Hi Vadim! Vadim Antonov wrote:

On Thu, 26 Oct 2006, Tony Li wrote:

...

Further, uRPF is frequently a very inefficient means of implementing BCP 38. Consider that you're going to either compare the source address against a table of 200,000 routes...

That would be, well, about 6 memory reads.

Radix trees are great.

They are indeed. If a radix trie is indeed used, you would expect to see about log2(200,000) + 1 = 19 reads on average.

...

or against a handful of prefixes that you've statically configured in an ACL.

Which will take much longer with line-by-line sequential matching.

Fortunately, modern ACL implementations frequently use TCAMs (1 read) or tree based structures (log2(handful) + 1) as well. As always, the details of a particular implementation are everything. YMMV. Tony