has led, ultimately, nowhere.

But, before delving into the fors and againsts of VLAN architectures, and whether or not it's worth implementing the technology, let's first explain this still rather immature technology.

There are different opinions about the strategic value of VLANs or, for that matter, what a VLAN is. After all, VLANs were only really introduced as an enhanced LAN switching capability.


One description is a set of location and topology-independent groups that communicate with each other as if on a common physical LAN.

Compare it to, say, an IPX network or an AppleTalk zone. These groups can talk to each other in a number of ways. They can be switch-based where a switched port belongs to one virtual LAN and all devices connected to that port must also belong to that VLAN. This is the most popular method employed.

The groups could also be MAC address-based. In this case the switch is required to create VLANs based on the MAC address of the connected devices. Each device has its own unique MAC address (and can therefore be associated with the user). This allows multiple VLANs to be supported per switch port.

Finally, the groups could be Layer 3 or protocol-based. This type of VLAN takes into account the protocol type or the group's address to determine VLAN membership, to enable the creation of separate VLANs per protocol or subnet.

But enough of the technical talk. Let's get down to the nitty-gritty and decide whether VLANs can be applied to typical networking environments.

Listen to any VLAN evangelist and they'll earbash you with claims that the technology makes it easier to observe high-volume traffic flows, isolates chatty protocols to increase network bandwidth and can separate workgroups from other traffic for security purposes.

They'll also cite the fact that VLAN members can share resources on centrally located servers without having to move to the same physical LAN segment. To put it simply, VLANs can track users' movements and move their privileges and memberships wherever they reconnect.

That's all fine and dandy in theory, but in practice the job of implementing a VLAN throws up a few curly ones. For starters it's a new technology, and with that honour comes a number of booby traps.

For at least two years now, the big switching vendors such as Cisco, Bay Networks, 3Com, Cabletron and Xylan have fostered their own proprietary VLAN solutions that extend beyond the boundaries of previously ratified standards.

An official standard, which these vendors must adhere to, is expected to be finalised late this year. IEEE 802.1q will determine VLAN frame formats, membership rules and management procedures.

And while VLANs act as an extension of existing LANs there are some skills which resellers will need to obtain to work in that mixed environment.

Ken Louis, a director at Lanlink, said resellers first have to sell switching hardware that supports VLANs before they can sell the benefits of VLANs themselves.

"But unless they have large customers that demand security and flexibility from their switched environment, resellers will have limited success," he said.

"We don't generally get tenders strictly for VLANs. "Rather, we get them for switched networks with VLAN potential and then promote the value-added benefits that VLANs can offer."

Michael Rubenstein, a systems engineer at Express Data, agreed that resellers need to be aware of specific customer needs.

"We are finding that as organisations expand they are starting to worry about segmenting the network into individual domains and ensuring network security is handled effectively," he said.

According to Bill Nixon, the network consultant manager for Memorex Telex's NSW branch, there is a dearth of training courses available to teach resellers key techniques such as connecting multiple VLANs to a file server.

"Once you divide the network up, the file server will be shared by multiple VLANs with each demanding different resources.

"But because VLAN technology is still relatively new, few training courses have addressed the issue of how to connect multiple VLANs to the one file server," Nixon said.


However, Rubenstein said drag and drop network management software takes much of the guesswork out of deploying VLANs.

VLANs can play in either a switched or routed environment, although switching is the most widely accepted topology because of its ability to offer faster throughput and simpler management - remember what routing tables look like?

Then there's all the additions, moves and changes that are inevitable in a VLAN-based environment when some lucky users will move from one workgroup to another, or in fact, reside in multiple workgroups.

But before you start thinking that every organisation is a potential VLAN gold mine that will rake in healthy profits, consider the argument presented by a number of analysts.

The US experience is that VLANs are probably not worth the trouble for organisations running networks with 500 or fewer end users. The reason being that smaller networks do not benefit much from VLANs because they do not suffer from broadcast traffic problems.

In Australia, the perceived market for VLANs is not so cut and dried.

Memorex Telex's Nixon said any organisation running a switched environment that connects more than 100 users could benefit from implementing a VLAN or two.

"Many users find switched environments hard to control," Nixon said. "Sure they offer fast throughput, but server maintenance is an issue.

"With its segmenting capability, a VLAN gives users greater control over where they locate their data," he added.

Sweet dreams

But is the market acceptance of VLANs high enough for resellers to go to sleep at night knowing they have invested in a technology that can turn a profit? Nixon reckons VLANs can represent a nice little earner as long as resellers understand the pitfalls involved with dabbling with a new technology.

"Resellers need to be familiar with issues such as segment management and file server and router maintenance. They also need to be aware that not all organisations would suit a VLAN deployment. They can only work at organisations with large, centrally located LANs," Nixon said.

"It would be impractical to sell a VLAN solution to an organisation that needs to connect a mass of regional offices spread across the country."

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