Egypt returned to the Internet earlier today by reversing the "kill switch" move it made last week when it withdrew router announcements, experts said.
To restore the country's connections , Egyptian Internet service providers (ISPs) re-configured their core routers so that they once again announced their presence, letting upstream providers and other networks reestablish data pathways.
"It was pretty much similar, except reversed, to what happened last week ," said Andree Toonk, the founder and lead developer of BGPmon, an open-source tool for monitoring BGP, or "border gateway protocol."
BGP is the protocol at the heart of the Internet's routing mechanism, and is used by routers to share information about the paths data traffic uses to "hop" from one network to another as it moves from a source to its destination.
The speed with which the networks reconnected was evidence that rather than physically plugging in cables, Egypt's ISPs simply began advertising their availability to other networks' routers using BGP, said Toonk.
"That, and the fact that it all happened at the same time shows the disconnect was probably not physical," said Toonk. Nor was the restoration today. "Everything was restored in about half an hour," he said.
According to Toonk's monitoring, the first BGP announcements for Egypt began at 9:30 a.m. UTC, or 11:30 a.m. local time. The start time Toonk cited was 4:30 a.m. ET and 1:30 a.m. PT in the U.S.
Internet monitoring company Renesys also pegged the reconnect time for the bulk of Egypt's networks at around 30 minutes.
Others said it took longer than that. "It wasn't quite as abrupt as last week," said Craig Labovitz, chief scientist at Arbor Networks in Chelmsford, Mass., today. "It took from a half hour to an hour."
The quick restoration of service also meant that the Egyptian government had likely ordered the digital blockage lifted, said Toonk, just as it forced ISPs to go offline last week.
Some ISPs and sites remained accessible outside Egypt during the five-day outage, said both Toonk and Labovitz, who were wary of assigning a reason for their survival when most of the country went dark. "There were a few percent of Egypt's ISPs, maybe four to five percent, that were left online," said Toonk. "Why they remained online, I don't know."
This chart from Arbor Networks shows Internet traffic returning in Egypt.
One of the sites that stayed alive was Bibliotheca Alexandrina , or The New Library of Alexandria.
Ismail Serageldin, the library's director, had used the site's availability to provide an update on the facility's security , which had been threatened by looters during the calls for President Hosni Mubarak's resignation. "The library is safe thanks to Egypt's youth, whether they be the staff of the Library or the representatives of the demonstrators, who are joining us in guarding the building from potential vandals and looters," said Serageldin in a message posted to the site Sunday.
Serageldin said that protesters had also helped secure the Egyptian Museum, although Western news organizations have reported that the Cairo museum, which houses the world's largest collection of Egyptian antiquities, had been broken into and some artifacts, including two mummies, destroyed.
The Egyptian Museum's Web site was offline as of 1:30 p.m. ET.
Other sites also stayed up, including Gulf Air, the national airline of the Kingdom of Bahrain. Gulf Air's site is hosted on servers physically located in Egypt.
"For the region, Egypt is a popular co-location site," said Labovitz, referring to data centers that house large numbers of servers.
The Egyptian ISP that connected Gulf Air to the Internet is used by a small network of Web servers, added Toonk, which may have been why it remained online while others dropped off the Internet. "We can only assume that some of the sites that stayed online had a high economic value," he said.
"We've seen some countries, like Myanmar, completely disconnect from the Internet before," said Labovitz when asked to put the five-day Egyptian blackout in perspective. "But what is unprecedented here is that a technologically advanced country disconnected."
The event was also a milestone for the impact it had on Egypt, Labovitz continued. "Communications, particularly the Internet, is so integral to the modern economy, it's clear that it's very difficult to not have [Internet] connectivity, because of economic as well as social and political pressure," he said.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is email@example.com .
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