Hi Emma, It is not necessary for VPP and the linux kernel to act the same way. They will both have their own reasons for acting the way they do.
From VPP’s point of view, the general programming model for all objects, is that if they were added explicitly by the user, then they must be removed explicitly, and in most cases the removal must be in reverse order to the addition. Removing a route on interface down would violate this model. Regards, neale From: <[email protected]> on behalf of emma sdi <[email protected]> Date: Monday 4 November 2019 at 11:07 To: vpp-dev <[email protected]> Subject: [vpp-dev] VPP Route Management vs Kernel Hi Dear VPP There is a difference between VPP and Kernel's behavior in route management. For instance, consider that a route like "ip route add x.x.x.x/x via y.y.y.y dev ethX" is added. It would be deleted when ethx down performed in Kernel. While The VPP behavior is that forwarding of that route entry in unicast-ip4-chain will be changed to dpo-drop. Now what will happen if we change the state of the interface to up again?! defined route associated with the kernel interface will be disappeared while VPP will make previously added route lives again. Which behavior is acceptable? and is it necessary for VPP to operate the same as kernel anyway? Kernel senario: given: ethX interface has ip and is up when: "ip route add x.x.x.x/x via y.y.y.y dev ethX" and "ifconfig ethX down" then: any route dose not exist for ethX in "route -n" output. then: "ifconfig ethX up" and any route dose not exist for ethX in "route -n" output again. VPP senario: given: GigabitEthernetX/0/0 interface has ip and is up when: "ip route add x.x.x.x/x via y.y.y.y GigabitEthernetX/0/0" and "set interface state GigabitEthernetX/0/0 down" then: "show ip fib x.x.x.x/x detail" => forwarding: unicast-ip4-chain ... dpo-drop then: "set interface state GigabitEthernetX/0/0 up" and "show ip fib x.x.x.x/x detail" => forwarding: unicast-ip4-chain ... arp-ipv4: via y.y.y.y GigabitEthernetX/0/0
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