CST3607 Class Notes 2019-05-09

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Three strategies for the transition from IPv4 to IPv6:

  • Dual Stack
  • Tunneling
    • A strategy used when two computers using IPv6 want to communicate with each other and the packet must pass through a region that uses IPv4.
    • The IPv6 packet is encapsulated in an IPv4 packet
    • The IPv4 packet carries an IPv6 packet as data, the protocol value is set to 41
  • Header Translation
    • The header of the IPv6 packet is converted to an IPv4 header
    • Used when a host wants to use IPv6, but the receiver does not understand IPv6

Advantages that IPv6 has over IPv4.

  • Larger address space. (This is the primary reason that IPv6 was developed.)
  • Better header format
  • New options
  • Allowance for extension
  • Support for resource allocation
  • Support for more security

IPv6 Addressing

  • IPv6 Tutorial [9tut.com]
  • Mastering IPv6 SLAAC Concepts and Configuration [ciscopress.com]
  • What is the problem with StateLess Automatic Address Configuration (SLAAC)?
    • With SLAAC, by default no DNS configuration is returned to the host.
  • IPv4/IPv6 subnet calculator
  • IPv6 addresses fall into one of three categories / transmission methods
    • Unicast
    • Multicast
    • Anycast addressing routes datagrams to a single member of a group of potential receivers that are all identified by the same destination address. This is a one-to-one-of-many association.
  • There are no broadcast addresses in IPv6.
  • Types of IPv6 addresses.
    • Link-local addresses are similar to APIPA addresses and start with FE80.
      • A link-local address is a network address that is valid only for communications within the network segment or the broadcast domain that the host is connected to.
      • Link-local addresses are not guaranteed to be unique beyond their network segment, therefore routers do not forward packets with link-local addresses.
      • Link-local addresses are most often assigned automatically through a process known as stateless address autoconfiguration or link-local address autoconfiguration.
    • Unique local addresses are similar to private IP addresses and start with FC00.
      • Unique local addresses may be used freely, without centralized registration, inside a single site or organization or spanning a limited number of sites or organizations.
      • They are routable only within the scope of such private networks, but not in the global IPv6 Internet.
    • Global addresses are like public IP addresses and start with 2000.
    • The IPv6 loopback address is ::1.

Global Unicast IPv6 Address

Global Routing Prefix

  • This is assigned by the ISP to a customer or site.
  • The Global Routing Prefix is determined by the prefix-length notation. (example /48 or /64).
  • This is similar to the network portion of an IPv4 address.

Subnet ID

  • This is similar to the subnet portion of an IPv4 address.
  • The difference is in IPv4 the subnet is borrowed from the host portion of the address.
  • In IPv6 the Subnet ID is a separate field (/48 to /64) and not necessarily part of the Interface ID.

Interface ID

  • The Interface ID uniquely identifies an interface on the local subnet.

IPv6 Address Format

IPv6 Address Format: x:x:x:x:x:x:x:x ? where x is a 16 bit hexadecimal field, and x represents four hexadecimal digits.

An example IPv6 Address: 2001:0000:5723:0000:0000:D14E:DBCA:0764

There are:

  • 8 groups of 4 hexadecimal digits, with each group separated by “:”
  • Each group represents 16 bits (4 hexadecimal digits * 4 bits)
  • Each hexadecimal digit is equal to 4 bits
  • Each pair of hexadecimal digits are equal to 8 bits = 1 byte.
  • Hex digits are not case sensitive, so “DBCA” is same as “dbca” or “DBca”?
  • Each group is referred to as a “hextet”

IPv6 (128-bit) address contains two parts:

  • The first 64-bits is known as the prefix. The prefix includes the network and subnet address. Because addresses are allocated based on physical location, the prefix also includes global routing information. The 64-bit prefix is often referred to as the global routing prefix.
  • The last 64-bits is the interface ID. This is the unique address assigned to an interface.

Note: Addresses are assigned to interfaces (network connections), not to the host. Each interface can have more than one IPv6 address.

IPv6: Zero Omission Rules

  • Rule 1: Omission of the Leading 0s:
    • Rule 1 allows you to remove all the leading 0s in each individual hextet.
  • Rule 2: Omission of the All-0 Hextets:
    • Rule 2 uses a double colon :: to represent a single “contiguous” set of all zero hextexts.
    • It can only be used once within an IPv6 address.


  • In OSPFv3, the interfaces and therefore the networks attached to them can be configured directly on the interface, in interface configuration mode.
  • This is because if we go with the interface configuration option, the router configuration process is added automatically.
    • Router1(config-if)#ipv6 ospf 10 area 0

What is the command to configure OSPFv3 on a router?

  • In global configuration mode?
  • In interface configuration mode?

Hands-On Lab-10: Chapter 14: IPv6

  • Using Cisco Packet Tracer v7.2 or newer.
    • Packet Tracer PKA for Lab-10 Chapter 14 IPv6
    • Use 1841 router, as it understands most of the IPv6 commands in this lab.
    • RouterSim and Packet Tracer do not recognize all of the necessary IPv6 commands.
  • You must be in class to get credit for completing this lab.
  • You will need your text book for the Hands-on lab instructions.

Read / Do

Assignment #8: IPv6 Zero Omission Rules

  • Use the document to enter your answers: Assignment #8: IPv6 Zero Omission Rules (rtf)
  • If you are using the hardcopy, instead of the the Template, enter your answers in pencil, in case you have to make changes.
    • Make sure to write as neat as possible so that I can read your answers.
    • Use a pencil!
    • If you insist on using a pen, and you have to make changes, use whiteout instead of crossing out and making a mess.
  • Cisco Exam Preparation – Studying for Results

Read / Do

Read / Do

  • Study for the Final Exam
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