Describes the necessary prerequisites for BGP deployment, including network readiness, essential configuration requirements, and factors that must be in place before implementation.
User group and task ID requirements
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You must be part of a user group associated with a task group that includes the required task IDs.
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Refer to the command reference guides to find the task IDs necessary for each command.
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Contact your AAA administrator for assistance if you suspect that your user group assignment is restricting access to use a command.
BGP table memory requirements
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The current internet BGP table contains approximately 1.1 million IPv4 routes and 200,000 IPv6 routes. Ensure your router has at least 5.5 GB of RAM to manage the full internet BGP table, with an average of two paths per route.
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You must plan for higher memory requirements as the IPv6 internet routing table continues to expand.
Hardware requirements
Use the Service Edge (SE) version of Route Processor (RP) cards, Route Switch Processor (RSP) cards, or fixed chassis routers for devices that need to maintain a full BGP table.
BGP read-only mode during startup
The BGP process enters READ_ONLY mode when it starts or restarts. During this convergence phase, BGP receives routes from peers, but delays best-path installation in the Routing Information Base (RIB).
Starting with Cisco IOS XR Release 26.3.1, redistributed connected routes no longer cause BGP to end READ_ONLY mode prematurely. Only the update-delay timer and neighbor establishment completion now control transitions from READ_ONLY mode.
The default update-delay timer value is five minutes. In scaled networks, this delay gives physical and bundle interfaces time to become ready. Best-path installation begins after the delay. This behavior can reduce the total router stabilization time after a reload.
To adjust the convergence window, configure bgp update-delay in router configuration mode. The supported range is 0 to 3,600 seconds.