Re: Improving use of rt_refcnt

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Wed, Jul 08, 2015 at 09:28:01PM -0700, Dennis Ferguson wrote:
> What this means is that your proposed use of the next
> hop IP address is a gratuitous indirection; you would be taking
> something which would be best done as
> 
>     <route lookup> -> <L2 header>
> 
> and instead turning this into
> 
>     <route lookup> -> <next hop IP address> -> <next hop address lookup> -> <L2 header>

This is the part I disagree with. There are generally two cases here:
- the BMP is a local network
- the BMP is not a local network

In the second case, the route can store a direct reference to the L2
address without artifical entries in the table and without additional
lookup. There are some potential issues to consider for dealing with
multiple interfaces sharing IP ranges, but that's a different question.

For the first case, storing cloned routed or doing a hashed target
lookup is very likely to have similar performance and often the latter
option is going to be faster.

Joerg