Peter Phaal wrote: > I think "pathologically broken" somewhat overstates the case. > Bidirectional sampling is allowed by the sFlow spec and other vendors > have made that choice. Another vendor used to implement egress only > sampling (also allowed) but unusual. I agree that ingress is the most > common and easiest to deal with, but a decent sFlow analyzer should be > able to handle all three cases without over / under counting.
Bidirectional sampling doesn't allow you to define an sampling perimeter on your switch topology. This means that if you if you have anything other than a trivial topology, you will end up double-counting your traffic. The only way to work around this is to get the collector to discard 50% of the samples or otherwise write down the amount of traffic by 50%, assuming a standard accounting perimeter configuration. This is broken. The thing is, this is ridiculously easy to fix in code. The hooks are already there. Nick
