[mpls-linux-general] Query about rt_set_nexthop

[Jagdish <jag...@de...>]

Hi
I am studying the mpls 1.0 version and I have a query regarding the mpls
patch applied on rt_set_nexthop method(route.c).

1) The patch is applied to if (fi)  part of the method. i.e the mpls code is
executed only fib_result->fi structure is not null.
     The patch is not applied to else part.  How we are making sure that fi
should not be null in case of mpls forwarding.

2) In the if(fi) loop there is a condition check
  if (fi->fib_mtu == 0) {
  The code is assigning the pmtu to 576 or whatever relevant if this
condition true. Otherwise no assignment of the pmtu taken place.
   There is no else block corresponding to the if. The mpls patch is applied
after if loop and it decrements the mtu size.
   If our control comes from the if loop then it seems ok to me as we are
assigning pmtu in each invocation.
   But if fib_mtu !=0 then the patch is decrementing the rtable->u.dst.pmtu
in each invocation( I feel rtable is static ).
   Please help me.

Regards
jagdish