Simple IPV6 OSPF configuration
Open Shortest Path First (OSPF) is a routing protocol for IP. It is a link-state protocol, as opposed to a distance-vector protocol. A link-state protocol makes routing decisions based on the states of the links that connect source and destination machines. The state of a link is a description of that interface and the relationship to its neighboring networking devices. The interface information includes the IPv6 prefix of the interface, the network mask, the type of network it is connected to, the routers connected to that network, and so forth. This information is propagated in various type of link-state advertisements (LSAs)
Configuring OSPF under IPV6 has small, but simplified implementation techniques. Here are some important differences:
- Router-ID is still in a 32 bit format (example 1.1.1.1)
- Area configuration is done on the interface level
- We can have multiple processes under one interface either logic or physical
Here we have a simple scenario in with two Area OSPF configuration using the IPV6 protocol with sample global prefix IP addresses.
So , next to examine the config files on all the routers. Router 4 is configured in Area 1 and all of the others are configured under the area 0. Before implementing any command scripts we must type in the following to enable proper IPV6 routing:
- ipv6 unicast-routing
- ipv6 cef
This is done on the global connfiguration mode. Let us see the rest of the important configuration on the routers.
R1
interface Loopback0
ip address 1.1.1.1 255.255.255.255
ipv6 address 3000::1/128
ipv6 ospf 1 area 0
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 3500::1/96
ipv6 ospf 1 area 0
!
interface FastEthernet1/0
no ip address
duplex auto
speed auto
ipv6 address 2001::1/64
ipv6 enable
ipv6 ospf 1 area 1
!
ipv6 router ospf 1
router-id 1.1.1.1
log-adjacency-changes
R2
interface Loopback0
ip address 2.2.2.2 255.255.255.255
ipv6 address 3000::2/128
ipv6 enable
ipv6 ospf 1 area 0
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 3500::2/96
ipv6 ospf 1 area 0
!
ipv6 router ospf 1
router-id 2.2.2.2
log-adjacency-changes
R3
interface Loopback0
ip address 2.2.2.2 255.255.255.255
ipv6 address 3000::2/128
ipv6 enable
ipv6 ospf 1 area 0
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 3500::2/96
ipv6 ospf 1 area 0
!
ipv6 router ospf 1
router-id 2.2.2.2
log-adjacency-changes
R4
interface Loopback0
ip address 4.4.4.4 255.255.255.255
ipv6 address 2002::1/128
ipv6 enable
ipv6 ospf 1 area 1
!
interface FastEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001::2/64
ipv6 enable
ipv6 ospf 1 area 1
!
ipv6 router ospf 1
router-id 4.4.4.4
log-adjacency-changes
To further examine and verify we see the new changes that are not used under the IPV4 configuration. The area is configured under the interface level ipv6 ospf 1 area 1. And we have kept the 32 bit format of the router-id address under the global router ospf proccess router-id 4.4.4.4.
To verify we can see that we have advertised the loopbacks and the wan links. The DR/BDR election is done in similar way like in IPV4. The router-id are our loopback addresses.
R1#sh ipv6 ospf neighbor
Neighbor ID Pri State Dead Time Interface ID Interface
2.2.2.2 1 FULL/DROTHER 00:00:39 4 FastEthernet0/0
3.3.3.3 1 FULL/DR 00:00:38 4 FastEthernet0/0
4.4.4.4 1 FULL/DR 00:00:37 4 FastEthernet1/0
Now let us look at the routing table of the R1 as it is playing the role of the ABR router in this scenario.
R1#sh ipv6 route
IPv6 Routing Table - 10 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
C 2001::/64 [0/0]
via ::, FastEthernet1/0
L 2001::1/128 [0/0]
via ::, FastEthernet1/0
O 2002::1/128 [110/1] <<< router R1 will propagate this route as InterArea
via FE80::CE06:FF:FEFC:0, FastEthernet1/0
LC 3000::1/128 [0/0]
via ::, Loopback0
O 3000::2/128 [110/1]
via FE80::CE01:FF:FEFC:0, FastEthernet0/0
O 3000::3/128 [110/1]
via FE80::CE02:FF:FEFC:0, FastEthernet0/0
C 3500::/96 [0/0]
via ::, FastEthernet0/0
L 3500::1/128 [0/0]
via ::, FastEthernet0/0
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0
To verify the InterArea connectivity and the routing exchange we will ping the loopback address of the R4 from the R2 router using the loopback as the source address.
R2#ping 2002::1 source loopback 0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2002::1, timeout is 2 seconds:
Packet sent with a source address of 3000::2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/45/72 ms
And we have a success. The routing OSPF domain has fully converged. Simple enough. More to come !!!
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