On Fri, Feb 4, 2011 at 7:21 AM, Roland Bless <[email protected]> wrote:
> Hi,
>
> Christopher Morrow wrote:
>> My feeling is this:
>> hop-by-hop processing will happen in slow-path (if you permit it to
>> happen at all), you can't build a router today with an asic that'll
>> know how to handle options which are created in the future :(
>
> while the latter is surely true, I don't think that this
> argument precludes to implement fast path processing
> of at least _some_ HbH options. I think that the current
> implemented strategy to simply pass all HbH options
> to the slow path CPU is broken.
>
> I'm not sure whether it is feasible, but couldn't the
> Fast Path (ASIC) at least check for:
> - known options to be processed in the fast path, e.g.,
>  some CONEX info field

which options? how often would you expect this list to update? routers
live in the network for ~7 years or so, in large networks. ASIC
updates mean very expensive (equipment, personnel, sla) changes are
required.

> - known options to be processed in the control plane,
>  i.e., punt packet to control path (slow path CPU),
>  e.g., some to intercept packets with a specific
>  router alert option
> - bypassing unknown options (depending on the specified
>  actions) in the fast-path

and hopefully with a consistent decision on which goes where here? I'd
hate for (for example) Cisco to turn left while Juniper turns right...
this also seems complex. Again, just providing a knob (and accepting
that it will happen) that the HBH options may just be ignored in the
public network may terminate this discussion completely.

-chris
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