Re: DTS testpmd and SCAPY integration

["Etelson, Gregory" <getelson@nvidia.com>]

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Hello Patrick,

> External email: Use caution opening links or attachments
> Thank you for sharing Gregory. I did not get an opportunity to look through the code today, but I did run
> through the presentation. A few points I noted:
> 1. The presentation shows an example testpmd testcase for creating a flow rule, and then shows a
> validation step in which standard out is compared against the expected string ("flow rule x created") and
> we can conclude whether we are able to create flow rules. Are you also sending packets according to the
> flow rules and validating that what is sent/received corresponds to the expected behavior of the flow
> rules? When I look at the old DTS framework, and an example flow rules testsuite
> (https://doc.dpdk.org/dts/test_plans/rte_flow_test_plan.html) which we want feature parity with, I think
> that validation for this testing framework needs to primarily rely on comparing packets sent and packets
> received.

The unit test infrastructure validates flow rule creation and
a result produced by that flow.
Flow result is triggered by a packet.
However, flow result validation does not always can be done by testing a packet.
Unit test implements 2 flow validation methods.

The first validation method tests testpmd output triggered by a test packet.

Example: use the MODIFY_FIELD action to copy packet VLAN ID to flow TAG item.
Flow tag is internal flow resource. It must be validated in DPDK application.

Test creates 2 flow rules:

Rule 1: use MODIFY_FILED to copy packet VLAN ID to flow TAG item
pattern eth / vlan / end \
actions modify_field op set dst_type tag ... src_type vlan_id ... / end

Rule 2: validate the TAG item:
pattern tag data is 0x31 ... / end actions mark id 0xaaa / rss / end

The test sends a packet with VLAN ID 0x31: / Dot1Q(vlan=0x31) /
The test matches tespmd output triggered by the packet for
`FDIR matched ID=0xaaa`.

The second validation method tests a packet after it was processed by a flow.

Unit test operates in a static environment. It does not compare
source and target packets. The test "knows" valid target packet configuration.

Example: push VLAN header into a packet.

There is a single flow rule in that example:
pattern eth / end \
actions of_push_vlan ethertype 0x8100 / \
         of_set_vlan_vid vlan_vid 3103 .../ port_id id 1 / end


There are 2 SCAPY processes in that test: `tg` runs on peer host and
sends a source packet. `vm` runs on the same host as testpmd. It validates
incoming packet.

Phase 0 prepares test packet on the `tg` and starts AsyncSniffer on the `vm`.
Phase 1 sends the packet.
Phase 2 validates the packet.
The test can repeat phases 1 and 2.


phase0:
   vm: |
     sniff = AsyncSniffer(iface=pf1vf0, filter='udp and src port 1234')

   tg: |
     udp_packet = Ether(src='11:22:33:44:55:66',
                        dst='aa:bb:cc:dd:ee:aa')/
                  IP(src='1.1.1.1', dst='2.2.2.2')/
                  UDP(sport=1234, dport=5678)/Raw('== TEST ==')

phase1: &phase1
   vm: sniff.start()
   tg: sendp(udp_packet, iface=pf1)

phase2: &phase2
   vm: |
     cap = sniff.stop()
     if len(cap[UDP]) > 0: cap[UDP][0][Ether].command()
   result:
 	vm: vlan=3103

>In any case, there may be some testsuites which can be written which are small 
>enough in scope
> that validating by standard out in this way may be appropriate. I'm not sure but we should keep our
> options open. 
> 
> 2. If the implementation overhead is not too significant for the configuration step in the DTS execution a
> "--fast" option like you use may be a good improvement for the framework. In your mind, is the main
> benefit A. reduced execution time, B. reduced user setup time (don't have to write full config file) or C.
> Something else?

A user must always provide test configuration.
However a host can already have prepared setup before the test execution.
In that case a user can skip host setup phase and reduce execution time.
 
> 
> Thanks for making this available to use so we can use it as a reference in making DTS better. :) 
> 
>