[ovs-discuss] OFPACT_DEC_TTL in kernel space

[Justin Pettit]

> On Jun 25, 2019, at 2:02 PM, Sagar A <ssadev42 at gmail.com> wrote:
> 
>> Is there a particular use-case that requires decrement?
>> 
> I have rule which wants to match on 'dst_ip' only. Since, code is touching 'ttl', it becomes a match condition. For flows with same 'dst_ip' and different ttls, result in different flows instead of having only one flow with 'dst_ip' as match condition. Any suggestion to solve the problem?

You are directly calling the kernel datapath interface and not using ovs-vswitchd?  If you're using ovs-vswitchd, it will take care of matching the TTL for you when it pushes the flow down to the kernel.  If not, then you'd need to propose changes to the kernel.  I don't know whether they would accept such a patch without a compelling reason, since there's arguably a more flexible (although less efficient in some cases) mechanism already in place.

--Justin