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DPDK's LPM table for IPv6 has a bug that truncates the next hop field of LPM rules. Given that the bug truncates the next hop field to 8 bits, the problem only happens when the largest next hop field is larger than 255. The truncation will be triggered during regular operation and saved in the table. And it always happens while iterating over LPM6 tables. In Gatekeeper, the problem manifests in an array of symptoms, for example (non-exhaustive list): 1. Failed asserts on FIB entries with an invalid action. This happens when one of the prefixes that map to the same truncated entry is removed and an access to one of the other prefixes is made. 2. Lots of extra editing activities from routing daemons. Since the FIB is never exactly how routing daemons expects it to be, routing daemon keeps editing the FIB. 3. The script show_fib6_grantor.lua of command gkctl may list multiple extra FIB entries with action GK_FWD_GRANTOR. The extra Grantor entries are just entries whose next hop field is being truncated to the next hop of a Grantor FIB entry.
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DPDK's LPM table for IPv6 has a bug that truncates the next hop field of LPM rules. Given that the bug truncates
the next hop field to 8 bits, the problem only happens when the largest next hop field is larger than 255.
The truncation will be triggered during regular operation and saved in the table. And it always happens while iterating over
LPM6 tables.
In Gatekeeper, the problem manifests in an array of symptoms, for example (non-exhaustive list):
Failed asserts on FIB entries with an invalid action. This happens when one of the prefixes that map to the same
truncated entry is removed and an access to one of the other prefixes is made.
Lots of extra editing activities from routing daemons. Since the FIB is never exactly how routing daemons expects
it to be, routing daemon keeps editing the FIB.
The script
show_fib6_grantor.luaof commandgkctlmay list multiple extra FIB entries with actionGK_FWD_GRANTOR.The extra Grantor entries are just entries whose next hop field is being truncated to the next hop of a Grantor FIB entry.