Example for Configuring OSPFv3 Route Summarization on an ASBR

This section provides an example showing how to configure OSPFv3 route summarization on an ASBR.

Networking Requirements

Routes with the same IPv6 prefix can be summarized into one route. On a large-scale OSPFv3 network, route lookup may slow down because of the large size of the routing table. To reduce the routing table size and simplify management, configure route summarization. With route summarization, if a link connected to a device within the IPv6 address range that has been summarized alternates between up and down, the link status change is not advertised to the devices beyond the IPv6 address range. This prevents route flapping and improves network stability.

In Figure 1, both the ASBR and Device A run OSPFv3. The ASBR imports three static routes with the same prefix: 2001:DB8:2::1/128, 2001:DB8:3::1/128, and 2001:DB8:4::1/128. To reduce the routing table size, simplify route management, and improve network stability, configure the ASBR to summarize the three static routes into route 2001::/16 and advertise the summary route only to area 0.

Figure 1 Example for configuring OSPFv3 route summarization on an ASBR

Interface 1 in this example represents GE 0/1/0.

Configuration Roadmap

The configuration roadmap is as follows:

Assign an IP address to each interface to ensure that devices on the network can communicate with each other.
Configure basic OSPFv3 functions on the ASBR and Device A.
Configure three static routes (2001:DB8:2::1/128, 2001:DB8:3::1/128, and 2001:DB8:4::1/128) and import them to OSPFv3.
Configure OSPFv3 route summarization on the ASBR.

Data Preparation

To complete the configuration, you need the following data:

Area 0
Router ID (1.1.1.1) of Device A
Router ID (2.2.2.2) of the ASBR

Procedure

Configure an IP address for each interface. For configuration details, see "Configuration Files" in this section.

Configure basic OSPFv3 functions.

# Configure Device A.

[~DeviceA] ospfv3 1
[*DeviceA-ospfv3-1] router-id 1.1.1.1
[*DeviceA-ospfv3-1] area 0.0.0.0
[*DeviceA-ospfv3-1-area-0.0.0.0] quit
[*DeviceA-ospfv3-1] quit
[*DeviceA] commit
[~DeviceA] interface gigabitethernet0/1/0
[~DeviceA-GigabitEthernet0/1/0] ospfv3 1 area 0
[*DeviceA-GigabitEthernet0/1/0] quit
[*DeviceA] commit

# Configure the ASBR.

[~ASBR] ospfv3 1
[*ASBR-ospfv3-1] router-id 2.2.2.2
[*ASBR-ospfv3-1] area 0.0.0.0
[*ASBR-ospfv3-1-area-0.0.0.0] quit
[*ASBR-ospfv3-1] quit
[*ASBR] commit
[~ASBR] interface gigabitethernet0/1/0
[~ASBR-GigabitEthernet0/1/0] ospfv3 1 area 0
[*ASBR-GigabitEthernet0/1/0] quit
[*ASBR] commit

# Run the display ospfv3 peer command to check whether an OSPFv3 neighbor relationship is established between Device A and the ASBR. The following example uses the command output on the ASBR:

[~ASBR] display ospfv3 peer

OSPFv3 Process (1)
OSPFv3 Area (0.0.0.0)
Neighbor ID      Pri State            Dead Time  Interface          Instance ID
1.1.1.1            1 Full/DR          00:00:37   GE0/1/0               0

Configure three static routes (2001:DB8:2::1/128, 2001:DB8:3::1/128, and 2001:DB8:4::1/128) and import them to OSPFv3.

[~ASBR] ipv6 route-static 2001:DB8:2::1 128 NULL0
[*ASBR] ipv6 route-static 2001:DB8:3::1 128 NULL0
[*ASBR] ipv6 route-static 2001:DB8:4::1 128 NULL0
[*ASBR] commit
[~ASBR] ospfv3 1
[*ASBR-ospfv3-1] import-route static
[*ASBR-ospfv3-1] quit
[~ASBR] commit

# Run the display ospfv3 lsdb command on the ASBR to check the OSPFv3 LSDB information. The AS-external LSA field information shows the three static routes.

[~ASBR] display ospfv3 lsdb
           OSPFv3 Router with ID (2.2.2.2) (Process 1)

               Link-LSA (Interface GE0/1/0)
Link State ID   Origin Router    Age   Seq#       CkSum      Prefix
0.0.0.18        1.1.1.1          172   0x80000002 0xa78d          1
0.0.0.18        2.2.2.2          117   0x80000002 0xde3b          1

               Router-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum    Link
0.0.0.1         1.1.1.1          115   0x80000002 0xd020      1
0.0.0.1         2.2.2.2          80    0x80000003 0xb633      1

               Network-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum 
0.0.0.18        1.1.1.1          115   0x80000001 0xd333

               Intra-Area-Prefix-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum   Prefix Reference      
0.0.0.1         1.1.1.1          115   0x80000001 0x279b       1 Network-LSA    

               AS-External-LSA
Link State ID   Origin Router    Age   Seq#       CkSum  Type  
0.0.0.1         2.2.2.2          76    0x80000001 0xade0 E2     0.0.0.2         2.2.2.2          76    0x80000001 0xb3d8 E2     0.0.0.3         2.2.2.2          76    0x80000001 0xb9d0 E2 
[~ASBR] display ospfv3 lsdb external

           OSPFv3 Router with ID (2.2.2.2) (Process 1)

               AS-External-LSA

  LS Age: 116
  LS Type: AS-External-LSA
  Link State ID: 0.0.0.1
  Originating Router: 2.2.2.2
  LS Seq Number: 0x80000001
  Retransmit Count: 0
  Checksum: 0xade0
  Length: 48
  Flags: (E|-|T)
   Metric Type: 2 (Larger than any link state path)
      Metric: 1
   Prefix: 2001:DB8:2::1/128
    Prefix Options: 0 (-|-|-|-|-)
    Tag: 1

  LS Age: 116
  LS Type: AS-External-LSA
  Link State ID: 0.0.0.2
  Originating Router: 2.2.2.2
  LS Seq Number: 0x80000001
  Retransmit Count: 0
  Checksum: 0xb3d8
  Length: 48    
  Flags: (E|-|T)
   Metric Type: 2 (Larger than any link state path)
      Metric: 1 
   Prefix: 2001:DB8:3::1/128
    Prefix Options: 0 (-|-|-|-|-)
    Tag: 1
  LS Age: 116

  LS Type: AS-External-LSA
  Link State ID: 0.0.0.3
  Originating Router: 2.2.2.2
  LS Seq Number: 0x80000001
  Retransmit Count: 0
  Checksum: 0xb9d0
  Length: 48    
  Flags: (E|-|T)
   Metric Type: 2 (Larger than any link state path)
      Metric: 1 
   Prefix: 2001:DB8:4::1/128
    Prefix Options: 0 (-|-|-|-|-)
    Tag: 1

Configure route summarization on the ASBR.
# Configure the ASBR to summarize the three static routes into route 2001::/16.
```
[~ASBR] ospfv3 1
[*ASBR-ospfv3-1] asbr-summary 2001:: 16
[*ASBR-ospfv3-1] quit
[*ASBR] commit
```

Verify the configuration.

Run the display ospfv3 lsdb command on the ASBR to check the OSPFv3 LSDB information. The following command output shows that the three static routes have been summarized into route 2001::/16.

[~ASBR] display ospfv3 lsdb

           OSPFv3 Router with ID (2.2.2.2) (Process 1)

               Link-LSA (Interface GE0/1/0)
Link State ID   Origin Router    Age   Seq#       CkSum      Prefix
0.0.0.18        1.1.1.1          643   0x80000002 0xa78d          1
0.0.0.18        2.2.2.2          588   0x80000002 0xde3b          1

               Router-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum    Link
0.0.0.1         1.1.1.1          586   0x80000002 0xd020      1
0.0.0.1         2.2.2.2          551   0x80000003 0xb633      1

               Network-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum 
0.0.0.18        1.1.1.1          586   0x80000001 0xd333

               Intra-Area-Prefix-LSA (Area 0.0.0.0)
Link State ID   Origin Router    Age   Seq#       CkSum   Prefix Reference      
0.0.0.1         1.1.1.1          586   0x80000001 0x279b       1 Network-LSA    

               AS-External-LSA
Link State ID   Origin Router    Age   Seq#       CkSum  Type  
0.0.0.4         2.2.2.2          123   0x80000001 0x606f E2    
[~ASBR] display ospfv3 lsdb external

           OSPFv3 Router with ID (2.2.2.2) (Process 1)

               AS-External-LSA

  LS Age: 133
  LS Type: AS-External-LSA
  Link State ID: 0.0.0.4
  Originating Router: 2.2.2.2
  LS Seq Number: 0x80000001
  Retransmit Count: 0
  Checksum: 0x606f
  Length: 36
  Flags: (E|-|T)
   Metric Type: 2 (Larger than any link state path)
      Metric: 2
   Prefix: 2001::/16
    Prefix Options: 0 (-|-|-|-|-)
    Tag: 1

# Run the display ospfv3 asbr-summary command on the ASBR to check information about the summarized route.

[~ASBR] display ospfv3 asbr-summary

OSPFv3 Process (1)
 Prefix                                 Prefix-Len   Matched          Status        
 2001::                                 16           3 [Active]       Advertised

Configuration Files

Device A configuration file

#
sysname Device A
#               
ospfv3 1        
 router-id 1.1.1.1
 area 0.0.0.0   
#               
interface GigabitEthernet0/1/0
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:DB8:1::2/64
 ospfv3 1 area 0.0.0.0
#               
return

ASBR configuration file

#
sysname ASBR
#               
ospfv3 1        
 router-id 2.2.2.2
 import-route static
 asbr-summary 2001:: 16
 area 0.0.0.0   
#               
interface GigabitEthernet0/1/0
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:DB8:1::1/64
 ospfv3 1 area 0.0.0.0
#               
ipv6 route-static 2001:DB8:2::1 128 NULL0
ipv6 route-static 2001:DB8:3::1 128 NULL0
ipv6 route-static 2001:DB8:4::1 128 NULL0
#               
return