Does a route to Null0 interface need to be configured for the IP address pool when NAT is configured for the NE20?
There must be a route that matches the IP address pool in the routing table.
Two situations exist:
(1) If the address pool and the address of the NAT outbound interface are in the same network segment, the route does not need to be configured for the address pool separately.
(2) If the address pool and the address of the NAT outbound interface are in the same network segment, a route to the router itself must be configured for the address pool separately. The mask of the route must be the same as that of the address. That is, the next hop can be configured to point to Null0.
In configuring an address pool, a mask must be specified with a view to querying the routing table through address + mask and marking the routing table matched with a "NAT tag bit".