Primarily OSPFv2 has suppored ipv4 unicast, and with MOSPF , we can also support ipv4 multicast routing.
With OSPFv3, we can also support both ipv4+ipv6 unicast and multicast routing within these two common AFI.
I will demonstrate how you can accomplish ipv4 routing on a pair of cisco devices, using OSPFv3.
Here's out topology;
The 6509 is configured for VRF so we have a simple vrf definition;
NOTE: We have two AFI defined but in reality I only need ipv4 unicast for this demo and just for ipv4 unicast routing.
On the ASR we 1st define our ospf -process #333 for ipv4 unicasting routing;
Very simple, we define a ospfv3 router instance with a unique process #. We must have one ipv4 address active for the RID. I made our process number match, but they do NOT have to match for ospf routing.
Next, we define our interfaces for the OSPFv3 process. This helps to eliminate the BDR/DR selection process, and speed up convergence. I've built these point-2-point interface as defined as p2p , in order to take advantage of this. In a multi-access lan, you obviously could not do this. So if you have more than 2 ospf routers on a common segment, then the ospf network-type will be of a broadcast type.
You may notice that I adjust the hello-interval to maxiumum value of 65535. This is a trick to reduce the number of hello that are process on a loopback interface. If you think about it, a hello interval of 10sec ( the default btw ) is useless on a interface that will never built adjacenies to another ospf router.
Okay so far this concludes the ASR side of things.
The 6509 is configured almost identical, but we a vrf definition due to we are in a VRF.
Okay now let's check out some of the ospfv3 show commands;
And now for a full interface show output;
1st the port-channel sub-interface;
notice I highlighted the ipv6 local EUI address. Yes you need ipv6 enable on the interface.
Now the loopback interface ;
notice I highlighted the ipv6 local EUI address. Yes you need ipv6 enable on the interface, & also the EUI address has been computed for a loopback interface. Also we can see the hello/dead timers
A few Key points to keep in mind;
- OSPFv3 supports multiple AFI ( ipv4 unicast/multicast ipv6 unicast/multicast )
- No need to run a OSPFv2 process for ipv4 routing, and a OSPFv3 process for ipv6 routing
- you can collaspe both AFI into one single OSPFv3 process
- It uses a ip6 link-local address for the ospf adjacenies
- you have to enable ipv6 under the interface
- OSPFv3 process #s are built globally
- You config the ospf process under the interfaces
- you must have ipv6 unicast-routing enabled globally , and regardless if you actually plan on routing ipv6 unicast prefixes
- the same show commands for classic OSPFv2 are support in OSPFv3
- the ospfv3 database are similar but a few new LSA and changes are added with OSPFv3 routing
- most advance routers support this ( cisco IOS, IOS-XR, Juniper, Brocade )
- Juniper SRX firewall support multiple AFI , but cisco ASA, Fortinet and Checkpoints does not
Freelance Network / Security Engineer
kfelix ----a---t---socpuppets ---d---o---t---com
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