Contents

Introduction· 1

Prerequisites· 1

Example: Configuring basic BGP· 1

Network configuration· 1

Analysis· 1

Applicable hardware and software versions· 1

Restrictions and guidelines· 2

Procedures· 3

Configuring IP addresses for interfaces· 3

Configuring IBGP· 3

Configuring EBGP· 4

Configuring BGP to redistribute direct routes on Switch B· 5

Verifying the configuration· 6

Configuration files· 6

Examples: Configuring BGP and IGP route redistribution· 8

Network configuration· 8

Analysis· 8

Applicable hardware and software versions· 8

Restrictions and guidelines· 9

Procedures· 10

Configuring IP addresses for interfaces· 10

Enabling OSPF· 10

Configuring EBGP connection· 10

Configuring BGP and IGP route redistribution· 11

Verifying the configuration· 12

Configuration files· 13

Introduction

This document provides BGP configuration examples.

Prerequisites

The configuration examples in this document were created and verified in a lab environment, and all the devices were started with the factory default configuration. When you are working on a live network, make sure you understand the potential impact of every command on your network.

This document assumes that you have basic knowledge of BGP.

Example: Configuring basic BGP

Network configuration

As shown in Figure 1, all switches run BGP. Run EBGP between Switch A and Switch B, and run IBGP between Switch B and Switch C so that Switch C can access the network 8.1.1.0/24 connected to Switch A.

Figure 1 Network diagram

Analysis

To enable Switch B to communicate with Switch C through loopback interfaces, enable OSPF in AS 65009.

By default, BGP does not advertise local networks. To enable Switch C to access the network 8.1.1.0/24 connected directly to Switch A, perform the following tasks:

·     Inject network 8.1.1.0/24 to the BGP routing table of Switch A.

·     Inject networks 3.1.1.0/24 and 9.1.1.0/24 to the BGP routing table of Switch B.

Applicable hardware and software versions

The following matrix shows the hardware and software versions to which this configuration example is applicable:

Restrictions and guidelines

When you configure basic BGP, follow these restrictions and guidelines:

·     Use loopback interfaces to establish IBGP connections to prevent route flapping caused by port state changes.

·     Loopback interfaces are virtual interfaces. Use the peer connect-interface command to specify the loopback interface as the source interface for establishing BGP connections.

·     The EBGP peers, Switch A and Switch B, are located in different ASs. Typically, their loopback interfaces are not reachable to each other, so the switches use directly connected interfaces to establish EBGP sessions.

Procedures

Configuring IP addresses for interfaces

# Configure an IP address for VLAN-interface 100.

<SwitchA> system-view

[SwitchA] interface Vlan-interface 100

[SwitchA-Vlan-interface100] ip address 8.1.1.1 24

# Configure IP addresses for other interfaces in the same way that VLAN-interface 100 is configured. (Details not shown.)

Configuring IBGP

Configuring Switch B

<SwitchB> system-view

[SwitchB] bgp 65009

[SwitchB-bgp-default] router-id 2.2.2.2

[SwitchB-bgp-default] peer 3.3.3.3 as-number 65009

[SwitchB-bgp-default] peer 3.3.3.3 connect-interface Loopback 0

[SwitchB-bgp-default] address-family ipv4 unicast

[SwitchB-bgp-default-ipv4] peer 3.3.3.3 enable

[SwitchB-bgp-default-ipv4] quit

[SwitchB-bgp-default] quit

[SwitchB] ospf 1

[SwitchB-ospf-1] area 0

[SwitchB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0

[SwitchB-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255

[SwitchB-ospf-1-area-0.0.0.0] quit

[SwitchB-ospf-1] quit

Configuring Switch C

<SwitchC> system-view

[SwitchC] bgp 65009

[SwitchC-bgp-default] router-id 3.3.3.3

[SwitchC-bgp-default] peer 2.2.2.2 as-number 65009

[SwitchC-bgp-default] peer 2.2.2.2 connect-interface Loopback 0

[SwitchC-bgp-default] address-family ipv4 unicast

[SwitchC-bgp-default-ipv4] peer 2.2.2.2 enable

[SwitchC-bgp-default-ipv4] quit

[SwitchC-bgp-default] quit

[SwitchC] ospf 1

[SwitchC-ospf-1] area 0

[SwitchC-ospf-1-area-0.0.0.0] network 3.3.3.3 0.0.0.0

[SwitchC-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255

[SwitchC-ospf-1-area-0.0.0.0] quit

[SwitchC-ospf-1] quit

# Display BGP peer information on Switch C.

[SwitchC] display bgp peer ipv4

 BGP local router ID : 3.3.3.3

 Local AS number : 65009

 Total number of peers : 1                 Peers in established state : 1

  * - Dynamically created peer

  Peer                    AS  MsgRcvd  MsgSent OutQ PrefRcv Up/Down  State

  2.2.2.2              65009        2        2    0       0 00:00:13 Established

The output shows that Switch C has established an IBGP peer relationship with Switch B.

Configuring EBGP

Configuring Switch A

<SwitchA> system-view

[SwitchA] bgp 65008

[SwitchA-bgp-default] router-id 1.1.1.1

[SwitchA-bgp-default] peer 3.1.1.1 as-number 65009

[SwitchA-bgp-default] address-family ipv4 unicast

[SwitchA-bgp-default-ipv4] peer 3.1.1.1 enable

[SwitchA-bgp-default-ipv4] network 8.1.1.0 24

[SwitchA-bgp-default-ipv4] quit

[SwitchA-bgp-default] quit

Configuring Switch B

[SwitchB] bgp 65009

[SwitchB-bgp-default] peer 3.1.1.2 as-number 65008

[SwitchB-bgp-default] address-family ipv4 unicast

[SwitchB-bgp-default-ipv4] peer 3.1.1.2 enable

[SwitchB-bgp-default-ipv4] quit

[SwitchB-bgp-default] quit

# Display BGP peer information on Switch B.

[SwitchB] display bgp peer ipv4

 BGP local router ID : 2.2.2.2

 Local AS number : 65009

 Total number of peers : 2                 Peers in established state : 2

  * - Dynamically created peer

  Peer                    AS  MsgRcvd  MsgSent OutQ PrefRcv Up/Down  State

  3.3.3.3              65009        4        4    0       0 00:02:49 Established

  3.1.1.2              65008        2        2    0       0 00:00:05 Established

The output shows that Switch B has established an IBGP peer relationship with Switch C and an EBGP peer relationship with Switch A.

# Display the BGP routing table on Switch A.

[SwitchA] display bgp routing-table ipv4

 Total number of routes: 1

 BGP local router ID is 1.1.1.1

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e – external       a - additional-path

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

* >  8.1.1.0/24         8.1.1.1         0                     32768   i

# Display the BGP routing table on Switch B.

[SwitchB] display bgp routing-table ipv4

 Total number of routes: 1

 BGP local router ID is 2.2.2.2

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e - external

               a - additional-path

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

* >e 8.1.1.0/24         3.1.1.2         0                     0       65008i

# Display the BGP routing table on Switch C.

[SwitchC] display bgp routing-table ipv4

 Total number of routes: 1

 BGP local router ID is 3.3.3.3

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e - external     a - additional-path

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

   i 8.1.1.0/24         3.1.1.2         0          100        0       65008i

The outputs show that Switch A has learned no route to AS 65009, and Switch C has learned network 8.1.1.0, but the next hop 3.1.1.2 is unreachable. As a result, the route is invalid.

Configuring BGP to redistribute direct routes on Switch B

# Configure Switch B.

[SwitchB] bgp 65009

[SwitchB-bgp-default] address-family ipv4 unicast

[SwitchB-bgp-default-ipv4] network 3.1.1.0 24

[SwitchB-bgp-default-ipv4] network 9.1.1.0 24

[SwitchB-bgp-default-ipv4] quit

[SwitchB-bgp-default] quit

# Display the BGP routing table on Switch A.

[SwitchA] display bgp routing-table ipv4

 Total number of routes: 3

 BGP local router ID is 1.1.1.1

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e - external      a - additional-path

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

* >e 3.1.1.0/24         3.1.1.1         0                     0       65009?

* >  8.1.1.0/24         8.1.1.1         0                     32768   i

* >e 9.1.1.0/24         3.1.1.1         0                     0       65009i

The output shows that route 9.1.1.0/24 has been added in Switch A's routing table.

# Display the BGP routing table on Switch C.

[SwitchC] display bgp routing-table ipv4

 Total number of routes: 3

 BGP local router ID is 3.3.3.3

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e - external     a - additional-path

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

* >i 3.1.1.0/24         2.2.2.2         0          100        0       ?

* >i 8.1.1.0/24         3.1.1.2         0          100        0       65008i

* >i 9.1.1.0/24         2.2.2.2         0          100        0       i 

The output shows that the route 8.1.1.0 becomes valid with the next hop as Switch A.

Verifying the configuration

# Verify that Switch C can ping 8.1.1.1.

[SwitchC] ping 8.1.1.1

Ping 8.1.1.1 (8.1.1.1): 56 data bytes, press CTRL_C to break

56 bytes from 8.1.1.1: icmp_seq=0 ttl=254 time=10.000 ms

56 bytes from 8.1.1.1: icmp_seq=1 ttl=254 time=4.000 ms

56 bytes from 8.1.1.1: icmp_seq=2 ttl=254 time=4.000 ms

56 bytes from 8.1.1.1: icmp_seq=3 ttl=254 time=3.000 ms

56 bytes from 8.1.1.1: icmp_seq=4 ttl=254 time=3.000 ms

--- Ping statistics for 8.1.1.1 ---

5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss

round-trip min/avg/max/std-dev = 3.000/4.800/10.000/2.638 ms

Configuration files

·     Switch A:

#

vlan 100

#

vlan 200

#

interface Loopback0

ip address 1.1.1.1 255.255.255.255

#

interface Vlan-interface100

 ip address 8.1.1.1 255.255.255.0

#

interface Vlan-interface200

 ip address 3.1.1.2 255.255.255.0

#

bgp 65008

router-id 1.1.1.1

peer 3.1.1.1 as-number 65009

#

address-family ipv4 unicast

network 8.1.1.0 255.255.255.0

peer 3.1.1.1 enable

#

·     Switch B:

#

vlan 200

#

vlan 300

#

interface Loopback0

ip address 2.2.2.2 255.255.255.255

#

interface Vlan-interface200

ip address 3.1.1.1 255.255.255.0

#

interface Vlan-interface300

ip address 9.1.1.1 255.255.255.0

#

bgp 65009

router-id 2.2.2.2

peer 3.1.1.2 as-number 65008

peer 3.3.3.3 as-number 65009

peer 3.3.3.3 connect-interface Loopback0

#

address-family ipv4 unicast

network 3.1.1.0 255.255.255.0

network 9.1.1.0 255.255.255.0

peer 3.1.1.2 enable

peer 3.3.3.3 enable

#

ospf 1

area 0.0.0.0

network 2.2.2.2 0.0.0.0

network 9.1.1.0 0.0.0.255

#

·     Switch C:

#

vlan 300

#

interface Loopback0

ip address 3.3.3.3 255.255.255.255

#

interface Vlan-interface300

ip address 9.1.1.2 255.255.255.0

#

bgp 65009

router-id 3.3.3.3

peer 2.2.2.2 as-number 65009

peer 2.2.2.2 connect-interface Loopback0

#

address-family ipv4 unicast

peer 2.2.2.2 enable

#

ospf 1

area 0.0.0.0

network 3.3.3.3 0.0.0.0

network 9.1.1.0 0.0.0.255

#

Examples: Configuring BGP and IGP route redistribution

Network configuration

As shown in Figure 2, all devices of company A belong to AS 65008 and all devices of company B belong to AS 65009. Run EBGP between Switch A and Switch B, and run OSPF between Switch B and Switch C to allow communication only between networks 9.1.2.0/24 and 8.1.1.0/24.

Figure 2 Network diagram

Analysis

To enable Switch B to communicate with Switch C through loopback interfaces, enable OSPF in AS 65009.

To enable Switch A to obtain the route to 9.1.2.0/24, configure BGP to redistribute routes from OSPF on Switch B. To enable Switch C to obtain the route to 8.1.1.0/24, configure OSPF to redistribute routes from BGP on Switch B.

Applicable hardware and software versions

The following matrix shows the hardware and software versions to which this configuration example is applicable:

Restrictions and guidelines

When you configure BGP and IGP route redistribution, follow these restrictions and guidelines:

·     Use loopback interfaces to establish IBGP connections to prevent route flapping caused by port state changes.

·     Loopback interfaces are virtual interfaces. Use the peer connect-interface command to specify the loopback interface as the source interface for establishing BGP connections.

·     The EBGP peers, Switch A and Switch B, are located in different ASs. Typically, their loopback interfaces are not reachable to each other, so the switches directly connected interfaces to establish EBGP sessions.

Procedures

Configuring IP addresses for interfaces

# Configure an IP address for VLAN-interface 100.

<SwitchA> system-view

[SwitchA] interface Vlan-interface 100

[SwitchA-Vlan-interface100] ip address 8.1.1.1 24

# Configure IP addresses for other interfaces in the same way that VLAN-interface 100 is configured. (Details not shown.)

Enabling OSPF

Enable OSPF in AS 65009.

Configuring Switch B

<SwitchB> system-view

[SwitchB] ospf 1

[SwitchB-ospf-1] area 0

[SwitchB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0

[SwitchB-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255

[SwitchB-ospf-1-area-0.0.0.0] quit

[SwitchB-ospf-1] quit

Configuring Switch C

<SwitchC> system-view

[SwitchC] ospf 1

[SwitchC-ospf-1] area 0

[SwitchC-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255

[SwitchC-ospf-1-area-0.0.0.0] network 9.1.2.0 0.0.0.255

[SwitchC-ospf-1-area-0.0.0.0] quit

[SwitchC-ospf-1] quit

Configuring EBGP connection

Configure the EBGP connection and inject network 8.1.1.0/24 to the BGP routing table of Switch A.

Configuring Switch A

<SwitchA> system-view

[SwitchA] bgp 65008

[SwitchA-bgp-default] router-id 1.1.1.1

[SwitchA-bgp-default] peer 3.1.1.1 as-number 65009

[SwitchA-bgp-default] address-family ipv4 unicast

[SwitchA-bgp-default-ipv4] peer 3.1.1.1 enable

[SwitchA-bgp-default-ipv4] network 8.1.1.0 24

[SwitchA-bgp-default-ipv4] quit

[SwitchA-bgp-default] quit

Configuring Switch B

[SwitchB] bgp 65009

[SwitchB-bgp-default] router-id 2.2.2.2

[SwitchB-bgp-default] peer 3.1.1.2 as-number 65008

[SwitchB-bgp-default] address-family ipv4 unicast

[SwitchB-bgp-default-ipv4] peer 3.1.1.2 enable

Configuring BGP and IGP route redistribution

# Configure route redistribution between BGP and OSPF on Switch B.

[SwitchB-bgp-default-ipv4] import-route ospf 1

[SwitchB-bgp-default-ipv4] quit

[SwitchB-bgp-default] quit

[SwitchB] ospf 1

[SwitchB-ospf-1] import-route bgp

[SwitchB-ospf-1] quit

# Display the BGP routing table on Switch A.

[SwitchA] display bgp routing-table ipv4

 Total number of routes: 3

 BGP local router ID is 1.1.1.1

 Status codes: * - valid, > - best, d - dampened, h - history

               s - suppressed, S - stale, i - internal, e - external              

       Origin: i - IGP, e - EGP, ? - incomplete

     Network            NextHop         MED        LocPrf     PrefVal Path/Ogn

* >  8.1.1.0/24         8.1.1.1         0                     32768   i

* >e 9.1.2.0/24         3.1.1.1         1                     0       65009?

The output shows that Switch A has obtained the route to 9.1.2.0/24.

# Display the OSPF routing table on Switch C.

[SwitchC] display ospf routing

          OSPF Process 1 with Router ID 3.3.3.3

                   Routing Table

                Topology base (MTID 0)

 Routing for network

 Destination        Cost     Type    NextHop         AdvRouter       Area

 9.1.1.0/24         1        Transit 9.1.1.2         3.3.3.3         0.0.0.0

9.1.2.0/24         1        Stub    9.1.2.1         192.168.0.63    0.0.0.0

 2.2.2.2/32         1        Stub    9.1.1.1         2.2.2.2         0.0.0.0

 Routing for ASEs

 Destination        Cost     Type    Tag         NextHop         AdvRouter

 8.1.1.0/24         1        Type2   1           9.1.1.1         2.2.2.2

 Total nets: 3

 Intra area: 2  Inter area: 0  ASE: 1  NSSA: 0

The output shows that Switch C has obtained the route to 8.1.1.0/24.

Verifying the configuration

# Ping 9.1.2.1 from 8.1.1.1 on Switch A. The ping operation succeeds.

[SwitchA] ping -a 8.1.1.1 9.1.2.1

Ping 9.1.2.1 (9.1.2.1) from 8.1.1.1: 56 data bytes, press CTRL_C to break

56 bytes from 9.1.2.1: icmp_seq=0 ttl=254 time=10.000 ms

56 bytes from 9.1.2.1: icmp_seq=1 ttl=254 time=12.000 ms

56 bytes from 9.1.2.1: icmp_seq=2 ttl=254 time=2.000 ms

56 bytes from 9.1.2.1: icmp_seq=3 ttl=254 time=7.000 ms

56 bytes from 9.1.2.1: icmp_seq=4 ttl=254 time=9.000 ms

--- Ping statistics for 9.1.2.1 ---

5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss

round-trip min/avg/max/std-dev = 2.000/8.000/12.000/3.406 ms

# Ping 8.1.1.1 from 9.1.2.1 on Switch C. The ping operation succeeds.

[SwitchC] ping -a 9.1.2.1 8.1.1.1

Ping 8.1.1.1 (8.1.1.1) from 9.1.2.1: 56 data bytes, press CTRL_C to break

56 bytes from 8.1.1.1: icmp_seq=0 ttl=254 time=9.000 ms

56 bytes from 8.1.1.1: icmp_seq=1 ttl=254 time=4.000 ms

56 bytes from 8.1.1.1: icmp_seq=2 ttl=254 time=3.000 ms

56 bytes from 8.1.1.1: icmp_seq=3 ttl=254 time=3.000 ms

56 bytes from 8.1.1.1: icmp_seq=4 ttl=254 time=3.000 ms

--- Ping statistics for 8.1.1.1 ---

5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss

round-trip min/avg/max/std-dev = 3.000/4.400/9.000/2.332 ms

# Ping 9.1.2.1 and 9.1.3.1 from 8.1.2.1 on Switch A. The ping operations fail.

[SwitchA] ping –a 8.1.2.1 9.1.2.1

Ping 9.1.2.1 (9.1.2.1) from 8.1.2.1: 56 data bytes, press CTRL_C to break

Request time out

Request time out

Request time out

Request time out

Request time out

--- Ping statistics for 9.1.2.1 ---

5 packet(s) transmitted, 0 packet(s) received, 100.0% packet loss

[SwitchA] ping –a 8.1.2.1 9.1.3.1

Ping 9.1.3.1 (9.1.3.1) from 8.1.2.1: 56 data bytes, press CTRL_C to break

Request time out

Request time out

Request time out

Request time out

Request time out

--- Ping statistics for 9.1.3.1 ---

5 packet(s) transmitted, 0 packet(s) received, 100.0% packet loss

# Ping 8.1.1.1 and 8.1.2.1 from 9.1.3.1 on Switch C. The ping operations fail.

[SwitchC] ping –a 9.1.3.1 8.1.1.1

Ping 8.1.1.1 (8.1.1.1) from 9.1.3.1: 56 data bytes, press CTRL_C to break

Request time out

Request time out

Request time out

Request time out

Request time out

--- Ping statistics for 8.1.1.1 ---

5 packet(s) transmitted, 0 packet(s) received, 100.0% packet loss

[SwitchC] ping –a 9.1.3.1 8.1.2.1

Ping 8.1.2.1 (8.1.2.1) from 9.1.3.1: 56 data bytes, press CTRL_C to break

Request time out

Request time out

Request time out

Request time out

Request time out

--- Ping statistics for 8.1.2.1 ---

5 packet(s) transmitted, 0 packet(s) received, 100.0% packet loss

Configuration files

·     Switch A:

#

vlan 100

#

vlan 200

#

vlan 600

#

interface Loopback0

ip address 1.1.1.1 255.255.255.255

#

interface Vlan-interface100

 ip address 8.1.1.1 255.255.255.0

#

interface Vlan-interface200

ip address 3.1.1.2 255.255.255.0

#

interface Vlan-interface600

ip address 8.1.2.1 255.255.255.0

#

bgp 65008

router-id 1.1.1.1

peer 3.1.1.1 as-number 65009

#

address-family ipv4 unicast

network 8.1.1.0 255.255.255.0

peer 3.1.1.1 enable

#

·     Switch B:

#

vlan 200

#

vlan 300

#

vlan 500

#

interface Loopback0

ip address 2.2.2.2 255.255.255.255

#

interface Vlan-interface200

ip address 3.1.1.1 255.255.255.0

#

interface Vlan-interface300

ip address 9.1.1.1 255.255.255.0

#

bgp 65009

router-id 2.2.2.2

peer 3.1.1.2 as-number 65008

#

address-family ipv4 unicast

import-route ospf 1

peer 3.1.1.2 enable

#

ospf 1

import-route bgp

area 0.0.0.0

network 2.2.2.2 0.0.0.0

network 9.1.1.0 0.0.0.255

#

·     Switch C:

#

vlan 300

#

vlan 400

#

interface Loopback0

ip address 3.3.3.3 255.255.255.255

#

interface Vlan-interface300

ip address 9.1.1.2 255.255.255.0

#

interface Vlan-interface400

ip address 9.1.2.1 255.255.255.0

#

interface Vlan-interface500

ip address 9.1.3.1 255.255.255.0

#

ospf 1

area 0.0.0.0

network 9.1.1.0 0.0.0.255

network 9.1.2.0 0.0.0.255

#