Has your computer been slow this week? Have you suffered from more outages than usual? There's a reason for that. The internet has grown too big!
A Vancouver, B.C. based internet monitoring firm, BGPMon, has noticed that internet outages have been well above the norm this week and are the highest seen in the past year.
Why?
512K
Step over the orange jumble of cables to find out what that enigmatic number means
512K ( 512,000) is the maximum number of routes that some older networks gear can handle. These older routers, made by Cisco, a California based company, are still used by smaller networks and regional internet providers, according to Andree Toonk, founder and lead developer of BGPMon. Currently the number of routes sit at 500,000. So what happened?
There was a bug at Verizon early this week that suddenly dumped 15,000 new internet destinations onto the network for about ten minutes. The result was that the number of routes spiked and sent servers into slow mode or dropped some of their destinations.
The problem arises because routers direct internet traffic to the correct destination, and rely on summaries of the destinations that are kept in tables in their memory. The default maximum size of that memory is 512K for older routers. Once that maximum is reached, three possible things can happen, Toonk said:
The router can switch to a slower mode, resulting in sluggish performance.
Some destinations may not end up in the table at all, making them unreachable.
The network operator may have to reboot the router, resulting in a few minutes of instability.
Internet users will experience:
Overall internet slowness if they rely on an internet service provider that's affected.
Slowness for certain websites or services that rely on affected internet service providers, even if their own ISP is not affected.
Cisco had warned users of the impending problem back in May.
While this is currently a temporary problem, these routers capacity is near full and the problem will continue to re-occur in the very near future. Omar Santos, senior incident manager for Cisco's Product Security Incident Response Team writes in a post on the Cisco Support Community website:
Since the early 1990s, we’ve watched as the number of entries on the Internet routing table has steadily grown. It wasn’t that long ago (2008) that the table reached 256k routes, triggering action by network administrators to ensure the continued growth of the Internet. Now that the table has passed 500,000 routes, it’s time to start preparing for another significant milestone – the 512k mark.
Looking Ahead to 512k
As an industry, we’ve known for some time that the Internet routing table growth could cause Ternary Content Addressable Memory (TCAM) resource exhaustion for some networking products. TCAM is a very important component of certain network switches and routers that stores routing tables. It is much faster than ordinary RAM (random access memory) and allows for rapid table lookups.
This webpage also posts fixes and links to fixes for providers.
https://supportforums.cisco.com/...
Omar hopes that this weeks warning will wake up internet providers to the problems coming up and rejig their routers, but he also worries that some won't, and slow internet may be a problem we will face for a while.
http://www.cbc.ca/...