Subject: [VRRP] why link-local address for ipv6 VRRP

From: Huafeng Lu <[email-masked]>
Date: Wed, 02 Jul 2008 18:01:09 +0800

Hi, VRRPers,

I'm new to this mail list...

While reading draft-ietf-vrrp-unified-spec-02, I found the virtual IPv6
address to be covered by the virtual router should be a link-local
address. On the VRRP routers that compose the virtual router, the
addresses used to send VRRP advertisements are also link-local. Is there
a reason to require link-local addresses? What's the possibility of
extending this to global addresses?

Thanks.
--
Huafeng
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From: "G. C." <[email-masked]>
Date: Wed, 2 Jul 2008 09:02:55 -0400

Hi Huafeng,

Based on my understanding of the draft, we allow the configuration of global
addresses too.

In the VRRP Advertisement packet, the draft states that the first address
must be link-local.  The other addresses can be global addresses.

Regards,
Georges Chung

---

From: Huafeng Lu <[email-masked]>
Date: Thu, 03 Jul 2008 13:27:35 +0800

G. C. ??:
> Hi Huafeng,
> 
> Based on my understanding of the draft, we allow the configuration of 
> global addresses too.
> 
> In the VRRP Advertisement packet, the draft states that the first 
> address must be link-local.  The other addresses can be global addresses.
> 
> Regards,
> Georges Chung

Thanks Georges. In other words, among the "IPvX addresses associated 
with the virtual router", at least one must be link-local, right? If so, 
why do we have to have a link-local virtual router address? (I think the 
all the "IPvX addresses associated with the virtual router" are the 
virtual addresses of the virtual router, and these virtual addresses are 
to be protected by VRRP, right?)

Thanks.
--
Huafeng

> On Wed, Jul 2, 2008 at 6:01 AM, Huafeng Lu <[email-masked] 
> <mailto:[email-masked]>> wrote:
> 
> 
>     Hi, VRRPers,
> 
>     [email-masked] <mailto:[email-masked]>

---

From: "G. C." <[email-masked]>
Date: Thu, 3 Jul 2008 09:51:26 -0400

Ideally, the draft would describe this further.  Currently, it not
explicitly stated.

One use is for Router Advertisement - a virtual router would have to use the
virtual link-local address as the source address.  When a backup router
transitions to master and starts sending out RAs, it too would need to use
the same source IP address.

Did someone see the need for this address for something else?

Cheers,
Georges

On Thu, Jul 3, 2008 at 1:27 AM, Huafeng Lu <[email-masked]> wrote:

> Thanks Georges. In other words, among the "IPvX addresses associated with
> the virtual router", at least one must be link-local, right? If so, why do
> we have to have a link-local virtual router address? (I think the all the
> "IPvX addresses associated with the virtual router" are the virtual
> addresses of the virtual router, and these virtual addresses are to be
> protected by VRRP, right?)
>
> Thanks.
> --
> Huafeng
>
>  On Wed, Jul 2, 2008 at 6:01 AM, Huafeng Lu <[email-masked] <mailto:
>> [email-masked]>> wrote:
>>
>>
>>    Hi, VRRPers,
>>

---

From: Bob Hinden <[email-masked]>
Date: Thu, 3 Jul 2008 08:37:29 -0700

Hi,

The main reason why the link-local address is the first address is  
because link-local addresses are used extensively in IPv6 neighbor  
discovery.   For example, a host's default route to a router will  
point to the link-local address, not a specific global address of the  
router.  In order for the hosts traffic to switch over to a backup  
router the link-local router of the router must be used by VRRPv6.

If this isn't clear, I suggest that one go and re-read the IPv6  
neighbor discovery and auto-configuration specifications to understand  
how IPv6 uses link-local addresses.  One need to understand ND and  
Auto-config inorder to understand how VRRPv6 works.

Regards,
Bob

On Jul 3, 2008, at 6:51 AM, G. C. wrote:

> One use is for Router Advertisement - a virtual router would have to  
> use the virtual link-local address as the source address.  When a  
> backup router transitions to master and starts sending out RAs, it  
> too would need to use the same source IP address.
>
> Based on my understanding of the draft, we allow the configuration  
> of global addresses too.
>
> with the virtual router", at least one must be link-local, right? If  
> so, why do we have to have a link-local virtual router address? (I  
> think the all the "IPvX addresses associated with the virtual  
> router" are the virtual addresses of the virtual router, and these  
> virtual addresses are to be protected by VRRP, right?)
>
> Thanks.
> --
> Huafeng
>
> On Wed, Jul 2, 2008 at 6:01 AM, Huafeng Lu <[email-masked] <mailto:[email-masked] 
> >> wrote:
>
>
>    Hi, VRRPers,
>