Can engineers and security teams even access prod systems anymore? Like, would "Bastion" hosts be reachable?
Wonder if they use Signal and Slack now?
Joking aside, I can see how an IRC network has potential to be used in these situations. Maybe FAMANG should work together to set something like this up. The problem is, a single IRC server is not fail safe, but a network of multiple servers would just see a netsplit, in which case users would switch servers.
Also, I remember back in the IRCnet days using simply telnet to connect to IRCnet just for fun and sending messages, so its a very easy protocol that can be understood in a global desaster scenario (just the PING replys where annoying in telnet).
While normally I know the advice is "Don't plan for mistakes not to happen, it's impossible, murphy's law, plan for efficient recovery for mistakes"... when it comes to "literally our entire infrastructure is no longer routable from the internet", I'm not sure there's a great alternative to "don't let that happen. ever." And yet, here facebook is.
Routing is one thing which you can't do without (then you need to fallback to phone communications), but DNS is something that's quite probable to not work well in a major disaster.
When I worked there, I wasn't aware of any 'test once per year' concept or directive.
Of course, FB is a really big place, so things are different in different areas.
Hmm well I mean for key people, ops and so on. Not for every employee.
Only a few people need that type of access, and they should have it ready. They need to bring more people there should be an easy way to do it.
Maybe the internal FB Messenger app has a slide button to switch to the backup network for those in need.
Having worked for 2 FAANG companies, I can tell you most core services like which FB Messenger would be using internal database services and relying on those which would be ineffective in a case like this as it would not work and the engineering cost to design them to support an external database would be a lot more than just paying for like 5 different external backup products for your SRE team.