30 Sep
2021
30 Sep
'21
12:31 p.m.
Hi
What it does allow is for *deliberate* blackholing for traffic; if you null-route a prefix, you now block incoming traffic from that subnet as well. This can be useful and it is how we are using URPF.
I don't think it is implied here, but just for clarification this is implementation detail. Loose and blackhole route does not imply this behaviour, It might, it might not, depending on vendor/implementation. JunOS by default considers null route as loose path satisfied, and you need 'set forwarding-options rpf-loose-mode-discard family X' to behave like you explain.
Yes even in cisco land for Ios XR SBRTBH you need set next-hop discard in route policy. You cannot use recursive lookup to null in urpf Brian