todo

基于linux内核2.6.9的mpls补丁

-remove NHLFE lookup from ipv4 slow path
-lsp ping
-RA label
-PF_MPLS
-move instructions to modules
-move SPEC_NH to modules reference by name (not ETH ID)
-multicast fwd
-load balance forward with algos as modules
-LER add hash under label stack
-clean up code
-make instructions be RTAs in netlink
-add shift to NF, TC and DS instructions
-add VRF instruction
-add priority instruction
-verify locking for nhlfe and ilm radix (RCU?)
-clean up source file documentation
-verify MTU change
-expose flush options to netlink userland
-port l2cc code to mpls-linux
-add l2cc proto
-test ppp support
-add ATM / FR support
-PHP support
-examples mapping EXP to queuing discipline
-per ILM or NHLFE locking?
-external ILM and NHLFE references?
-get MPLS to load unload as a module
-SMP safe?
-debug toggle via netlink
* PRIO1 20040207
  RCAS :Allocations in control plane use GPF_ATOMIC because we are working
  under a spinlock. This is suboptimal. We should define a better locking
  scheme (most MII/MOI modifications are performed in user context, after
  a IOCTL).  We could define a better locking scheme and revert to GPF_KERNEL