Re: Proposed interface for per-packet mesh-ttl

On Thu, 16 Aug 2007 12:21:14 -0700
"Luis Carlos Cobo" [off-list ref] wrote:

On 7/30/07, Stephen Hemminger [off-list ref] wrote:

quoted

it would need an IP ttl to mesh mapping. The fundamental thing is to try
and avoid topology specific options bleeding all the way up the socket layer,
especially since the network layer is involved and may need to multipath.

I think the cleanest way would be to add a ll_ttl (ll for link layer)
field to struct sock and a SO_LL_TTL socket option that sets both the
field and a flag in sk->flags. This way it is useful for any driver
that can do mesh or any other protocol that involves a ttl at link
layer (not that I'm aware of any).

However I guess you are not supposed to add new socket options nor
modify struct socket too often so I'd appreciate feedback on whether
this would be considered a good approach.

-- 
Luis Carlos Cobo Rus       GnuPG ID: 44019B60
cozybit Inc.

The problem with socket options is how does the application know
the correct policy? Pushing configuration to application is just deferring
the problem, not solving it.  You want some policy to be done by the
infrastructure; that means kernel, libraries, daemons, etc. Doing it in
the application is often inflexible and unusable.