3. Solving asymmetric routing with BGP communities

One of the most advanced and highly requested use cases we’ve seen over the last year is achieving traffic symmetry. When enterprises use stateful firewalls or specific network appliances on-premises, return traffic must flow back through the exact same appliance it originated from. If it doesn't, the traffic is dropped. Customers are successfully solving this by using BGP route policies to match against specific standard BGP communities. By tagging routes with specific communities on-premises, Cloud Router can read those tags via inbound policies and adjust the route preference by manipulating the MED accordingly.

This helps ensure that Google Cloud inherently understands the stateful topology of the on-premises network and routes the return traffic symmetrically. Dive deeper: To learn how to architect stateful traffic symmetry using BGP community tags, explore: Using BGP communities to create traffic symmetry.