ovs-vtep

#! /usr/bin/env python
# Copyright (C) 2013 Nicira, Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Limitations:
#     - Doesn't support multicast other than "unknown-dst"

import argparse
import re
import shlex
import subprocess
import sys
import time

import ovs.dirs
import ovs.util
import ovs.daemon
import ovs.unixctl.server
import ovs.vlog
from six.moves import range
import six


VERSION = "0.99"

root_prefix = ""

__pychecker__ = 'no-reuseattr'  # Remove in pychecker >= 0.8.19.
vlog = ovs.vlog.Vlog("ovs-vtep")
exiting = False

ps_name = ""
ps_type = ""
Tunnel_Ip = ""
Lswitches = {}
Bindings = {}
ls_count = 0
tun_id = 0
bfd_bridge = "vtep_bfd"
bfd_ref = {}


def call_prog(prog, args_list):
    cmd = [prog, "-vconsole:off"] + args_list
    output = subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()
    if len(output) == 0 or output[0] is None:
        output = ""
    else:
        output = output[0].decode().strip()
    return output


def ovs_vsctl(args):
    return call_prog("ovs-vsctl", shlex.split(args))


def ovs_ofctl(args):
    return call_prog("ovs-ofctl", shlex.split(args))


def vtep_ctl(args):
    return call_prog("vtep-ctl", shlex.split(args))


def unixctl_exit(conn, unused_argv, unused_aux):
    global exiting
    exiting = True
    conn.reply(None)


class Logical_Switch(object):
    def __init__(self, ls_name, ps_name):
        global ls_count
        self.name = ls_name
        ls_count += 1
        self.short_name = ps_name + "_vtep_ls" + str(ls_count)
        vlog.info("creating lswitch %s (%s)" % (self.name, self.short_name))
        self.ports = {}
        self.tunnels = {}
        self.local_macs = set()
        self.remote_macs = {}
        self.unknown_dsts = set()
        self.setup_ls()
        self.replication_mode = "service_node"

    def __del__(self):
        vlog.info("destroying lswitch %s" % self.name)

    def setup_ls(self):

        if ps_type:
            ovs_vsctl("--may-exist add-br %s -- set Bridge %s datapath_type=%s"
                      % (self.short_name, self.short_name, ps_type))
        else:
            ovs_vsctl("--may-exist add-br %s" % self.short_name)

        ovs_vsctl("br-set-external-id %s vtep_logical_switch true"
                  % self.short_name)
        ovs_vsctl("br-set-external-id %s logical_switch_name %s"
                  % (self.short_name, self.name))

        vtep_ctl("clear-local-macs %s" % self.name)
        vtep_ctl("add-mcast-local %s unknown-dst %s" % (self.name, Tunnel_Ip))

        ovs_ofctl("del-flows %s" % self.short_name)
        ovs_ofctl("add-flow %s priority=0,action=drop" % self.short_name)

    def cleanup_ls(self):
        for port_no, tun_name, remote_ip in six.itervalues(self.tunnels):
            del_bfd(remote_ip)

    def update_flood(self):
        flood_ports = list(self.ports.values())

        # Traffic flowing from one 'unknown-dst' should not be flooded to
        # port belonging to another 'unknown-dst'.
        for tunnel in self.unknown_dsts:
            port_no = self.tunnels[tunnel][0]
            ovs_ofctl("add-flow %s table=1,priority=1,in_port=%s,action=%s"
                      % (self.short_name, port_no, ",".join(flood_ports)))

        # Traffic coming from a VTEP physical port should always be flooded to
        # all the other physical ports that belong to that VTEP device and
        # this logical switch.  If the replication mode is service node then
        # send to one unknown_dst node (the first one here); else we assume the
        # replication mode is source node and we send the packet to all
        # unknown_dst nodes.
        for tunnel in self.unknown_dsts:
            port_no = self.tunnels[tunnel][0]
            flood_ports.append(port_no)
            if self.replication_mode == "service_node":
                break

        ovs_ofctl("add-flow %s table=1,priority=0,action=%s"
                  % (self.short_name, ",".join(flood_ports)))

    def add_lbinding(self, lbinding):
        vlog.info("adding %s binding to %s" % (lbinding, self.name))
        port_no = ovs_vsctl("get Interface %s ofport" % lbinding)
        self.ports[lbinding] = port_no
        ovs_ofctl("add-flow %s in_port=%s,action=learn(table=1,"
                  "priority=1000,idle_timeout=15,cookie=0x5000,"
                  "NXM_OF_ETH_DST[]=NXM_OF_ETH_SRC[],"
                  "output:NXM_OF_IN_PORT[]),resubmit(,1)"
                  % (self.short_name, port_no))

        self.update_flood()

    def del_lbinding(self, lbinding):
        vlog.info("removing %s binding from %s" % (lbinding, self.name))
        port_no = self.ports[lbinding]
        ovs_ofctl("del-flows %s in_port=%s" % (self.short_name, port_no))
        del self.ports[lbinding]
        self.update_flood()

    def add_tunnel(self, tunnel, tunnel_key):
        global tun_id
        vlog.info("adding tunnel %s" % tunnel)
        encap, ip = tunnel.split("/")

        if encap != "vxlan_over_ipv4":
            vlog.warn("unsupported tunnel format %s" % encap)
            return

        tun_id += 1
        tun_name = "vx" + str(tun_id)

        ovs_vsctl("add-port %s %s -- set Interface %s type=vxlan "
                  "options:key=%s options:remote_ip=%s"
                  % (self.short_name, tun_name, tun_name, tunnel_key, ip))

        for i in range(10):
            port_no = ovs_vsctl("get Interface %s ofport" % tun_name)
            if port_no != "-1":
                break
            elif i == 9:
                vlog.warn("couldn't create tunnel %s" % tunnel)
                ovs_vsctl("del-port %s %s" % (self.short_name, tun_name))
                return

            # Give the system a moment to allocate the port number
            time.sleep(0.5)

        self.tunnels[tunnel] = (port_no, tun_name, ip)

        add_bfd(ip)

        ovs_ofctl("add-flow %s table=0,priority=1000,in_port=%s,"
                  "actions=resubmit(,1)"
                  % (self.short_name, port_no))

    def del_tunnel(self, tunnel):
        vlog.info("removing tunnel %s" % tunnel)

        port_no, tun_name, remote_ip = self.tunnels[tunnel]
        ovs_ofctl("del-flows %s table=0,in_port=%s"
                  % (self.short_name, port_no))
        ovs_vsctl("del-port %s %s" % (self.short_name, tun_name))

        del_bfd(remote_ip)

        del self.tunnels[tunnel]

    def update_local_macs(self):
        flows = ovs_ofctl("dump-flows %s cookie=0x5000/-1,table=1"
                          % self.short_name).splitlines()
        macs = set()
        for f in flows:
            mac = re.split(r'.*dl_dst=(.*) .*', f)
            if len(mac) == 3:
                macs.add(mac[1])

        for mac in macs.difference(self.local_macs):
            vlog.info("adding local ucast %s to %s" % (mac, self.name))
            vtep_ctl("add-ucast-local %s %s %s" % (self.name, mac, Tunnel_Ip))

        for mac in self.local_macs.difference(macs):
            vlog.info("removing local ucast %s from %s" % (mac, self.name))
            vtep_ctl("del-ucast-local %s %s" % (self.name, mac))

        self.local_macs = macs

    def add_remote_mac(self, mac, tunnel):
        port_no = self.tunnels.get(tunnel, (0, ""))[0]
        if not port_no:
            return

        ovs_ofctl("add-flow %s table=1,priority=1000,dl_dst=%s,action=%s"
                  % (self.short_name, mac, port_no))

    def del_remote_mac(self, mac):
        ovs_ofctl("del-flows %s table=1,dl_dst=%s" % (self.short_name, mac))

    def update_remote_macs(self):
        remote_macs = {}
        unknown_dsts = set()
        tunnels = set()
        parse_ucast = True

        column = vtep_ctl("--columns=tunnel_key find logical_switch "
                          "name=%s" % self.name)
        tunnel_key = column.partition(":")[2].strip()
        if tunnel_key and isinstance(eval(tunnel_key), six.integer_types):
            vlog.info("update_remote_macs: using tunnel key %s in %s"
                      % (tunnel_key, self.name))
        else:
            vlog.info("Invalid tunnel key %s in %s post VTEP DB requery"
                      % (tunnel_key, self.name))
            return

        mac_list = vtep_ctl("list-remote-macs %s" % self.name).splitlines()
        for line in mac_list:
            if (line.find("mcast-mac-remote") != -1):
                parse_ucast = False
                continue

            entry = re.split(r'  (.*) -> (.*)', line)
            if len(entry) != 4:
                continue

            if parse_ucast:
                remote_macs[entry[1]] = entry[2]
            else:
                if entry[1] != "unknown-dst":
                    continue

                unknown_dsts.add(entry[2])

            tunnels.add(entry[2])

        old_tunnels = set(self.tunnels.keys())

        for tunnel in tunnels.difference(old_tunnels):
            self.add_tunnel(tunnel, tunnel_key)

        for tunnel in old_tunnels.difference(tunnels):
            self.del_tunnel(tunnel)

        for mac in six.iterkeys(remote_macs):
            if (self.remote_macs.get(mac) != remote_macs[mac]):
                self.add_remote_mac(mac, remote_macs[mac])

        for mac in six.iterkeys(self.remote_macs):
            if mac not in remote_macs:
                self.del_remote_mac(mac)

        self.remote_macs = remote_macs

        replication_mode = vtep_ctl("get logical_switch %s replication_mode"
                                    % self.name)

        # Replication mode is an optional column and if it is not set,
        # replication mode defaults to service_node.
        if replication_mode == "[]":
            replication_mode = "service_node"

        # If the logical switch level replication mode has changed then
        # update to that value.
        update_flood_set = False
        if replication_mode != self.replication_mode:
            self.replication_mode = replication_mode
            vlog.info("%s replication mode changed to %s" %
                      (self.name, self.replication_mode))
            update_flood_set = True

        if (self.unknown_dsts != unknown_dsts):
            self.unknown_dsts = unknown_dsts
            update_flood_set = True

        # If either the replication mode has changed or the unknown
        # destinations set has changed, update the flooding decision.
        if update_flood_set is True:
            self.update_flood()

    def update_stats(self):
        # Map Open_vSwitch's "interface:statistics" to columns of
        # vtep's logical_binding_stats. Since we are using the 'interface' from
        # the logical switch to collect stats, packets transmitted from it
        # is received in the physical switch and vice versa.
        stats_map = {'tx_packets': 'packets_to_local',
                     'tx_bytes': 'bytes_to_local',
                     'rx_packets': 'packets_from_local',
                     'rx_bytes': 'bytes_from_local'}

        # Go through all the logical switch's interfaces that end with "-l"
        # and copy the statistics to logical_binding_stats.
        for interface in six.iterkeys(self.ports):
            if not interface.endswith("-l"):
                continue
            # Physical ports can have a '-' as part of its name.
            vlan, remainder = interface.split("-", 1)
            pp_name, logical = remainder.rsplit("-", 1)
            uuid = vtep_ctl("get physical_port %s vlan_stats:%s"
                            % (pp_name, vlan))
            if not uuid:
                continue

            for mapfrom, mapto in six.iteritems(stats_map):
                value = ovs_vsctl("get interface %s statistics:%s"
                                  % (interface, mapfrom)).strip('"')
                vtep_ctl("set logical_binding_stats %s %s=%s"
                         % (uuid, mapto, value))

    def run(self):
        self.update_local_macs()
        self.update_remote_macs()
        self.update_stats()


def get_vtep_tunnel(remote_ip):
    # Get the physical_locator record for the local tunnel end point.
    column = vtep_ctl("--columns=_uuid find physical_locator "
                      "dst_ip=%s" % Tunnel_Ip)
    local = column.partition(":")[2].strip()
    if not local:
        return (None, None, None)

    # Get the physical_locator record for the remote tunnel end point.
    column = vtep_ctl("--columns=_uuid find physical_locator "
                      "dst_ip=%s" % remote_ip)
    remote = column.partition(":")[2].strip()
    if not remote:
        return (None, None, None)

    column = vtep_ctl("--columns=_uuid find tunnel "
                      "local=%s remote=%s" % (local, remote))
    tunnel = column.partition(":")[2].strip()

    return (local, remote, tunnel)


def create_vtep_tunnel(remote_ip):
    local, remote, tunnel = get_vtep_tunnel(remote_ip)
    if not local or not remote:
        return None

    if not tunnel:
        vlog.info("creating tunnel record in vtep for remote_ip:%s"
                  % remote_ip)
        tunnel = vtep_ctl("add physical_switch %s tunnels @tun -- "
                          "--id=@tun create Tunnel local=%s remote=%s"
                          % (ps_name, local, remote))
    return tunnel


def destroy_vtep_tunnel(remote_ip):
    local, remote, tunnel = get_vtep_tunnel(remote_ip)
    if tunnel:
        vlog.info("destroying tunnel record in vtep for remote_ip:%s"
                  % remote_ip)
        vtep_ctl("remove physical_switch %s tunnels %s "
                 "-- --if-exists destroy tunnel %s"
                 % (ps_name, tunnel, tunnel))


def add_bfd(remote_ip):
    # The VTEP emulator creates one OVS bridge for every logical switch.
    # Multiple logical switches can have multiple OVS tunnels to the
    # same machine (with different tunnel ids). But VTEP schema expects
    # a single BFD session between two physical locators. Therefore
    # create a separate bridge ('bfd_bridge') and create a single OVS tunnel
    # between two phsyical locators (using reference counter).
    if remote_ip in bfd_ref:
        bfd_ref[remote_ip] += 1
        return

    vlog.info("adding bfd tunnel for remote_ip:%s" % remote_ip)

    port_name = "bfd" + remote_ip
    # Don't enable BFD yet. Enabling or disabling BFD is based on
    # the controller setting a value in VTEP DB's tunnel record.
    ovs_vsctl("--may-exist add-port %s %s "
              " -- set Interface %s type=vxlan options:remote_ip=%s"
              % (bfd_bridge, port_name, port_name, remote_ip))
    bfd_ref[remote_ip] = 1

    # Ideally, we should create a 'tunnel' record in the VTEP DB here.
    # To create a 'tunnel' record, we need 2 entries in 'physical_locator'
    # table (one for local and one for remote). But, 'physical_locator'
    # can be created/destroyed asynchronously when the remote controller
    # adds/removes entries in Ucast_Macs_Remote table. To prevent race
    # conditions, pass the responsibility of creating a 'tunnel' record
    # to run_bfd() which runs more often.


def del_bfd(remote_ip):
    if remote_ip in bfd_ref:
        if bfd_ref[remote_ip] == 1:
            port_name = "bfd" + remote_ip
            vlog.info("deleting bfd tunnel for remote_ip:%s" % remote_ip)
            ovs_vsctl("--if-exists del-port %s" % port_name)
            destroy_vtep_tunnel(remote_ip)
            del bfd_ref[remote_ip]
        else:
            bfd_ref[remote_ip] -= 1


def run_bfd():
    bfd_ports = ovs_vsctl("list-ports %s" % bfd_bridge).split()
    for port in bfd_ports:
        remote_ip = ovs_vsctl("get interface %s options:remote_ip" % port)
        tunnel = create_vtep_tunnel(remote_ip)
        if not tunnel:
            continue

        bfd_params_default = {'bfd_params:enable': 'false',
                              'bfd_params:min_rx': 1000,
                              'bfd_params:min_tx': 100,
                              'bfd_params:decay_min_rx': 0,
                              'bfd_params:cpath_down': 'false',
                              'bfd_params:check_tnl_key': 'false'}
        bfd_params_values = {}

        for key, default in six.iteritems(bfd_params_default):
            column = vtep_ctl("--if-exists get tunnel %s %s"
                              % (tunnel, key))
            if not column:
                bfd_params_values[key] = default
            else:
                bfd_params_values[key] = column

        for key, value in six.iteritems(bfd_params_values):
            new_key = key.replace('_params', '')
            ovs_vsctl("set interface %s %s=%s" % (port, new_key, value))

        bfd_status = ['bfd_status:state', 'bfd_status:forwarding',
                      'bfd_status:diagnostic', 'bfd_status:remote_state',
                      'bfd_status:remote_diagnostic']
        for key in bfd_status:
            value = ovs_vsctl("--if-exists get interface %s %s" % (port, key))
            if value:
                vtep_ctl("set tunnel %s %s=%s" % (tunnel, key, value))
            else:
                new_key = key.replace('bfd_status:', '')
                vtep_ctl("remove tunnel %s bfd_status %s" % (tunnel, new_key))

        vtep_ctl("set tunnel %s bfd_status:enabled=%s"
                 % (tunnel, bfd_params_values['bfd_params:enable']))

        # Add the defaults as described in VTEP schema to make it explicit.
        bfd_lconf_default = {'bfd_config_local:bfd_dst_ip': '169.254.1.0',
                             'bfd_config_local:bfd_dst_mac':
                             '00:23:20:00:00:01'}
        for key, value in six.iteritems(bfd_lconf_default):
            vtep_ctl("set tunnel %s %s=%s" % (tunnel, key, value))

        # bfd_config_remote options from VTEP DB should be populated to
        # corresponding OVS DB values.
        bfd_dst_ip = vtep_ctl("--if-exists get tunnel %s "
                              "bfd_config_remote:bfd_dst_ip" % (tunnel))
        if not bfd_dst_ip:
            bfd_dst_ip = "169.254.1.1"

        bfd_dst_mac = vtep_ctl("--if-exists get tunnel %s "
                               "bfd_config_remote:bfd_dst_mac" % (tunnel))
        if not bfd_dst_mac:
            bfd_dst_mac = "00:23:20:00:00:01"

        ovs_vsctl("set interface %s bfd:bfd_dst_ip=%s "
                  "bfd:bfd_remote_dst_mac=%s bfd:bfd_local_dst_mac=%s"
                  % (port, bfd_dst_ip,
                     bfd_lconf_default['bfd_config_local:bfd_dst_mac'],
                     bfd_dst_mac))


def add_binding(binding, ls):
    vlog.info("adding binding %s" % binding)

    vlan, pp_name = binding.split("-", 1)
    pbinding = binding + "-p"
    lbinding = binding + "-l"

    # Create a patch port that connects the VLAN+port to the lswitch.
    # Do them as two separate calls so if one side already exists, the
    # other side is created.
    ovs_vsctl("add-port %s %s "
              " -- set Interface %s type=patch options:peer=%s"
              % (ps_name, pbinding, pbinding, lbinding))
    ovs_vsctl("add-port %s %s "
              " -- set Interface %s type=patch options:peer=%s"
              % (ls.short_name, lbinding, lbinding, pbinding))

    port_no = ovs_vsctl("get Interface %s ofport" % pp_name)
    patch_no = ovs_vsctl("get Interface %s ofport" % pbinding)
    vlan_ = vlan.lstrip('0')
    if vlan_:
        ovs_ofctl("add-flow %s in_port=%s,dl_vlan=%s,action=strip_vlan,%s"
                  % (ps_name, port_no, vlan_, patch_no))
        ovs_ofctl("add-flow %s in_port=%s,action=mod_vlan_vid:%s,%s"
                  % (ps_name, patch_no, vlan_, port_no))
    else:
        ovs_ofctl("add-flow %s in_port=%s,action=%s"
                  % (ps_name, port_no, patch_no))
        ovs_ofctl("add-flow %s in_port=%s,action=%s"
                  % (ps_name, patch_no, port_no))

    # Create a logical_bindings_stats record.
    if not vlan_:
        vlan_ = "0"
    vtep_ctl("set physical_port %s vlan_stats:%s=@stats -- "
             "--id=@stats create logical_binding_stats packets_from_local=0"
             % (pp_name, vlan_))

    ls.add_lbinding(lbinding)
    Bindings[binding] = ls.name


def del_binding(binding, ls):
    vlog.info("removing binding %s" % binding)

    vlan, pp_name = binding.split("-", 1)
    pbinding = binding + "-p"
    lbinding = binding + "-l"

    port_no = ovs_vsctl("get Interface %s ofport" % pp_name)
    patch_no = ovs_vsctl("get Interface %s ofport" % pbinding)
    vlan_ = vlan.lstrip('0')
    if vlan_:
        ovs_ofctl("del-flows %s in_port=%s,dl_vlan=%s"
                  % (ps_name, port_no, vlan_))
        ovs_ofctl("del-flows %s in_port=%s" % (ps_name, patch_no))
    else:
        ovs_ofctl("--strict del-flows %s in_port=%s" % (ps_name, port_no))
        ovs_ofctl("--strict del-flows %s in_port=%s" % (ps_name, patch_no))

    ls.del_lbinding(lbinding)

    # Destroy the patch port that connects the VLAN+port to the lswitch
    ovs_vsctl("del-port %s %s -- del-port %s %s"
              % (ps_name, pbinding, ls.short_name, lbinding))

    # Remove the record that links vlan with stats in logical_binding_stats.
    vtep_ctl("remove physical_port %s vlan_stats %s" % (pp_name, vlan))

    del Bindings[binding]


def handle_physical():
    # Gather physical ports except the patch ports we created
    ovs_ports = ovs_vsctl("list-ports %s" % ps_name).split()
    ovs_port_set = set([port for port in ovs_ports if port[-2:] != "-p"])

    vtep_pp_set = set(vtep_ctl("list-ports %s" % ps_name).split())

    for pp_name in ovs_port_set.difference(vtep_pp_set):
        vlog.info("adding %s to %s" % (pp_name, ps_name))
        vtep_ctl("add-port %s %s" % (ps_name, pp_name))

    for pp_name in vtep_pp_set.difference(ovs_port_set):
        vlog.info("deleting %s from %s" % (pp_name, ps_name))
        vtep_ctl("del-port %s %s" % (ps_name, pp_name))

    new_bindings = set()
    for pp_name in vtep_pp_set:
        binding_set = set(vtep_ctl("list-bindings %s %s"
                                   % (ps_name, pp_name)).splitlines())

        for b in binding_set:
            vlan, ls_name = b.split()
            if ls_name not in Lswitches:
                Lswitches[ls_name] = Logical_Switch(ls_name, ps_name)

            binding = "%s-%s" % (vlan, pp_name)
            ls = Lswitches[ls_name]
            new_bindings.add(binding)

            if binding in Bindings:
                if Bindings[binding] == ls_name:
                    continue
                else:
                    del_binding(binding, Lswitches[Bindings[binding]])

            add_binding(binding, ls)

    dead_bindings = set(Bindings.keys()).difference(new_bindings)
    for binding in dead_bindings:
        ls_name = Bindings[binding]
        ls = Lswitches[ls_name]

        del_binding(binding, ls)

        if not len(ls.ports):
            ls.cleanup_ls()
            ovs_vsctl("del-br %s" % Lswitches[ls_name].short_name)
            vtep_ctl("clear-local-macs %s" % Lswitches[ls_name].name)
            del Lswitches[ls_name]


def setup():
    br_list = ovs_vsctl("list-br").split()
    if (ps_name not in br_list):
        ovs.util.ovs_fatal(0, "couldn't find OVS bridge %s" % ps_name, vlog)

    global ps_type
    ps_type = ovs_vsctl("get Bridge %s datapath_type" % ps_name).strip('"')

    call_prog("vtep-ctl", ["set", "physical_switch", ps_name,
                           'description="OVS VTEP Emulator"'])

    tunnel_ips = vtep_ctl("get physical_switch %s tunnel_ips"
                          % ps_name).strip('[]"').split(", ")
    if len(tunnel_ips) != 1 or not tunnel_ips[0]:
        ovs.util.ovs_fatal(0, "exactly one 'tunnel_ips' should be set", vlog)

    global Tunnel_Ip
    Tunnel_Ip = tunnel_ips[0]

    ovs_ofctl("del-flows %s" % ps_name)

    # Remove any logical bridges from the previous run
    for br in br_list:
        if ovs_vsctl("br-get-external-id %s vtep_logical_switch"
                     % br) == "true":
            # Remove the remote side of any logical switch
            ovs_ports = ovs_vsctl("list-ports %s" % br).split()
            for port in ovs_ports:
                port_type = ovs_vsctl("get Interface %s type"
                                      % port).strip('"')
                if port_type != "patch":
                    continue

                peer = ovs_vsctl("get Interface %s options:peer"
                                 % port).strip('"')
                if (peer):
                    ovs_vsctl("del-port %s" % peer)

            ovs_vsctl("del-br %s" % br)

        if br == bfd_bridge:
            bfd_ports = ovs_vsctl("list-ports %s" % bfd_bridge).split()
            for port in bfd_ports:
                remote_ip = ovs_vsctl("get interface %s options:remote_ip"
                                      % port)
                destroy_vtep_tunnel(remote_ip)

            ovs_vsctl("del-br %s" % br)

    if ps_type:
        ovs_vsctl("add-br %s -- set Bridge %s datapath_type=%s"
                  % (bfd_bridge, bfd_bridge, ps_type))
    else:
        ovs_vsctl("add-br %s" % bfd_bridge)

    # Remove local-mac entries from the previous run.  Otherwise, if a vlan
    # binding is removed while the emulator is *not* running, the corresponding
    # local-mac entries are never cleaned up.
    vtep_ls = set(vtep_ctl("list-ls").split())
    for ls_name in vtep_ls:
        vtep_ctl("clear-local-macs %s" % ls_name)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("ps_name", metavar="PS-NAME",
                        help="Name of physical switch.")
    parser.add_argument("--root-prefix", metavar="DIR",
                        help="Use DIR as alternate root directory"
                        " (for testing).")
    parser.add_argument("--version", action="version",
                        version="%s %s" % (ovs.util.PROGRAM_NAME, VERSION))

    ovs.vlog.add_args(parser)
    ovs.daemon.add_args(parser)
    args = parser.parse_args()
    ovs.vlog.handle_args(args)
    ovs.daemon.handle_args(args)

    global root_prefix
    if args.root_prefix:
        root_prefix = args.root_prefix

    global ps_name
    ps_name = args.ps_name

    ovs.daemon.daemonize()

    ovs.unixctl.command_register("exit", "", 0, 0, unixctl_exit, None)
    error, unixctl = ovs.unixctl.server.UnixctlServer.create(None,
                                                             version=VERSION)
    if error:
        ovs.util.ovs_fatal(error, "could not create unixctl server", vlog)

    setup()

    while True:
        unixctl.run()
        if exiting:
            break

        handle_physical()

        for ls_name, ls in six.iteritems(Lswitches):
            ls.run()

        run_bfd()

        poller = ovs.poller.Poller()
        unixctl.wait(poller)
        poller.timer_wait(1000)
        poller.block()

    unixctl.close()

if __name__ == '__main__':
    try:
        main()
    except SystemExit:
        # Let system.exit() calls complete normally
        raise
    except:
        vlog.exception("traceback")
        sys.exit(ovs.daemon.RESTART_EXIT_CODE)