I don't have any specific use-case in mind for mpls ttl match. I think I misunderstood nw_ttl implementation.
Thanks, Ravi -----Original Message----- From: Ben Pfaff [mailto:b...@nicira.com] Sent: Thursday, May 24, 2012 10:41 AM To: Kerur, Ravi Cc: dev@openvswitch.org Subject: Re: [ovs-dev] MPLS and VLAN QinQ patch On Thu, May 24, 2012 at 07:25:52PM +0200, ravi.ke...@telekom.com wrote: > > As for the TTL, I don't think that any OpenFlow version allows for > > matching on an IP TTL, so there is no support-by-analogy for > > matching on the MPLS TTL. Is there another reason to support > > matching on the MPLS TTL? > > I see there is a capability to match on nw_ttl so thought it would > make sense to add a match for mpls_ttl. nw_ttl is part of the kernel-to-user interface but it is not exposed via OpenFlow. I think that the same is true of the TTL in your MPLS patch? > When IP packets traverse MPLS tunnels, IP TTL is copied into MPLS TTL > and it is copied back into IP when they exit. Hence thought of > providing a match for that. Maybe that is enough to make a case for an OpenFlow MPLS TTL match, but I don't follow. You might have to spell out the use case step-by-step for me to understand. > > > > It occurs to me that we could drop the NXAST_SET_MPLS_LABEL and > > > > NXAST_SET_MPLS_TC actions because these can be implemented > > > > through "register load" actions. OpenFlow 1.2 also dropped the > > > > similar OFPAT_ actions, for the same reason, so maybe we > > > > shouldn't bother with NXAST_ actions for them as they don't have > > > > any additional benefit for OpenFlow 1.0 with Nicira extensions. > > > > > > Same argument as above. In this case it isn't quite clear to me > > > how set_mpls_label and set_mpls_tc be implemented via reg_load. > > > Any pointers? > > > > In ovs-ofctl syntax, the "load" actions would look like this: > > load:123->NXM_OF_MPLS_TC[] > > load:5->NXM_OF_MPLS_LABEL[] > > > Thanks for the information. I will work on it after 1.1 is ready. I doubt you need to take any action to make this work. It should "just work" without any further changes. Thanks, Ben. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
