Re: [Patch iproute2] u32: add terminal parameter

[Cong Wang <xiyou.wangcong@gmail.com>]

On Tue, Apr 15, 2014 at 6:00 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> On 04/14/14 21:57, Cong Wang wrote:
>
>> So essentially why u32 filters can't just do matching without bothering
>
>
> u32 is a special animal. You can actually have intermediate nodes
> which are _not_ terminal. i.e you can build a tree of hashes which
> interconnect other hashes eventually leading to terminal nodes.
>

I knew, I thought at least classid is an alternative for action, that is,
one doing classify and one doing some other action.

>
>> classid especially when they are attached to an ingress qdisc? I still
>> fail to see a reason why I have to care about classid here.
>
>
> It is more of a historical artifact with "benefits".
> Historical in that egress qdiscs with classes existed before ingress;
> so it makes sense to keep the syntax people are already familiar with.
> Benefits because infact with the right approach the flowid even at
> ingress can be used as input(look at the route classifier for example
> and association with route accounting of the source).
>

I see. The next question would be what is a reasonable classid
value for a classless qdisc? Or can we set it to some value to express
"we don't care"?

Thanks!