Monday, April 16, 2018 11:12 AM, Adrien Mazarguil: > Subject: Re: [dpdk-dev] [PATCH v3 3/4] ethdev: add TTL change actions in > flow API > > Hi Shahaf, > > On Mon, Apr 16, 2018 at 05:48:19AM +0000, Shahaf Shuler wrote: > > Hi Qi, > > > > Am wondering if we can make the below more generic and not tailored for > specific use cases. > > Regarding this, please see my previous answer [1] where I asked Qi to make > his changes more focused on the use case at hand when it became clear all > this work was targeting OpenFlow.
OK, I missed that. Sorry for jumping in late. > > The OF specification [2] defines the behavior associated with each action, for > instance when a TTL is 0 or decrementing it would yield 0, the packet must be > dropped. Translating this to a generic decrement action for any packet field > is > not so easy and not convenient. I am not sure I understand why. It is to set -1 in the TTL field of the generic action. We can define the corner cases more carefully as part of the actions. For example - no wrap around. I did not understood the drop if TTL is 0 is part of the action (it is not described the action description[1]). Is this the case? I think it is wrong approach to introduce a "combo" actions (both decrements and drops if value) in rte_flow. I would model such operation by a set of (pseudo code) 1. ACTION_FIELD_DEC_INC , ACTION_GO_TO_GROUP 2. (in next group) matching on the TTL , ACTION_DROP > > Therefore my opinion is that if OF actions as defined by this specification > are > supported as hardware capabilities, it makes sense to define dedicated > rte_flow actions for each of them (although "OF" should be part of their > name for clarity). I still think we may need in the future to support copy/increment/decrement of fields not specifically related to OF. It is better to have APIs which will not change or have double meaning. [1] [1] +Action: ``IP_TTL_DEC`` +^^^^^^^^^^^^^^^^^^^^^^ + +Decrement IPv4 TTL or IPv6 hop limit field and update the IP checksum, +only applies to packets that contain specific MPLS headers. + +.. _table_rte_flow_action_ip_ttl_dec: + +.. table:: IP_TTL_DEC > > I'll comment the patch proper in a separate message. > > [1] > https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdpd > k.org%2Fml%2Farchives%2Fdev%2F2018- > April%2F096857.html&data=02%7C01%7Cshahafs%40mellanox.com%7C6d2b > 747ae47841bc55e508d5a371d2f4%7Ca652971c7d2e4d9ba6a4d149256f461b%7 > C0%7C0%7C636594631626247567&sdata=3oTbKT6QwS1WiAIrkF885dEU76ep4 > xreuHoHiwDA2Ec%3D&reserved=0 > [2] > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fw > ww.opennetworking.org%2Fimages%2Fstories%2Fdownloads%2Fsdn- > resources%2Fonf-specifications%2Fopenflow%2Fopenflow-spec- > v1.3.0.pdf&data=02%7C01%7Cshahafs%40mellanox.com%7C6d2b747ae4784 > 1bc55e508d5a371d2f4%7Ca652971c7d2e4d9ba6a4d149256f461b%7C0%7C1% > 7C636594631626247567&sdata=e6uelVwIu1poE2uIvEJELuIzela8H%2B8HclQE5 > EdKEaM%3D&reserved=0 > > -- > Adrien Mazarguil > 6WIND
