OSPFv3 via Vman hangs at EX_START

[Alex16]

Hi folks
We had two X450a with core licence connected directly with a cable that was user for OSPFv3 peering. that worked perfectly.
Now we had to put some other extreme switches in the middle that transport this via a VMAN. since then OSPFv3 state is EX_START which is not good.
The two X450a can ping themself using IPv4 and V6 so L2 seems good.
OSPF (for IPv4) works.
Link is in broadcast mode and i tried several MTU settings.
I have XOS 12.3.

Is it a software issue that would be fixed with 15.* or is there something else you can see ?
Any idea will be welcomed. But I don't want to update XOS just to give it a try, these devices are sensitive.

Regards
Alex

[Alex16]

Thanks all for you feedback

Link type cannot be configured. it says :

Warning! Link type configuration is not supported
Link type will always be broadcast

We have Jumbo enabled all the way between these devices.
I changed MTU size on both OSPFv3 devices by typing :

configure vlan ospfv3_peer router-discovery ipv6 link-mtu 1200

is that the right command to change the frame size ?
If yes, that's what I tried earlier and i think 1200 should be small enough.
PS : I was able to ping with unfragmented packets up to 9100 from one device to the other.

[Paul_Russo]

Hey Alex I would be curious on if the two suggestions above have helped. VMANs are just a L2 tunnel and I have never seen them deny OSPF for end customer networks.

If the two suggestions above do not work, especially Daniel's, then please open a case as this should be working.

Please provide an update if you can.
P

[dflouret]

Maybe a problem with frame size? Are Jumbo Frames enabled in the vMAN ports?

Remember that vMAN adds 4 bytes to the packet...

[LeVar_Pulliam]

Alex,

regarding the OSPF configuration, have you tried changing the link-type to "Point-Point"?