bgpd: Ensure addpath does not withdraw selected route in some situations (backport #19210) #19286
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Currently when configuring bgp to send up to 6 additional routes after the selected, there exists a timing window where it can decide to send a withdrawal for the selected. Thus leaving a non-selected on the sent to router. The code loops over the paths in the start of the function, skipping the best path and finding up to X additional paths to send. When this is done, it looks at the list generated compared to all the paths and sends withdrawals for all those no-longer possibly selected. Since bestpath sending is elsewhere we end up with a situation where it's possible to send a withdrawal for the selected. Modify the code in the second loop to no longer send a withdrawal in this case for the selected. Signed-off-by: Donald Sharp <sharpd@nvidia.com> (cherry picked from commit c9084f0)
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Currently when configuring bgp to send up to 6 additional routes after the selected, there exists a timing window where it can decide to send a withdrawal for the selected. Thus leaving a non-selected on the sent to router. The code loops over the paths in the start of the function, skipping the best path and finding up to X additional paths to send. When this is done, it looks at the list generated compared to all the paths and sends withdrawals for all those no-longer possibly selected. Since bestpath sending is elsewhere we end up with a situation where it's possible to send a withdrawal for the selected. Modify the code in the second loop to no longer send a withdrawal in this case for the selected.
This is an automatic backport of pull request #19210 done by Mergify.