docs/user-guide/bgpcep-guide/bgp/bgp-user-guide-bgp-peering.rst

   1 .. _bgp-user-guide-bgp-peering:
   2
   3 BGP Peering
   4 ===========
   5 To exchange routing information between two BGP systems (peers), it is required to configure a peering on both BGP speakers first.
   6 This mean that each BGP speaker has a white list of neighbors, representing remote peers, with which the peering is allowed.
   7 The TCP connection is established between two peers and they exchange messages to open and confirm the connection parameters followed by routes exchange.
   8
   9 Here is a sample basic neighbor configuration:
  10
  11 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
  12
  13 **Method:** ``POST``
  14
  15 **Content-Type:** ``application/xml``
  16
  17 **Request Body:**
  18
  19 .. code-block:: xml
  20    :linenos:
  21    :emphasize-lines: 2,5,6,11,12,17,19
  22
  23    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
  24        <neighbor-address>192.0.2.1</neighbor-address>
  25        <timers>
  26            <config>
  27                <hold-time>90</hold-time>
  28                <connect-retry>10</connect-retry>
  29            </config>
  30        </timers>
  31        <transport>
  32            <config>
  33                <remote-port>179</remote-port>
  34                <passive-mode>false</passive-mode>
  35                <!--<local-address>192.0.2.5</local-address>-->
  36            </config>
  37        </transport>
  38        <config>
  39            <peer-type>INTERNAL</peer-type>
  40        </config>
  41        <afi-safis>
  42            ...
  43        </afi-safis>
  44    </neighbor>
  45
  46 @line 2: IP address of the remote BGP peer. Also serves as an unique identifier of a neighbor in a list of neighbors.
  47
  48 @line 5: Proposed number of seconds for value of the Hold Timer. Default value is **90**.
  49
  50 @line 6: Time interval in seconds between attempts to establish session with the peer. Effective in active mode only. Default value is **30**.
  51
  52 @line 11: Remote port number to which the local BGP is connecting. Effective in active mode only. Default value **179**.
  53
  54 @line 12: Wait for peers to issue requests to open a BGP session, rather than initiating sessions from the local router. Default value is **false**.
  55
  56 @line 13: Optional Local IP (either IPv4 or IPv6) address used to establish connections to the remote peer. Effective in active mode only.
  57
  58 @line 17: Explicitly designate the peer as internal or external. Default value is **INTERNAL**.
  59
  60 @line 19: Enable families.
  61
  62 -----
  63
  64 Once the remote peer is connected and it advertised routes to local BGP system, routes are stored in peer's RIBs.
  65 The RIBs can be checked via REST:
  66
  67 **URL:** ``/restconf/operational/bgp-rib:bgp-rib/rib/bgp-example/peer/bgp:%2F%2F192.0.2.1``
  68
  69 **Method:** ``GET``
  70
  71 **Response Body:**
  72
  73 .. code-block:: xml
  74    :linenos:
  75    :emphasize-lines: 8,13,35,40,62,66
  76
  77    <peer xmlns="urn:opendaylight:params:xml:ns:yang:bgp-rib">
  78        <peer-id>bgp://192.0.2.1</peer-id>
  79        <supported-tables>
  80            <afi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:ipv4-address-family</afi>
  81            <safi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:unicast-subsequent-address-family</safi>
  82        </supported-tables>
  83        <peer-role>ibgp</peer-role>
  84        <adj-rib-in>
  85            <tables>
  86                <afi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:ipv4-address-family</afi>
  87                <safi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:unicast-subsequent-address-family</safi>
  88                <ipv4-routes xmlns="urn:opendaylight:params:xml:ns:yang:bgp-inet">
  89                    <ipv4-route>
  90                        <path-id>0</path-id>
  91                        <prefix>10.0.0.10/32</prefix>
  92                        <attributes>
  93                            <as-path></as-path>
  94                            <origin>
  95                                <value>igp</value>
  96                            </origin>
  97                            <local-pref>
  98                                <pref>100</pref>
  99                            </local-pref>
 100                            <ipv4-next-hop>
 101                                <global>10.10.1.1</global>
 102                            </ipv4-next-hop>
 103                        </attributes>
 104                    </ipv4-route>
 105                </ipv4-routes>
 106                <attributes>
 107                    <uptodate>true</uptodate>
 108                </attributes>
 109            </tables>
 110        </adj-rib-in>
 111        <effective-rib-in>
 112            <tables>
 113                <afi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:ipv4-address-family</afi>
 114                <safi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:unicast-subsequent-address-family</safi>
 115                <ipv4-routes xmlns="urn:opendaylight:params:xml:ns:yang:bgp-inet">
 116                    <ipv4-route>
 117                        <path-id>0</path-id>
 118                        <prefix>10.0.0.10/32</prefix>
 119                        <attributes>
 120                            <as-path></as-path>
 121                            <origin>
 122                                <value>igp</value>
 123                            </origin>
 124                            <local-pref>
 125                                <pref>100</pref>
 126                            </local-pref>
 127                            <ipv4-next-hop>
 128                                <global>10.10.1.1</global>
 129                            </ipv4-next-hop>
 130                        </attributes>
 131                    </ipv4-route>
 132                </ipv4-routes>
 133                <attributes>
 134                    <uptodate>true</uptodate>
 135                </attributes>
 136            </tables>
 137        </effective-rib-in>
 138        <adj-rib-out>
 139            <tables>
 140                <afi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:ipv4-address-family</afi>
 141                <safi xmlns:x="urn:opendaylight:params:xml:ns:yang:bgp-types">x:unicast-subsequent-address-family</safi>
 142                <ipv4-routes xmlns="urn:opendaylight:params:xml:ns:yang:bgp-inet"></ipv4-routes>
 143                <attributes></attributes>
 144            </tables>
 145        </adj-rib-out>
 146    </peer>
 147
 148 @line 8: **Adj-RIB-In** - Per-peer RIB, which contains unprocessed routes that has been advertised to local BGP speaker by the remote peer.
 149
 150 @line 13: Here is the reported route with destination *10.0.0.10/32* in Adj-RIB-In.
 151
 152 @line 35: **Effective-RIB-In** - Per-peer RIB, which contains processed routes as a result of applying inbound policy to Adj-RIB-In routes.
 153
 154 @line 40: Here is the reported route with destination *10.0.0.10/32*, same as in Adj-RIB-In, as it was not touched by import policy.
 155
 156 @line 62: **Adj-RIB-Out** - Per-peer RIB, which contains routes for advertisement to the peer by means of the local speaker's UPDATE message.
 157
 158 @line 66: The peer's Adj-RIB-Out is empty as there are no routes to be advertise from local BGP speaker.
 159
 160 -----
 161
 162 Also the same route should appeared in Loc-RIB now:
 163
 164 **URL:** ``/restconf/operational/bgp-rib:bgp-rib/rib/bgp-example/loc-rib/tables/bgp-types:ipv4-address-family/bgp-types:unicast-subsequent-address-family/ipv4-routes``
 165
 166 **Method:** ``GET``
 167
 168 **Response Body:**
 169
 170 .. code-block:: xml
 171    :linenos:
 172    :emphasize-lines: 4,6,8,11,14
 173
 174    <ipv4-routes xmlns="urn:opendaylight:params:xml:ns:yang:bgp-inet">
 175        <ipv4-route>
 176            <path-id>0</path-id>
 177            <prefix>10.0.0.10/32</prefix>
 178            <attributes>
 179                <as-path></as-path>
 180                <origin>
 181                    <value>igp</value>
 182                </origin>
 183                <local-pref>
 184                    <pref>100</pref>
 185                </local-pref>
 186                <ipv4-next-hop>
 187                    <global>10.10.1.1</global>
 188                </ipv4-next-hop>
 189            </attributes>
 190        </ipv4-route>
 191    </ipv4-routes>
 192
 193 @line 4: **Destination** - IPv4 Prefix Address.
 194
 195 @line 6: **AS_PATH** - mandatory attribute, contains a list of the autonomous system numbers through that routing information has traversed.
 196
 197 @line 8: **ORIGIN** - mandatory attribute, indicates an origin of the route - **ibgp**, **egp**, **incomplete**.
 198
 199 @line 11: **LOCAL_PREF** - indicates a degree of preference for external routes, higher value is preferred.
 200
 201 @line 14: **NEXT_HOP** - mandatory attribute, defines IP address of the router that should be used as the next hop to the destination.
 202
 203 -----
 204
 205 There are much more attributes that may be carried along with the destination:
 206
 207 **BGP-4 Path Attributes**
 208
 209 * **MULTI_EXIT_DISC** (MED)
 210    Optional attribute, to be used to discriminate among multiple exit/entry points on external links, lower number is preferred.
 211
 212    .. code-block:: xml
 213
 214       <multi-exit-disc>
 215        <med>0</med>
 216       </multi-exit-disc>
 217
 218
 219 * **ATOMIC_AGGREGATE**
 220    Indicates whether AS_SET was excluded from AS_PATH due to routes aggregation.
 221
 222    .. code-block:: xml
 223
 224       <atomic-aggregate/>
 225
 226 * **AGGREGATOR**
 227    Optional attribute, contains AS number and IP address of a BGP speaker which performed routes aggregation.
 228
 229    .. code-block:: xml
 230
 231       <aggregator>
 232           <as-number>65000</as-number>
 233           <network-address>192.0.2.2</network-address>
 234       </aggregator>
 235
 236 * **Unrecognised**
 237    Optional attribute, used to store optional attributes, unrecognized by a local BGP speaker.
 238
 239    .. code-block:: xml
 240
 241       <unrecognized-attributes>
 242           <partial>true</partial>
 243           <transitive>true</transitive>
 244           <type>101</type>
 245           <value>0101010101010101</value>
 246       </unrecognized-attributes>
 247
 248 **Route Reflector Attributes**
 249
 250 * **ORIGINATOR_ID**
 251    Optional attribute, carries BGP Identifier of the originator of the route.
 252
 253    .. code-block:: xml
 254
 255       <originator-id>
 256           <originator>41.41.41.41</originator>
 257       </originator-id>
 258
 259 * **CLUSTER_LIST**
 260    Optional attribute, contains a list of CLUSTER_ID values representing the path that the route has traversed.
 261
 262    .. code-block:: xml
 263
 264       <cluster-id>
 265           <cluster>40.40.40.40</cluster>
 266       </cluster-id>
 267
 268 * **Communities**
 269    Optional attribute, may be used for policy routing.
 270
 271    .. code-block:: xml
 272
 273       <communities>
 274           <as-number>65000</as-number>
 275           <semantics>30740</semantics>
 276       </communities>
 277
 278 **Extended Communities**
 279
 280 * **Route Target**
 281    Identifies one or more routers that may receive a route.
 282
 283    .. code-block:: xml
 284
 285       <extended-communities>
 286           <transitive>true</transitive>
 287           <route-target-ipv4>
 288               <global-administrator>192.0.2.2</global-administrator>
 289               <local-administrator>123</local-administrator>
 290           </route-target-ipv4>
 291       </extended-communities>
 292       <extended-communities>
 293           <transitive>true</transitive>
 294           <as-4-route-target-extended-community>
 295                   <as-4-specific-common>
 296                   <as-number>65000</as-number>
 297                   <local-administrator>123</local-administrator>
 298               </as-4-specific-common>
 299           </as-4-route-target-extended-community>
 300       </extended-communities>
 301
 302
 303 * **Route Origin**
 304    Identifies one or more routers that injected a route.
 305
 306    .. code-block:: xml
 307
 308       <extended-communities>
 309           <transitive>true</transitive>
 310           <route-origin-ipv4>
 311               <global-administrator>192.0.2.2</global-administrator>
 312               <local-administrator>123</local-administrator>
 313           </route-origin-ipv4>
 314       </extended-communities>
 315       <extended-communities>
 316           <transitive>true</transitive>
 317           <as-4-route-origin-extended-community>
 318               <as-4-specific-common>
 319                   <as-number>65000</as-number>
 320                   <local-administrator>123</local-administrator>
 321               </as-4-origin-common>
 322           </as-4-route-target-extended-community>
 323       </extended-communities>
 324
 325
 326 * **Link Bandwidth**
 327    Carries the cost to reach external neighbor.
 328
 329    .. code-block:: xml
 330
 331       <extended-communities>
 332           <transitive>true</transitive>
 333           <link-bandwidth-extended-community>
 334               <bandwidth>BH9CQAA=</bandwidth>
 335           </link-bandwidth-extended-community>
 336       </extended-communities>
 337
 338 * **AIGP**
 339    Optional attribute, carries accumulated IGP metric.
 340
 341    .. code-block:: xml
 342
 343       <aigp>
 344           <aigp-tlv>
 345               <metric>120</metric>
 346           </aigp-tlv>
 347       </aigp>
 348
 349
 350 .. note:: When the remote peer disconnects, it disappear from operational state of local speaker instance and advertised routes are removed too.
 351
 352 External peering configuration
 353 ''''''''''''''''''''''''''''''
 354 An example above provided configuration for internal peering only.
 355 Following configuration sample is intended for external peering:
 356
 357 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 358
 359 **Method:** ``POST``
 360
 361 **Content-Type:** ``application/xml``
 362
 363 **Request Body:**
 364
 365 .. code-block:: xml
 366    :linenos:
 367    :emphasize-lines: 5
 368
 369    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 370        <neighbor-address>192.0.2.3</neighbor-address>
 371        <config>
 372            <peer-type>EXTERNAL</peer-type>
 373            <peer-as>64999</peer-as>
 374        </config>
 375    </neighbor>
 376
 377 @line 5: AS number of the remote peer.
 378
 379 Local AS
 380 ''''''''
 381
 382 .. figure:: ./images/local-as.png
 383    :align: middle
 384    :alt: BGP eBGP with Local AS setup.
 385
 386 The local-AS feature allows a router(eBGP) to appear to be a member of a second autonomous system (AS), in addition to its real AS.
 387
 388 In updates sent from R3 to R2, the AS_SEQUENCE in the AS_PATH attribute contains "62 63". And updates sent from R2 to R3, the AS_SEQUENCE in the AS_PATH attribute contains "62 65".
 389
 390 AS 62 will be prepended to updates that are sent to and received from R3.
 391
 392 Following configuration sample is intended for external peering with Local AS:
 393
 394 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 395
 396 **Method:** ``POST``
 397
 398 **Content-Type:** ``application/xml``
 399
 400 **Request Body:**
 401
 402 .. code-block:: xml
 403    :linenos:
 404    :emphasize-lines: 5,6
 405
 406    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 407        <neighbor-address>192.0.2.3</neighbor-address>
 408        <config>
 409            <peer-type>EXTERNAL</peer-type>
 410            <peer-as>64999</peer-as>
 411            <local-as>65100</local-as>
 412        </config>
 413    </neighbor>
 414
 415 @line 5: AS number of the remote peer.
 416
 417 @line 6: Local AS number of the remote peer.
 418
 419 Route reflector configuration
 420 '''''''''''''''''''''''''''''
 421 The local BGP speaker can be configured with a specific *cluster ID*.
 422 Following example adds the cluster ID to the existing speaker instance:
 423
 424 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/global/config``
 425
 426 **Method:** ``PUT``
 427
 428 **Content-Type:** ``application/xml``
 429
 430 **Request Body:**
 431
 432 .. code-block:: xml
 433    :linenos:
 434    :emphasize-lines: 4
 435
 436    <config>
 437        <router-id>192.0.2.2</router-id>
 438        <as>65000</as>
 439        <route-reflector-cluster-id>192.0.2.1</route-reflector-cluster-id>
 440    </config>
 441
 442 @line 4: Route-reflector cluster id to use when local router is configured as a route reflector.
 443    The *router-id* is used as a default value.
 444
 445 -----
 446
 447 Following configuration sample is intended for route reflector client peering:
 448
 449 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 450
 451 **Method:** ``POST``
 452
 453 **Content-Type:** ``application/xml``
 454
 455 **Request Body:**
 456
 457 .. code-block:: xml
 458    :linenos:
 459    :emphasize-lines: 8
 460
 461    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 462        <neighbor-address>192.0.2.4</neighbor-address>
 463        <config>
 464            <peer-type>INTERNAL</peer-type>
 465        </config>
 466        <route-reflector>
 467            <config>
 468                <route-reflector-client>true</route-reflector-client>
 469            </config>
 470        </route-reflector>
 471    </neighbor>
 472
 473 @line 8: Configure the neighbor as a route reflector client. Default value is *false*.
 474
 475 Route reflector and Multiple Cluster IDs
 476 ''''''''''''''''''''''''''''''''''''''''
 477
 478 An optional non-transitive attribute called CLUSTER_LIST is modified when a route reflector reflects a prefix.
 479 For loop prevention the route reflector adds its own cluster ID to, and discards any update containing router's own cluster ID.
 480 Using multiple cluster IDs allows updates to propagate to nodes that reside in a different cluster.
 481
 482
 483 .. figure:: ./images/MultipleClustersIds.png
 484    :alt: BGP RR Multiple Cluster IDs setup.
 485
 486 Following configuration sample is intended for route reflector client peering using specific cluster id:
 487
 488 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 489
 490 **Method:** ``POST``
 491
 492 **Content-Type:** ``application/xml``
 493
 494 **Request Body:**
 495
 496 .. code-block:: xml
 497    :linenos:
 498    :emphasize-lines: 5,8
 499
 500    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 501        <neighbor-address>192.0.2.4</neighbor-address>
 502        <config>
 503            <peer-type>INTERNAL</peer-type>
 504            <route-reflector-cluster-id>192.0.2.4</route-reflector-cluster-id>
 505        </config>
 506        <route-reflector>
 507            <config>
 508                <route-reflector-client>true</route-reflector-client>
 509            </config>
 510        </route-reflector>
 511    </neighbor>
 512
 513 @line 5: Route-reflector cluster id to use for this specific neighbor when local router is configured as a route reflector.
 514
 515 @line 8: Configure the neighbor as a route reflector client. Default value is *false*.
 516
 517 MD5 authentication configuration
 518 ''''''''''''''''''''''''''''''''
 519 The OpenDaylight BGP implementation is supporting TCP MD5 for authentication.
 520 Sample configuration below shows how to set authentication password for a peer:
 521
 522 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 523
 524 **Method:** ``POST``
 525
 526 **Content-Type:** ``application/xml``
 527
 528 **Request Body:**
 529
 530 .. code-block:: xml
 531    :linenos:
 532    :emphasize-lines: 4
 533
 534    <neighbor xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 535        <neighbor-address>192.0.2.5</neighbor-address>
 536        <config>
 537            <auth-password>topsecret</auth-password>
 538        </config>
 539    </neighbor>
 540
 541 @line 4: Configures an MD5 authentication password for use with neighboring devices.
 542
 543 BGP Peer Group
 544 ''''''''''''''
 545
 546 Allows the creation of a peer group configuration that applies to all peers configured as part of the group.
 547
 548 A sample peer group configuration follows:
 549
 550 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/peer-groups``
 551
 552 **Method:** ``POST``
 553
 554 **Content-Type:** ``application/xml``
 555
 556 **Request Body:**
 557
 558 .. code-block:: xml
 559    :linenos:
 560    :emphasize-lines: 2
 561
 562    <peer-group xmlns="urn:opendaylight:params:xml:ns:yang:bgp:openconfig-extensions">
 563        <peer-group-name>internal-neighbor</peer-group-name>
 564        <config>
 565            <peer-type>INTERNAL</peer-type>
 566            <peer-as>64496</peer-as>
 567        </config>
 568        <transport>
 569            <config>
 570                <remote-port>179</remote-port>
 571                <passive-mode>true</passive-mode>
 572            </config>
 573        </transport>
 574        <timers>
 575            <config>
 576                <hold-time>180</hold-time>
 577                <connect-retry>10</connect-retry>
 578            </config>
 579        </timers>
 580        <route-reflector>
 581            <config>
 582                <route-reflector-client>false</route-reflector-client>
 583            </config>
 584        </route-reflector>
 585        <afi-safis>
 586            <afi-safi>
 587                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:IPV4-UNICAST</afi-safi-name>
 588                <!--Advertise N Paths
 589                <receive>true</receive>
 590                <send-max>0</send-max>-->
 591            </afi-safi>
 592            <afi-safi>
 593                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:IPV6-UNICAST</afi-safi-name>
 594            </afi-safi>
 595            <afi-safi>
 596                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:IPV4-LABELLED-UNICAST</afi-safi-name>
 597            </afi-safi>
 598            <afi-safi>
 599                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:IPV6-LABELLED-UNICAST</afi-safi-name>
 600            </afi-safi>
 601            <afi-safi>
 602                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:L3VPN-IPV4-UNICAST</afi-safi-name>
 603            </afi-safi>
 604            <afi-safi>
 605                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:L3VPN-IPV6-UNICAST</afi-safi-name>
 606            </afi-safi>
 607            <afi-safi>
 608                <afi-safi-name xmlns:x="http://openconfig.net/yang/bgp-types">x:L2VPN-EVPN</afi-safi-name>
 609            </afi-safi>
 610            <afi-safi>
 611                <afi-safi-name>LINKSTATE</afi-safi-name>
 612            </afi-safi>
 613            <afi-safi>
 614                <afi-safi-name>IPV4-FLOW</afi-safi-name>
 615            </afi-safi>
 616            <afi-safi>
 617                <afi-safi-name>IPV6-FLOW</afi-safi-name>
 618            </afi-safi>
 619            <afi-safi>
 620                <afi-safi-name>IPV4-L3VPN-FLOW</afi-safi-name>
 621            </afi-safi>
 622            <afi-safi>
 623                <afi-safi-name>IPV6-L3VPN-FLOW</afi-safi-name>
 624            </afi-safi>
 625        </afi-safis>
 626    </peer-group>
 627
 628 @line 2: Peer Group Identifier.
 629
 630 -----
 631
 632 A sample basic neighbor configuration using a peer group follows:
 633
 634 **URL:** ``/restconf/config/openconfig-network-instance:network-instances/network-instance/global-bgp/openconfig-network-instance:protocols/protocol/openconfig-policy-types:BGP/bgp-example/bgp/neighbors``
 635
 636 **Method:** ``POST``
 637
 638 **Content-Type:** ``application/xml``
 639
 640 **Request Body:**
 641
 642 .. code-block:: xml
 643    :linenos:
 644    :emphasize-lines: 4
 645
 646    <neighbor>
 647       <neighbor-address>192.0.2.1</neighbor-address>
 648       <config>
 649          <peer-group>/bgp/neighbors/neighbor/bgp/peer-groups/peer-group[peer-group-name="internal-neighbor"]</peer-group>
 650       </config>
 651    </neighbor>
 652
 653 @line 4: Peer group identifier.
 654
 655 .. note:: Existing neighbor configuration can be reconfigured (change configuration parameters) anytime.
 656    As a result, established connection is dropped, peer instance is recreated with a new configuration settings and connection re-established.
 657
 658 .. note:: The BGP configuration is persisted on OpendDaylight shutdown and restored after the re-start.