Kernel IP Forwarding path

[Suresh Kumar Subramanian]

Hi,

I am so interested to tune the kernel forwarding path.


My questions are,

Is it possible, to  expose some API to user space to manipulate the routing table (Ex: add equal cost /unequal cost routes for load balancing?
Is it possible, to change the routing flow ( i want to add some custom module before route look up) and expose some API to user space?
Is it possible , to influence the routing look up mechanism?

I am not able to find the good docuements for this.
can some one share some good tutorial /link?

Thanks
suresh