Thursday, August 14, 2014

On Tuesday many internet routers, used to find the pathways to different parts of the web, reached their memory limit of 512,000 entries in the tables they use to store the routes, causing problems for many users.

A router is used to direct a user towards the area of the internet where they will find the content they are looking for, e.g. a web page. The recent problem was caused by the arbitrary memory limit built into the design of many aging routers. A limit was needed to prevent the cost of hardware from becoming prohibitively expensive in the days when physical data storage was still comparatively expensive. This small amount of memory in turn limits the number of directions which can be stored on a single router leading to different parts of the internet. When this limit was reached, it caused outages of services among Internet Service Providers. Many routers, including older ones provided by Cisco Systems Inc., are limited to storing a total of 512,000 routes or paths.

This limit was reached on Tuesday, reported to have been triggered by Verizon publishing another 15,000 paths. Those affected included eBay, LastPass, and clients of the web hosting company Liquid Web, who lost much of their services until Verizon withdrew some of these new paths. Problems nevertheless continued throughout the day, even after the withdrawal.

A longer term fix is possible, but it would require manually replacing old routers with newer, more capable ones. It is hard to tell what issues would temporarily cascade though the internet by taking down routers from part of the internet for maintenance. Many experts have warned that problems could continue until these difficult fixes have been implemented, although the recent switch to a newer form of IP Addresses, IPv6, will temporarily help the issue. Wired News reported that Andre Toonk, a network engineer, had stated that the number of network outages on the internet, typically around 1,500, yesterday peaked at 2,587, enough to become clearly noticeable.