[LARTC] under Linux how is FTB derived from routing table

[LARTC] under Linux how is FTB derived from routing table

[yuxiao jia]

Hi

There are two processes about routing. (as deepak email said)
Forwarding is a process of moving packets from input
to output based on:
  - Forwarding Table
  - Information in the Packet.

Routing: The Process by which the Forwarding table is
built and maintianed.
  - One or more routing protocols
  - Procedures to converting routing information to
forwarding table.

Forwarding is handled by Forwarding Information Bases
(FIB) or Forwarding Tables, which runs quite
independent of the rouitng protocol's Tables. The FIBs
are derived from the routing tables ( on lesser
systems, the routing table can be directly used for
forwarding)

I want to know under Linux how is FIB derived from routing table

Can I  control which routes are selected to be
installed into Forwarding Tables --by  varying the
route preferences

For example, I want put routing table into forwarding table by order of
prefix
/8.../10..../24.../30..

This order will make worse case lookup according to longest perfix match..

thanks

yuxiao


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