'Basic OSPFv3 Configuration'

[spj2019]

Hi, 
I'm trying to setup a simple OSPFv3 configuration for IPv4. (Packet Tracer doesn't help me on this as there is only support for IPv6, so I need some hw to try it out. ). I've defined a simple transit network using a 10.100.20.0/16 network. Internally the L3 switches (Cisco 3650 with IOS 15.2) have their own LANs, 10.200.10.0/24 and 10.200.20.0/24 respectively.  I don't need IPv6 addresses. 

So I've defined :

L3-Router1

router ospfv3 10
router-id 10.200.10.1
address-family ipv4 unicast
exit-address-family

interface Vlan100
ip address 10.100.10.1 255.255.0.0
 ipv6 enable 
 ospfv3 10 ipv4 area 0
interface Vlan700
 ip address 10.200.10.1 255.255.255.0
 ipv6 enable
 ospfv3 10 ipv4 area 0

On L3-Router2

router ospfv3 10
router-id 10.200.20.1
address-family ipv4 unicast
exit-address-family

interface Vlan100
ip address 10.100.10.2 255.255.0.0
 ipv6 enable 
 ospfv3 10 ipv4 area 0
interface Vlan700
 ip address 10.200.20.1 255.255.255.0
 ipv6 enable
 ospfv3 10 ipv4 area 0

OSPFv3 comes up but if I run some show commands I find a Neighbor but no OSPF routes:

#sh ospfv3 database

OSPFv3 10 address-family ipv4 (router-id 10.200.20.1)

Router Link States (Area 0)

ADV Router Age Seq# Fragment ID Link count Bits
10.200.10.1 968 0x80000092 0 1 None
10.200.20.1 967 0x8000008B 0 1 None

Link (Type-8) Link States (Area 0)

ADV Router Age Seq# Link ID Interface
10.200.20.1 55 0x80000001 37 Vl700
10.200.10.1 964 0x80000003 36 Vl100
10.200.20.1 968 0x80000001 41 Vl100

Intra Area Prefix Link States (Area 0)

ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
10.200.10.1 90 0x80000006 0 0x2001 0
10.200.20.1 55 0x80000002 0 0x2001 0

#sh ospfv3 database neighbor

OSPFv3 10 address-family ipv4 (router-id 10.200.20.1)

Neighbor ID Pri State Dead Time Interface ID Interface
10.200.10.1 0 FULL/ - 00:00:31 36 Vlan100

#sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
C 10.200.0.0/24 is directly connected, Vlan700
L 10.200.20.1/32 is directly connected, Vlan700
C 10.100.0.0/16 is directly connected, Vlan100
L 10.100.10.2/32 is directly connected, Vlan100

Did I miss something ? Thought it would be rather straight-forward except for the IP family concept, which is very new to me. Basically I get the same results running the sh commands on the other side, no OSPF routes. What have I done wrong? 
Thank you for any advice!

[Giuseppe Larosa]

Hello Spj2019,

support of address family in OSPFv3 is provided by means of the instance-id.

0-31 unicast IPv6

64-95 unicast IPv4

try under address-family ipv4 unicast to set an instance id of 64 (it should be the default for this address family)

Another aspect is to assign IPv6 addresses to interfaces not only link local addresses.

Yes I have seen examples setting ipv6 addresses not simply ipv6 enable command under interface.

You may try this too.

Edit:

have you enabled ipv6 unicast-routing in global config ?

Edit2

In the example I have seen ospfv3 is also enabled for address-family IPv6 unicast on the same links.

Using

ospfv3 10 ipv6 area 0

on all links see if the behaviour changes.

Hope to help

Giuseppe

[spj2019]

Thanks Giuseppe. My requirements are only for IPv4, not IPV6, so I think I can't use link local addresses. I'll look into the instance concept which is new to me : I have yet to understand how to use them. 

Yes, ipv6 unicast-routing is defined. 

Regards, spj

[Giuseppe Larosa]

Hello,

OSPFv3 works on IPv6 link local addresses, also for routing IPv4 this is the reason why virtual-links are not supported for IPv4 address family.

In the example I have seen IPv6 addresses are assigned to the interfaces and also routing for IPv6 address family is enabled on the same links.

Hope to help

Giuseppe

[Harold Ritter]

Your configuration looks good. It should work. I suspect a bug. What IOS version do you use?

The following looks like a bug:

C 10.200.0.0/24 is directly connected, Vlan700

should be

C 10.200.20.0/24 is directly connected, Vlan700

Which leads me to believe that this is a bug.

Regards,

[spj2019]

Hi,

the version I'm using is 15.2. I guess we'll have to check the known bugs for that...

Cheers, spj

[Harold Ritter]

15.2 is quite old. I would suggest you try with something more recent.

Regards,

[spj2019]

Hi, 
By chance I noticed that when running the     sh ospfv3 interface    command, one of the vlan interfaces was down because no devices were physically attached to it. Once I plugged in a laptop, the vlan came up and the route was published in Ospfv3. So the configuration does work if all interfaces are up. Sorry, I haven't used vlan interfaces very often... Thanks for your help & time!   
spj

[Giuseppe Larosa]

Hello spj2019,

>> By chance I noticed that when running the     sh ospfv3 interface    command, one of the vlan interfaces was down because no devices were physically attached to it. Once I plugged in a laptop, the vlan came up and the route was published in Ospfv3.

Yes SVI interfaces , L3 Vlan interfaces are logical interfaces but their state is not always up/up like it is for loopbacks.

Their line state is UP if at least one L2 switchport is UP and in STP forwarding state either an access port a trunk port that allows that L2 Vlan.

This was called autostate.

The SVI interface should act as the gateway for the associated L2 Vlan, if no ports are alive in corresponding L2 Vlan the SVI is not useful anymore and the whole IP subnet is actually "unplugged".

Nice to know that you have solved your issue.

Link local addresses are enough to run OSPFv3 as expected in theory.

Hope to help

Giuseppe