Ifindex rt #209
Ifindex rt #209
Conversation
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I'm not sure rejecting unconditionally an existing route with a different next hop is the correct behavior. From a FIB perspective, I agree that now we should only have 1 next hop for any given route. Yet, from a RIB perspective, we can have different next hop for the same route. We would need a differentiator (eg: metric, link speed, ...) to decide the best route to render from the ROB to the FIB. With dynamic routing, won't we have multiple gateways for a single route ? |
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Let's keep it simple for the current design. Mid term, next hop group shall be considered in order to support multiple gateways and interfaces with their updates. Dynamic routing will benefit of nhg for such Grout datapath. Rejecting helps to avoid a miss configuration for the time being and I understand that it is enough for the routing/FIB manager. |
There is different topic like ecmp, route selection from rib. But it's not the topic of this commit.
When you do: My patch doesn't change anything. Grout don't support multiple next nop in the rib now. It just return an error when we tried to do that. When multipe nexthop will be support, this commit is not need. Until that i believe it useful to get an error when a route is not added in the rib. |
Previously, adding a route that already existed would silently succeed if exist_ok was true, even when the nexthop was different. This behavior is incorrect, as the user expects either the same route with the same nexthop to exist, or an error to be returned. This patch ensures that an error is returned when a route exists with a different nexthop, regardless of the exist_ok flag. Signed-off-by: Maxime Leroy <[email protected]>
Previously, attempting to delete a route whose nexthop is directly connected (i.e., not a gateway) would fail with -EBUSY. For example: add ip address 6.6.7.7/24 iface p4 add ip route 83.0.0.0/24 via 6.6.7.7 del ip route 83.0.0.0/24 error: command failed: Device or resource busy This behavior stems from route4/6_del, which checks whether the nexthop is a gateway before allowing deletion. If not, it assumes the nexthop is still in use and blocks the operation. However, there is no functional reason to prevent deletion in this case. The underlying rib4/6_del logic ensures that a nexthop is only fully removed when its reference count drops to zero—preserving it as long as it's still needed by a connected route. Signed-off-by: Maxime Leroy <[email protected]>
Thanks to this commit, the following type of route can be added: ip route add 10.0.0.2 via 172.1.1.2 dev p0 WIP -> just to get feedback Signed-off-by: Maxime Leroy <[email protected]>
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Understood, looks nice ! |
Add capacity to configure route with interface and gateway.
For now, it's just a WIP series.
We need that for FRR plugin.