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Example for Configuring Basic BGP Functions

Example for Configuring Basic BGP Functions

May 24, 2024

Network Requirement

As shown in Figure. 1, BGP runs on all the switches.

An EBGP connection is established between Switch A and Switch B, and IBGP fullmesh connections are established between Switch B, Switch C, and Switch D. 

Configure IBGP connections between Switch B, Switch C, and Switch D.

Configure an EBGP connection between Switch A and Switch B.

 Figure 1. BGP configuration

Procedure

This section describes the steps of how to configure basic BGP functions on SwitchA, SwitchB, SwitchC and SwitchD.

Switch A

Step1         Configure the VLANs and VLAN interfaces.

admin@SwitchA# set vlans vlan-id 10 l3-interface vlan10 admin@SwitchA# set vlans vlan-id 20 l3-interface vlan20 admin@SwitchA# set interface gigabit-ethernet te-1/1/1 family ethernet-switching native-vlan-id 10 admin@SwitchA# set interface gigabit-ethernet te-1/1/2 family ethernet-switching native-vlan-id 20 admin@SwitchA# set l3-interface vlan-interface vlan10 address 192.168.10.1 prefix-length 24 admin@SwitchA# set l3-interface vlan-interface vlan20 address 192.168.20.1 prefix-length 24

Step2        Configure an EBGP connection.

admin@SwitchA# set protocols bgp router-id 1.1.1.1 admin@SwitchA# set protocols bgp local-as 100 admin@SwitchA# set protocols bgp neighbor 192.168.20.2 remote-as 200 admin@SwitchA# set protocols bgp ebgp-requires-policy false

Step3        Enable IP routing.

admin@SwitchA# set ip routing enable true

Step4         Commit the configurations.

admin@SwitchA# commit

Switch B

Step1         Configure the VLANs and VLAN interfaces.

admin@SwitchB# set vlans vlan-id 20 l3-interface vlan20 admin@SwitchB# set vlans vlan-id 30 l3-interface vlan30 admin@SwitchB# set vlans vlan-id 40 l3-interface vlan40 admin@SwitchB# set interface gigabit-ethernet te-1/1/2 family ethernet-switching native-vlan-id 20 admin@SwitchB# set interface gigabit-ethernet te-1/1/3 family ethernet-switching native-vlan-id 30 admin@SwitchB# set interface gigabit-ethernet te-1/1/4 family ethernet-switching native-vlan-id 40 admin@SwitchB# set l3-interface vlan-interface vlan20 address 192.168.20.2 prefix-length 24 admin@SwitchB# set l3-interface vlan-interface vlan30 address 192.168.30.1 prefix-length 24 admin@SwitchB# set l3-interface vlan-interface vlan40 address 192.168.40.1 prefix-length 24

Step2        Configure EBGP and IBGP connections.

admin@SwitchB# set protocols bgp router-id 2.2.2.2 admin@SwitchB# set protocols bgp local-as 200 admin@SwitchB# set protocols bgp neighbor 192.168.20.1 remote-as 100 admin@SwitchB# set protocols bgp neighbor 192.168.30.2 remote-as 200 admin@SwitchB# set protocols bgp neighbor 192.168.40.2 remote-as 200 admin@SwitchB# set protocols bgp ebgp-requires-policy false

Step3        Enable IP routing.

admin@SwitchB# set ip routing enable true

Step4         Commit the configurations.

admin@SwitchB# commit

Switch C

Step1         Configure the VLANs and VLAN interfaces.

admin@SwitchC# set vlans vlan-id 30 l3-interface vlan30 admin@SwitchC# set vlans vlan-id 50 l3-interface vlan50 admin@SwitchC# set interface gigabit-ethernet te-1/1/4 family ethernet-switching native-vlan-id 30 admin@SwitchC# set interface gigabit-ethernet te-1/1/5 family ethernet-switching native-vlan-id 50 admin@SwitchC# set l3-interface vlan-interface vlan30 address 192.168.30.2 prefix-length 24 admin@SwitchC# set l3-interface vlan-interface vlan50 address 192.168.50.1 prefix-length 24

Step2        Configure the IBGP connection.

admin@SwitchC# set protocols bgp router-id 3.3.3.3 admin@SwitchC# set protocols bgp local-as 200 admin@SwitchC# set protocols bgp neighbor 192.168.30.1 remote-as 200 admin@SwitchC# set protocols bgp neighbor 192.168.50.2 remote-as 200

Step3        Enable IP routing.

admin@SwitchC# set ip routing enable true

Step4         Commit the configurations.

admin@SwitchC# commit

Switch D

Step1         Configure the VLANs and VLAN interfaces.

admin@SwitchD# set vlans vlan-id 40 l3-interface vlan40 admin@SwitchD# set vlans vlan-id 50 l3-interface vlan50 admin@SwitchD# set interface gigabit-ethernet te-1/1/4 family ethernet-switching native-vlan-id 40 admin@SwitchD# set interface gigabit-ethernet te-1/1/5 family ethernet-switching native-vlan-id 50 admin@SwitchD# set l3-interface vlan-interface vlan40 address 192.168.40.2 prefix-length 24 admin@SwitchD# set l3-interface vlan-interface vlan50 address 192.168.50.2 prefix-length 24

Step2        Configure the IBGP connection.

admin@SwitchD# set protocols bgp router-id 4.4.4.4 admin@SwitchD# set protocols bgp local-as 200 admin@SwitchD# set protocols bgp neighbor 192.168.40.1 remote-as 200 admin@SwitchD# set protocols bgp neighbor 192.168.50.1 remote-as 200

Step3        Enable IP routing.

admin@SwitchD# set ip routing enable true

Step4         Commit the configurations.

admin@SwitchD# commit

Viewing BGP Peer Status on Switch B

admin@SwitchB# run show bgp neighbor BGP neighbor on vlan20: 192.168.20.1, remote AS 100, local AS 200, external link BGP version 4, remote router ID 1.1.1.1, local router ID 2.2.2.2 BGP state = Idle Last read 00:15:06, Last write never Hold time is 180, keepalive interval is 60 seconds Graceful restart information: Local GR Mode: Helper* Remote GR Mode: NotApplicable R bit: False Timers: Configured Restart Time(sec): 120 Received Restart Time(sec): 0 Message statistics: Inq depth is 0 Outq depth is 0 Sent Rcvd Opens: 0 0 Notifications: 0 0 Updates: 0 0 Keepalives: 0 0 Route Refresh: 0 0 Capability: 0 0 Total: 0 0 Minimum time between advertisement runs is 0 seconds For address family: IPv4 Unicast Not part of any update group Community attribute sent to this neighbor(all) 0 accepted prefixes Connections established 0; dropped 0 Last reset 00:15:06, Waiting for Peer IPv6 LLA BGP Connect Retry Timer in Seconds: 120 Read thread: off Write thread: off FD used: -1 BGP neighbor is 192.168.30.2, remote AS 200, local AS 200, internal link Administratively shut down BGP version 4, remote router ID 3.3.3.3, local router ID 2.2.2.2 BGP state = Idle Last read 00:15:06, Last write never Hold time is 180, keepalive interval is 60 seconds Graceful restart information: Local GR Mode: Helper* Remote GR Mode: NotApplicable R bit: False Timers: Configured Restart Time(sec): 120 Received Restart Time(sec): 0 Message statistics: Inq depth is 0 Outq depth is 0 Sent Rcvd Opens: 0 0 Notifications: 0 0 Updates: 0 0 Keepalives: 0 0 Route Refresh: 0 0 Capability: 0 0 Total: 0 0 Minimum time between advertisement runs is 600 seconds For address family: IPv4 Unicast Not part of any update group Advertise bestpath per AS via addpath Override ASNs in outbound updates if aspath equals remote-as Community attribute sent to this neighbor(all) 0 accepted prefixes Connections established 0; dropped 0 Last reset 00:15:06, No AFI/SAFI activated for peer External BGP neighbor may be up to 255 hops away. BGP Connect Retry Timer in Seconds: 111 Peer Authentication Enabled Read thread: off Write thread: off FD used: -1 BGP neighbor is 192.168.40.2, remote AS 200, local AS 200, internal link BGP version 4, remote router ID 4.4.4.4, local router ID 2.2.2.2 BGP state = Active Last read 00:15:06, Last write never Hold time is 180, keepalive interval is 60 seconds Graceful restart information: Local GR Mode: Helper* Remote GR Mode: NotApplicable R bit: False Timers: Configured Restart Time(sec): 120 Received Restart Time(sec): 0 Message statistics: Inq depth is 0 Outq depth is 0 Sent Rcvd Opens: 0 0 Notifications: 0 0 Updates: 0 0 Keepalives: 0 0 Route Refresh: 0 0 Capability: 0 0 Total: 0 0 Minimum time between advertisement runs is 0 seconds For address family: IPv4 Unicast Not part of any update group Advertise bestpath per AS via addpath Override ASNs in outbound updates if aspath equals remote-as Community attribute sent to this neighbor(all) 0 accepted prefixes Connections established 0; dropped 0 Last reset 00:15:06, No AFI/SAFI activated for peer External BGP neighbor may be up to 255 hops away. BGP Connect Retry Timer in Seconds: 111 Peer Authentication Enabled Read thread: off Write thread: off FD used: -1

Configuring Switch A to Advertise Route 192.168.10.0/24

admin@SwitchA# set protocols bgp ipv4-unicast network 192.168.10.0/24 admin@SwitchA# commit


View the BGP routing table of Switch B:

admin@SwitchB# run show bgp show bgp ipv4 unicast ===================== BGP table version is 2, local router ID is 4.4.4.4, vrf id 0 Default local pref 100, local AS 200 Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, i internal, r RIB-failure, S Stale, R Removed Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 192.168.10.0/24 192.168.20.1 0 100 32768 i Displayed 1 routes and 1 total paths show bgp ipv6 unicast ===================== No BGP prefixes displayed, 0 exist


View the BGP routing table of Switch C:

admin@SwitchC# run show bgp show bgp ipv4 unicast ===================== BGP table version is 2, local router ID is 3.3.3.3, vrf id 0 Default local pref 100, local AS 200 Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, i internal, r RIB-failure, S Stale, R Removed Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 192.168.10.0/24 192.168.20.1 0 100 32768 i Displayed 1 routes and 1 total paths show bgp ipv6 unicast ===================== No BGP prefixes displayed, 0 exist

The preceding command output display that the route to destination 192.168.10.0/24 becomes invalid because the next hop address of this route is unreachable. 

Configuring Switch B to Advertise a Connected Route

admin@SwitchB# set protocols bgp ipv4-unicast redistribute connected admin@SwitchB# commit

Ping 192.168.10.1 on Switch C:

admin@SwitchC# run ping 192.168.10.1 PING 192.168.10.1 (192.168.10.1) 56(84) bytes of data. 64 bytes from 192.168.10.1: icmp_req=1 ttl=63 time=4.68 ms 64 bytes from 192.168.10.1: icmp_req=2 ttl=63 time=4.46 ms 64 bytes from 192.168.10.1: icmp_req=3 ttl=63 time=5.35 ms 64 bytes from 192.168.10.1: icmp_req=4 ttl=63 time=4.52 ms 64 bytes from 192.168.10.1: icmp_req=5 ttl=63 time=4.51 ms 192.168.10.1 ping statistics — 5 packets transmitted, 5 received, 0% packet loss, time 4017ms rtt min/avg/max/mdev = 4.460/4.709/5.358/0.338 ms

View the BGP routing table of Switch C:

admin@SwitchC# run show bgp show bgp ipv4 unicast ===================== BGP table version is 2, local router ID is 3.3.3.3, vrf id 0 Default local pref 100, local AS 200 Status codes: s suppressed, d damped, h history, * valid, > best, = multipath, i internal, r RIB-failure, S Stale, R Removed Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 192.168.10.0/24 192.168.20.1 0 100 32768 i *> 192.168.40.0/24 192.168.30.1 0 100 32768 i 192.168.30.0/24 192.168.30.1 0 100 32768 i *> 192.168.10.0/24 192.168.30.1 0 100 32768 i Displayed 4 routes and 4 total paths show bgp ipv6 unicast ===================== No BGP prefixes displayed, 0 exist

 

 

 

 

 

 

 

 

 

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