Merge pull request #732 from c-po/t3310-bfd

bfd: T3310: migrate to get_config_dict() and FRR reload

6 files changed, 273 insertions, 255 deletions

diff --git a/data/configd-include.json b/data/configd-include.json
index e50dbf1b2..aabd7232e 100644
--- a/data/configd-include.json
+++ b/data/configd-include.json
@@ -32,6 +32,7 @@
 "nat66.py",
 "ntp.py",
 "policy-local-route.py",
+"protocols_bfd.py",
 "protocols_bgp.py",
 "protocols_igmp.py",
 "protocols_isis.py",
diff --git a/data/templates/frr/bfd.frr.tmpl b/data/templates/frr/bfd.frr.tmpl
index 9e5ad3379..3b3d13f9d 100644
--- a/data/templates/frr/bfd.frr.tmpl
+++ b/data/templates/frr/bfd.frr.tmpl
@@ -1,22 +1,44 @@
 !
 bfd
-{% for peer in old_peers %}
- no peer {{ peer.remote }}{% if peer.multihop %} multihop{% endif %}{% if peer.src_addr %} local-address {{ peer.src_addr }}{% endif %}{% if peer.src_if %} interface {{ peer.src_if }}{% endif %}
-
-{% endfor %}
-!
-{% for peer in new_peers %}
- peer {{ peer.remote }}{% if peer.multihop %} multihop{% endif %}{% if peer.src_addr %} local-address {{ peer.src_addr }}{% endif %}{% if peer.src_if %} interface {{ peer.src_if }}{% endif %}
-
- detect-multiplier {{ peer.multiplier }}
- receive-interval {{ peer.rx_interval }}
- transmit-interval {{ peer.tx_interval }}
-{% if peer.echo_mode %}
- echo-mode
+{% if profile is defined and profile is not none %}
+{%   for profile_name, profile_config in profile.items() %}
+ profile {{ profile_name }}
+  detect-multiplier {{ profile_config.interval.multiplier }}
+  receive-interval {{ profile_config.interval.receive }}
+  transmit-interval {{ profile_config.interval.transmit }}
+{%     if profile_config.interval['echo-interval'] is defined and profile_config.interval['echo-interval'] is not none %}
+  echo-interval {{ profile_config.interval['echo-interval'] }}
+{%     endif %}
+{%     if profile_config['echo-mode'] is defined %}
+  echo-mode
+{%     endif %}
+{%     if profile_config.shutdown is defined %}
+  shutdown
+{%     else %}
+  no shutdown
+{%     endif %}
+  exit
+{%   endfor %}
 {% endif %}
-{% if peer.echo_interval != '' %}
- echo-interval {{ peer.echo_interval }}
+{% if peer is defined and peer is not none %}
+{%   for peer_name, peer_config in peer.items() %}
+ peer {{ peer_name }}{{ ' multihop' if peer_config.multihop is defined }}{{ ' local-address ' + peer_config.source.address if peer_config.source is defined and peer_config.source.address is defined }}{{ ' interface ' + peer_config.source.interface if peer_config.source is defined and peer_config.source.interface is defined }}
+  detect-multiplier {{ peer_config.interval.multiplier }}
+  receive-interval {{ peer_config.interval.receive }}
+  transmit-interval {{ peer_config.interval.transmit }}
+{%     if peer_config.interval['echo-interval'] is defined and peer_config.interval['echo-interval'] is not none %}
+ echo-interval {{ peer_config.interval['echo-interval'] }}
+{%     endif %}
+{%     if peer_config['echo-mode'] is defined %}
+  echo-mode
+{%     endif %}
+{%     if peer_config.shutdown is defined %}
+  shutdown
+{%     else %}
+  no shutdown
+{%     endif %}
+  exit
+{%   endfor %}
 {% endif %}
- {% if not peer.shutdown %}no {% endif %}shutdown
-{% endfor %}
+ exit
 !
diff --git a/interface-definitions/include/bfd-common.xml.i b/interface-definitions/include/bfd-common.xml.i
new file mode 100644
index 000000000..ff73e4b20
--- /dev/null
+++ b/interface-definitions/include/bfd-common.xml.i
@@ -0,0 +1,72 @@
+<!-- included start from bfd-common.xml.i -->
+<leafNode name="echo-mode">
+  <properties>
+    <help>Enables the echo transmission mode</help>
+    <valueless/>
+  </properties>
+</leafNode>
+<node name="interval">
+  <properties>
+    <help>Configure timer intervals</help>
+  </properties>
+  <children>
+    <leafNode name="receive">
+      <properties>
+        <help>Minimum interval of receiving control packets</help>
+        <valueHelp>
+          <format>10-60000</format>
+          <description>Interval in milliseconds</description>
+        </valueHelp>
+        <constraint>
+          <validator name="numeric" argument="--range 10-60000"/>
+        </constraint>
+      </properties>
+      <defaultValue>300</defaultValue>
+    </leafNode>
+    <leafNode name="transmit">
+      <properties>
+        <help>Minimum interval of transmitting control packets</help>
+        <valueHelp>
+          <format>10-60000</format>
+          <description>Interval in milliseconds</description>
+        </valueHelp>
+        <constraint>
+          <validator name="numeric" argument="--range 10-60000"/>
+        </constraint>
+      </properties>
+      <defaultValue>300</defaultValue>
+    </leafNode>
+    <leafNode name="multiplier">
+      <properties>
+        <help>Multiplier to determine packet loss</help>
+        <valueHelp>
+          <format>2-255</format>
+          <description>Remote transmission interval will be multiplied by this value</description>
+        </valueHelp>
+        <constraint>
+          <validator name="numeric" argument="--range 2-255"/>
+        </constraint>
+      </properties>
+      <defaultValue>3</defaultValue>
+    </leafNode>
+    <leafNode name="echo-interval">
+      <properties>
+        <help>Echo receive transmission interval</help>
+        <valueHelp>
+          <format>10-60000</format>
+          <description>The minimal echo receive transmission interval that this system is capable of handling</description>
+        </valueHelp>
+        <constraint>
+          <validator name="numeric" argument="--range 10-60000"/>
+        </constraint>
+      </properties>
+    </leafNode>
+  </children>
+</node>
+<leafNode name="shutdown">
+  <properties>
+    <help>Disable this peer</help>
+    <valueless/>
+  </properties>
+</leafNode>
+<!-- included end -->
diff --git a/interface-definitions/protocols-bfd.xml.in b/interface-definitions/protocols-bfd.xml.in
index 8900e7955..cc3c3bf12 100644
--- a/interface-definitions/protocols-bfd.xml.in
+++ b/interface-definitions/protocols-bfd.xml.in
@@ -11,7 +11,7 @@
         <children>
           <tagNode name="peer">
             <properties>
-              <help>Configures a new BFD peer to listen and talk to</help>
+              <help>Configures BFD peer to listen and talk to</help>
               <valueHelp>
                 <format>ipv4</format>
                 <description>BFD peer IPv4 address</description>
@@ -26,6 +26,18 @@
               </constraint>
             </properties>
             <children>
+              <leafNode name="profile">
+                <properties>
+                  <help>Use settings from BFD profile</help>
+                  <completionHelp>
+                    <path>protocols bfd profile</path>
+                  </completionHelp>
+                  <valueHelp>
+                    <format>txt</format>
+                    <description>BFD profile name</description>
+                  </valueHelp>
+                </properties>
+              </leafNode>
               <node name="source">
                 <properties>
                   <help>Bind listener to specified interface/address, mandatory for IPv6</help>
@@ -42,6 +54,9 @@
                   <leafNode name="address">
                     <properties>
                       <help>Local address to bind our peer listener to</help>
+                      <completionHelp>
+                        <script>${vyos_completion_dir}/list_local_ips.sh --both</script>
+                      </completionHelp>
                       <valueHelp>
                         <format>ipv4</format>
                         <description>Local IPv4 address used to connect to the peer</description>
@@ -58,79 +73,28 @@
                   </leafNode>
                 </children>
               </node>
-              <node name="interval">
-                <properties>
-                  <help>Configure timer intervals</help>
-                </properties>
-                <children>
-                  <leafNode name="receive">
-                    <properties>
-                      <help>Minimum interval of receiving control packets</help>
-                      <valueHelp>
-                        <format>10-60000</format>
-                        <description>Interval in milliseconds</description>
-                      </valueHelp>
-                      <constraint>
-                        <validator name="numeric" argument="--range 10-60000"/>
-                      </constraint>
-                    </properties>
-                  </leafNode>
-                  <leafNode name="transmit">
-                    <properties>
-                      <help>Minimum interval of transmitting control packets</help>
-                      <valueHelp>
-                        <format>10-60000</format>
-                        <description>Interval in milliseconds</description>
-                      </valueHelp>
-                      <constraint>
-                        <validator name="numeric" argument="--range 10-60000"/>
-                      </constraint>
-                    </properties>
-                  </leafNode>
-                  <leafNode name="multiplier">
-                    <properties>
-                      <help>Multiplier to determine packet loss</help>
-                      <valueHelp>
-                        <format>2-255</format>
-                        <description>Remote transmission interval will be multiplied by this value</description>
-                      </valueHelp>
-                      <constraint>
-                        <validator name="numeric" argument="--range 2-255"/>
-                      </constraint>
-                    </properties>
-                  </leafNode>
-                  <leafNode name="echo-interval">
-                    <properties>
-                      <help>Echo receive transmission interval</help>
-                      <valueHelp>
-                        <format>10-60000</format>
-                        <description>The minimal echo receive transmission interval that this system is capable of handling</description>
-                      </valueHelp>
-                      <constraint>
-                        <validator name="numeric" argument="--range 10-60000"/>
-                      </constraint>
-                    </properties>
-                  </leafNode>
-                </children>
-              </node>
-              <leafNode name="shutdown">
-                <properties>
-                  <help>Disable this peer</help>
-                  <valueless/>
-                </properties>
-              </leafNode>
+              #include <include/bfd-common.xml.i>
               <leafNode name="multihop">
                 <properties>
                   <help>Allow this BFD peer to not be directly connected</help>
                   <valueless/>
                 </properties>
               </leafNode>
-              <leafNode name="echo-mode">
-                <properties>
-                  <help>Enables the echo transmission mode</help>
-                  <valueless/>
-                </properties>
-              </leafNode>
+            </children>
+          </tagNode>
+          <tagNode name="profile">
+            <properties>
+              <help>Configure BFD profile used by individual peer</help>
+              <valueHelp>
+                <format>txt</format>
+                <description>Name of BFD profile</description>
+              </valueHelp>
+              <constraint>
+                <regex>^[-_a-zA-Z0-9]{1,32}$</regex>
+              </constraint>
+            </properties>
+            <children>
+              #include <include/bfd-common.xml.i>
             </children>
           </tagNode>
         </children>
diff --git a/smoketest/scripts/cli/test_protocols_bfd.py b/smoketest/scripts/cli/test_protocols_bfd.py
index 996a54a9d..80e5daa7c 100755
--- a/smoketest/scripts/cli/test_protocols_bfd.py
+++ b/smoketest/scripts/cli/test_protocols_bfd.py
@@ -26,7 +26,7 @@ PROCESS_NAME = 'bfdd'
 base_path = ['protocols', 'bfd']
 
 dum_if = 'dum1001'
-neighbor_config = {
+peers = {
     '192.0.2.10' : {
         'intv_rx'    : '500',
         'intv_tx'    : '600',
@@ -36,7 +36,7 @@ neighbor_config = {
     '192.0.2.20' : {
         'echo_mode'  : '',
         'intv_echo'  : '100',
-        'intv_mult'  : '111',
+        'intv_mult'  : '100',
         'intv_rx'    : '222',
         'intv_tx'    : '333',
         'shutdown'   : '',
@@ -52,20 +52,35 @@ neighbor_config = {
         },
 }
 
+profiles = {
+    'foo' : {
+        'echo_mode'  : '',
+        'intv_echo'  : '100',
+        'intv_mult'  : '101',
+        'intv_rx'    : '222',
+        'intv_tx'    : '333',
+        'shutdown'   : '',
+        },
+    'bar' : {
+        'intv_mult'  : '102',
+        'intv_rx'    : '444',
+        },
+}
+
 def getFRRconfig():
     return cmd('vtysh -c "show run" | sed -n "/^bfd/,/^!/p"')
 
 def getBFDPeerconfig(peer):
     return cmd(f'vtysh -c "show run" | sed -n "/^ {peer}/,/^!/p"')
 
+def getBFDProfileconfig(profile):
+    return cmd(f'vtysh -c "show run" | sed -n "/^ {profile}/,/^!/p"')
+
 class TestProtocolsBFD(unittest.TestCase):
     def setUp(self):
         self.session = ConfigSession(os.getpid())
-        self.session.set(['interfaces', 'dummy', dum_if, 'address', '192.0.2.1/24'])
-        self.session.set(['interfaces', 'dummy', dum_if, 'address', '2001:db8::1/64'])
 
     def tearDown(self):
-        self.session.delete(['interfaces', 'dummy', dum_if])
         self.session.delete(base_path)
         self.session.commit()
         del self.session
@@ -73,8 +88,8 @@ class TestProtocolsBFD(unittest.TestCase):
         # Check for running process
         self.assertTrue(process_named_running(PROCESS_NAME))
 
-    def test_bfd_simple(self):
-        for peer, peer_config in neighbor_config.items():
+    def test_bfd_peer(self):
+        for peer, peer_config in peers.items():
             if 'echo_mode' in peer_config:
                 self.session.set(base_path + ['peer', peer, 'echo-mode'])
             if 'intv_echo' in peer_config:
@@ -99,7 +114,7 @@ class TestProtocolsBFD(unittest.TestCase):
 
         # Verify FRR bgpd configuration
         frrconfig = getFRRconfig()
-        for peer, peer_config in neighbor_config.items():
+        for peer, peer_config in peers.items():
             tmp = f'peer {peer}'
             if 'multihop' in peer_config:
                 tmp += f' multihop'
@@ -124,5 +139,43 @@ class TestProtocolsBFD(unittest.TestCase):
             if 'shutdown' not in peer_config:
                 self.assertIn(f' no shutdown', peerconfig)
 
+    def test_bfd_profile(self):
+        peer = '192.0.2.10'
+
+        for profile, profile_config in profiles.items():
+            if 'echo_mode' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'echo-mode'])
+            if 'intv_echo' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'interval', 'echo-interval', profile_config["intv_echo"]])
+            if 'intv_mult' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'interval', 'multiplier', profile_config["intv_mult"]])
+            if 'intv_rx' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'interval', 'receive', profile_config["intv_rx"]])
+            if 'intv_tx' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'interval', 'transmit', profile_config["intv_tx"]])
+            if 'shutdown' in profile_config:
+                self.session.set(base_path + ['profile', profile, 'shutdown'])
+
+        self.session.set(base_path + ['peer', peer, 'profile', list(profiles)[0]])
+
+        # commit changes
+        self.session.commit()
+
+        # Verify FRR bgpd configuration
+        for profile, profile_config in profiles.items():
+            config = getBFDProfileconfig(f'profile {profile}')
+            if 'echo_mode' in profile_config:
+                self.assertIn(f' echo-mode', config)
+            if 'intv_echo' in profile_config:
+                self.assertIn(f' echo-interval {profile_config["intv_echo"]}', config)
+            if 'intv_mult' in profile_config:
+                self.assertIn(f' detect-multiplier {profile_config["intv_mult"]}', config)
+            if 'intv_rx' in profile_config:
+                self.assertIn(f' receive-interval {profile_config["intv_rx"]}', config)
+            if 'intv_tx' in profile_config:
+                self.assertIn(f' transmit-interval {profile_config["intv_tx"]}', config)
+            if 'shutdown' not in profile_config:
+                self.assertIn(f' no shutdown', config)
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/src/conf_mode/protocols_bfd.py b/src/conf_mode/protocols_bfd.py
index d1e551cad..a43eed504 100755
--- a/src/conf_mode/protocols_bfd.py
+++ b/src/conf_mode/protocols_bfd.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2019-2020 VyOS maintainers and contributors
+# Copyright (C) 2019-2021 VyOS maintainers and contributors
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 or later as
@@ -17,191 +17,97 @@
 import os
 
 from sys import exit
-from copy import deepcopy
 
 from vyos.config import Config
+from vyos.configdict import dict_merge
 from vyos.template import is_ipv6
-from vyos.template import render
+from vyos.template import render_to_string
 from vyos.util import call
 from vyos.validate import is_ipv6_link_local
+from vyos.xml import defaults
 from vyos import ConfigError
+from vyos import frr
 from vyos import airbag
 airbag.enable()
 
-config_file = r'/tmp/bfd.frr'
-
-default_config_data = {
-    'new_peers': [],
-    'old_peers' : []
-}
-
-# get configuration for BFD peer from proposed or effective configuration
-def get_bfd_peer_config(peer, conf_mode="proposed"):
-    conf = Config()
-    conf.set_level('protocols bfd peer {0}'.format(peer))
-
-    bfd_peer = {
-        'remote': peer,
-        'shutdown': False,
-        'src_if': '',
-        'src_addr': '',
-        'multiplier': '3',
-        'rx_interval': '300',
-        'tx_interval': '300',
-        'multihop': False,
-        'echo_interval': '',
-        'echo_mode': False,
-    }
-
-    # Check if individual peer is disabled
-    if conf_mode == "effective" and conf.exists_effective('shutdown'):
-        bfd_peer['shutdown'] = True
-    if conf_mode == "proposed" and conf.exists('shutdown'):
-        bfd_peer['shutdown'] = True
-
-    # Check if peer has a local source interface configured
-    if conf_mode == "effective" and conf.exists_effective('source interface'):
-        bfd_peer['src_if'] = conf.return_effective_value('source interface')
-    if conf_mode == "proposed" and conf.exists('source interface'):
-        bfd_peer['src_if'] = conf.return_value('source interface')
-
-    # Check if peer has a local source address configured - this is mandatory for IPv6
-    if conf_mode == "effective" and conf.exists_effective('source address'):
-        bfd_peer['src_addr'] = conf.return_effective_value('source address')
-    if conf_mode == "proposed" and conf.exists('source address'):
-        bfd_peer['src_addr'] = conf.return_value('source address')
-
-    # Tell BFD daemon that we should expect packets with TTL less than 254
-    # (because it will take more than one hop) and to listen on the multihop
-    # port (4784)
-    if conf_mode == "effective" and conf.exists_effective('multihop'):
-        bfd_peer['multihop'] = True
-    if conf_mode == "proposed" and conf.exists('multihop'):
-        bfd_peer['multihop'] = True
-
-    # Configures the minimum interval that this system is capable of receiving
-    # control packets. The default value is 300 milliseconds.
-    if conf_mode == "effective" and conf.exists_effective('interval receive'):
-        bfd_peer['rx_interval'] = conf.return_effective_value('interval receive')
-    if conf_mode == "proposed" and conf.exists('interval receive'):
-        bfd_peer['rx_interval'] = conf.return_value('interval receive')
-
-    # The minimum transmission interval (less jitter) that this system wants
-    # to use to send BFD control packets.
-    if conf_mode == "effective" and conf.exists_effective('interval transmit'):
-        bfd_peer['tx_interval'] = conf.return_effective_value('interval transmit')
-    if conf_mode == "proposed" and conf.exists('interval transmit'):
-        bfd_peer['tx_interval'] = conf.return_value('interval transmit')
-
-    # Configures the detection multiplier to determine packet loss. The remote
-    # transmission interval will be multiplied by this value to determine the
-    # connection loss detection timer. The default value is 3.
-    if conf_mode == "effective" and conf.exists_effective('interval multiplier'):
-        bfd_peer['multiplier'] = conf.return_effective_value('interval multiplier')
-    if conf_mode == "proposed" and conf.exists('interval multiplier'):
-        bfd_peer['multiplier'] = conf.return_value('interval multiplier')
-
-    # Configures the minimal echo receive transmission interval that this system is capable of handling
-    if conf_mode == "effective" and conf.exists_effective('interval echo-interval'):
-        bfd_peer['echo_interval'] = conf.return_effective_value('interval echo-interval')
-    if conf_mode == "proposed" and conf.exists('interval echo-interval'):
-        bfd_peer['echo_interval'] = conf.return_value('interval echo-interval')
-
-    # Enables or disables the echo transmission mode
-    if conf_mode == "effective" and conf.exists_effective('echo-mode'):
-        bfd_peer['echo_mode'] = True
-    if conf_mode == "proposed" and conf.exists('echo-mode'):
-        bfd_peer['echo_mode'] = True
-
-    return bfd_peer
-
-def get_config():
-    bfd = deepcopy(default_config_data)
-    conf = Config()
-    if not (conf.exists('protocols bfd') or conf.exists_effective('protocols bfd')):
-        return None
+def get_config(config=None):
+    if config:
+        conf = config
     else:
-        conf.set_level('protocols bfd')
-
-    # as we have to use vtysh to talk to FRR we also need to know
-    # which peers are gone due to a config removal - thus we read in
-    # all peers (active or to delete)
-    for peer in conf.list_effective_nodes('peer'):
-        bfd['old_peers'].append(get_bfd_peer_config(peer, "effective"))
-
-    for peer in conf.list_nodes('peer'):
-        bfd['new_peers'].append(get_bfd_peer_config(peer))
-
-    # find deleted peers
-    set_new_peers = set(conf.list_nodes('peer'))
-    set_old_peers = set(conf.list_effective_nodes('peer'))
-    bfd['deleted_peers'] = set_old_peers - set_new_peers
+        conf = Config()
+    base = ['protocols', 'bfd']
+    bfd = conf.get_config_dict(base, get_first_key=True)
+
+    # Bail out early if configuration tree does not exist
+    if not conf.exists(base):
+        return bfd
+
+    # We have gathered the dict representation of the CLI, but there are
+    # default options which we need to update into the dictionary retrived.
+    # XXX: T2665: we currently have no nice way for defaults under tag
+    # nodes, thus we load the defaults "by hand"
+    default_values = defaults(base + ['peer'])
+    if 'peer' in bfd:
+        for peer in bfd['peer']:
+            bfd['peer'][peer] = dict_merge(default_values, bfd['peer'][peer])
+
+    if 'profile' in bfd:
+        for profile in bfd['profile']:
+            bfd['profile'][profile] = dict_merge(default_values, bfd['profile'][profile])
 
     return bfd
 
 def verify(bfd):
-    if bfd is None:
+    if not bfd:
         return None
 
-    # some variables to use later
-    conf = Config()
-
-    for peer in bfd['new_peers']:
-        # IPv6 link local peers require an explicit local address/interface
-        if is_ipv6_link_local(peer['remote']):
-            if not (peer['src_if'] and peer['src_addr']):
-                raise ConfigError('BFD IPv6 link-local peers require explicit local address and interface setting')
-
-        # IPv6 peers require an explicit local address
-        if is_ipv6(peer['remote']):
-            if not peer['src_addr']:
-                raise ConfigError('BFD IPv6 peers require explicit local address setting')
-
-        # multihop require source address
-        if peer['multihop'] and not peer['src_addr']:
-            raise ConfigError('Multihop require source address')
-
-        # multihop and echo-mode cannot be used together
-        if peer['multihop'] and peer['echo_mode']:
-            raise ConfigError('Multihop and echo-mode cannot be used together')
-
-        # multihop doesn't accept interface names
-        if peer['multihop'] and peer['src_if']:
-            raise ConfigError('Multihop and source interface cannot be used together')
-
-        # echo interval can be configured only with enabled echo-mode
-        if peer['echo_interval'] != '' and not peer['echo_mode']:
-            raise ConfigError('echo-interval can be configured only with enabled echo-mode')
-
-    # check if we deleted peers are not used in configuration
-    if conf.exists('protocols bgp'):
-        bgp_as = conf.list_nodes('protocols bgp')[0]
-
-        # check BGP neighbors
-        for peer in bfd['deleted_peers']:
-            if conf.exists('protocols bgp {0} neighbor {1} bfd'.format(bgp_as, peer)):
-                raise ConfigError('Cannot delete BFD peer {0}: it is used in BGP configuration'.format(peer))
-            if conf.exists('protocols bgp {0} neighbor {1} peer-group'.format(bgp_as, peer)):
-                peer_group = conf.return_value('protocols bgp {0} neighbor {1} peer-group'.format(bgp_as, peer))
-                if conf.exists('protocols bgp {0} peer-group {1} bfd'.format(bgp_as, peer_group)):
-                    raise ConfigError('Cannot delete BFD peer {0}: it belongs to BGP peer-group {1} with enabled BFD'.format(peer, peer_group))
+    if 'peer' in bfd:
+        for peer, peer_config in bfd['peer'].items():
+            # IPv6 link local peers require an explicit local address/interface
+            if is_ipv6_link_local(peer):
+                if 'source' not in peer_config or len(peer_config['source'] < 2):
+                    raise ConfigError('BFD IPv6 link-local peers require explicit local address and interface setting')
+
+            # IPv6 peers require an explicit local address
+            if is_ipv6(peer):
+                if 'source' not in peer_config or 'address' not in peer_config['source']:
+                    raise ConfigError('BFD IPv6 peers require explicit local address setting')
+
+            if 'multihop' in peer_config:
+                # multihop require source address
+                if 'source' not in peer_config or 'address' not in peer_config['source']:
+                    raise ConfigError('BFD multihop require source address')
+
+                # multihop and echo-mode cannot be used together
+                if 'echo_mode' in peer_config:
+                    raise ConfigError('Multihop and echo-mode cannot be used together')
+
+                # multihop doesn't accept interface names
+                if 'source' in peer_config and 'interface' in peer_config['source']:
+                    raise ConfigError('Multihop and source interface cannot be used together')
 
     return None
 
 def generate(bfd):
-    if bfd is None:
+    if not bfd:
+        bfd['new_frr_config'] = ''
         return None
 
-    render(config_file, 'frr/bfd.frr.tmpl', bfd)
-    return None
+    bfd['new_frr_config'] = render_to_string('frr/bfd.frr.tmpl', bfd)
 
 def apply(bfd):
-    if bfd is None:
-        return None
-
-    call("vtysh -d bfdd -f " + config_file)
-    if os.path.exists(config_file):
-        os.remove(config_file)
+    # Save original configuration prior to starting any commit actions
+    frr_cfg = frr.FRRConfig()
+    frr_cfg.load_configuration()
+    frr_cfg.modify_section('^bfd', '')
+    frr_cfg.add_before(r'(ip prefix-list .*|route-map .*|line vty)', bfd['new_frr_config'])
+    frr_cfg.commit_configuration()
+
+    # If FRR config is blank, rerun the blank commit x times due to frr-reload
+    # behavior/bug not properly clearing out on one commit.
+    if bfd['new_frr_config'] == '':
+        for a in range(5):
+            frr_cfg.commit_configuration()
 
     return None