Beware of the upside-down network

by Raymond Keneipp

December 13, 2000 —

The availability of broadband access technologies is dramatically changing the way
companies support small offices and home workers. With DSL and cable data services,
companies can connect small offices and telecommuters at high speeds, often in excess
of 1 Mbps.

While the enhanced throughput is an improvement, the new technology has created some
problems for companies trying to support large numbers of small office workers with
high-speed connections.

Only a couple of years ago 1.5-Mbps T1 service was considered high speed, and at
most companies only a handful of T1s supported all employees. Most corporate sites
connected remote branches at 56 Kbps using frame relay and concentrated these access
lines into a T1 or 45-Mbps T3 link at the headquarters site. The teleworkers dialed in
via ISDN.

Now these same companies may have hundreds of remote locations connected at 1 Mbps,
with most of the data traffic to these sites coming from the company headquarters.

Problems arise when the headquarters site fails to increase its access bandwidth at
the same rate as the remote sites' bandwidth. When that happens, the sum of the
bandwidth of the access lines is 10 or 20 times greater than the bandwidth into
corporate headquarters, creating an upside-down network that can be subject to severe
congestion at the headquarters. The problem is aggravated by the fact that most
companies force remote sites to access the Internet via the headquarters site so they
can insure proper security.

Before you convert your remote sites to broadband nodes, be sure you have enough
bandwidth at headquarters to support the new high-speed remote sites. Also, talk to
your service provider about providing firewall services for remote branches so that
those sites can connect to the Internet directly. This should reduce the bandwidth
requirements at the home office.

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