Internet Protocol Version 6 Solicited Node Multicast

Recap – IPV4 Address Resolution Protocol Assume 30 nodes in a network of IP 1.1.1.1 – 1.1.1.30 Initially each node is unknown to other. Now, Node 1.1.1.5 want to communicate to 1.1.1.25. It does not know the destination node mac 1.1.1.5 builds a ARP packet with src ip 1.1.1.5 destination ip 1.1.1.25;src mac address and destination mac address FF:FF:FF:FF:FF:FF (broadcast) Hey ALL in the subnet respond to me All nodes in the segment need to process the ARP packet, NOT AN EFFICIENT METHOD Recap – IPV4 Address Resolution Protocol

IPV4 Address Resolution Protocol is not an efficient method Eliminate the broadcast method, adapt multicasting for neighbor discovery. What next ? Challenges of IPv6 protocol design group ? In a broadcast network type, how do I limit neighbor discovery to a specific group? If I miss one in the segment? What is the IPv6 neighbor discovery strategy? A source node knows the destination IPv6 address? Yes If a source node could derive/GUESS the multicast IPv6 from the known destination IPv6 address will it suffice the need - Yes How to implement the strategy? When IPv6 is activated in an interface of node, let the interface also get assigned AUTOMATICALLY with an another address derived from its own IPv6 Address ? Call it as “Solicited Multicast Address” as it helps neighbor solicitation IP Version 6

Solicited Node Multicast Address Assigned with IPv6 Address 2001::/64 MAC Address 0000.0000.0001 Expanded EUI-64 IPv6 Address 2001:0:0:0:200:FF00:FE00:0001 Rules of Solicited Node Multicast Address Prefix of all solicited node multicast address is ff02::1:ff_ _:_ _ _ _/104 Derive the remaining 24 bits from the IPv6 address. Last 24 bits are used to arrive 128 bit IPv6 solicited multicast So, solicited multicast address of Node 1 ff02::1:ff00:1 Solicited Node Multicast Address

Neighbor Discovery with Solicited Multicast Address Node2’s knowledge My IPv6 Address My MAC Address Destination(Node 1) IPv6 Address Node 1 MAC address to be discovered Node2’s Neighbor(Node1) Discovery Let me guess Node 1 Solicited Node Multicast Address as I know its IPv6 Address of Node2 Apply Solicited Node Multicast Address rules as said the earlier slide Found ff02::1:ff00:1 Node2’s Discovery of Node 1 Possibilities are there more than one node of address ff02::1:ff00:1 exist in the network since it is a GUESS Is it broadcast or multicast or uni-cast Theoretically it is not a broadcast, but in reality it is Ideally it is uni-cast, but it can become a MULTICAST when more than one node exist of address ff02::1:ff00:1 by accident Further areas to explore IPv6 protocol is build with resilience to embrace Multicast with ease, provided we create an environment for it Adaption of IPv6 at Layer 2 is required hand in hand Multicast Listener Discovery (MLD) snooping an example Neighbor Discovery with Solicited Multicast Address