For over 10 years, enterprise networks have been taking advantage of wireless LANs in one form or another. Most WLANs in enterprise networks are based on access points that connect directly to the wired network. Recently, the concept of wireless switching for WLANs has made them more useful for large-scale enterprise wireless implementations.
Now a new class of WLANs is on the horizon — wireless mesh networks. While mesh technology is available today, standardized gear is still a way off, so anyone planning on building a mesh network needs to have a good plan for the future in place.
Wireless mesh or MWLAN is based on the concept that access points can have up to three functions — connecting to users, connecting to other access points and connecting to the wired network. The access points connect to users with IEEE 802.11a or b/g technology. Access points then self-organize and connect to each other forming a partial mesh, using a “transit technology.” The access points collectively determine the routing through the mesh. Only a few access points connect to the wired network.
If an access point fails or becomes overly congested, the mesh re-organizes around the access point, maintaining connectivity to the wired network. Since not every access point needs connectivity to the wired network, most access points can be mounted anywhere that power can be provided, like posts or streetlights.
MWLANs are perfect for outdoor areas in a campus setting or when providing access to an entire city. The self-healing and self-organizing properties also make them ideal for some large enterprises or educational institutions that have these requirements. While not a typical application, MWLANs may also be useful to companies with large, internal, open spaces like manufacturers with large plants. Since most access points require only power, MWLANs may provide a better solution than regular or switched Wi-Fi in such settings.
Management of this kind of automatic network is both simple and complex at the same time. When everything is working, very little intervention may be required. If something breaks, then management becomes critical. New wireless management techniques are becoming better, but MWLANs add a new twist that needs to be considered.
Many cities are talking about delivering metro-wide Wi-Fi or what is being called muni-networking (municipal), based on deployments of MWLANs. For cities, not only is technology choice an issue, so is delivery of the service. Some cities have partnered with vendors like Earthlink, MetroFi or others that have deployed municipal networks before. The city lays out the rules and then selects one or more companies to operate the MWLAN for them. The city leaves the capital and operational costs up to the vendor, forcing the vendor to take some of the risk. Milpitas and San Francisco in California have both followed this model.
Here in Canada, Toronto has recently announced its own muni-network to be delivered by Toronto Hydro Telecom Inc. (THT). THT is owned by Toronto Hydro Corp., which in turn is owned by the City of Toronto. THT currently acts as a service provider of sorts, with a network of fibre in Toronto Hydro right-of-ways. Customers wanting high-speed connections between sites in the city could get this access from THT. This provides a great back-haul network for THT to use for a muni-network.
THT issued an RFP in February, and hopes to have an equipment vendor chosen by the end of this month. THT says the downtown core portion of the network will be deployed by the end of June 2006 and expand in phases. In this deployment THT will own and operate the network. THT’s plan is to provide free access for six months and then to provide paid service after that. This is a rather ambitious plan, in terms of timeframes and operational issues.
The real problem with MWLANs is the “transit network.” A great deal of data and control communication takes place between the access points, but right now no vendor’s gear works together with another’s. Last month, after three years of talks, vendors agreed on a proposal that will create an interoperable standard under IEEE 802.11s for this communication. This will lead to a ratified standard that most vendors will follow. A first draft is expected this July, with a final working draft pencilled in for late next year. An approved standard is expected by July 2008. Vendors will likely ship products that meet the final working draft early in 2008. Today’s technology is proprietary, so solutions from vendors shipped in the next two years will not meet the 802.11s specification and will need to be replaced.
Although there are several companies delivering proprietary MWLAN gear, there is no overwhelming market leader. Tropos, Motorola (MeshNetworks), Nortel and Cisco (Airespace) have solutions, as do many other companies. All of these vendors are likely to support 802.11s at some point, since most are actively involved in the standard.
However, standardization will not solve everything. Some companies, like Go Networks, are building equipment using Wi-Max (IEEE 802.16) as the transit network. This approach is not compatible with 802.11s, so there will still be market fragmentation.
With all the changes about to happen to MWLANs in the very near future, customers should closely examine what they are buying from their vendors. The new standard will make obsolete a lot of current equipment. An extensive pilot, looking at the whole system, should precede any deployment, along with an agreement discussing upgrade costs. Customers need to do their homework before making any decisions.
MWLAN products have come a long way in the years since their first appearance, but will need to come further, using one coherent standard, to become as successful as Wi-Fi.
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–Kanellakis worked at Enterasys Networks and its predecessor Cabletron Systems for almost 15 years. These days he is enjoying spending time with his family and looking for interesting ventures to pursue.
