Hi Ben,
My goal is to implement a decap action that would decap a packet with
external IP addresses, and then have the decapped packet, with
internal IP addresses, do a flow lookup again.
Can this be achieved using resubmit?
Thanks!
Yimin
On Fri, May 4, 2012 at 9:37 AM, Ben Pfaff <b...@nicira.com> wrote:
> You can read PORTING in the root of the tree.
>
> It would be best if you'd explain your goal first, instead of doing a
> deep dive into implementation details.
>
> On Fri, May 04, 2012 at 09:20:38AM +0800, YIMIN CHEN wrote:
>> Hi Ben,
>>
>> Thank you for the detailed information! I read this part of the code,
>> and have some confusion. Can you please review the following to see if
>> my understanding of code is correct?
>>
>> 1) ofproto/ code is userspace code, and datapath/ code is the actual dp code.
>> 2) ofproto handles the rule insertion from control plane, and datapath
>> handles the actual flow lookup.
>> 3) resubmit is handled in userspace? I saw the resubmit logic
>> xlate_nicira_action() is in ofproto I didn't see find any code in
>> datapath that handles resubmit, not even in ovs-ofctl.c. Is
>> xlate_nicira_action() doing flow insertion with resubmit action or
>> actually performing the dp actions? I am confused.
>>
>> What is the relationship between ofproto userspace and the dp code?
>> what is the difference between xlate table action and odp action?
>>
>> I think I am very confused, if there is any documentation I can read
>> to understand this design better, would you please give me a pointer?
>>
>> Thanks!
>> Yimin
>>
>> On Thu, May 3, 2012 at 11:30 AM, Ben Pfaff <b...@nicira.com> wrote:
>> > It's documented in nicira-ext.h:
>> >
>> > /* Action structures for NXAST_RESUBMIT and NXAST_RESUBMIT_TABLE.
>> > *
>> > * These actions search one of the switch's flow tables:
>> > *
>> > * - For NXAST_RESUBMIT_TABLE only, if the 'table' member is not 255,
>> > then
>> > * it specifies the table to search.
>> > *
>> > * - Otherwise (for NXAST_RESUBMIT_TABLE with a 'table' of 255, or for
>> > * NXAST_RESUBMIT regardless of 'table'), it searches the current flow
>> > * table, that is, the OpenFlow flow table that contains the flow from
>> > * which this action was obtained. If this action did not come from a
>> > * flow table (e.g. it came from an OFPT_PACKET_OUT message), then
>> > table 0
>> > * is the current table.
>> > *
>> > * The flow table lookup uses a flow that may be slightly modified from the
>> > * original lookup:
>> > *
>> > * - For NXAST_RESUBMIT, the 'in_port' member of struct
>> > nx_action_resubmit
>> > * is used as the flow's in_port.
>> > *
>> > * - For NXAST_RESUBMIT_TABLE, if the 'in_port' member is not
>> > OFPP_IN_PORT,
>> > * then its value is used as the flow's in_port. Otherwise, the
>> > original
>> > * in_port is used.
>> > *
>> > * - If actions that modify the flow (e.g. OFPAT_SET_VLAN_VID) precede
>> > the
>> > * resubmit action, then the flow is updated with the new values.
>> > *
>> > * Following the lookup, the original in_port is restored.
>> > *
>> > * If the modified flow matched in the flow table, then the corresponding
>> > * actions are executed. Afterward, actions following the resubmit in the
>> > * original set of actions, if any, are executed; any changes made to the
>> > * packet (e.g. changes to VLAN) by secondary actions persist when those
>> > * actions are executed, although the original in_port is restored.
>> > *
>> > * Resubmit actions may be used any number of times within a set of
>> > actions.
>> > *
>> > * Resubmit actions may nest to an implementation-defined depth. Beyond
>> > this
>> > * implementation-defined depth, further resubmit actions are simply
>> > ignored.
>> > *
>> > * NXAST_RESUBMIT ignores 'table' and 'pad'. NXAST_RESUBMIT_TABLE requires
>> > * 'pad' to be all-bits-zero.
>> > *
>> > * Open vSwitch 1.0.1 and earlier did not support recursion. Open vSwitch
>> > * before 1.2.90 did not support NXAST_RESUBMIT_TABLE.
>> > */
>> > struct nx_action_resubmit {
>> > ovs_be16 type; /* OFPAT_VENDOR. */
>> > ovs_be16 len; /* Length is 16. */
>> > ovs_be32 vendor; /* NX_VENDOR_ID. */
>> > ovs_be16 subtype; /* NXAST_RESUBMIT. */
>> > ovs_be16 in_port; /* New in_port for checking flow table.
>> > */
>> > uint8_t table; /* NXAST_RESUBMIT_TABLE: table to use.
>> > */
>> > uint8_t pad[3];
>> > };
>> > OFP_ASSERT(sizeof(struct nx_action_resubmit) == 16);
>> >
>> > and in ovs-ofctl(8):
>> >
>> > resubmit:port
>> > resubmit([port],[table])
>> > Re-searches this OpenFlow flow table (or the table
>> > whose
>> > number is specified by table) with the in_port
>> > field
>> > replaced by port (if port is specified) and executes
>> > the
>> > actions found, if any, in addition to any other
>> > actions
>> > in this flow entry.
>> >
>> > Recursive resubmit actions are obeyed up to an
>> > implemen‐
>> > tation-defined maximum depth. Open vSwitch 1.0.1
>> > and
>> > earlier did not support recursion; Open vSwitch
>> > before
>> > 1.2.90 did not support table.
>> >
>> >
>> > On Thu, May 03, 2012 at 09:54:08AM +0800, YIMIN CHEN wrote:
>> >> Hi Ben,
>> >>
>> >> Thank you for your reply! I saw there is some code about resubmit
>> >> Nicira extension action, but that seems to be in userspace ofproto.c,
>> >> not in datapath, so I didn't know that is related. Could you help
>> >> clarify for me how does resubmit work?
>> >>
>> >>
>> >> Thanks!
>> >> Yimin
>> >>
>> >> On Wed, May 2, 2012 at 12:40 PM, Ben Pfaff <b...@nicira.com> wrote:
>> >> > On Wed, May 02, 2012 at 10:53:10AM +0800, YIMIN CHEN wrote:
>> >> >> I am looking at ovs dp code, and is looking at a correct way for a
>> >> >> flow to traverse the table twice. The goal is like this:
>> >> >>
>> >> >> flow lookup => tbl_lookup()
>> >> >> perform actions => execute_actions() which changes the packet
>> >> >> flow lookup using the new packet => tbl_lookup()
>> >> >> perform actions on the new packet => execute_actions.
>> >> >
>> >> > Do you want the "resubmit" Nicira extension action?
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