Today’s Connection Issues to Eve


Today we saw a large outage to CCP’s servers in London as the number of BGP routes advertised on the Internet passed a critical milestone. If you are unfamiliar with BGP, the easiest definition is that it is the protocol used to allow major ISPs to talk to each-other and share information on where to send traffic in order for it to reach its destination. Without ISPs peering using BGP, routers would not know to send traffic and nothing would reach the target host.

Certain models of Cisco routers that have not been modified from their default configuration became unstable after accepting more than 512,000 routes. Users all across the Internet saw strange behavior as routers began to drop traffic, slowly pass traffic through software routing, or crashing entirely. I saw my connection to CCP’s server in London from San Francisco become unreachable for several hours.


This issue has been written about months ago, but it seems that a lot of people were caught by surprise. There is even a Cisco approved interim fix to buy more time by allocating additional memory space to store additional IPv4 routes (1).

Further reading on this topic can be found on this r/networking post.

(1) CAT 6500 and 7600 Series Routers and Switches TCAM Allocation Adjustment Procedures [link]