Has anyone measured the per hop flooding delay that is incurred in modern routers?
If this is small compared to geographic delay (speed of light delay) then there is no need for this work. Many routers forward packets directly to a line card CPU and coordinate flooding among line card CPU processors, a bit like flooding inside the chassis. Worst case for a high priority process is about two interrupt times. Interrupt times on a modern CPU is about 100 usec. If there are a lot of LSA being flooded, then many LSA can be picked up in one system call if driver code is written to allow this. Even where this goes to the CPU, modern code is smart enough to have the SPF run in a different thread or process, so as not to hold up any further flooding. There was a presentation in NANOG on this topic about 5 years ago or more but I don't have a pointer to the URL at the moment. The assertion in the abstract that "The delay due to the involvement of the control-plane adversely affects OSPF convergence" is not supported in the draft and certainly not in my experience. The SPF time is typically long compared to the sum of per hop flooding delays due to hitting a CPU. Curtis _______________________________________________ OSPF mailing list [email protected] https://www.ietf.org/mailman/listinfo/ospf
