Internet service provider (ISP) UUnet suffered an outage last week which resulted in at least 400 of its customers, including the London Stock Exchange and Ford, being denied Internet access.
Customers who depend on UUnet's Docklands point of presence found their Internet access down from 4am on 5 October for up to 36 hours. The service is now working normally.
According to a UUnet spokesman, the problems occurred after the company attempted a "serious upgrade" during a regular maintenance session.
"During the work we discovered that routers were 'poisoning' each other - problems on one router were having an effect on the next - so we had to go through them all one by one. We regret the incident and offer our apologies to customers affected."
One user directly affected was electronics firm Brother at its Wrexham site. Systems engineer Chris Woods said, "We use ISDN provided by UUnet for order processing and EDI. The situation is on the verge of becoming critical. We chose the UUnet service because of its 100% guarantees."
His colleague Darryl McCormack said, "We were having to print orders and use a fax machine - it is creating a massive amount of work. We shall be looking at the service level agreement [SLA] to get compensation, but we are less interested in getting crumbs from UUnet's table than finding out what it intends to do to make sure this doesn't happen again. I can't believe it had no fail-over to back-up the system."
Asked what companies can do to protect themselves against ISP outages, Gartner Group senior analyst Michal Halama said, "Companies can do little except go to a reputable ISP and get a decent SLA because it is not practical to have an extra ISP waiting in the wings or for companies to set up their own Net connection. But ISPs ought to have fail-over."
Web pages at the stock exchange and Ford were down for the period of the outage.
UUnet SLAs promise: "The UUnet network will be available 100% of the timeÉ Should these specified levels of service fail to be achieved, UUnet will credit the customer's account."
The UUnet spokesman said, "We will be looking at the SLAs and will be playing by the rules."