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IPv6 NDP Neighbor Discovery protocol in IPv6 is useful for  Router Discovery SLAAC Duplicate Address Detection (DAD) Neighbour MAC Discovery Router Discovery Hosts learn the IPv6 addresses of the available IPv6 routers in the same subnet using NDP messages. Two messages RS and RA help routers or hosts to learn addressing and subnetting information. Router Solicitation (RS): Hosts send RS message to the "all IPv6 routers" using local- scope multicast address - FF02::2. This message asks all the IPv6 routers on the local-link only to identify themselves. Router Advertisement (RA): RA messages sent by the router lists many details including the link-local IPv6 address of the router. Routers reply to the RS messages by sending the RA message to the unicast address of the requested host. Also, routers send unsolicited RA messages periodically to "all the IPv6 hosts" using the Local-scope multicast address - FF02::1. Neighbour MAC Discovery

1. Local Scope Multicast Addresses Multicast addresses that begin with FF02::/16 have a link-local scope i.e., routers will not forward these packets outside the local subnet. Multicast addresses that begin with FF08::/16 have an organizational-local scope i.e., packets sent to these addresses are forwarded throughout the enterprise but not out the internet. Command to verify the Local-scope Multicast addresses is show ipv6 interface G0/0 Key IPv6 Local-scope Multicast Addresses Multicast address Used to send data to IPv4 equivalent FF02::1 All nodes (All IPv6 interfaces that are on the link) A subnet broadcast address FF02::2 All routers (All IPv6 router interfaces on the link) None FF02::5 All OSPFv6 routers 224.0.0.5 FF02::6 All OSPFv6-Designated Routers 224.0.0.6 FF02::9 All RIPng routers 224.0.0.9 FF02::A All EIGRPv6 routers 224.0.0.10 FF02::1:2 All DHCPv6 Relay Agent Routers None 2. Solicied-Node Multicast Addresses It is also a Link-local multicas

Each IPv6 host including routers uses an additional unicast address called a Link-local address. Link-Local addresses are used for some overhead protocols that stay local to one subnet but not for transferring data.                                                                                                          eg., NDP (Neigbour Discovery protocol) which is the same as IPv4's ARP. Also, Routers use link-local addresses as the next-hop IP address in IPv6 routes. IPv6 hosts use Link-local addresses of the router(in the same subnet) as the default gateway address. Link-local addresses are unicast addresses, not multicast. Routers do not route packets with the link-local destination address. Every IPv6 host interface (and router interface) can create its own link-local address automatically, solving some initialization problems in hosts.  How Routers create Link-local addresses? IOS can create automatically or it can be configured using the command - IPv6

Static unicast address configuration There are 2 ways to configure the static address on routers, Configure the full 128-bit address using the ipv6 address interface subcommand.                        eg., ipv6 address 2001:DB6:1111:2::1/64                                                                                          Only configure the 64-bit prefix and let the router derive the second half of the address (Interface ID) using modified EUI-64. How to generate a unique interface ID using Modified EUI-64? EUI - Extended Unique Identifier 64 Bits 24 Bits 16 Bits 24 Bits Subnet Prefix Ist Half of MAC FFFE 2nd Half of MAC Invert the 7th Bit Example: Step 1: MAC address of the Interface - 1523.6131.7568 Step 2: Divide the MAC into two half parts              152361                             317568 Step 3: Insert FFFE in the middle              152361        FFFE            317568 Step 4: Write in the IPv6 format             1523:61FF: FE31:756

Global Unicast Address Works like Public IPv4 addresses. Should be registered with numbering authority. Assigned as a Global routing prefix by ISP. Can be used to connect to the internet. Globally unique.   Unique Local Unicast Address Works like Private IPv4 addresses. No need to register with numbering authority. Unable to connect to the internet directly. Same addresses can be used in multiple organizations. Unique Local Unicast Address Format 8 Bits 40 Bits 16 Bits 64 Bits FD Global ID (Pseudo-random) Subnet Interface ID Global routing prefix: Reserved block of IPv6 addresses, that only one company can use. Address Type First Hex Digits Global Unicast 2 or 3(originally); all not otherwise reserved. Unique Local FD Multicast FF Link-Local FE80 IPv6 subnet ID is also called as Subnet-router anycast address. Host IPv6 addresses can be configured statically and

To enter Global configuration command           config t Change/rename router name            R1# config t            R1(config)#hostname MST Enable Password           MST(config)# enable password cisco Configure Telnet Password           MST(config)#line vty 04           MST(config-line)# password cisco           MST(config-line)# login           MST(config-line)#exit Configure IP address          MST#config t          MST(config)#int fa 0/0          MST(config-if)#ip address 10.0.0.100  255.255.255.0          MST(config-if)#no shut          MST(config-if)# Configure Password Encryption         MST#config t         MST(config)#service password-encryption         MST(config)# do show run User Creation      MST(config)#username admin privilege 15 password cisco (15 - Full access) To check the password encryption           MST(config)#do sh run l in pass