#!/usr/bin/env python3
#
# Copyright (C) 2020-2024 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
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .
from sys import exit
from sys import argv
from vyos.base import Warning
from vyos.config import Config
from vyos.configdict import dict_merge
from vyos.configdict import node_changed
from vyos.configverify import verify_prefix_list
from vyos.configverify import verify_route_map
from vyos.configverify import verify_vrf
from vyos.template import is_ip
from vyos.template import is_interface
from vyos.template import render_to_string
from vyos.utils.dict import dict_search
from vyos.utils.network import get_interface_vrf
from vyos.utils.network import is_addr_assigned
from vyos.utils.process import process_named_running
from vyos.utils.process import call
from vyos import ConfigError
from vyos import frr
from vyos import airbag
airbag.enable()
def get_config(config=None):
if config:
conf = config
else:
conf = Config()
vrf = None
if len(argv) > 1:
vrf = argv[1]
base_path = ['protocols', 'bgp']
# eqivalent of the C foo ? 'a' : 'b' statement
base = vrf and ['vrf', 'name', vrf, 'protocols', 'bgp'] or base_path
bgp = conf.get_config_dict(base, key_mangling=('-', '_'),
get_first_key=True, no_tag_node_value_mangle=True)
bgp['dependent_vrfs'] = conf.get_config_dict(['vrf', 'name'],
key_mangling=('-', '_'),
get_first_key=True,
no_tag_node_value_mangle=True)
# Remove per interface MPLS configuration - get a list if changed
# nodes under the interface tagNode
interfaces_removed = node_changed(conf, base + ['interface'])
if interfaces_removed:
bgp['interface_removed'] = list(interfaces_removed)
# Assign the name of our VRF context. This MUST be done before the return
# statement below, else on deletion we will delete the default instance
# instead of the VRF instance.
if vrf:
bgp.update({'vrf' : vrf})
# We can not delete the BGP VRF instance if there is a L3VNI configured
# FRR L3VNI must be deleted first otherwise we will see error:
# "FRR error: Please unconfigure l3vni 3000"
tmp = ['vrf', 'name', vrf, 'vni']
if conf.exists_effective(tmp):
bgp.update({'vni' : conf.return_effective_value(tmp)})
# We can safely delete ourself from the dependent vrf list
if vrf in bgp['dependent_vrfs']:
del bgp['dependent_vrfs'][vrf]
bgp['dependent_vrfs'].update({'default': {'protocols': {
'bgp': conf.get_config_dict(base_path, key_mangling=('-', '_'),
get_first_key=True,
no_tag_node_value_mangle=True)}}})
if not conf.exists(base):
# If bgp instance is deleted then mark it
bgp.update({'deleted' : ''})
return bgp
# We have gathered the dict representation of the CLI, but there are default
# options which we need to update into the dictionary retrived.
bgp = conf.merge_defaults(bgp, recursive=True)
# We also need some additional information from the config, prefix-lists
# and route-maps for instance. They will be used in verify().
#
# XXX: one MUST always call this without the key_mangling() option! See
# vyos.configverify.verify_common_route_maps() for more information.
tmp = conf.get_config_dict(['policy'])
# Merge policy dict into "regular" config dict
bgp = dict_merge(tmp, bgp)
return bgp
def verify_vrf_as_import(search_vrf_name: str, afi_name: str, vrfs_config: dict) -> bool:
"""
:param search_vrf_name: search vrf name in import list
:type search_vrf_name: str
:param afi_name: afi/safi name
:type afi_name: str
:param vrfs_config: configuration dependents vrfs
:type vrfs_config: dict
:return: if vrf in import list retrun true else false
:rtype: bool
"""
for vrf_name, vrf_config in vrfs_config.items():
import_list = dict_search(
f'protocols.bgp.address_family.{afi_name}.import.vrf',
vrf_config)
if import_list:
if search_vrf_name in import_list:
return True
return False
def verify_vrf_import_options(afi_config: dict) -> bool:
"""
Search if afi contains one of options
:param afi_config: afi/safi
:type afi_config: dict
:return: if vrf contains rd and route-target options return true else false
:rtype: bool
"""
options = [
f'rd.vpn.export',
f'route_target.vpn.import',
f'route_target.vpn.export',
f'route_target.vpn.both'
]
for option in options:
if dict_search(option, afi_config):
return True
return False
def verify_vrf_import(vrf_name: str, vrfs_config: dict, afi_name: str) -> bool:
"""
Verify if vrf exists and contain options
:param vrf_name: name of VRF
:type vrf_name: str
:param vrfs_config: dependent vrfs config
:type vrfs_config: dict
:param afi_name: afi/safi name
:type afi_name: str
:return: if vrf contains rd and route-target options return true else false
:rtype: bool
"""
if vrf_name != 'default':
verify_vrf({'vrf': vrf_name})
if dict_search(f'{vrf_name}.protocols.bgp.address_family.{afi_name}',
vrfs_config):
afi_config = \
vrfs_config[vrf_name]['protocols']['bgp']['address_family'][
afi_name]
if verify_vrf_import_options(afi_config):
return True
return False
def verify_vrflist_import(afi_name: str, afi_config: dict, vrfs_config: dict) -> bool:
"""
Call function to verify
if scpecific vrf contains rd and route-target
options return true else false
:param afi_name: afi/safi name
:type afi_name: str
:param afi_config: afi/safi configuration
:type afi_config: dict
:param vrfs_config: dependent vrfs config
:type vrfs_config:dict
:return: if vrf contains rd and route-target options return true else false
:rtype: bool
"""
for vrf_name in afi_config['import']['vrf']:
if verify_vrf_import(vrf_name, vrfs_config, afi_name):
return True
return False
def verify_remote_as(peer_config, bgp_config):
if 'remote_as' in peer_config:
return peer_config['remote_as']
if 'peer_group' in peer_config:
peer_group_name = peer_config['peer_group']
tmp = dict_search(f'peer_group.{peer_group_name}.remote_as', bgp_config)
if tmp: return tmp
if 'interface' in peer_config:
if 'remote_as' in peer_config['interface']:
return peer_config['interface']['remote_as']
if 'peer_group' in peer_config['interface']:
peer_group_name = peer_config['interface']['peer_group']
tmp = dict_search(f'peer_group.{peer_group_name}.remote_as', bgp_config)
if tmp: return tmp
if 'v6only' in peer_config['interface']:
if 'remote_as' in peer_config['interface']['v6only']:
return peer_config['interface']['v6only']['remote_as']
if 'peer_group' in peer_config['interface']['v6only']:
peer_group_name = peer_config['interface']['v6only']['peer_group']
tmp = dict_search(f'peer_group.{peer_group_name}.remote_as', bgp_config)
if tmp: return tmp
return None
def verify_afi(peer_config, bgp_config):
# If address_family configured under neighboor
if 'address_family' in peer_config:
return True
# If address_family configured under peer-group
# if neighbor interface configured
peer_group_name = None
if dict_search('interface.peer_group', peer_config):
peer_group_name = peer_config['interface']['peer_group']
elif dict_search('interface.v6only.peer_group', peer_config):
peer_group_name = peer_config['interface']['v6only']['peer_group']
# if neighbor IP configured.
if 'peer_group' in peer_config:
peer_group_name = peer_config['peer_group']
if peer_group_name:
tmp = dict_search(f'peer_group.{peer_group_name}.address_family', bgp_config)
if tmp: return True
return False
def verify(bgp):
if 'deleted' in bgp:
if 'vrf' in bgp:
# Cannot delete vrf if it exists in import vrf list in other vrfs
for tmp_afi in ['ipv4_unicast', 'ipv6_unicast']:
if verify_vrf_as_import(bgp['vrf'], tmp_afi, bgp['dependent_vrfs']):
raise ConfigError(f'Cannot delete VRF instance "{bgp["vrf"]}", ' \
'unconfigure "import vrf" commands!')
else:
# We are running in the default VRF context, thus we can not delete
# our main BGP instance if there are dependent BGP VRF instances.
if 'dependent_vrfs' in bgp:
for vrf, vrf_options in bgp['dependent_vrfs'].items():
if vrf != 'default':
if dict_search('protocols.bgp', vrf_options):
raise ConfigError('Cannot delete default BGP instance, ' \
'dependent VRF instance(s) exist(s)!')
if 'vni' in vrf_options:
raise ConfigError('Cannot delete default BGP instance, ' \
'dependent L3VNI exists!')
return None
if 'system_as' not in bgp:
raise ConfigError('BGP system-as number must be defined!')
# Verify BMP
if 'bmp' in bgp:
# check bmp flag "bgpd -d -F traditional --daemon -A 127.0.0.1 -M rpki -M bmp"
if not process_named_running('bgpd', 'bmp'):
raise ConfigError(
f'"bmp" flag is not found in bgpd. Configure "set system frr bmp" and restart bgp process'
)
# check bmp target
if 'target' in bgp['bmp']:
for target, target_config in bgp['bmp']['target'].items():
if 'address' not in target_config:
raise ConfigError(f'BMP target "{target}" address must be defined!')
# Verify vrf on interface and bgp section
if 'interface' in bgp:
for interface in bgp['interface']:
error_msg = f'Interface "{interface}" belongs to different VRF instance'
tmp = get_interface_vrf(interface)
if 'vrf' in bgp:
if bgp['vrf'] != tmp:
vrf = bgp['vrf']
raise ConfigError(f'{error_msg} "{vrf}"!')
elif tmp != 'default':
raise ConfigError(f'{error_msg} "{tmp}"!')
peer_groups_context = dict()
# Common verification for both peer-group and neighbor statements
for neighbor in ['neighbor', 'peer_group']:
# bail out early if there is no neighbor or peer-group statement
# this also saves one indention level
if neighbor not in bgp:
continue
for peer, peer_config in bgp[neighbor].items():
# Only regular "neighbor" statement can have a peer-group set
# Check if the configure peer-group exists
if 'peer_group' in peer_config:
peer_group = peer_config['peer_group']
if 'peer_group' not in bgp or peer_group not in bgp['peer_group']:
raise ConfigError(f'Specified peer-group "{peer_group}" for '\
f'neighbor "{neighbor}" does not exist!')
if 'remote_as' in peer_config:
is_ibgp = True
if peer_config['remote_as'] != 'internal' and \
peer_config['remote_as'] != bgp['system_as']:
is_ibgp = False
if peer_group not in peer_groups_context:
peer_groups_context[peer_group] = is_ibgp
elif peer_groups_context[peer_group] != is_ibgp:
raise ConfigError(f'Peer-group members must be '
f'all internal or all external')
if 'local_role' in peer_config:
#Ensure Local Role has only one value.
if len(peer_config['local_role']) > 1:
raise ConfigError(f'Only one local role can be specified for peer "{peer}"!')
if 'local_as' in peer_config:
if len(peer_config['local_as']) > 1:
raise ConfigError(f'Only one local-as number can be specified for peer "{peer}"!')
# Neighbor local-as override can not be the same as the local-as
# we use for this BGP instane!
asn = list(peer_config['local_as'].keys())[0]
if asn == bgp['system_as']:
raise ConfigError('Cannot have local-as same as system-as number')
# Neighbor AS specified for local-as and remote-as can not be the same
if dict_search('remote_as', peer_config) == asn and neighbor != 'peer_group':
raise ConfigError(f'Neighbor "{peer}" has local-as specified which is '\
'the same as remote-as, this is not allowed!')
# ttl-security and ebgp-multihop can't be used in the same configration
if 'ebgp_multihop' in peer_config and 'ttl_security' in peer_config:
raise ConfigError('You can not set both ebgp-multihop and ttl-security hops')
# interface and ebgp-multihop can't be used in the same configration
if 'ebgp_multihop' in peer_config and 'interface' in peer_config:
raise ConfigError(f'Ebgp-multihop can not be used with directly connected '\
f'neighbor "{peer}"')
# Check if neighbor has both override capability and strict capability match
# configured at the same time.
if 'override_capability' in peer_config and 'strict_capability_match' in peer_config:
raise ConfigError(f'Neighbor "{peer}" cannot have both override-capability and '\
'strict-capability-match configured at the same time!')
# Check spaces in the password
if 'password' in peer_config and ' ' in peer_config['password']:
raise ConfigError('Whitespace is not allowed in passwords!')
# Some checks can/must only be done on a neighbor and not a peer-group
if neighbor == 'neighbor':
# remote-as must be either set explicitly for the neighbor
# or for the entire peer-group
if not verify_remote_as(peer_config, bgp):
raise ConfigError(f'Neighbor "{peer}" remote-as must be set!')
if not verify_afi(peer_config, bgp):
Warning(f'BGP neighbor "{peer}" requires address-family!')
# Peer-group member cannot override remote-as of peer-group
if 'peer_group' in peer_config:
peer_group = peer_config['peer_group']
if 'remote_as' in peer_config and 'remote_as' in bgp['peer_group'][peer_group]:
raise ConfigError(f'Peer-group member "{peer}" cannot override remote-as of peer-group "{peer_group}"!')
if 'interface' in peer_config:
if 'peer_group' in peer_config['interface']:
peer_group = peer_config['interface']['peer_group']
if 'remote_as' in peer_config['interface'] and 'remote_as' in bgp['peer_group'][peer_group]:
raise ConfigError(f'Peer-group member "{peer}" cannot override remote-as of peer-group "{peer_group}"!')
if 'v6only' in peer_config['interface']:
if 'peer_group' in peer_config['interface']['v6only']:
peer_group = peer_config['interface']['v6only']['peer_group']
if 'remote_as' in peer_config['interface']['v6only'] and 'remote_as' in bgp['peer_group'][peer_group]:
raise ConfigError(f'Peer-group member "{peer}" cannot override remote-as of peer-group "{peer_group}"!')
# Only checks for ipv4 and ipv6 neighbors
# Check if neighbor address is assigned as system interface address
vrf = None
vrf_error_msg = f' in default VRF!'
if 'vrf' in bgp:
vrf = bgp['vrf']
vrf_error_msg = f' in VRF "{vrf}"!'
if is_ip(peer) and is_addr_assigned(peer, vrf):
raise ConfigError(f'Can not configure local address as neighbor "{peer}"{vrf_error_msg}')
elif is_interface(peer):
if 'peer_group' in peer_config:
raise ConfigError(f'peer-group must be set under the interface node of "{peer}"')
if 'remote_as' in peer_config:
raise ConfigError(f'remote-as must be set under the interface node of "{peer}"')
if 'source_interface' in peer_config['interface']:
raise ConfigError(f'"source-interface" option not allowed for neighbor "{peer}"')
# Local-AS allowed only for EBGP peers
if 'local_as' in peer_config:
remote_as = verify_remote_as(peer_config, bgp)
if remote_as == bgp['system_as']:
raise ConfigError(f'local-as configured for "{peer}", allowed only for eBGP peers!')
for afi in ['ipv4_unicast', 'ipv4_multicast', 'ipv4_labeled_unicast', 'ipv4_flowspec',
'ipv6_unicast', 'ipv6_multicast', 'ipv6_labeled_unicast', 'ipv6_flowspec',
'l2vpn_evpn']:
# Bail out early if address family is not configured
if 'address_family' not in peer_config or afi not in peer_config['address_family']:
continue
# Check if neighbor has both ipv4 unicast and ipv4 labeled unicast configured at the same time.
if 'ipv4_unicast' in peer_config['address_family'] and 'ipv4_labeled_unicast' in peer_config['address_family']:
raise ConfigError(f'Neighbor "{peer}" cannot have both ipv4-unicast and ipv4-labeled-unicast configured at the same time!')
# Check if neighbor has both ipv6 unicast and ipv6 labeled unicast configured at the same time.
if 'ipv6_unicast' in peer_config['address_family'] and 'ipv6_labeled_unicast' in peer_config['address_family']:
raise ConfigError(f'Neighbor "{peer}" cannot have both ipv6-unicast and ipv6-labeled-unicast configured at the same time!')
afi_config = peer_config['address_family'][afi]
if 'conditionally_advertise' in afi_config:
if 'advertise_map' not in afi_config['conditionally_advertise']:
raise ConfigError('Must speficy advertise-map when conditionally-advertise is in use!')
# Verify advertise-map (which is a route-map) exists
verify_route_map(afi_config['conditionally_advertise']['advertise_map'], bgp)
if ('exist_map' not in afi_config['conditionally_advertise'] and
'non_exist_map' not in afi_config['conditionally_advertise']):
raise ConfigError('Must either speficy exist-map or non-exist-map when ' \
'conditionally-advertise is in use!')
if {'exist_map', 'non_exist_map'} <= set(afi_config['conditionally_advertise']):
raise ConfigError('Can not specify both exist-map and non-exist-map for ' \
'conditionally-advertise!')
if 'exist_map' in afi_config['conditionally_advertise']:
verify_route_map(afi_config['conditionally_advertise']['exist_map'], bgp)
if 'non_exist_map' in afi_config['conditionally_advertise']:
verify_route_map(afi_config['conditionally_advertise']['non_exist_map'], bgp)
# T4332: bgp deterministic-med cannot be disabled while addpath-tx-bestpath-per-AS is in use
if 'addpath_tx_per_as' in afi_config:
if dict_search('parameters.deterministic_med', bgp) == None:
raise ConfigError('addpath-tx-per-as requires BGP deterministic-med paramtere to be set!')
# Validate if configured Prefix list exists
if 'prefix_list' in afi_config:
for tmp in ['import', 'export']:
if tmp not in afi_config['prefix_list']:
# bail out early
continue
if afi == 'ipv4_unicast':
verify_prefix_list(afi_config['prefix_list'][tmp], bgp)
elif afi == 'ipv6_unicast':
verify_prefix_list(afi_config['prefix_list'][tmp], bgp, version='6')
if 'route_map' in afi_config:
for tmp in ['import', 'export']:
if tmp in afi_config['route_map']:
verify_route_map(afi_config['route_map'][tmp], bgp)
if 'route_reflector_client' in afi_config:
peer_group_as = peer_config.get('remote_as')
if peer_group_as is None or (peer_group_as != 'internal' and peer_group_as != bgp['system_as']):
raise ConfigError('route-reflector-client only supported for iBGP peers')
else:
if 'peer_group' in peer_config:
peer_group_as = dict_search(f'peer_group.{peer_group}.remote_as', bgp)
if peer_group_as is None or (peer_group_as != 'internal' and peer_group_as != bgp['system_as']):
raise ConfigError('route-reflector-client only supported for iBGP peers')
# T5833 not all AFIs are supported for VRF
if 'vrf' in bgp and 'address_family' in peer_config:
unsupported_vrf_afi = {
'ipv4_flowspec',
'ipv6_flowspec',
'ipv4_labeled_unicast',
'ipv6_labeled_unicast',
'ipv4_vpn',
'ipv6_vpn',
}
for afi in peer_config['address_family']:
if afi in unsupported_vrf_afi:
raise ConfigError(
f"VRF is not allowed for address-family '{afi.replace('_', '-')}'"
)
# Throw an error if a peer group is not configured for allow range
for prefix in dict_search('listen.range', bgp) or []:
# we can not use dict_search() here as prefix contains dots ...
if 'peer_group' not in bgp['listen']['range'][prefix]:
raise ConfigError(f'Listen range for prefix "{prefix}" has no peer group configured.')
peer_group = bgp['listen']['range'][prefix]['peer_group']
if 'peer_group' not in bgp or peer_group not in bgp['peer_group']:
raise ConfigError(f'Peer-group "{peer_group}" for listen range "{prefix}" does not exist!')
if not verify_remote_as(bgp['listen']['range'][prefix], bgp):
raise ConfigError(f'Peer-group "{peer_group}" requires remote-as to be set!')
# Throw an error if the global administrative distance parameters aren't all filled out.
if dict_search('parameters.distance.global', bgp) != None:
for key in ['external', 'internal', 'local']:
if dict_search(f'parameters.distance.global.{key}', bgp) == None:
raise ConfigError('Missing mandatory configuration option for '\
f'global administrative distance {key}!')
# TCP keepalive requires all three parameters to be set
if dict_search('parameters.tcp_keepalive', bgp) != None:
if not {'idle', 'interval', 'probes'} <= set(bgp['parameters']['tcp_keepalive']):
raise ConfigError('TCP keepalive incomplete - idle, keepalive and probes must be set')
# Address Family specific validation
if 'address_family' in bgp:
for afi, afi_config in bgp['address_family'].items():
if 'distance' in afi_config:
# Throw an error if the address family specific administrative
# distance parameters aren't all filled out.
for key in ['external', 'internal', 'local']:
if key not in afi_config['distance']:
raise ConfigError('Missing mandatory configuration option for '\
f'{afi} administrative distance {key}!')
if afi in ['ipv4_unicast', 'ipv6_unicast']:
vrf_name = bgp['vrf'] if dict_search('vrf', bgp) else 'default'
# Verify if currant VRF contains rd and route-target options
# and does not exist in import list in other VRFs
if dict_search(f'rd.vpn.export', afi_config):
if verify_vrf_as_import(vrf_name, afi, bgp['dependent_vrfs']):
raise ConfigError(
'Command "import vrf" conflicts with "rd vpn export" command!')
if not dict_search('parameters.router_id', bgp):
Warning(f'BGP "router-id" is required when using "rd" and "route-target"!')
if dict_search('route_target.vpn.both', afi_config):
if verify_vrf_as_import(vrf_name, afi, bgp['dependent_vrfs']):
raise ConfigError(
'Command "import vrf" conflicts with "route-target vpn both" command!')
if dict_search('route_target.vpn.export', afi_config):
raise ConfigError(
'Command "route-target vpn export" conflicts '\
'with "route-target vpn both" command!')
if dict_search('route_target.vpn.import', afi_config):
raise ConfigError(
'Command "route-target vpn import" conflicts '\
'with "route-target vpn both" command!')
if dict_search('route_target.vpn.import', afi_config):
if verify_vrf_as_import(vrf_name, afi, bgp['dependent_vrfs']):
raise ConfigError(
'Command "import vrf conflicts" with "route-target vpn import" command!')
if dict_search('route_target.vpn.export', afi_config):
if verify_vrf_as_import(vrf_name, afi, bgp['dependent_vrfs']):
raise ConfigError(
'Command "import vrf" conflicts with "route-target vpn export" command!')
# Verify if VRFs in import do not contain rd
# and route-target options
if dict_search('import.vrf', afi_config) is not None:
# Verify if VRF with import does not contain rd
# and route-target options
if verify_vrf_import_options(afi_config):
raise ConfigError(
'Please unconfigure "import vrf" commands before using vpn commands in the same VRF!')
# Verify if VRFs in import list do not contain rd
# and route-target options
if verify_vrflist_import(afi, afi_config, bgp['dependent_vrfs']):
raise ConfigError(
'Please unconfigure import vrf commands before using vpn commands in dependent VRFs!')
# FRR error: please unconfigure vpn to vrf commands before
# using import vrf commands
if 'vpn' in afi_config['import'] or dict_search('export.vpn', afi_config) != None:
raise ConfigError('Please unconfigure VPN to VRF commands before '\
'using "import vrf" commands!')
# Verify that the export/import route-maps do exist
for export_import in ['export', 'import']:
tmp = dict_search(f'route_map.vpn.{export_import}', afi_config)
if tmp: verify_route_map(tmp, bgp)
# per-vrf sid and per-af sid are mutually exclusive
if 'sid' in afi_config and 'sid' in bgp:
raise ConfigError('SID per VRF and SID per address-family are mutually exclusive!')
# Checks only required for L2VPN EVPN
if afi in ['l2vpn_evpn']:
if 'vni' in afi_config:
for vni, vni_config in afi_config['vni'].items():
if 'rd' in vni_config and 'advertise_all_vni' not in afi_config:
raise ConfigError('BGP EVPN "rd" requires "advertise-all-vni" to be set!')
if 'route_target' in vni_config and 'advertise_all_vni' not in afi_config:
raise ConfigError('BGP EVPN "route-target" requires "advertise-all-vni" to be set!')
return None
def generate(bgp):
if not bgp or 'deleted' in bgp:
return None
bgp['frr_bgpd_config'] = render_to_string('frr/bgpd.frr.j2', bgp)
return None
def apply(bgp):
if 'deleted' in bgp:
# We need to ensure that the L3VNI is deleted first.
# This is not possible with old config backend
# priority bug
if {'vrf', 'vni'} <= set(bgp):
call('vtysh -c "conf t" -c "vrf {vrf}" -c "no vni {vni}"'.format(**bgp))
bgp_daemon = 'bgpd'
# Save original configuration prior to starting any commit actions
frr_cfg = frr.FRRConfig()
# Generate empty helper string which can be ammended to FRR commands, it
# will be either empty (default VRF) or contain the "vrf