Example for Configuring Load Balancing Among Tunnels to Which Remotely Leaked IPv6 VPN Routes Recurse

If there are multiple tunnels between PEs on the backbone network, configuring load balancing among tunnels can fully utilize network resources and enhance the reliability of VPN services on the backbone network.

Networking Requirements

If multiple tunnels, such as LDP LSPs and TE tunnels, exist between PE peers on the MPLS backbone network of a BGP/MPLS IPv6 VPN, load balancing among tunnels can be configured to distribute IPv6 VPN traffic to the tunnels and prevent network congestion.

On the network shown in Figure 1, two links exist between PE1 and PE2 in the basic BGP/MPLS IPv6 VPN networking: an LDP LSP (PE1-P1-PE2) and a TE tunnel (PE1-P2-PE2). All IPv6 VPN traffic is forwarded over the LSP according to the default tunnel policy, which may cause the link of PE1 <-> P1 <-> PE2 to be busy and the link of PE1 <-> P2 <-> PE2 to be idle.

To address this issue, configure load balancing among tunnels on the MPLS backbone network to distribute IPv6 VPN traffic evenly to the two tunnels.

Figure 1 Configuring load balancing among tunnels to which remotely leaked IPv6 VPN routes recurse

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

Configuration Notes

When configuring load balancing among tunnels to which remotely leaked IPv6 VPN routes recurse, ensure that the tunnels existing in the system can meet the requirements of the configured tunnel policy.

Configuration Roadmap

The configuration roadmap is as follows:

Configure OSPF on the MPLS backbone network to ensure IP connectivity on the backbone network.
Configure MPLS, MPLS LDP, and MPLS TE both globally and per interface on required devices of the MPLS backbone network and establish an LDP LSP and an MPLS TE tunnel between PEs.
Configure an IPv6-address-family-supporting VPN instance on each PE and bind the interface that connects a PE to a CE to the VPN instance on that PE.
Create a tunnel policy on PE1 to distribute traffic to the LDP LSP and TE tunnel between PE1 and PE2.
Apply the tunnel policy to the VPN instance IPv6 address family on PE1.

Procedure

Configure a basic BGP/MPLS IPv6 VPN.
For configuration details, see Example for Configuring a Basic BGP/MPLS IPv6 VPN.
- Configure OSPF on the MPLS backbone network so that the PEs can learn the routes to each other's loopback interface.
- Configure MPLS and MPLS LDP both globally and per interface on PE1, P1, and PE2 to set up an LDP LSP along the PEs.
- Establish a VPNv6 peer relationship between PEs.
- Configure a VPN instance that supports the IPv6 address family on each PE and bind the interface that connects a PE to a CE to the VPN instance on that PE.
- Enable BGP between the PEs and CE and import the routes to the loopback interface into BGP on the CE.

Enable MPLS TE on PE1, P2, and PE2 and establish TE tunnels between PEs. For configuration details, see Configuration Files in this section.

After completing the configurations, run the display ipv6 routing-table vpn-instance command on PE1. The command output shows that PE1 has learned the route to the loopback interface on the CE.

<PE1> display ipv6 routing-table vpn-instance vpn1
Routing Table : vpn1
         Destinations : 4        Routes : 4

 Destination  : 2001:db8:0:1:2::1             PrefixLength : 128
 NextHop      : ::FFFF:3.3.3.9                  Preference   : 255
 Cost         : 0                               Protocol     : BGP
 RelayNextHop : ::                              TunnelID     : 0x800011
 Interface    : GigabitEthernet0/1/0            Flags        : RD

 Destination  : 2001:db8:9::                    PrefixLength : 28
 NextHop      : 2001:db8:9::1                   Preference   : 0
 Cost         : 0                               Protocol     : Direct
 RelayNextHop : ::                              TunnelID     : 0x0
 Interface    : LoopBack2                       Flags        : D

 Destination  : 2001:db8:9::1                   PrefixLength : 128
 NextHop      : ::1                             Preference   : 0
 Cost         : 0                               Protocol     : Direct
 RelayNextHop : ::                              TunnelID     : 0x0
 Interface    : LoopBack2                       Flags        : D

 Destination  : FE80::                          PrefixLength : 10
 NextHop      : ::                              Preference   : 0
 Cost         : 0                               Protocol     : Direct
 RelayNextHop : ::                              TunnelID     : 0x0
 Interface    : NULL0                           Flags        : D
<PE1> display ipv6 routing-table vpn-instance vpn1 2001:db8:0:1:2::1 verbose
Routing Table : vpn1
Summary Count : 1

 Destination  : 2001:db8:0:1:2::1               PrefixLength : 128
 NextHop      : ::FFFF:3.3.3.9                  Preference   : 255
 Neighbour    : ::3.3.3.9                       ProcessID    : 0
 Label        : 1027                            Protocol     : IBGP
 State        : Active Adv Relied               Cost         : 0
 Entry ID     : 21                              EntryFlags   : 0x80024904
 Reference Cnt: 2                               Tag          : 0
 IndirectID   : 0x24                            Age          : 895sec 
 RelayNextHop : ::                               TunnelID     : 0x0000000001004c4ba2
 Interface    :  GigabitEthernet0/1/0                Flags        : RD

The command output shows that PE1 recurses the route to 2001:db8:0:1:2::1/128 to only the LSP since no tunnel policy is applied to the VPN instance IPv6 address family, and the outbound interface is GE 0/1/8.

Apply the tunnel policy to the VPN instance IPv6 address family on PE1.

Configure a tunnel policy in select-sequence mode to make tunnels be selected in the order of TE tunnels and LSPs and to set the number of tunnels participating in load balancing to 2.

# Configure PE1.

[~PE1] tunnel-policy te-lsp-l2
[*PE1-tunnel-policy-te-lsp-l2] tunnel select-seq cr-lsp lsp load-balance-number 2
[*PE1-tunnel-policy-te-lsp-l2] quit

# Apply the tunnel policy to the VPN instance IPv6 address family.

[*PE1] ip vpn-instance vpn1
[*PE1-vpn-instance-vpn1] ipv6-family
[*PE1-vpn-instance-vpn1-af-ipv6] tnl-policy te-lsp-l2
[*PE1-vpn-instance-vpn1-af-ipv6] quit
[*PE1-vpn-instance-vpn1] quit
[*PE1] commit

Verify the configuration.

After completing the configurations, run the display ipv6 routing-table vpn-instance verbose command on PE1. The command output shows that the route to the loopback interface on the CE recurses to two tunnels.

<PE1> display ipv6 routing-table vpn-instance vpn1 2001:db8:0:1:2::1 verbose
Routing Table : vpn1
Summary Count : 1

 Destination  : 2001:db8:0:1:2::1               PrefixLength : 128
 NextHop      : ::FFFF:3.3.3.9                  Preference   : 255
 Neighbour    : ::                              ProcessID    : 0
 Label        : 1027                            Protocol     : BGP
 State        : Active Adv Relied               Cost         : 0
 Entry ID     : 21                              EntryFlags   : 0x80024904
 Reference Cnt: 2                               Tag          : 0
 IndirectID   : 0x24                            Age          : 895sec 
 RelayNextHop : ::                              TunnelID     : 0x000000000300000001
 Interface    : Tunnel1                         Flags        : RD
 RelayNextHop : ::                              TunnelID     : 0x0000000001004c4ba2
 Interface    : GigabitEthernet0/1/0                Flags        : RD

Load balancing between tunnels to which remote cross routes recurse is successfully deployed on the IPv6 VPN.

Configuration Files

PE1 configuration file

#
 sysname PE1
#
ip vpn-instance vpn1
 ipv6-family
  route-distinguisher 100:1
  apply-label per-instance
  tnl-policy te-lsp-l2
  vpn-target 1:1 export-extcommunity
  vpn-target 1:1 import-extcommunity
#
mpls lsr-id 1.1.1.9
#
mpls
 mpls te
 mpls te cspf
 mpls rsvp-te
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
 mpls
 mpls te
 mpls rsvp-te
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.2.1.1 255.255.255.0
 mpls
 mpls ldp
#
interface LoopBack1
 ip address 1.1.1.9 255.255.255.255
#
interface LoopBack2
 ip binding vpn-instance vpn1
 ipv6 enable
 ipv6 address 2001:db8:9::1 128
#
interface Tunnel1
 ip address unnumbered interface LoopBack1
 tunnel-protocol mpls te
 destination 3.3.3.9
 mpls te tunnel-id 100
 mpls te reserved-for-binding
#
bgp 100
 peer 3.3.3.9 as-number 100
 peer 3.3.3.9 connect-interface LoopBack1
 #
 ipv4-family unicast
  undo synchronization
  peer 3.3.3.9 enable
 #
 ipv6-family vpnv6
  policy vpn-target
  peer 3.3.3.9 enable
#
ospf 1
 opaque-capability enable
 area 0.0.0.0
  mpls-te enable 
  network 1.1.1.9 0.0.0.0
  network 10.2.1.0 0.0.0.255
  network 10.1.1.0 0.0.0.255
#
tunnel-policy te-lsp-l2
 tunnel select-seq cr-lsp lsp load-balance-number 2
#
return

P1 configuration file

#
 sysname P1
#
mpls lsr-id 2.2.2.9
#
mpls
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.2.1.2 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.3.1.1 255.255.255.0
 mpls
 mpls ldp
#
interface LoopBack1
 ip address 2.2.2.9 255.255.255.255
#
ospf 1
 opaque-capability enable
 area 0.0.0.0
  mpls-te enable 
  network 2.2.2.9 0.0.0.0
  network 10.2.1.0 0.0.0.255
  network 10.3.1.0 0.0.0.255
#
return

P2 configuration file

#
 sysname P2
#
mpls lsr-id 4.4.4.9
#
mpls
 mpls te
 mpls te cspf
 mpls rsvp-te
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
 mpls
 mpls te
 mpls rsvp-te
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.4.1.1 255.255.255.0
 mpls
 mpls te
 mpls rsvp-te
#
interface LoopBack1
 ip address 4.4.4.9 255.255.255.255
#
ospf 1
 opaque-capability enable
 area 0.0.0.0
  mpls-te enable 
  network 4.4.4.9 0.0.0.0
  network 10.4.1.0 0.0.0.255
  network 10.1.1.0 0.0.0.255
#
return

PE2 configuration file

#
 sysname PE2
#
ip vpn-instance vpn1
 ipv6-family
  route-distinguisher 100:1
  apply-label per-instance
  vpn-target 1:1 export-extcommunity
  vpn-target 1:1 import-extcommunity
#
mpls lsr-id 3.3.3.9
#
mpls
 mpls te
 mpls te cspf
 mpls rsvp-te
#
mpls ldp
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.4.1.2 255.255.255.0
 mpls
 mpls te
 mpls rsvp-te
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.3.1.2 255.255.255.0
 mpls
 mpls ldp
#
interface GigabitEthernet0/1/16
 undo shutdown
 ipv6 enable
 ip binding vpn-instance vpn1
 ipv6 address 2001:db8:2::1 64
#
interface LoopBack1
 ip address 3.3.3.9 255.255.255.255
#
bgp 100
 peer 1.1.1.9 as-number 100
 peer 1.1.1.9 connect-interface LoopBack1
 #
 ipv4-family unicast
  undo synchronization
  peer 1.1.1.9 enable
 #
 ipv6-family vpnv6
  policy vpn-target
  peer 1.1.1.9 enable
#
 ipv6-family vpn-instance vpn1
  peer 2001:db8:2::2 as-number 65410
#
ospf 1
 opaque-capability enable
 area 0.0.0.0
  mpls-te enable 
  network 3.3.3.9 0.0.0.0
  network 10.3.1.0 0.0.0.255
  network 10.4.1.0 0.0.0.255
#
return

CE1 configuration file

#
 sysname CE1
#
interface GigabitEthernet0/1/0
 undo shutdown
 ipv6 enable
 ipv6 address 2001:db8:2::2 64
#
interface LoopBack1
 ipv6 enable
 ipv6 address 2001:db8:0:1:2::1/128
#
bgp 65410
 router-id 10.10.10.10
 peer 2001:db8:2::1 as-number 100
 #
 ipv6-family unicast
  undo synchronization
  network 2001:db8:0:1:2::1 128
  peer 2001:db8:2::1 enable
#
return