same link-local address on multiple interface and OSPFv3

[Matjaž Straus Istenič]

Dear list,

I've run into a problem with OSPFv3 on the router which was manually configured with the same IPv6 link-local address on several OSPF-enabled interfaces, say fe80::1 on all interfaces. Well, that was 4 years ago and almost forgotten by now. Today, I have run into a similar issue on another vendor's equipment -- OSPF declares a valid and operational neighbor down when some other non-OSPF interface with the same link-local address (fe80::x for example) fails (?). "Address fe80::x is not ready", he says.

It looks a *bug* to me. OSPF should not have a problem if the same link-local addresses are used on different interfaces. These addresses are only sent in Link LSAs (Type 8) and do not appear in any others. And they always come in pairs - interface/address.

Workaround is rather simple: use different link-local addresses on IPv6-enabled interfaces and you are safe. But, nevertheless, I think using same link-local pairs on links should not get you into any trouble, right?

Kind regards,
	Matjaž

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Matjaž Straus Istenič, Arnes
matjaz.straus at arnes.si
Tel: +386 1 4798877 Mob: +386 40 200403 Fax: +386 1 4798878
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