[c-nsp] Static routes syntax

[Higham, Josh]

> david.ponsdesserre at uk.bnpparibas.com
> 
> Specifying a numerical next hop on a directly connected 
> interface will prevent the router from performing ARP or each 
> destination address.
> However, if the interface with the next hop goes down and the 
> numerical next hop is reachable through a recursive route, 
> you should specify both the next hop IP address and the 
> interface through which the next hop should be found. For 
> example, ip route 0.0.0.0 0.0.0.0 Serial 3/3 192.168.20.1.

On a point-to-point link, you don't need to worry about the routing
using arp.  In that case I have a slight preference for using the
interface and not the IP, because it makes it a bit easier to change
interface IP addressing.  It's not a big difference though.

Thanks,
Josh