I have some queries in "draft-ietf-vrrp-unified-spec-02", Please help me to clarify the same.
1) Question : Virtual router can be configured with one or more IPv6 address. I would like to know the application scenario, why multiple IPv6 virtual address are required in virtual address.
6.1. Parameters per Virtual Router
IPv6_Addresses One or more IPv6 addresses associated with
this virtual router. Configured item. No
default. The first address must be the Link-
Local address associated with the virtual
router.
2) Question: When the Master router goes down and before it comes up(restarts), if any other node in the network configures the same IPv6 address of Master router and backup router is not available, then there will be a address
conflict in the network. This scnario will happen when DAD is not performed(Owner address) by Master when it restarts.
8.2.2. ND Neighbor Solicitation
Note that on a restarting Master router where the VRRP protected
address is the interface address, (that is, priority 255) duplicate
address detection (DAD) may fail, as the Backup router may answer
that it owns the address. One solution is to not run DAD in this
case.
3) Question: The draft discuss about how to fill the source address when sending out a Redirect message by a virtual router.
But I would like to know what is the actual scnario where Redirct is used when hosts are connected
to virtual routers.
8.2.1. ICMPv6 Redirects
The IPv6 source address of an ICMPv6 redirect should be the address
the end host used when making its next hop routing decision. If a
VRRP router is acting as Master for virtual router(s) containing
addresses it does not own, then it must determine which virtual
router the packet was sent to when selecting the redirect source
address. A method to deduce the virtual router used is to examine
the destination MAC address in the packet that triggered the
redirect.
4) The following is my understanding from the Draft, Please correct if it is wrong
This problem will happen when accept mode flag is disbaled(all host route associated with virtual address
will get deleted), so when a packet is received for a virtual address which is not address owner, the virtual
router should drop the packet and should not forward it.
8.3.1. Potential Forwarding Loop
A VRRP router SHOULD not forward packets addressed to the IPvX
Address it becomes Master for if it is not the owner. Forwarding
these packets would result in unnecessary traffic. Also in the case
of LANs that receive packets they transmit (e.g., token ring) this
can result in a forwarding loop that is only terminated when the IPvX
TTL expires.
One such mechanism for VRRP routers is to add/delete a reject host
route for each adopted IPvX address when transitioning to/from MASTER
state.
The RFC states that the VRRP advertisement can have multiple virtual IPv6 addresses. How are these addresses used by the VRRP router & host device ?