Understanding the implementation of BFD
No network is completely fault-proof! Hardware issues or incorrect configurations can happen. To mitigate the effects of these failures, it is essential to have a well-designed network that includes mechanisms to minimize their impact.
Every ExpressRoute circuit is established with a primary and secondary connection between a redundant pair of CE/partner edge routers and Microsoft edge routers (as shown in Figure 6.32). The routing between these two sides is managed by BGP, which also detects any downlinks and automatically switches to the other available link:
Figure 6.32 – ExpressRoute redundancy
BGP uses two key parameters to detect link failures and initiate failover—the keep-alive time and the holdtime. Keep-alive messages are sent between the routers to confirm that the connection is still active. The frequency of these messages is determined by the configured keep-alive time. On Microsoft...
