[ovs-discuss] datapath flow and openflow flow

Justin Pettit jpettit at nicira.com
Wed Dec 17 08:30:18 UTC 2014


> On Dec 17, 2014, at 12:09 AM, Yang Yannan <601358880 at qq.com> wrote:
> 
> openflow flows support multiple tables. datapath flows comprise only a single table. so how openflow flows in multiple tables are transfered into datapath flow in a single table, especially when openflow flows  contain the action resubmit?

The datapath is just a cache of recently seen traffic.  When a packet arrives, if it doesn't match in the cache, it is processed through the OpenFlow tables.  For example, let's say a packet matches the following OpenFlow flows:

    table_id=0,in_port=1,action=resubmit(,1)
    table_id=1,dl_dst=01:23:45:67:89:ab,action=3

The datpath flow can just look like the following, even though there were multiple tables in OpenFlow:

    in_port=1,dl_dst=01:23:45:67:89:ab,action=3

This is obviously a trivial example, but it illustrates the concept.  Figuring out how to generate that datapath flow can be fairly complicated, so a lot of OVS's code is devoted to that.

--Justin





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