I would be interested to know how many "software" (for want of a better description) routers are in live production in this kind of environment i.e. the 99.9999% Uptime variety, from speaking to people albeit randomly in data centres it would seem to be more common than one might expect.
It is indeed very common. That is why there are several implementations of BGP and routing software available. These are used in dozens and dozens of commercial products some of which are sold as IP routers, plain and simple. In any case, 5 nines and 6 nines are not always what the marketing department claims. They often exclude planned maintenance periods so if you reboot once a week or you have a crash after changing a config, that doesn't count against the 5 nines. In addition, the 5 nines figure generally applies to the network, not to individual devices within it. Networks can be designed so that the failure of a device does not cause a network outage. This whole issue is so complex that you just can't make blanket recommendations. Even the biggest networks don't just buy and deploy big iron. They run every new router model and software release through an extensive battery of tests. Then they write operational guidelines telling people which features can be used in which situations. They do this to avoid crashes and network outages because the big iron (Cisco/Juniper) simply cannot provide that on its own. A smart small company can get excellent results from Linux routers (although I would take a serious look at FreeBSD or OpenBSD for this). Process is as important as hardware. --Michael Dillon