vpp/test/test_udp.py

#!/usr/bin/env python3
import unittest
from framework import tag_fixme_vpp_workers
from framework import VppTestCase, VppTestRunner

from vpp_udp_encap import find_udp_encap, VppUdpEncap
from vpp_udp_decap import VppUdpDecap
from vpp_ip_route import (
    VppIpRoute,
    VppRoutePath,
    VppIpTable,
    VppMplsLabel,
    VppMplsTable,
    VppMplsRoute,
    FibPathType,
    FibPathProto,
)
from vpp_neighbor import VppNeighbor
from vpp_papi import VppEnum

from scapy.packet import Raw
from scapy.layers.l2 import Ether
from scapy.layers.inet import IP, UDP, ICMP
from scapy.layers.inet6 import IPv6
from scapy.contrib.mpls import MPLS

NUM_PKTS = 67
ENTROPY_PORT_MIN = 0x3 << 14
ENTROPY_PORT_MAX = 0xFFFF


@tag_fixme_vpp_workers
class TestUdpEncap(VppTestCase):
    """UDP Encap Test Case"""

    @classmethod
    def setUpClass(cls):
        super(TestUdpEncap, cls).setUpClass()

    @classmethod
    def tearDownClass(cls):
        super(TestUdpEncap, cls).tearDownClass()

    def setUp(self):
        super(TestUdpEncap, self).setUp()

        # create 2 pg interfaces
        self.create_pg_interfaces(range(4))

        # setup interfaces
        # assign them different tables.
        table_id = 0
        self.tables = []

        for i in self.pg_interfaces:
            i.admin_up()

            if table_id != 0:
                tbl = VppIpTable(self, table_id)
                tbl.add_vpp_config()
                self.tables.append(tbl)
                tbl = VppIpTable(self, table_id, is_ip6=1)
                tbl.add_vpp_config()
                self.tables.append(tbl)

            i.set_table_ip4(table_id)
            i.set_table_ip6(table_id)
            i.config_ip4()
            i.resolve_arp()
            i.config_ip6()
            i.resolve_ndp()
            table_id += 1

    def tearDown(self):
        for i in self.pg_interfaces:
            i.unconfig_ip4()
            i.unconfig_ip6()
            i.set_table_ip4(0)
            i.set_table_ip6(0)
            i.admin_down()
        super(TestUdpEncap, self).tearDown()

    def validate_outer4(self, rx, encap_obj, sport_entropy=False):
        self.assertEqual(rx[IP].src, encap_obj.src_ip_s)
        self.assertEqual(rx[IP].dst, encap_obj.dst_ip_s)
        if sport_entropy:
            self.assert_in_range(rx[UDP].sport, ENTROPY_PORT_MIN, ENTROPY_PORT_MAX)
        else:
            self.assertEqual(rx[UDP].sport, encap_obj.src_port)
        self.assertEqual(rx[UDP].dport, encap_obj.dst_port)

    def validate_outer6(self, rx, encap_obj, sport_entropy=False):
        self.assertEqual(rx[IPv6].src, encap_obj.src_ip_s)
        self.assertEqual(rx[IPv6].dst, encap_obj.dst_ip_s)
        if sport_entropy:
            self.assert_in_range(rx[UDP].sport, ENTROPY_PORT_MIN, ENTROPY_PORT_MAX)
        else:
            self.assertEqual(rx[UDP].sport, encap_obj.src_port)
        self.assertEqual(rx[UDP].dport, encap_obj.dst_port)

    def validate_inner4(self, rx, tx, ttl=None):
        self.assertEqual(rx[IP].src, tx[IP].src)
        self.assertEqual(rx[IP].dst, tx[IP].dst)
        if ttl:
            self.assertEqual(rx[IP].ttl, ttl)
        else:
            self.assertEqual(rx[IP].ttl, tx[IP].ttl)

    def validate_inner6(self, rx, tx, hlim=None):
        self.assertEqual(rx.src, tx[IPv6].src)
        self.assertEqual(rx.dst, tx[IPv6].dst)
        if hlim:
            self.assertEqual(rx.hlim, hlim)
        else:
            self.assertEqual(rx.hlim, tx[IPv6].hlim)

    def test_udp_encap(self):
        """UDP Encap test"""

        #
        # construct a UDP encap object through each of the peers
        # v4 through the first two peers, v6 through the second.
        # The last encap is v4 and is used to check the codepath
        # where 2 different udp encap objects are processed at the
        # same time
        #
        udp_encap_0 = VppUdpEncap(
            self, self.pg0.local_ip4, self.pg0.remote_ip4, 330, 440
        )
        udp_encap_1 = VppUdpEncap(
            self, self.pg1.local_ip4, self.pg1.remote_ip4, 331, 441, table_id=1
        )
        udp_encap_2 = VppUdpEncap(
            self, self.pg2.local_ip6, self.pg2.remote_ip6, 332, 442, table_id=2
        )
        udp_encap_3 = VppUdpEncap(
            self, self.pg3.local_ip6, self.pg3.remote_ip6, 333, 443, table_id=3
        )
        udp_encap_4 = VppUdpEncap(
            self, self.pg0.local_ip4, self.pg0.remote_ip4, 334, 444
        )
        udp_encap_0.add_vpp_config()
        udp_encap_1.add_vpp_config()
        udp_encap_2.add_vpp_config()
        udp_encap_3.add_vpp_config()
        udp_encap_4.add_vpp_config()

        self.logger.info(self.vapi.cli("sh udp encap"))

        self.assertTrue(find_udp_encap(self, udp_encap_2))
        self.assertTrue(find_udp_encap(self, udp_encap_3))
        self.assertTrue(find_udp_encap(self, udp_encap_0))
        self.assertTrue(find_udp_encap(self, udp_encap_1))
        self.assertTrue(find_udp_encap(self, udp_encap_4))

        #
        # Routes via each UDP encap object - all combinations of v4 and v6.
        #
        route_4o4 = VppIpRoute(
            self,
            "1.1.0.1",
            24,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_0.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
            table_id=1,
        )
        # specific route to match encap4, to test encap of 2 packets using 2
        # different encap
        route_4o4_2 = VppIpRoute(
            self,
            "1.1.0.2",
            32,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_4.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
            table_id=1,
        )
        route_4o6 = VppIpRoute(
            self,
            "1.1.2.1",
            32,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_2.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
        )
        route_6o4 = VppIpRoute(
            self,
            "2001::1",
            128,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_1.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP6,
                )
            ],
        )
        route_6o6 = VppIpRoute(
            self,
            "2001::3",
            128,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_3.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP6,
                )
            ],
        )
        route_4o6.add_vpp_config()
        route_6o6.add_vpp_config()
        route_6o4.add_vpp_config()
        route_4o4.add_vpp_config()
        route_4o4_2.add_vpp_config()

        #
        # 4o4 encap
        # we add a single packet matching the last encap at the beginning of
        # the packet vector so that we encap 2 packets with different udp
        # encap object at the same time
        #
        p_4o4 = (
            Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac)
            / IP(src="2.2.2.2", dst="1.1.0.1")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        p_4o4_2 = (
            Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac)
            / IP(src="2.2.2.2", dst="1.1.0.2")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        rx = self.send_and_expect(
            self.pg1, p_4o4_2 * 1 + p_4o4 * (NUM_PKTS - 1), self.pg0
        )
        # checking encap4 magic packet
        p = rx.pop(0)
        self.validate_outer4(p, udp_encap_4)
        p = IP(p["UDP"].payload.load)
        self.validate_inner4(p, p_4o4_2)
        self.assertEqual(udp_encap_4.get_stats()["packets"], 1)
        # checking remaining packets for encap0
        for p in rx:
            self.validate_outer4(p, udp_encap_0)
            p = IP(p["UDP"].payload.load)
            self.validate_inner4(p, p_4o4)
        self.assertEqual(udp_encap_0.get_stats()["packets"], NUM_PKTS - 1)

        #
        # 4o6 encap
        #
        p_4o6 = (
            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
            / IP(src="2.2.2.2", dst="1.1.2.1")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        rx = self.send_and_expect(self.pg0, p_4o6 * NUM_PKTS, self.pg2)
        for p in rx:
            self.validate_outer6(p, udp_encap_2)
            p = IP(p["UDP"].payload.load)
            self.validate_inner4(p, p_4o6)
        self.assertEqual(udp_encap_2.get_stats()["packets"], NUM_PKTS)

        #
        # 6o4 encap
        #
        p_6o4 = (
            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
            / IPv6(src="2001::100", dst="2001::1")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        rx = self.send_and_expect(self.pg0, p_6o4 * NUM_PKTS, self.pg1)
        for p in rx:
            self.validate_outer4(p, udp_encap_1)
            p = IPv6(p["UDP"].payload.load)
            self.validate_inner6(p, p_6o4)
        self.assertEqual(udp_encap_1.get_stats()["packets"], NUM_PKTS)

        #
        # 6o6 encap
        #
        p_6o6 = (
            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
            / IPv6(src="2001::100", dst="2001::3")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        rx = self.send_and_expect(self.pg0, p_6o6 * NUM_PKTS, self.pg3)
        for p in rx:
            self.validate_outer6(p, udp_encap_3)
            p = IPv6(p["UDP"].payload.load)
            self.validate_inner6(p, p_6o6)
        self.assertEqual(udp_encap_3.get_stats()["packets"], NUM_PKTS)

        #
        # A route with an output label
        # the TTL of the inner packet is decremented on LSP ingress
        #
        route_4oMPLSo4 = VppIpRoute(
            self,
            "1.1.2.22",
            32,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=1,
                    labels=[VppMplsLabel(66)],
                )
            ],
        )
        route_4oMPLSo4.add_vpp_config()

        p_4omo4 = (
            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
            / IP(src="2.2.2.2", dst="1.1.2.22")
            / UDP(sport=1234, dport=1234)
            / Raw(b"\xa5" * 100)
        )
        rx = self.send_and_expect(self.pg0, p_4omo4 * NUM_PKTS, self.pg1)
        for p in rx:
            self.validate_outer4(p, udp_encap_1)
            p = MPLS(p["UDP"].payload.load)
            self.validate_inner4(p, p_4omo4, ttl=63)
        self.assertEqual(udp_encap_1.get_stats()["packets"], 2 * NUM_PKTS)

    def test_udp_encap_entropy(self):
        """UDP Encap src port entropy test"""

        #
        # construct a UDP encap object through each of the peers
        # v4 through the first two peers, v6 through the second.
        # use zero source port to enable entropy per rfc7510.
        #
        udp_encap_0 = VppUdpEncap(self, self.pg0.local_ip4, self.pg0.remote_ip4, 0, 440)
        udp_encap_1 = VppUdpEncap(
            self, self.pg1.local_ip4, self.pg1.remote_ip4, 0, 441, table_id=1
        )
        udp_encap_2 = VppUdpEncap(
            self, self.pg2.local_ip6, self.pg2.remote_ip6, 0, 442, table_id=2
        )
        udp_encap_3 = VppUdpEncap(
            self, self.pg3.local_ip6, self.pg3.remote_ip6, 0, 443, table_id=3
        )
        udp_encap_0.add_vpp_config()
        udp_encap_1.add_vpp_config()
        udp_encap_2.add_vpp_config()
        udp_encap_3.add_vpp_config()

        self.logger.info(self.vapi.cli("sh udp encap"))

        self.assertTrue(find_udp_encap(self, udp_encap_0))
        self.assertTrue(find_udp_encap(self, udp_encap_1))
        self.assertTrue(find_udp_encap(self, udp_encap_2))
        self.assertTrue(find_udp_encap(self, udp_encap_3))

        #
        # Routes via each UDP encap object - all combinations of v4 and v6.
        #
        route_4o4 = VppIpRoute(
            self,
            "1.1.0.1",
            24,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_0.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
            table_id=1,
        )
        route_4o6 = VppIpRoute(
            self,
            "1.1.2.1",
            32,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_2.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
        )
        route_6o4 = VppIpRoute(
            self,
            "2001::1",
            128,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_1.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP6,
                )
            ],
        )
        route_6o6 = VppIpRoute(
            self,
            "2001::3",
            128,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    type=FibPathType.FIB_PATH_TYPE_UDP_ENCAP,
                    next_hop_id=udp_encap_3.id,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP6,
                )
            ],
        )
        route_4o4.add_vpp_config()
        route_4o6.add_vpp_config()
        route_6o6.add_vpp_config()
        route_6o4.add_vpp_config()

        #
        # 4o4 encap
        #
        p_4o4 = []
        for i in range(NUM_PKTS):
            p_4o4.append(
                Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac)
                / IP(src="2.2.2.2", dst="1.1.0.1")
                / UDP(sport=1234 + i, dport=1234)
                / Raw(b"\xa5" * 100)
            )
        rx = self.send_and_expect(self.pg1, p_4o4, self.pg0)
        sports = set()
        for i, p in enumerate(rx):
            self.validate_outer4(p, udp_encap_0, True)
            sports.add(p["UDP"].sport)
            p = IP(p["UDP"].payload.load)
            self.validate_inner4(p, p_4o4[i])
        self.assertEqual(udp_encap_0.get_stats()["packets"], NUM_PKTS)
        self.assertGreater(
            len(sports), 1, "source port {} is not an entropy value".format(sports)
        )

        #
        # 4o6 encap
        #
        p_4o6 = []
        for i in range(NUM_PKTS):
            p_4o6.append(
                Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
                / IP(src="2.2.2.2", dst="1.1.2.1")
                / UDP(sport=1234 + i, dport=1234)
                / Raw(b"\xa5" * 100)
            )
        rx = self.send_and_expect(self.pg0, p_4o6, self.pg2)
        sports = set()
        for p in rx:
            self.validate_outer6(p, udp_encap_2, True)
            sports.add(p["UDP"].sport)
            p = IP(p["UDP"].payload.load)
            self.validate_inner4(p, p_4o6[i])
        self.assertEqual(udp_encap_2.get_stats()["packets"], NUM_PKTS)
        self.assertGreater(
            len(sports), 1, "source port {} is not an entropy value".format(sports)
        )

        #
        # 6o4 encap
        #
        p_6o4 = []
        for i in range(NUM_PKTS):
            p_6o4.append(
                Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
                / IPv6(src="2001::100", dst="2001::1")
                / UDP(sport=1234 + i, dport=1234)
                / Raw(b"\xa5" * 100)
            )
        rx = self.send_and_expect(self.pg0, p_6o4, self.pg1)
        sports = set()
        for p in rx:
            self.validate_outer4(p, udp_encap_1, True)
            sports.add(p["UDP"].sport)
            p = IPv6(p["UDP"].payload.load)
            self.validate_inner6(p, p_6o4[i])
        self.assertEqual(udp_encap_1.get_stats()["packets"], NUM_PKTS)
        self.assertGreater(
            len(sports), 1, "source port {} is not an entropy value".format(sports)
        )

        #
        # 6o6 encap
        #
        p_6o6 = []
        for i in range(NUM_PKTS):
            p_6o6.append(
                Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
                / IPv6(src="2001::100", dst="2001::3")
                / UDP(sport=1234 + i, dport=1234)
                / Raw(b"\xa5" * 100)
            )
        rx = self.send_and_expect(self.pg0, p_6o6, self.pg3)
        sports = set()
        for p in rx:
            self.validate_outer6(p, udp_encap_3, True)
            sports.add(p["UDP"].sport)
            p = IPv6(p["UDP"].payload.load)
            self.validate_inner6(p, p_6o6[i])
        self.assertEqual(udp_encap_3.get_stats()["packets"], NUM_PKTS)
        self.assertGreater(
            len(sports), 1, "source port {} is not an entropy value".format(sports)
        )

    def test_udp_decap(self):
        """UDP Decap test"""
        #
        # construct a UDP decap object for each type of protocol
        #

        # IPv4
        udp_api_proto = VppEnum.vl_api_udp_decap_next_proto_t
        next_proto = udp_api_proto.UDP_API_DECAP_PROTO_IP4
        udp_decap_0 = VppUdpDecap(self, 1, 220, next_proto)

        # IPv6
        next_proto = udp_api_proto.UDP_API_DECAP_PROTO_IP6
        udp_decap_1 = VppUdpDecap(self, 0, 221, next_proto)

        # MPLS
        next_proto = udp_api_proto.UDP_API_DECAP_PROTO_MPLS
        udp_decap_2 = VppUdpDecap(self, 1, 222, next_proto)

        udp_decap_0.add_vpp_config()
        udp_decap_1.add_vpp_config()
        udp_decap_2.add_vpp_config()

        #
        # Routes via the corresponding pg after the UDP decap
        #
        route_4 = VppIpRoute(
            self,
            "1.1.1.1",
            32,
            [VppRoutePath("0.0.0.0", self.pg0.sw_if_index)],
            table_id=0,
        )

        route_6 = VppIpRoute(
            self, "2001::1", 128, [VppRoutePath("::", self.pg1.sw_if_index)], table_id=1
        )

        route_mo4 = VppIpRoute(
            self,
            "3.3.3.3",
            32,
            [VppRoutePath("0.0.0.0", self.pg2.sw_if_index)],
            table_id=2,
        )

        route_4.add_vpp_config()
        route_6.add_vpp_config()
        route_mo4.add_vpp_config()

        #
        # Adding neighbors to route the packets
        #
        n_4 = VppNeighbor(self, self.pg0.sw_if_index, "00:11:22:33:44:55", "1.1.1.1")
        n_6 = VppNeighbor(self, self.pg1.sw_if_index, "11:22:33:44:55:66", "2001::1")
        n_mo4 = VppNeighbor(self, self.pg2.sw_if_index, "22:33:44:55:66:77", "3.3.3.3")

        n_4.add_vpp_config()
        n_6.add_vpp_config()
        n_mo4.add_vpp_config()

        #
        # MPLS decapsulation config
        #
        mpls_table = VppMplsTable(self, 0)
        mpls_table.add_vpp_config()
        mpls_route = VppMplsRoute(
            self,
            77,
            1,
            [
                VppRoutePath(
                    "0.0.0.0",
                    0xFFFFFFFF,
                    nh_table_id=2,
                    proto=FibPathProto.FIB_PATH_NH_PROTO_IP4,
                )
            ],
        )
        mpls_route.add_vpp_config()

        #
        # UDP over ipv4 decap
        #
        p_4 = (
            Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
            / IP(src=self.pg0.remote_ip4, dst=self.pg0.local_ip4)
            / UDP(sport=1111, dport=220)
            / IP(src="2.2.2.2", dst="1.1.1.1")
            / UDP(sport=1234, dport=4321)
            / Raw(b"\xa5" * 100)
        )

        rx = self.send_and_expect(self.pg0, p_4 * NUM_PKTS, self.pg0)
        p_4 = IP(p_4["UDP"].payload)
        for p in rx:
            p = IP(p["Ether"].payload)
            self.validate_inner4(p, p_4, ttl=63)

        #
        # UDP over ipv6 decap
        #
        p_6 = (
            Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac)
            / IPv6(src=self.pg1.remote_ip6, dst=self.pg1.local_ip6)
            / UDP(sport=2222, dport=221)
            / IPv6(src="2001::100", dst="2001::1")
            / UDP(sport=1234, dport=4321)
            / Raw(b"\xa5" * 100)
        )

        rx = self.send_and_expect(self.pg1, p_6 * NUM_PKTS, self.pg1)
        p_6 = IPv6(p_6["UDP"].payload)
        p = IPv6(rx[0]["Ether"].payload)
        for p in rx:
            p = IPv6(p["Ether"].payload)
            self.validate_inner6(p, p_6, hlim=63)

        #
        # UDP over mpls decap
        #
        p_mo4 = (
            Ether(src=self.pg2.remote_mac, dst=self.pg2.local_mac)
            / IP(src=self.pg2.remote_ip4, dst=self.pg2.local_ip4)
            / UDP(sport=3333, dport=222)
            / MPLS(label=77, ttl=1)
            / IP(src="4.4.4.4", dst="3.3.3.3")
            / UDP(sport=1234, dport=4321)
            / Raw(b"\xa5" * 100)
        )

        self.pg2.enable_mpls()
        rx = self.send_and_expect(self.pg2, p_mo4 * NUM_PKTS, self.pg2)
        self.pg2.disable_mpls()
        p_mo4 = IP(MPLS(p_mo4["UDP"].payload).payload)
        for p in rx:
            p = IP(p["Ether"].payload)
            self.validate_inner4(p, p_mo4, ttl=63)


@tag_fixme_vpp_workers
class TestUDP(VppTestCase):
    """UDP Test Case"""

    @classmethod
    def setUpClass(cls):
        super(TestUDP, cls).setUpClass()

    @classmethod
    def tearDownClass(cls):
        super(TestUDP, cls).tearDownClass()

    def setUp(self):
        super(TestUDP, self).setUp()
        self.vapi.session_enable_disable(is_enable=1)
        self.create_loopback_interfaces(2)

        table_id = 0

        for i in self.lo_interfaces:
            i.admin_up()

            if table_id != 0:
                tbl = VppIpTable(self, table_id)
                tbl.add_vpp_config()

            i.set_table_ip4(table_id)
            i.config_ip4()
            table_id += 1

        # Configure namespaces
        self.vapi.app_namespace_add_del_v4(
            namespace_id="0", sw_if_index=self.loop0.sw_if_index
        )
        self.vapi.app_namespace_add_del_v4(
            namespace_id="1", sw_if_index=self.loop1.sw_if_index
        )

    def tearDown(self):
        for i in self.lo_interfaces:
            i.unconfig_ip4()
            i.set_table_ip4(0)
            i.admin_down()
        self.vapi.session_enable_disable(is_enable=0)
        super(TestUDP, self).tearDown()

    def test_udp_transfer(self):
        """UDP echo client/server transfer"""

        # Add inter-table routes
        ip_t01 = VppIpRoute(
            self,
            self.loop1.local_ip4,
            32,
            [VppRoutePath("0.0.0.0", 0xFFFFFFFF, nh_table_id=1)],
        )
        ip_t10 = VppIpRoute(
            self,
            self.loop0.local_ip4,
            32,
            [VppRoutePath("0.0.0.0", 0xFFFFFFFF, nh_table_id=0)],
            table_id=1,
        )
        ip_t01.add_vpp_config()
        ip_t10.add_vpp_config()

        # Start builtin server and client
        uri = "udp://" + self.loop0.local_ip4 + "/1234"
        error = self.vapi.cli(
            "test echo server appns 0 fifo-size 4 no-echo" + "uri " + uri
        )
        if error:
            self.logger.critical(error)
            self.assertNotIn("failed", error)

        error = self.vapi.cli(
            "test echo client mbytes 10 appns 1 "
            + "fifo-size 4 no-output test-bytes "
            + "syn-timeout 2 no-return uri "
            + uri
        )
        if error:
            self.logger.critical(error)
            self.assertNotIn("failed", error)

        self.logger.debug(self.vapi.cli("show session verbose 2"))

        # Delete inter-table routes
        ip_t01.remove_vpp_config()
        ip_t10.remove_vpp_config()


if __name__ == "__main__":
    unittest.main(testRunner=VppTestRunner)