Hi Dimitar, In VPP’s FIB weight and preference are attributes of a path not of a route. The weight controls [un]equal cost load-balancing across the paths and preference controls which paths to use when they are [un]available (i.e. BFD down), a kind of poor man’s fast re-route.
It’s my understanding that Linux preference/metric applies to the route and is set based on the admin distance of the route’s originator (e.g. static, OSPF, etc). The route with the best metric/AD is the one used for forwarding, this is route arbitration performed by a RIB, only the route with the best metric/AD should be programmed into a forwarding table and hence programmed into VPP’s FIB. /neale From: <vpp-dev@lists.fd.io> on behalf of Dimitar Ivanov <d...@telco.com> Date: Wednesday 15 April 2020 at 14:52 To: "vpp-dev@lists.fd.io" <vpp-dev@lists.fd.io> Subject: [vpp-dev] frp_preference and frp_weight size #vnet Hi, I'm working with vers.19.08 and see something that cannot understand. Currently in FIB route path definition preference and weight are u8. In same time preference(metric) in Linux kernel is 32 bit value. My target is to inject routes in VPP and to keep same parameters like in Linux kernel. So here i face the conflict. And this is most visible when examine IPv6 routing table in Linux, where default metric/preference of default route is 1024. Question is how to overcome this problem where is possible Linux kernel to have routes with metric bigger than 255 and in same time VPP Fib do not allow this ? I saw that with this patch https://gerrit.fd.io/r/c/vpp/+/7586 is introduced preference and weight become from u32 to u16. Now weight and preference are u8. Is there some plans VPP Fib to accepts preference bigger than u8 ? Is there some workaround for this problem ? Regards, Dimitar
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