Bug 2232380

Summary: OVN router policies do not support ecmp symmetric reply
Product: Red Hat Enterprise Linux Fast Datapath Reporter: Dumitru Ceara <dceara>
Component: ovn23.09Assignee: OVN Team <ovnteam>
Status: NEW --- QA Contact: Jianlin Shi <jishi>
Severity: unspecified Docs Contact:
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Version: FDP 23.JCC: ctrautma, jiji, pdiak, pepalani, surya
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Description Dumitru Ceara 2023-08-16 14:55:29 UTC 
Description of problem:

OVN gateway routers support "ecmp_symmetric_reply" behavior for ecmp static routes since v20.09.0 (https://github.com/ovn-org/ovn/commit/4fdca656857d4a5caeec35ae813888cb9e403e5e)

However, the routing decision can be overridden through re-route logical router policies.  These, in turn, support specifying multiple next-hops (ECMP) since v21.03.0 (https://github.com/ovn-org/ovn/commit/35b00c7e79900787e510bb203c5cddfb895f6c4f).

It's desirable that router policies also support the "ecmp_symmetric_reply" semantics, in order to allow reply traffic to always be sent out on the same path on which the initiating traffic was received.

This behavior should be on-demand, opt-in, configurable through a new Logical_Router_Policy option, e.g. "ecmp_symmetric_reply".