Hi Ben, On Fri, Dec 13, 2013 at 12:28:21AM -0800, Ben Pfaff wrote: > I've been a little frustrated with the current approach to MPLS, because it > seems quite difficult to understand. One particularly difficult bit for > me is the variables used during translation, e.g. mpls_depth_delta and > pre_push_mpls_lse. And what we end up with is support for a single MPLS > label, which I don't think is going to make any real-world users happy. > > I think that we can do something easier to understand and more powerful > by just keeping track of all the labels in struct flow. This patch is a > first stab at that. It's incomplete--in particular I have not implemented > commit_mpls_action() because it seems slightly tricky and it's very late > at night here--and obviously untested, but I'd appreciate feedback on the > approach.
Its quite a bit of code to digest but in general my feeling at this point is that this approach could be made to work. There are a number of corner cases that my patchset (the previous approach) tries to address. And I believe they contributed to most of the more difficult to understand code. I have tried mentally running through a number of them to see how they might work out with this new approach. One that seems slightly tricky is the following in the case that MPLS LSEs are being pushed before VLAN tags. Assuming no VLAN is present in the original packet: push_vlan,push_mpls,push_vlan Or, alternatively, if a VLAN is present in the original packet: set_vlan_vid,push_mpls,push_vlan I believe that with this new approach the first VLAN action would be silently dropped. I believe that this case could be handled using recirculation and in the mean time detected and rejected. But I wanted to bring it to your attention to see how you feel about it. > I think that if this works out then it would obviate the need for patches > "odp: Allow VLAN actions after MPLS actions" and "lib: Support pushing of > MPLS LSE before or after VLAN tag". Yes, that seems likely. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
