How to write traffic tests using PTF adapter

Overview

PtfTestAdapter provides an interface to send and receive traffic in the same way as ptf.base_tests.BaseTest object in PTF framework. It makes use of ptf_nn_agent.py script running on PTF host, connects to it over TCP and initialize PTF data plane thread.

NOTE a good network connection between sonic-mgmt node and PTF host is required for traffic tests to be stable.

Usage in pytest

You can use ptfadapter fixture which runs ptf_nn_agent.py on PTF and yields PtfTestAdapter object.

Example test case code using PTF adapter:

import ptf.testutils as testutils
import ptf.mask as mask

def test_some_traffic(duthost, ptfadapter):
    pkt = testutils.simple_tcp_packet(
        eth_dst=duthost.facts["router_mac"],
        eth_src=ptfadapter.dataplane.get_mac(*list(ptfadapter.dataplane.ports.keys())[0]),
        ip_src='1.1.1.1',
        ip_dst='192.168.0.1',
        ip_ttl=64,
        tcp_sport=1234,
        tcp_dport=4321)

    exp_pkt = pkt.copy()
    exp_pkt = mask.Mask(exp_pkt)
    exp_pkt.set_do_not_care_scapy(packet.Ether, 'dst')
    exp_pkt.set_do_not_care_scapy(packet.Ether, 'src')
    exp_pkt.set_do_not_care_scapy(packet.IP, 'ttl')
    exp_pkt.set_do_not_care_scapy(packet.IP, 'chksum')

    testutils.send(ptfadapter, 5, pkt)
    testutils.verify_packet_any_port(ptfadapter, exp_pkt, ports=[28, 29, 30, 31])

If you have changed interface configuration on PTF host (like MAC address change) or you want to run PTF providing custom parameters you can use reinit method, e.g.:

def test_some_traffic(ptfadapter):
    ptfadapter.reinit({'qlen': 1000})
    # rest of the test ...