CSCwr85402 Ignore frag filter #646
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If "fragmentFlags" is present in a rule simply ignore them. The fragmentFlags are supposed to match on second packet on that has a fragment bit set. The issue with this match is that since its a fragment it cannot match on ports so it effectively becomes an ip allow all filter without regard to ports that overrides any other filter with specific ports. Its assumed that a frag filter will be applied as an independent filter and not merged with any port specific filter. If CT is also enabled as such with a port match, Ovs will automatically reassemble / refragment all the packets for that port match to work. So there is no specific need of a fragment filter. Of course if the frag filter is the only allow rule configured that also will not be supported.
tbachman
approved these changes
Nov 13, 2025
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If "fragmentFlags" is present in a rule simply ignore them.
The fragmentFlags are supposed to match on second packet on that has a fragment bit set. The issue with this match is that since its a fragment it cannot match on ports so it effectively becomes an ip allow all filter without regard to ports that overrides any other filter with specific ports.
Its assumed that a frag filter will be applied as an independent filter and not merged with any port specific filter.
If CT is also enabled as such with a port match, Ovs will automatically reassemble / refragment all the packets for that port match to work. So there is no specific need of a fragment filter.
Of course if the frag filter is the only allow rule configured that also will not be supported.