resend: multiple routing table roadmap (format fix)

[Li, Qing]

> 
> Surely, routing table should contain a cached pointer to an 
> entry in L2 table (ARP in case of Ethernet), to not do double 
> lookups. But still separate those tables...
> 

  The routing table contains only the interface route, from this
  interface route the L2 table is accessed for on net hosts.
  So it's a one-to-many relationship.

  How do you propose the L2 entry caching be done ?

  -- Qing