Network Systems

CCNA1 Module 12: IPv6 Addressing

This is part of the CCNA1 Introduction to Networks course. This page will be updated with texts in the future… for now, please refer to my lecture on my YouTube channel.


Summary of the Module 12

  • IPv4 has a theoretical maximum of 4.3 billion addresses.
  • The IETF has created various protocols and tools to help network administrators migrate their networks to IPv6. The migration techniques can be divided into three categories: dual stack, tunneling, and translation.
  • IPv6 addresses are 128 bits in length and written as a string of hexadecimal values.
  • The preferred format for writing an IPv6 address is x:x:x:x:x:x:x:x, with each “x” consisting of four hexadecimal values.
  • There are three types of IPv6 addresses: unicast, multicast, and anycast.
  • An IPv6 unicast address uniquely identifies an interface on an IPv6-enabled device.
  • IPv6 global unicast addresses (GUAs) are globally unique and routable on the IPv6 internet.
  • An IPv6 link-local address (LLA) enables a device to communicate with other IPv6-enabled devices on the same link and only on that link (subnet).
  • The command to configure an IPv6 GUA on an interface is ipv6 address ipv6-address/prefix-length.
  • A device obtains a GUA dynamically through ICMPv6 messages. IPv6 routers periodically send out ICMPv6 RA messages, every 200 seconds, to all IPv6-enabled devices on the network.
  • RA messages have three methods: SLAAC, SLAAC with a stateless DHCPv6 server, and stateful DHCPv6 (no SLAAC).
  • The interface ID can be created using the EUI-64 process or a randomly generated 64-bit number.
  • The EUIs process uses the 48-bit Ethernet MAC address of the client and inserts another 16 bits in the middle of MAC address to create a 64-bit interface ID.
  • Depending upon the operating system, a device may use a randomly generated interface ID.
  • All IPv6 devices must have an IPv6 LLA. An LLA can be configured manually or created dynamically.
  • Cisco routers automatically create an IPv6 LLA whenever a GUA is assigned to the interface.
  • There are two types of IPv6 multicast addresses: well-known multicast addresses and solicited node multicast addresses.
  • Two commonIPv6 assigned multicast groups are: ff02::1 All-nodes multicast group and ff02::2 All-routers multicast group.
  • A solicited-node multicast address is similar to the all-nodes multicast address. The advantage of a solicited-node multicast address is that it is mapped to a special Ethernet multicast address.
  • IPv6 was designed with subnetting in mind. A separate subnet ID field in the IPv6 GUA is used to create subnets.

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