Re: why link-local address for ipv6 VRRP
Bob Hinden <rmh <at> alderaan.com>
2008-07-03 15:37:29 GMT
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.
On Jul 3, 2008, at 6:51 AM, G. C. wrote:
> 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?
> On Thu, Jul 3, 2008 at 1:27 AM, Huafeng Lu <Huafeng.Lv <at> sun.com> wrote:
> 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
> 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?)
> On Wed, Jul 2, 2008 at 6:01 AM, Huafeng Lu <Huafeng.Lv <at> sun.com <mailto:Huafeng.Lv <at> sun.com
> >> wrote:
> 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?
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