Example for Configuring Inter-AS VPN Option B with an ASBR Functioning as an RR

In a scenario in which the backbone network spans two ASs, ASBRs need to advertise VPNv4 routes through MP-EBGP. When multiple PEs exist in the ASs, you can configure an ASBR as an RR to simplify configurations.

Networking Requirements

On the network shown in Figure 1, CE1, CE2, and CE3 belong to the same VPN; PE2 is not in the same AS as PE1 and PE3. It is required that inter-AS VPN Option B be deployed to interconnect CE1, CE2, and CE3. To lower configuration complexities, you can configure ASBR1 as an RR rather than set up an MP-IBGP peer relationship between PE1 and PE3. Then, ASBR1 reflects the routes sent from PE1 to PE3 and the routes sent from PE3 to PE1, and then sends the optimal route to ASBR2.

Figure 1 Inter-AS VPN Option B with an ASBR functioning as an RR

Interfaces 1 through 3 in this example represent GE 0/1/0, GE 0/1/8, and GE 0/1/16, respectively.


Device Name

Interface

IP Address

CE1

Loopback 1

11.11.11.11/32

GE 0/1/0

10.1.1.1/24

PE1

Loopback 1

1.1.1.1/32

GE 0/1/0

10.1.1.2/24

GE 0/1/8

10.10.1.2/24

CE3

Loopback 1

33.33.33.33/32

GE 0/1/0

10.3.1.1/24

PE3

Loopback 1

3.3.3.3/32

GE 0/1/0

10.3.1.2/24

GE 0/1/8

10.30.1.2/24

ASBR1

Loopback 1

5.5.5.5/32

GE 0/1/0

10.10.1.1/24

GE 0/1/8

10.21.1.1/24

GE 0/1/16

10.30.1.1/24

ASBR2

Loopback 1

6.6.6.6/32

GE 0/1/0

10.40.1.1/24

GE 0/1/8

10.21.1.2/24

CE2

Loopback 1

22.22.22.22/32

GE 0/1/0

10.2.1.1/24

PE2

Loopback 1

2.2.2.2/32

GE 0/1/0

10.40.1.2/24

GE 0/1/8

10.2.1.2/24

Configuration Notes

When configuring inter-AS VPN Option B with an ASBR functioning as an RR, note the following:

  • ASBR1 needs to be configured as an RR with PE1 and PE3 to serve as clients.

  • ASBR1 does not filter the received VPNv4 routes based on VPN targets.

Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure an IGP on the MPLS backbone network for IP connectivity between the ASBR and PE in the same AS, and set up an MPLS LDP LSP between the ASBR and PE in the same AS.

  2. Set up EBGP peer relationships between PEs and CEs and set up MP-IBGP peer relationships between the PEs and ASBRs.

  3. Configure VPN instances on PEs, but not ASBRs.

  4. Enable MPLS on the interface that connects one ASBR to the other ASBR, set up an MP-EBGP peer relationship between the ASBRs.

  5. Configure ASBR1 as an RR.

Data Preparation

To complete the configuration, you need the following data:

  • MPLS LSR IDs of PE1 (1.1.1.1), PE2 (2.2.2.2), PE3 (3.3.3.3), ASBR1 (5.5.5.5), and ASBR2 (6.6.6.6)

  • Name (vpna), RD (100:1, 200:2 and 100:3), and export and import VPN targets (111:1) of the VPN instance on each PE

Procedure

  1. On the MPLS backbone networks in AS100 and AS200, configure an IGP to interconnect the PE and ASBR on each network.

    This example uses OSPF as the IGP. For configuration details, see Configuration Files in this section.

    After the configurations are complete, the OSPF neighbor relationships can be established between the PEs and ASBRs. Run the display ospf peer command. The command output shows that the neighbor relationship is in the Full state. Run the display ip routing-table command. The command output shows that PEs or ASBRs have learned the routes to each other's loopback interface.

  2. Configure MPLS and MPLS LDP both globally and per interface on each node of the MPLS backbone network in each AS and set up LDP LSPs.

    # Configure PE1.

    [~PE1] mpls lsr-id 1.1.1.1
[*PE1] mpls
[*PE1-mpls] quit
[*PE1] mpls ldp
[*PE1-mpls-ldp] quit
[*PE1] interface gigabitethernet 0/1/0
[*PE1-GigabitEthernet0/1/0] mpls
[*PE1-GigabitEthernet0/1/0] mpls ldp
[*PE1-GigabitEthernet0/1/0] commit
[~PE1-GigabitEthernet0/1/0] quit

    The configurations of PE2 and PE3 are similar to the configuration of PE1. For configuration details, see Configuration Files in this section.

    # Configure ASBR1.

    [~ASBR1] mpls lsr-id 5.5.5.5
[*ASBR1] mpls
[*ASBR1-mpls] quit
[*ASBR1] mpls ldp
[*ASBR1-mpls-ldp] quit
[*ASBR1] interface gigabitethernet 0/1/0
[*ASBR1-GigabitEthernet0/1/0] mpls
[*ASBR1-GigabitEthernet0/1/0] mpls ldp
[*ASBR1-GigabitEthernet0/1/0] commit
[*ASBR1-GigabitEthernet0/1/0] quit
[*ASBR1] interface gigabitethernet 0/1/16
[*ASBR1-GigabitEthernet0/1/16] mpls
[*ASBR1-GigabitEthernet0/1/16] mpls ldp
[*ASBR1-GigabitEthernet0/1/16] commit
[~ASBR1-GigabitEthernet0/1/16] quit

    The configuration of ASBR2 is similar to the configuration of ASBR1. For configuration details, see Configuration Files in this section.

    After the configurations are complete, the LDP session can be established between the PE and ASBR. Run the display mpls ldp session command on each device. The command output shows that the Status field is Operational. The following example uses the command output on PE1.

    <PE1> display mpls ldp session
 LDP Session(s) in Public Network
 Codes: LAM(Label Advertisement Mode), SsnAge Unit(DDD:HH:MM)
 An asterisk (*) before a session means the session is being deleted.
 -------------------------------------------------------------------------
 PeerID             Status      LAM  SsnRole  SsnAge      KASent/Rcv
 -------------------------------------------------------------------------
 5.5.5.5:0          Operational DU   Passive  0000:00:01  5/5
 -------------------------------------------------------------------------
 TOTAL: 1 session(s) Found.

  3. Set up an MP-IBGP peer relationship between the PE and ASBR in the same AS.

    # Configure PE1.

    [~PE1] bgp 100
[*PE1-bgp] peer 5.5.5.5 as-number 100
[*PE1-bgp] peer 5.5.5.5 connect-interface loopback 1
[*PE1-bgp] ipv4-family vpnv4
[*PE1-bgp-af-vpnv4] peer 5.5.5.5 enable
[*PE1-bgp-af-vpnv4] commit
[~PE1-bgp-af-vpnv4] quit
[~PE1-bgp] quit

    The configurations of PE2 and PE3 are similar to the configuration of PE1. For configuration details, see Configuration Files in this section.

    # Configure ASBR1.

    [~ASBR1] bgp 100
[*ASBR1-bgp] peer 1.1.1.1 as-number 100
[*ASBR1-bgp] peer 1.1.1.1 connect-interface loopback 1
[*ASBR1-bgp] peer 3.3.3.3 as-number 100
[*ASBR1-bgp] peer 3.3.3.3 connect-interface loopback 1
[*ASBR1-bgp] ipv4-family vpnv4
[*ASBR1-bgp-af-vpnv4] peer 1.1.1.1 enable
[*ASBR1-bgp-af-vpnv4] peer 3.3.3.3 enable
[*ASBR1-bgp-af-vpnv4] commit
[~ASBR1-bgp-af-vpnv4] quit
[~ASBR1-bgp] quit

    The configuration of ASBR2 is similar to the configuration of ASBR1. For configuration details, see Configuration Files in this section.

    After completing the configurations, run the display bgp vpnv4 all peer command on the PEs or ASBRs. The command output shows that MP-IBGP peer relationships have been established between the PEs and ASBRs. The following example uses the command output on PE1.

    <ASBR1> display bgp vpnv4 all peer
BGP local router ID : 1.1.1.1
 Local AS number : 100
 Total number of peers : 2                 Peers in established state : 3
  Peer            V    AS  MsgRcvd  MsgSent    OutQ  Up/Down    State        PrefRcv
  5.5.5.5         4   100   12      18         0     00:09:38   Established   0

  4. Configure VPN instances on PEs and connect the CEs to the PEs.

    # Configure PE1.

    [~PE1] ip vpn-instance vpna
[*PE1-vpn-instance-vpna] ipv4-family
[*PE1-vpn-instance-vpna-af-ipv4] route-distinguisher 100:1
[*PE1-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*PE1-vpn-instance-vpna-af-ipv4] quit
[*PE1-vpn-instance-vpna] quit
[*PE1] interface gigabitethernet 0/1/8
[*PE1-GigabitEthernet0/1/8] ip binding vpn-instance vpna
[*PE1-GigabitEthernet0/1/8] ip address 10.1.1.2 24
[*PE1-GigabitEthernet0/1/8] commit
[~PE1-GigabitEthernet0/1/8] quit

    The configurations of PE2 and PE3 are similar to the configuration of PE1. For configuration details, see Configuration Files in this section.

    After completing the configurations, run the display ip vpn-instance verbose command on PEs to view the configurations of VPN instances.

    <PE1> display ip vpn-instance verbose
 Total VPN-Instances configured : 1
 Total IPv4 VPN-Instances configured : 1 
 Total IPv6 VPN-Instances configured : 0
 VPN-Instance Name and ID : vpna, 1
  Interfaces : GigabitEthernet0/1/8
 Address family ipv4 
  Create date : 2009/09/18 11:30:35
  Up time : 0 days, 00 hours, 05 minutes and 19 seconds
  Vrf Status : UP
  Route Distinguisher : 100:1
  Export VPN Targets :  111:1
  Import VPN Targets :  111:1
  Label policy: label per route
  The diffserv-mode Information is : uniform
  The ttl-mode Information is : pipe

  5. Set up EBGP peer relationships between PEs and CEs and import VPN routes to the loopback interfaces of the CEs.

    # Configure CE1.

    [~CE1] interface loopback 1
[*CE1-Loopback1] ip address 11.11.11.11 32
[*CE1-Loopback1] quit
[*CE1] bgp 65001
[*CE1-bgp] peer 10.1.1.2 as-number 100
[*CE1-bgp] network 11.11.11.11 32
[*CE1-bgp] quit
[*CE1] commit

    The configurations of CE2 and CE3 are similar to the configuration of CE1. For configuration details, see Configuration Files in this section.

    # Configure PE1.

    [~PE1] bgp 100
[~PE1-bgp] ipv4-family vpn-instance vpna
[*PE1-bgp-vpna] peer 10.1.1.1 as-number 65001
[*PE1-bgp-vpna] commit
[~PE1-bgp-vpna] quit

    The configurations of PE2 and PE3 are similar to the configuration of PE1. For configuration details, see Configuration Files in this section.

    After completing the configurations, run the display bgp vpnv4 vpn-instance peer command on PEs. The command output shows that BGP peer relationships have been established between PEs and CEs.

    The following example uses the peer relationship between PE1 and CE1.

    <PE1> display bgp vpnv4 vpn-instance vpna peer
 BGP local router ID : 1.1.1.1
 Local AS number : 100
 Total number of peers : 1            Peers in established state : 1
  Peer            V    AS  MsgRcvd  MsgSent    OutQ  Up/Down    State        PrefRcv
  10.1.1.1        4   65001  11     9          0     00:06:37   Established  1

  6. Enable MPLS on the interface that connects one ASBR to the other ASBR, set up an MP-EBGP peer relationship between the ASBRs, and configure the ASBRs not to filter received VPNv4 routes based on VPN targets.

    # On ASBR 1, enable MPLS on GE 0/1/8 connected to ASBR 2.
    [~ASBR1] interface GigabitEthernet 0/1/8
[~ASBR1-GigabitEthernet0/1/8] ip address 10.21.1.1 24
[*ASBR1-GigabitEthernet0/1/8] mpls
[*ASBR1-GigabitEthernet0/1/8] quit
[*ASBR1] commit

    # On ASBR1, set up an MP-EBGP peer relationship between ASBR1 and ASBR2, and configure ASBR1 not to filter received VPNv4 routes.

    [~ASBR1] bgp 100
[~ASBR1-bgp] peer 10.21.1.2 as-number 200
[*ASBR1-bgp] ipv4-family vpnv4
[*ASBR1-bgp-af-vpnv4] peer 10.21.1.2 enable
[*ASBR1-bgp-af-vpnv4] undo policy vpn-target
[*ASBR1-bgp-af-vpnv4] commit
[~ASBR1-bgp-af-vpnv4] quit
[~ASBR1-bgp] quit

    The configuration of ASBR2 is similar to the configuration of ASBR1. For configuration details, see Configuration Files in this section.

  7. Configure ASBR1 as an RR to reflect the VPNv4 routes from PE1 to PE3, and reflect the VPNv4 routes from PE3 to PE1.

    # Configure ASBR1.

    [~ASBR1] bgp 100
[~ASBR1-bgp] ipv4-family vpnv4
[*ASBR1-bgp-af-vpnv4] peer 1.1.1.1 reflect-client
[*ASBR1-bgp-af-vpnv4] peer 3.3.3.3 reflect-client
[*ASBR1-bgp-af-vpnv4] commit
[~ASBR1-bgp-af-vpnv4] quit
[~ASBR1-bgp] quit

  8. Verify the configuration.

    After completing the configurations, run the display bgp vpnv4 all routing-table command on the ASBRs. The command output shows routes sent from PEs. The following example uses the command output on ASBR2.

    <ASBR2> display bgp vpnv4 all routing-table
 BGP Local router ID is 6.6.6.6
 Status codes: * - valid, > - best, d - damped, x - best external, a - add path,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete


 Total number of routes from all PE: 3
 Route Distinguisher: 100:1


      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  11.11.11.11/32     5.5.5.5         0          100        0      ?
 Route Distinguisher: 200:2


      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  22.22.22.22/32     2.2.2.2         0          100        0      ?
 Route Distinguisher: 100:3



      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn

 *>i  33.33.33.33/32     5.5.5.5         0          100        0      ?

    CE1, CE2, and CE3 can successfully ping each other.

    <CE1> ping -a 11.11.11.11 33.33.33.33
  PING 33.33.33.33: 56  data bytes, press CTRL_C to break
    Reply from 33.33.33.33: bytes=56 Sequence=1 ttl=252 time=120 ms
    Reply from 33.33.33.33: bytes=56 Sequence=2 ttl=252 time=73 ms
    Reply from 33.33.33.33: bytes=56 Sequence=3 ttl=252 time=111 ms
    Reply from 33.33.33.33: bytes=56 Sequence=4 ttl=252 time=86 ms
    Reply from 33.33.33.33: bytes=56 Sequence=5 ttl=252 time=110 ms
  --- 33.33.33.33 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 73/100/120 ms

Configuration Files

  • CE1 configuration file

    #
 sysname CE1
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
#
interface Loopback1
 undo shutdown
 ip address 11.11.11.11 255.255.255.255
#
bgp 65001
 peer 10.1.1.2 as-number 100
 network 11.11.11.11 255.255.255.255
 #
 ipv4-family unicast
  undo synchronization
  peer 10.1.1.2 enable
#
return

  • PE1 configuration file

    #
 sysname PE1
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 100:1
  apply-label per-instance
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#
mpls lsr-id 1.1.1.1
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.10.1.2 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip binding vpn-instance vpna
 ip address 10.1.1.2 255.255.255.0
#
interface LoopBack1
 ip address 1.1.1.1 255.255.255.255
#
bgp 100
 peer 5.5.5.5 as-number 100
 peer 5.5.5.5 connect-interface LoopBack1
 #
 ipv4-family unicast
  undo synchronization
  peer 5.5.5.5 enable
 #
 ipv4-family vpnv4
  policy vpn-target
  peer 5.5.5.5 enable
 #
 ipv4-family vpn-instance vpna
  peer 10.1.1.1 as-number 65001
#
ospf 1
 area 0.0.0.0
  network 10.10.1.0 0.0.0.255
  network 1.1.1.1 0.0.0.0
#
return

  • PE3 configuration file

    #
 sysname PE3
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 100:3
  apply-label per-instance
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#
mpls lsr-id 3.3.3.3
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.30.1.2 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip binding vpn-instance vpna
 ip address 10.3.1.2 255.255.255.0
#
interface LoopBack1
 ip address 3.3.3.3 255.255.255.255
#
bgp 100
 peer 5.5.5.5 as-number 100
 peer 5.5.5.5 connect-interface LoopBack1
 #
 ipv4-family unicast
  undo synchronization
  peer 5.5.5.5 enable
 #
 ipv4-family vpnv4
  policy vpn-target
  peer 5.5.5.5 enable
 #
 ipv4-family vpn-instance vpna
  peer 10.3.1.1 as-number 65003
#
ospf 1
 area 0.0.0.0
  network 3.3.3.3 0.0.0.0
  network 10.30.1.0 0.0.0.255
#
return

  • CE3 configuration file

    #
 sysname CE3
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.3.1.1 255.255.255.0
#
interface Loopback1
 undo shutdown
 ip address 33.33.33.33 255.255.255.255
#
bgp 65003
 peer 10.3.1.2 as-number 100
 network 33.33.33.33 255.255.255.255
 #
 ipv4-family unicast
  undo synchronization
  peer 10.3.1.2 enable
#
return

  • ASBR1 configuration file

    #
 sysname ASBR1
#
mpls lsr-id 5.5.5.5
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.10.1.1 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.21.1.1 255.255.255.0
 mpls
#
interface GigabitEthernet0/1/16
 undo shutdown
 ip address 10.30.1.1 255.255.255.0
 mpls
 mpls ldp
#
interface LoopBack1
 ip address 5.5.5.5 255.255.255.255
#
bgp 100
 peer 1.1.1.1 as-number 100
 peer 1.1.1.1 connect-interface LoopBack1
 peer 3.3.3.3 as-number 100
 peer 3.3.3.3 connect-interface LoopBack1
 peer 10.21.1.2 as-number 200
 #
 ipv4-family unicast
  undo synchronization
  peer 1.1.1.1 enable
  peer 3.3.3.3 enable
  peer 10.21.1.2 enable
 #
 ipv4-family vpnv4
  undo policy vpn-target
  peer 1.1.1.1 enable
  peer 1.1.1.1 reflect-client
  peer 3.3.3.3 enable
  peer 3.3.3.3 reflect-client
  peer 10.21.1.2 enable
#
ospf 1
 area 0.0.0.0
  network 5.5.5.5 0.0.0.0
  network 10.10.1.0 0.0.0.255
  network 10.30.1.0 0.0.0.255
#
return

  • ASBR2 configuration file

    #
 sysname ASBR1
#
mpls lsr-id 6.6.6.6
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.40.1.1 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.21.1.2 255.255.255.0
 mpls
#
interface LoopBack1
 ip address 6.6.6.6 255.255.255.255
#
bgp 200
 peer 2.2.2.2 as-number 200
 peer 2.2.2.2 connect-interface LoopBack1
 peer 10.21.1.1 as-number 100
 #
 ipv4-family unicast
  undo synchronization
  peer 2.2.2.2 enable
  peer 10.21.1.1 enable
 #
 ipv4-family vpnv4
  undo policy vpn-target
  peer 2.2.2.2 enable
  peer 10.21.1.1 enable
#
ospf 1
 area 0.0.0.0
  network 6.6.6.6 0.0.0.0
  network 10.40.1.0 0.0.0.255
#
return

  • PE2 configuration file

    #
 sysname PE2
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 200:2
  apply-label per-instance
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#
mpls lsr-id 2.2.2.2
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.40.1.2 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip binding vpn-instance vpna
 ip address 10.2.1.2 255.255.255.0
#
interface LoopBack1
 ip address 2.2.2.2 255.255.255.255
#
bgp 200
 peer 6.6.6.6 as-number 200
 peer 6.6.6.6 connect-interface LoopBack1
 #
 ipv4-family unicast
  undo synchronization
  peer 6.6.6.6 enable
 #
 ipv4-family vpnv4
  policy vpn-target
  peer 6.6.6.6 enable
 #
 ipv4-family vpn-instance vpna
  peer 10.2.1.1 as-number 65002
#
ospf 1
 area 0.0.0.0
  network 10.40.1.0 0.0.0.255
  network 2.2.2.2 0.0.0.0
#
return

  • CE2 configuration file

    #
 sysname CE2
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.2.1.1 255.255.255.0
#
interface Loopback1
 undo shutdown
 ip address 22.22.22.22 255.255.255.255
#
bgp 65002
 peer 10.2.1.2 as-number 200
 network 22.22.22.22 255.255.255.255
 #
 ipv4-family unicast
  undo synchronization
  peer 10.2.1.2 enable
#
return
Parent Topic: Configuration Examples for BGP/MPLS IP VPN
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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