On Jan 28, 2009, Dino Farinacci wrote:
You cannot push around 10^10 entries and store them everywhere. [...]
Dino - I think we should experimentally compare ALT with other mapping systems before we decide whether pull-based or push-based mapping systems are better. Dismissing push-based mapping systems without corroborating data would be a bit premature in my opinion. In the absence of experimentation results, I would actually argue in favor of push-based mapping systems based on some analytical reasoning: Pull-based mapping systems have two important disadvantages compared to push-based mapping systems: - Performance penalty, i.e., additional propagation latencies for some packets, and higher loss probabilities for packets that take a sub- optimal path - Robustness penalty due to a new online dependency on components off the actual transmission path. (FWIW: All pull-based mapping systems have this penalty. Mapping requests must be routed via overlay infrastructure because the direct route is unknown at that time.) Furthermore, I do not share your concerns regarding push-based mapping systems: BGP is pushing routing data already today, and this works fine. Any routing-scalability-related issues with BGP are not due to BGP being push-based; they are due to frequent updates and a high load for core routers. Both of these issues would go away in an address indirection architecture (be it LISP, Ivip, APT, or Six/One Router), independent of whether you use a pull- or push-based mapping system. In conclusion: The overlay approach of ALT is certainly an interesting idea. But I think it would be premature to conclude that it is the only viable solution before we have more evidence to back this claim. - Christian PS: I admit that I have never been really good in avoiding cross- posting. But this is obviously my all-time negative record... _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
