Feeds

Routing instability causes net traffic chaos

Interweb routing chart snarl-up

Next gen security for virtualised datacentres

Surfers experienced problems accessing parts of the internet Monday, following the flare-up of router instability problems.

Security watchers pinned the problem on "garbage" being thrown into global BGP (Border Gateway Routing) lookup tables, causing entries to become unnecessarily long. Some backbone routers with older software versions are unable to process this traffic, resulting in sessions getting dropped and problems reaching parts of the internet as a result.

BGP is a core routing protocol which, put simply, maps the best available routes for traffic to flow across the interweb. These routing tables have become snarled up with junk in the loose equivalent of motorists being instructed to go around a roundabout 20 times before proceeding with their journey. As a result traffic has become snarled up and, in some cases, may only be able to access parts of the net via the back-roads.

"The source of the problem appears to be with AS 47868 causing AS paths to become too long," writes Marcus H Sachs, director of the SANS Internet Storm Center. "Not much you can do about it unless you have access to your BGP router, in which case you might want to either block AS 47868 or limit the length of any AS path."

BGP autonomous system (AS) numbers represent unique routing domains, which are typically linked to administrative domains. These work something like place names, indicating the fastest routes on the information super-highway, with the important difference that these routing tables are not fixed but periodically updated.

Danny McPherson, chief security officer at Arbor Networks, explained that routers still running versions of Cisco software older than three years old didn’t allocate enough buffer space for "silly long AS paths, and so they blow chunks when they receive the update".

"However, other vendor implementations and patched versions happily propagate the update, apparently through numerous intermediate ASes, so seemingly random sets of BGP routers in the routing system were taking a dump, or dropping sessions with malformed AS path complaints," he notes.

Similar problems caused global routing instability five years ago, McPherson notes in a detailed technical dissection of the problem here.

The practical upshot of the problem is not altogether clear.

UK traffic stats from LINX look normal, but elsewhere Slashdot reports a "single mis-configured router is apparently able to cause a DOS for a huge chunk of the net". ®

The essential guide to IT transformation

More from The Register

next story
The Return of BSOD: Does ANYONE trust Microsoft patches?
Sysadmins, you're either fighting fires or seen as incompetents now
Microsoft: Azure isn't ready for biz-critical apps … yet
Microsoft will move its own IT to the cloud to avoid $200m server bill
Oracle reveals 32-core, 10 BEEELLION-transistor SPARC M7
New chip scales to 1024 cores, 8192 threads 64 TB RAM, at speeds over 3.6GHz
US regulators OK sale of IBM's x86 server biz to Lenovo
Now all that remains is for gov't offices to ban the boxes
Object storage bods Exablox: RAID is dead, baby. RAID is dead
Bring your own disks to its object appliances
Nimble's latest mutants GORGE themselves on unlucky forerunners
Crossing Sandy Bridges without stopping for breath
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
BYOD's dark side: Data protection
An endpoint data protection solution that adds value to the user and the organization so it can protect itself from data loss as well as leverage corporate data.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?