BGP Graceful Restart: What It Is and When It Actually Helps
BGP Graceful Restart (GR) is one of those features you turn on everywhere because the vendor datasheet says it improves availability — and then you spend the next year debugging weird convergence behavior because of it. Let me break down what GR actually does, and more importantly, when it helps versus when it makes things worse. The Problem It Solves When a BGP speaker restarts (software upgrade, process crash, failover), it tears down all its sessions. Every peer withdraws the routes it learned from that speaker, and the network reconverges. This takes time — seconds to minutes, depending on your topology. ...