Remote branch offices present a challenge. Workers need access to the same data as their colleagues at headquarters, but local-area network protocols are not designed for use over slower wide-area networks. LAN protocols are inefficient, says Hugues Meyrath, director of product marketing at Brocade Communications Systems Inc. Before any actual data is transmitted, “there’s about 100 acknowledgements that go back and forth over the wire,” he said.
The overhead isn’t noticeable on LANs, but on many WANs, “that’s suddenly a few minutes of wait time.”
You could install file servers at the remote locations to store copies of the data employees need as well as data created and used locally. This raises problems such as ensuring different copies of the data agree and administering those remote servers – making sure they are properly backed up, for instance.
wafs reduces waiting time
Another option is Wide-Area File Services, or WAFS. WAFS products from several manufacturers, including Cisco. Brocade and Tacit Networks use an appliance at the branch office that works with a counterpart at the data centre, providing more efficient access to centrally stored data.
They do this two ways. First, the remote appliance caches data. It checks with the data centre to make sure its copy is up to date. If so, it avoids retransmitting. Second, the WAFS appliances communicate between themselves more efficiently. For instance, says John Henze, director of marketing for caching services at San Jose, Calif.-based Cisco Systems Inc., WAFS appliances may forward less than 10 per cent of the messages normally sent between a client and a server.
WAFS products began appearing about two years ago. Meyrath says they address a substantial need, since the average enterprise has around 300 remote locations. Henze says WAFS works best over WAN links capable of 256-megabit-per-second throughput or more, though it will work at lower speeds. Meyrath says WAFS provides maximum benefits where the latency over a traditional WAN connection is high, which tends to be true of longer-distance links.
WAFS simplifies remote-office administration, Meyrath adds, because there is n oneed to worry about backing up remote data. Data cached on the remote WAFS appliances is only a copy of what is stored centrally, so remote users’ data will be backed up as part of normal data centre backups.
