BGP

Border Gateway Protocol (BGP) is an inter-domain routing protocol designed to provide loop-free routing links between organizations. BGP is designed to run over a reliable transport protocol using Port 179. BGP is used to connect a local network to an external network in order to access the Internet or to connect to other organizations.

EBGP

External Border Gateway Protocol (EBGP) runs between two BGP routers in different autonomous systems. EBGP routes received from an EBGP peer can be advertised to EBGP and IBGP peers. EBGP is used between organizations or between an organization and its Internet Service provider. When connecting to an external organization, external BGP peering sessions are created. In EBGP peers, attributes like local preference are not sent. When the route is advertised to an EBGP peer, the next hop is changed to a local router.

IBGP

Internal Border Gateway Protocol (IBGP) runs between two BGP routers in the same autonomous system. IBGP routes received from an IBGP peer cannot be advertised to another IBGP peer but can be advertised to an EBGP peer. IBGP is used within the same organization. BGP peers within the same organization exchange routing information through internal BGP peering sessions. In IBGP peers, attributes like local preference are sent. When the route is advertised to an IBGP peer, the next hop remains unchanged.

Router ID

BGP uses router ID to identify BGP-speaking peers. The BGP router ID is represented by an IPv4 address. The BGP router ID must be unique to the BGP peers in a network.

Speaker and Peer

A peer device is a BGP-speaking router that has an active TCP connection to another BGP-speaking device. BGP devices do not necessarily need to be directly connected. A BGP speaker is the local router and a peer is any other BGP-speaking network device.

When a TCP connection is established between peers, each BGP peer initially exchanges all its routes; the complete BGP routing table with the other peer. After this, only incremental updates are sent after a change in network topology or routing policy. Peers exchange special messages called keep alive messages.

Autonomous System (AS)

An autonomous system is a network controlled by a single technical administration entity. In BGP, autonomous systems are used in individual routing domains with local routing policies. Each routing domain can support multiple routing protocols. However, each routing protocol is administered separately. Other routing protocols can dynamically exchange routing information with BGP through redistribution.

Attributes

BGP has a number of complex attributes used to determine a path to a remote network. These attributes allow greater flexibility and enable a complex routing decision to ensure that the path to a remote network is the best possible path. BGP always propagates the best path to any peers. BGP attributes are carried in update packets.

Local Preference Attribute

If there are multiple exit points from the AS, the local preference attribute is used to select the exit point for a specific route. A higher local preference is always preferred.

Next-Hop Attribute

The EBGP next-hop attribute is the IP address that is used to reach the advertising router. For EBGP peers, the next-hop address is the IP address of the connection between the peers. For IBGP, the EBGP next-hop address is carried into the local AS.

Filters

A number of different filter methods control the sending and receiving of BGP updates. BGP updates can be filtered with route information as a basis, or with communities as a basis. Packets that do not match the configured filters are dropped.

Synchronization

When a BGP router receives information about a network from an IBGP neighbor, it does not use that information until a matching route is learned via an IGP or static route. This is called synchronization. It also does not advertise that route to an EBGP neighbor unless a matching route is in the routing table. It is recommended to turn off synchronization when all routers in the autonomous system use BGP.

BGP Path Selection

When a BGP speaker receives updates from multiple autonomous systems that describe different paths to the same destination, the speaker must choose the single best path for reaching that destination. When chosen, the selected path is entered into the BGP routing table and propagated to its neighbors. The decision is based on the value of attributes that the update contains and other BGP-configurable factors.

  1. If the next hop address is reachable, consider it.

  2. Prefer the largest local preference attribute.

  3. If the local preference is the same, prefer the route this local router originated.

  4. Prefer the route with the shortest AS path.

  5. If this is equal, prefer the route with the origin set to originated (through BGP); IGP is preferred to EGP, followed by incomplete.

  6. If the origin codes are the same, prefer the route with the lowest MED.

  7. If the MED is the same, prefer EBGP over IBGP.

  8. Prefer the closest path.

  9. Finally, if all paths are equal, prefer the path with lowest BGP router ID.

Timers

BGP implementation maintains different timers for Peers and Route updates.

  • The keep alive interval is the time within which keep alive messages are sent to peers.

  • The hold time is the interval following which a peer is declared inactive after not receiving a keep alive message from it.

  • The route advertisement interval is the interval between sending BGP routing updates.

  • The Connection Retry timer is the amount of time to wait before reopening a TCP connection.

  • The AS Originate Interval is the interval between two subsequent update messages for internal peers.

BGP Route Reflector

To avoid loops, an IBGP router doesn’t advertise the prefix it learned from one IBGP neighbor to another IBGP neighbor. Therefore, all the IBGP neighbors must be fully meshed with each other to learn the complete network. However, this is not practical in a large IBGP network. If there are X number of IBGP routers, then there will be X * [X-1]/2 IBGP sessions that must be established, which would be a huge administrative overhead. In this case, route reflectors are used.

Route reflectors are a way to avoid full meshing between IBGP neighbors, but still get the benefits of a full mesh. In the route reflector method, a IBGP router is selected to act as a route reflector. Other IBGP routers in the network act as route reflector clients. When a route reflector learns a prefix from one of its IBGP neighbors, the route reflector advertises the prefix to all its route reflector clients. For redundancy purposes, more than one router can be configured to act as a route reflector.

A route reflector must adhere to the rules below in advertising the routes while advertising the prefixes.

  1. A route reflector can re-advertise the prefixes it learned from non-RR IBGP neighbors, RR IBGP neighbors, and EBGP neighbors to its RR client.

  2. A route reflector should not re-advertise the prefixes it learned from a non-RR IBGP neighbor to other non-RR IBGP neighbors.

  3. A route reflector can re-advertise the prefixes it learned from RR IBGP neighbors to its non-RR IBGP neighbors.

BGP Configuration

This section explains basic BGP configuration commands. For details on FRRouting, an IP routing suite which implements BGP protocols, refer to FRRouting documentation at https://frrouting.org/.

BGP Default Configuration

Parameter

Default Value

BGP Status

Active

Synchronization

Disabled

Preference

None

Peer

None

Connection retry time

120 seconds

Hold time

180 seconds

Keep alive

60 seconds

Route Advertisement Interval

30 seconds

EBGP Multihop

Disable

AS Number

65100

Router ID

None

Figure 9. BGP Topology

Save the BGP Configuration

This section explains the steps to save the BGP configuration. The BGP routing is handled via FRR module and the configuration must be saved in two steps.

  1. Edit the /etc/config_db.json and in the DEVICE_METADATA section, delete the bgp_asn line and add the docker_routing_config_mode line as shown below. This step is needed only once.

    "DEVICE_METADATA": {

     

    "localhost": {

     

     

    "buffer_model": "traditional",

     

     

    "default_bgp_status": "up",

     

     

    "default_pfcwd_status": "disable",

     

     

    "hostname": "sonic",

     

     

    "hwsku": "sse_g3748",

     

     

    "mac": "0C:C4:7A:2E:1D:6D",

     

     

    "platform": "arm64-supermicro_sse_g3748-r0",

     

     

    "bgp_asn": "65100",

     

     

    "docker_routing_config_mode": "split",

     

     

    "type": "not-provisioned"

     

    }

    },

  2. Reboot the switch for the above change to take effect.

  3. The vtysh command invokes FRRouting mode. After configuring the BGP, the configuration must be saved in FRRouting mode and again in SONiC mode.

    Example Config:

    admin@sonic:~$ sudo -i

    root@sonic:~# vtysh

    Hello, this is FRRouting (version 7.5.1-sonic).

    Copyright 1996-2005 Kunihiro Ishiguro, et al.

    sonic# configure terminal

    sonic(config)# router bgp 65100

    sonic(config-router)# no bgp ebgp-requires-policy

    sonic(config-router)# neighbor 10.0.0.2 remote-as 65100

    sonic(config-router)# end

    sonic# write

    sonic# exit

    root@sonic:~# config save -y

Note: If the command no bgp ebgp-requires-policy is not used, then the routes may be exchanged with a BGP peer without proper policies.

Enable BGP

BGP is disabled by default. Follow the steps below to enable BGP.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-65535)>

Enable BGP and configure the AS number of the BGP Speaker.

4

End

Exit configuration mode.

Note: The no router bgp command disables BGP in the switch.

BGP Peer

Follow the steps below to configure BGP Peer.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-65535)>

Enable BGP and configure the AS number of the BGP Speaker.

4

bgp router-id <bgp router id (ip-address)>

Configure the BGP Identifier of the BGP Speaker.

5

neighbor <ip-address> remote-as <AS no (1-65535)>

Create a peer and initiate the connection to the peer.

6

neighbor <ip-address> {advertisement-interval <0-600 seconds>}

Optional: Configure the neighbor interval.

7

neighbor <ip-address> timers {keepalive <seconds> | holdtime <seconds>}

Optional: Configure the neighbor KeepAlive Time and Hold Time intervals.

8

Exit

Exit BGP Router mode.

9

End

Exit configuration mode.
Notes: 

To delete the configured values, use the no form of the respective commands:

  • no neighbor <ip-address>

  • no neighbor <ip-address> {advertisement-interval}

  • no neighbor <ip-address> timers {keepalive | holdtime}

Attributes

Follow the steps below to configure BGP Attributes.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-4294967295)>

Enable BGP and configure the AS number of the BGP Speaker.

4

bgp router-id <bgp router id (ip-address)>

Configure the BGP Identifier of the BGP Speaker.

5

neighbor <ip-address> remote-as <AS no (1-4294967295)>

Create a Peer and initiate the optional connection to the peer.

6

bgp default local-preference <local Pref Value 0-4294967295>

Optional: Configure the Default Local Preference value.

7

neighbor <ip-address> ebgp-multihop

Optional: Enable BGP to establish a connection with external peers that are not directly connected.

8

Exit

Exit BGP Router mode.

9

End

Exit configuration mode.
Notes: 

To delete the configured values, use the no form of the respective commands:

  • no bgp default local-preference

  • no neighbor <ip-address> ebgp-multihop

Network

Follow the steps below to configure the network through BGP.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-65535)>

Enable BGP and configure the AS number of the BGP Speaker.

4

no bgp ebgp-requires-policy

Disable the Require policy on EBGP.

5

address-family ipv4 unicast

Declare the neighbors with whom normal "IPv4 unicast" routes must be exchanged.

6

network <A.B.C.D> <A.B.C.D/M>

Configure the network.

  • A.B.C.D: The network number.

  • A.B.C.D/M: The IPv4 prefix.

7

exit-address-family

Exit address-family mode.

8

Exit

Exit BGP Router mode.

9

End

Exit configuration mode.
Notes: 

  • The command no network <A.B.C.D> <A.B.C.D/M> removes the configured network.

  • If the command no bgp ebgp-requires-policy is not used, then the routes may be exchanged with BGP peer without proper policies.

Redistribute Connected

Follow the steps below to redistribute connect through BGP.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-65535)>

Enable BGP and configure the AS number of the BGP Speaker.

4

no bgp ebgp-requires-policy

Disable the Require policy on EBGP.

5

address-family ipv4 unicast

Declare the neighbors with whom normal "IPv4 unicast" routes must be exchanged.

6

redistribute connected

Redistribute connected routes to internal and external BGP peers.

7

exit-address-family

Exit address-family mode.

8

Exit

Exit BGP Router mode.

9

End

Exit configuration mode.

Note: The command no redistribute connected stops the routes connected to internal and external BGP peers.

Redistribute Static

Follow the steps below to redistribute connect through BGP.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

router bgp <AS no (1-65535)>

Enable BGP and configure the AS number of the BGP Speaker.

4

no bgp ebgp-requires-policy

Disable the Require policy on EBGP.

5

address-family ipv4 unicast

Declare the neighbors with whom normal "IPv4 unicast" routes must be exchanged.

6

redistribute static

Redistribute static routes to internal and external BGP peers.

7

exit-address-family

Exit address-family mode.

8

Exit

Exit BGP Router mode.

9

End

Exit configuration mode.

Note: The command no redistribute static stops the static routes to internal and external BGP peers.

BGP Configuration Example

This section shows a sample BGP configuration.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure terminal

Enter configuration mode.

3

no route bgp < (1-4294967295) AS number>

Remove the default router (65100).

4

router bgp < (1-4294967295) AS number>

Add a new router.

5

bgp router-id <A.B.C.D>

Manually configure the router identifier. Specify router-id as a valid IPv4 or IPv6 address.

6

neighbor <A.B.C.D Neighbor address> remote-as < (1-4294967295) AS number>

Manually configure the neighbor address and remote-as value.

7

bgp default local-preference (0-4294967295)

Configure the default local preference value.

8

neighbor <A.B.C.D Neighbor address> ebgp-multihop (1-255)

Configure the ebgp-multihop value. Specify ebgp-multihop as a maximum hop count.

9

neighbor <A.B.C.D Neighbor address> timers (0-65535) connect

Configure timers.

  • timers: The Keepalive interval.

  • connect: The BGP connect timer.

10

neighbor <A.B.C.D Neighbor address> advertisement-interval (0-600)

Configure the advertisement interval.

  • advertisement-interval: A time in seconds.

11

End

Exit configuration mode in FRRouting.

12

show ip bgp neighbors

Display the configured BGP neighbor.

13

show ip bgp summary

Display the configured BGP details.

14

exit

Exit FRRouting.

15

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

The following example shows commands used to configure and display BGP.

  • Switch A (SONiC) input:

    admin@sonic: ~$ sudo vtysh

    Hello, this is FRRouting (version 7.5.1-sonic).

    Copyright 1996-2005 Kunihiro Ishiguro, et al.

    sonic# configure terminal

    sonic(config)# no router bgp 65100

    sonic(config)# router bgp 200

    sonic(config-router) # bgp router-id 192.168.100.1

    sonic(config-router) # no bgp ebgp-requires-policy

    sonic(config-router) # neighbor 192.168.100.2 remote-as 300

    sonic(config-router) # bgp default local-preference 50

    sonic(config-router) # neighbor 192.168.100.2 ebgp-multihop

    sonic(config-router) # neighbor 192.168.100.2 timers 10 10

    sonic(config-router) # neighbor 192.168.100.2 advertisement-interval 5

    sonic(config-router) # end

    sonic# exit

    admin@sonic: ~$

  • Switch B input:

    admin@sonic: ~$ sudo vtysh

    Hello, this is FRRouting (version 7.5.1-sonic).

    Copyright 1996-2005 Kunihiro Ishiguro, et al.

    sonic# configure terminal

    sonic(config)# no router bgp 65100

    sonic(config)# router bgp 300

    sonic(config-router) # bgp router-id 192.168.100.2

    sonic(config-router) # no bgp ebgp-requires-policy

    sonic(config-router) # neighbor 192.168.100.1 remote-as 200

    sonic(config-router) # bgp default local-preference 50

    sonic(config-router) # neighbor 192.168.100.1 ebgp-multihop

    sonic(config-router) # neighbor 192.168.100.1 timers 10 10

    sonic(config-router) # neighbor 192.168.100.1 advertisement-interval 5

    sonic(config-router) # end

    sonic# exit

    admin@sonic: ~$

  • Switch A output:

    admin@sonic: ~$ show ip bgp neighbors

    BGP neighbor is 192.168.100.2, remote AS 300, local AS 200, external link

     

    BGP version 4, remote router ID 192.168.100.2, local router ID 192.168.100.1

     

    BGP state = Established, up for 00:02:51

     

    Last read 00:00:05, Last write 00:00:21

     

    Hold time is 10, keepalive interval is 3 seconds

     

    Configured hold time is 10, keepalive interval is 3 seconds

     

    Neighbor capabilities:

     

     

    4 Byte AS: advertised and received

     

     

    AddPath:

     

     

     

    IPv4 Unicast: RX advertised IPv4 Unicast

     

     

    Route refresh: advertised and received(new)

     

     

    Address Family IPv4 Unicast: advertised and received

     

     

    Hostname Capability: advertised (name: sonic, domain name: n/a) not received

     

     

    Graceful Restart Capability: advertised and received

     

     

     

    Remote Restart timer is 120 seconds

     

     

     

    Address families by peer:

     

     

     

     

    IPv4 Unicast(preserved)

     

    Graceful restart information:

     

     

    End-of-RIB send: IPv4 Unicast

     

     

    End-of-RIB received: IPv4 Unicast

     

     

    Local GR Mode: Helper*

     

     

    Remote GR Mode: Restart

     

     

    R bit: False

     

     

    Timers:

     

     

     

    Configured Restart Time(sec): 120

     

     

     

    Received Restart Time(sec): 120

     

     

    IPv4 Unicast:

     

     

     

    F bit: True

     

     

     

    End-of-RIB sent: Yes

     

     

     

    End-of-RIB sent after update: Yes

     

     

     

    End-of-RIB received: Yes

     

     

     

    Timers:

     

     

     

     

    Configured Stale Path Time(sec): 360

     

    Message statistics:

     

     

    Inq depth is 0

     

     

    Outq depth is 0

     

     

     

    		  

    Sent

    Rcvd

     

     

     

     

     

     

     

    Opens:

    3

    3

     

     

     

     

     

     

     

    Notifications:

    6

    0

     

     

     

     

     

     

     

    Updates

    2

    2

     

     

     

     

     

     

     

    Keepalives:

    7

    17

     

     

     

     

     

     

     

    Route Refresh:

    1

    0

     

     

     

     

     

     

     

    Capability:

    0

    0

     

     

     

     

     

     

     

    Total:

    19

    22

     

     

     

     

     

     

     

    Minimum time between advertisement runs is 5 seconds

     

    For address family: IPv4 Unicast

     

     

    Update group 3, subgroup 2

     

     

    Packet Queue length 0

     

     

    Community attribute sent to this neighbor(all)

     

     

    Inbound updates discarded due to missing policy

     

     

    Outbound updates discarded due to missing policy

     

     

    0 accepted prefixes

     

     

     

     

     

     

     

     

     

     

     

     

     

    Connections established 2; dropped 1

     

     

    Last reset 00:02:55, No AFI/SAFI activated for peer

     

     

    Message received that caused BGP to send a NOTIFICATION:

     

     

     

    FFFFFFFF

    FFFFFFFF

    FFFFFFFF

    FFFFFFFF

     

     

     

    00350104

    012C005A

    C0A86402

    18021601

     

     

     

    04000100

    01020040

    06005A00

    01018041

     

     

     

    04000001

    2C

     

     

     

     

    External BGP neighbor may be up to 255 hops away.

    Local host: 192.168.100.1, Local port: 179

    Foreign host: 192.168.100.2, Foreign port: 38373

    Nexthop: 192.168.100.1

    Nexthop global: fe80::ec4:7aff:fe2e:1635

    Nexthop local: fe80::ec4:7aff:fe2e:1635

    BGP connection: shared network

    BGP Connect Retry Timer in Seconds: 120

    Estimated round trip time: 2 ms

    Read thread: on Write thread: on FD used: 25

    admin@sonic: ~$

    admin@sonic: ~$ sudo vtysh

    Hello, this is FRRouting (version 7.5.1-sonic).

    Copyright 1996-2005 Kunihiro Ishiguro, et al.

     

     

     

     

     

     

     

     

     

     

     

    sonic# show bgp summary

    IPv4 Unicast Summary:

    BGP router identifier 192.168.100.1, local AS number 200 vrf-id 0

    BGP table version 0

    RIB entries 0, using 0 bytes of memory

    Peers 1, using 21 KiB of memory

     

    		                    

    Neighbor

    V

    AS

    MsgRcvd

    MsgSent

    TblVer

    InQ

    OutQ

    Up/Down

    State/PfxRcd

    PfxSnt

    192.168.100.2

    4

    300

    69

    36

    0

    0

    0

    00:11:24

    (Policy)

    (Policy)

     

     

     

     

     

     

     

     

     

     

     

    Total number of neighbors 1

    sonic#

  • Switch B output:

    admin@sonic: ~$ show ip bgp neighbors

    BGP neighbor is 192.168.100.1, remote AS 200, local AS 300, external link

     

    BGP version 4, remote router ID 192.168.100.1, local router ID 192.168.100.2

     

    BGP state = Established, up for 00:03:51

     

    Last read 00:00:05, Last write 00:00:21

     

    Hold time is 10, keepalive interval is 3 seconds

     

    Configured hold time is 10, keepalive interval is 3 seconds

     

    Neighbor capabilities:

     

     

    4 Byte AS: advertised and received

     

     

    AddPath:

     

     

     

    IPv4 Unicast: RX advertised IPv4 Unicast

     

     

    Route refresh: advertised and received(new)

     

     

    Address Family IPv4 Unicast: advertised and received

     

     

    Hostname Capability: advertised (name: sonic, domain name: n/a) not received

     

     

    Graceful Restart Capability: advertised and received

     

     

     

    Remote Restart timer is 120 seconds

     

     

     

    Address families by peer:

     

     

     

     

    IPv4 Unicast(preserved)

     

    Graceful restart information:

     

     

    End-of-RIB send: IPv4 Unicast

     

     

    End-of-RIB received: IPv4 Unicast

     

     

    Local GR Mode: Helper*

     

     

    Remote GR Mode: Restart

     

     

    R bit: False

     

     

    Timers:

     

     

     

    Configured Restart Time(sec): 120

     

     

     

    Received Restart Time(sec): 120

     

     

    IPv4 Unicast:

     

     

     

    F bit: True

     

     

     

    End-of-RIB sent: Yes

     

     

     

    End-of-RIB sent after update: Yes

     

     

     

    End-of-RIB received: Yes

     

     

     

    Timers:

     

     

     

     

    Configured Stale Path Time(sec): 360

     

    Message statistics:

     

     

    Inq depth is 0

     

     

    Outq depth is 0

     

     

     

    		  

    Sent

    Rcvd

     

     

     

     

     

     

     

    Opens:

    5

    5

     

     

     

     

     

     

     

    Notifications:

    5

    6

     

     

     

     

     

     

     

    Updates

    2

    2

     

     

     

     

     

     

     

    Keepalives:

    17

    15

     

     

     

     

     

     

     

    Route Refresh:

    1

    0

     

     

     

     

     

     

     

    Capability:

    0

    0

     

     

     

     

     

     

     

    Total:

    30

    28

     

     

     

     

     

     

     

    Minimum time between advertisement runs is 5 seconds

     

    For address family: IPv4 Unicast

     

     

    Update group 3, subgroup 2

     

     

    Packet Queue length 0

     

     

    Community attribute sent to this neighbor(all)

     

     

    Inbound updates discarded due to missing policy

     

     

    Outbound updates discarded due to missing policy

     

     

    0 accepted prefixes

     

     

     

     

     

     

     

     

     

     

     

     

     

    Connections established 2; dropped 1

     

     

    Last reset 00:02:55, No AFI/SAFI activated for peer

     

     

    Message received that caused BGP to send a NOTIFICATION:

     

     

     

    FFFFFFFF

    FFFFFFFF

    FFFFFFFF

    FFFFFFFF

     

     

     

    00350104

    012C005A

    C0A86402

    18021601

     

     

     

    04000100

    01020040

    06005A00

    01018041

     

     

     

    04000001

    2C

     

     

     

     

    External BGP neighbor may be up to 255 hops away.

    Local host: 192.168.100.2, Local port: 179

    Foreign host: 192.168.100.1, Foreign port: 38373

    Nexthop: 192.168.100.2

    Nexthop global: fe80::ec4:7ade:fe2f:8675

    Nexthop local: fe80::ec4:7ade:fe2f:8675

    BGP connection: shared network

    BGP Connect Retry Timer in Seconds: 120

    Estimated round trip time: 2 ms

    Read thread: on Write thread: on FD used: 25

    admin@sonic: ~$

    admin@sonic: ~$ sudo vtysh

    Hello, this is FRRouting (version 7.5.1-sonic).

    Copyright 1996-2005 Kunihiro Ishiguro, et al.

     

     

     

     

     

     

     

     

     

     

     

    sonic# show bgp summary

    IPv4 Unicast Summary:

    BGP router identifier 192.168.100.3, local AS number 300 vrf-id 0

    BGP table version 0

    RIB entries 0, using 0 bytes of memory

    Peers 1, using 21 KiB of memory

     

    		                    

    Neighbor

    V

    AS

    MsgRcvd

    MsgSent

    TblVer

    InQ

    OutQ

    Up/Down

    State/PfxRcd

    PfxSnt

    192.168.100.1

    4

    200

    36

    69

    0

    0

    0

    00:15:24

    (Policy)

    (Policy)

     

     

     

     

     

     

     

     

     

     

     

    Total number of neighbors 1

    sonic#

Route Reflector Configuration

This section shows a sample BGP configuration for route reflector.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure

Enter configuration mode.

3

router bgp < (1-4294967295) AS number>

Add a new router.

4

neighbor <A.B.C.D Neighbor address> remote-as < (1-4294967295) AS number>

Configure neighbor address and remote-as.

5

neighbor <A.B.C.D Neighbor address> route-reflector-client

Configure a neighbor as route-reflector-client.

6

End

Exit configuration mode in FRRouting.

7

write

Optional: Save this configuration to be part of bgpd.conf.

8

exit

Exit FRRouting.

9

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.

The following example shows the commands used to configure route-reflector-client.

admin@sonic:~$ sudo -i

root@sonic:~# vtysh

Hello, this is FRRouting (version 7.5.1-sonic).

Copyright 1996-2005 Kunihiro Ishiguro, et al.

sonic# configure terminal

sonic(config)# router bgp 65100

sonic(config-router)# neighbor 10.0.0.2 remote-as 65100

sonic(config-router)# neighbor 10.0.0.2 route-reflector-client

sonic(config-router)# end

sonic# write

sonic# exit

root@sonic:~# config save -y

BGP IPv6 Configuration

This section shows a sample IPv6 BGP configuration.

Step

Command

Description

1

sudo vtysh

Enter FRRouting.

2

configure

Enter configuration mode.

3

router bgp < (1-4294967295) AS number>

Add a new router.

4

neighbor <A.B.C.D Neighbor address> remote-as < (1-4294967295) AS number>

Configure a neighbor's IPv6 address and remote-as.

5

neighbor <A.B.C.D Neighbor address> route-reflector-client

Configure a neighbor as route-reflector-client.

6

End

Exit configuration mode in FRRouting.

7

write

Optional: Save this configuration to be part of bgpd.conf.

8

exit

Exit FRRouting.

9

sudo config save –y

Optional: Save the current configuration to be part of the startup configuration.