A wide area network (WAN) disaster recovery plan is a vital component of an organisation's overall disaster recovery plan, but possibly an overlooked one. Bringing remote users back online, along with the data centres they connect to, should be high on a WAN engineer's list of priorities.

Why does your business need a WAN disaster recovery plan?

Why do organisations need a WAN disaster recovery plan? Simply put, a DR plan is a step-by-step approach to recovering from what is certainly going to be the worst day in the history of the company, a natural or man-made disaster. Floods, tornadoes, hurricanes, or even a terrorist attack can affect businesses of any sise, from the largest corporation to the smallest mom-and-pop store, and the organisation's ability to recover from that event will be a function of its disaster recovery plans. The notion of being able to quickly respond to any significant disruption to the network, with a clear course of action and a laid-out plan, is what most IT administrators should strive for. However, the reality is that DR projects almost always seem to get pushed to the bottom of IT's priority list. Even if business continuity is brought to the fore, the focus tends to be on the data centre. This approach, while covering the back-end systems, leaves the WAN in question -- and remote users in the lurch.

Being prepared to deal with the loss of connectivity between remote sites and the head office should always be a concern for network administrators. Technology trends like server consolidation and migration back to the data centre, as well as the latest cloud computing push, are making the WAN link at these remote sites even more vital to business operations. In early generations of WAN connectivity, which were significantly slower and more costly, enterprise architectures and applications focused on a store-and-forward approach to data: storing it locally at remote sites, then pushing those changes back to the head office. However, the lower-cost and higher-bandwidth WAN connectivity of today allows applications to move more toward a real-time, centrally managed data centre. This approach has obvious benefits, both in managing a consolidated architecture and minimising the hardware footprint at remote sites, but it also requires a new approach to dealing with a consolidated architecture.

New options for your WAN disaster recovery plan

As the speeds and feeds of branch connectivity continue to ramp up, WAN disaster recovery plans will need to take that increased bandwidth into account. The good news is that wireless wide area networking (WWAN) connectivity options, including 3G and in some areas 4G, have ramped up as well. Several networking vendors are building WWAN options into their equipment, either with dedicated wireless cards or by enabling USB ports on their gear to accept wireless modems. While WWAN connectivity would provide only a fraction of the performance of a Carrier Ethernet link, a wireless approach will still allow a remote site a reasonable amount of bandwidth during a disaster.

WAN disaster recovery further reading
The importance of WAN optimisation technology in disaster recovery programs

Challenges of performing disaster recovery across the WAN

WAN optimisation enhances disaster recovery plans

Network disaster recovery planning and the WAN

Using WAN clustering for disaster recovery

Using WAN optimisation to improve virtual disaster recovery

Organisations can also take advantage of the pervasiveness of consumer broadband in their WAN disaster recovery plans. In the event of a disruption at a remote office, even typically cubicle-bound employees could temporarily become teleworkers, connecting to the home office from their home networks. Unless the company has a business need to gather displaced workers into the same physical space, telecommuting could be a quicker and lower-cost alternative to renting temporary office space.

The WAN should also factor in to the data centre disaster recovery plans. Beyond figuring out how to link remote sites to a hot site or secondary data centre, the components that make up the wide area network, including any WAN accelerators, should be included in the hardware inventory available at the alternate site. While application acceleration would seem to be a low priority on the recovery plan, bear in mind that an alternate site will probably be equipped with a lower-speed connection than the primary data centre, and not including WAN optimisation components will only make the situation worse. Backups of any configuration setting for all WAN devices, including any routers, modems and acceleration appliances, should be kept in a secure location, ensuring that the WAN administrator does not have to completely reinvent the wheel when configuring these devices after a disaster. Likewise, updating of this backup should be included as part of the change-control process for managing the WAN.

Ultimately, an organisation's disaster recovery plan is actually more about restoring business operations to as normal as possible, as quickly as possible, than it is about specifically recovering databases or restoring services. To that end, being mindful of the folks on the other end of the WAN link is as important as being mindful of those on the local area network. Building a plan around business resumption will let engineers be ready for any disaster, wherever it may strike.

This was first published in February 2011