The speed of BGP network propagation

Sadly, a lot of networks struggle to get consistent network announcements to work right, often resulting in totally backwards-from-logic routing:

However even those networks that do get most regions down, regions like Asia are much harder to get to route correctly, partly due to local ISPs either dealing with overloaded links or their links not always following logical geographic points. When we see a BGP update message for our prefix, that provider+location combo wins (or if they are late, loses)

This could be slightly flawed, since some networks might have hard to observe mechanisms for quickly sending routing information inside their network, but those initial route updates internally may not be sensible network paths. , If you look at ORD (Chicago) and MIA (Miami) you can see other carriers pick up the route from telia at another location, and hand it over to our provider before 20 seconds later, it arrives as a direct route.

Source: blog.benjojo.co.uk