“We are all good. BGP established!”
That was the entire useful update after a long night of routers, firewalls, and provider emails.
The small network had just received its own autonomous-system number from ARIN. That meant it could establish BGP sessions with more than one provider and advertise its own route instead of treating each circuit as an isolated connection.
ARIN had approved the number on May 21. Now we were testing the network configuration behind it.
The approval was only the paperwork. The network still had to work. My job was to turn the new number into a working route without breaking the circuits already carrying traffic.
One provider terminated on a router, while BGP ran from firewalls behind it. The session therefore needed multihop configured correctly. A setting of one hop was never going to reach a peer that sat several hops away.
The thread went back and forth through the evening. Was the provider side correct? Was the customer equipment correct? Which address should peer with which? Were the route filters ready to prevent one provider's routes from leaking into the other?
The final problem came down to changing the multihop value from one to three.
The change was small. It was also the difference between a configured session and an established one.
Once the session came up, the new autonomous-system number had a working route through the provider. The second provider was part of the same dual-provider design.
The message went out at the end of the night from my phone: “We are all good. BGP established!”