Your employer - a legal company - is working on a large case, involving several different regional offices. The client's chief counsel has sprung a surprise visit on you, and she's arriving from New York tomorrow. Your legal team has to collect all of the outstanding case data from several parts of the company, and there are reams of documents to process - but the broadband network is down. Your CEO just kicked you out the boardroom, and now you're kicking yourself for not building appropriate reduncancy into your network. How could this have been avoided?
With companies dependent on the Internet for intra-and inter-company communications, the threat of network downtime is more unacceptable. But measures are available to large and small companies to prevent the worst.
"It starts with establishing a service level agreement with your main service provider," says Ted Bissell, managing consultant at the PA Consulting Group. "You should discuss about what kinds of outages to expect." If your SLA says your network will be up in 30 minutes after a failure, that might be theoretically acceptable.
"When suppliers are a problem, you agree an escalation path. You define a series of outage levels, and in the most severe category you end up with a quick level of escalation to senior management," Bissell continues. That sounds fair, but if our legal company's network stays down all night, no amount of escalation the following morning will get back the business they'll lose.
To really avoid the problem, two broadband links from different service providers might be necessary - but beware: "If you take two service providers, they might both rent the same access from BT and end up in the same fibre duct," says Margaret Hopkins, principal analyst at telecommunications market watcher Analysys Mason. "So you'd have to talk to your service providers to ensure your links are in different ducts."
To be truly redundant, connect to different broadband providers from different sides of the building, says Bissell. "Service provider A comes in through one part of the building, and service provider B comes through the waste facility. If a road digger goes through provider A's line, provider B can happily continue providing data service." That solves the problem of an immediate physical rupture, but doesn't avoid problems at the exchange. If something happens to an exchange and both broadband connections are housed there, your business users will soon realise how inadequate your broadband continuity plan is. So, the savvy IT department will ensure that the different broadband links are connected to different points of presence. But the further you get from large cities, the harder this could be, Hopkins warns. Companies too far out may only have one point of presence to choose from.
George Yun, principal at Interactive Broadband Consulting Group, reminds network planners to consider the fail-over process between links. If one link fails, does the network understand how to automatically bring the other one up and keep it running, and how long will the switchover take? Several companies provide dual-link routers that can help with the fail-over process. There is also the added benefit of aggregation. When both links are up and running, the local area network (LAN) sees them as a single, higher-speed wide area network (WAN) link.
Yun also says a wireless connection can help as a back-up for a data network. "Back-up satellite links might be ideal. They're often slow, with high latency, he admits. "They're also expensive. But the problem with alternative fixed wireless solutions like Wimax is that you don't have ubiquitous coverage." In the UK there's little WiMax at all. Microwave links can also be used for high speed line of sight connectivity, backing up faster links between buildings in a metropolitan area network.
Will firms with several branch offices want to invest in a redundant high-speed link for each of them? Such decisions require a cost-benefit analysis, says Yun. One possibility is to equip offices with cheap alternative links (maybe even a dial-up modem) as back-up, providing some connectivity in an emergency. The other option is to build efficiency into the wide area network at the start, using caching systems that store certain data locally for access during a network failure.
Satellite, microwave and highly-redundant landline links from different parts of the building might be an option for enterprises and diligent mid-sized companies, but not for many smaller firms. Hopkins says that many small office and home office (Soho) users or very small businesses could get away with a 3G link, such as the dongle offered by network operator 3 for laptop connections with a flat rate fee. Whichever route a company chooses, backup is becoming increasingly important. Now most senior executives are used to always-on connectivity, an extra monthly investment will leave you safe, not sorry.