Revert "bgpd: Handle Addpath capability using dynamic capabilities" (backport) #17940
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This reverts commit 05cf9d0. TL;DR; Handling BGP AddPath capability is not trivial (possible) dynamically. When the sender is AddPath-capable and sends NLRIs encoded with AddPath ID, and at the same time the receiver sends AddPath capability "disable-addpath-rx" (flag update) via dynamic capabilities, both peers are out of sync about the AddPath state. The receiver thinks already he's not AddPath-capable anymore, hence it tries to parse NLRIs as non-AddPath, while they are actually encoded as AddPath. AddPath capability itself does not provide (in RFC) any mechanism on backward compatible way to handle NLRIs if they come mixed (AddPath + non-AddPath). This explains why we have failures in our CI periodically. Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
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This reverts commit 05cf9d0.
TL;DR; Handling BGP AddPath capability is not trivial (possible) dynamically.
When the sender is AddPath-capable and sends NLRIs encoded with AddPath ID, and at the same time the receiver sends AddPath capability "disable-addpath-rx" (flag update) via dynamic capabilities, both peers are out of sync about the AddPath state. The receiver thinks already he's not AddPath-capable anymore, hence it tries to parse NLRIs as non-AddPath, while they are actually encoded as AddPath.
AddPath capability itself does not provide (in RFC) any mechanism on backward compatible way to handle NLRIs if they come mixed (AddPath + non-AddPath).
This explains why we have failures in our CI periodically.