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ip v6

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  • The Internet will be transformed after IPv6 fully replaces its less versatile parent years from now. Nevertheless, IPv4 is in no danger of disappearing overnight. Rather, it will coexist with and then gradually be replaced by IPv6. This change has already begun, particularly in Europe, Japan, and Asia Pacific.
    These areas are exhausting their allotted IPv4 addresses, which makes IPv6 all the more attractive. In addition to its technical and business potential, IPv6 offers a virtually unlimited supply of IP addresses. The existing IPv4 provides some 2 billion useable addresses with its 32‑bit address space.
    IPv6, because of its generous 128-bit address space, will generate a virtually unlimited stock of addresses—enough to allocate more than the entire IPv4 Internet address space to everyone on the planet.
    Consequently, some countries, such as Japan, are aggressively adopting IPv6. Others, such as those in the European Union, are moving toward IPv6, and China is considering building pure IPv6 networks from the ground up.
    As of October 1, 2003, even in North America, where Internet addresses are abundant, the U.S. Department of Defense (DoD) mandated that all new equipment purchased be IPv6-capable. In fact, the department intends to switch entirely to IPv6 equipment by 2008. As these examples illustrate, IPv6 enjoys strong momentum.
  • This despite increasingly intense conservation efforts
    PPP/DHCP address sharing
    CIDR (classless inter-domain routing
    NAT (network address translation)
    plus some address reclamation
    Theoretical limit of 32-bit space: ~4 billion devices Practical limit of 32-bit space: ~250 million devices (RFC 3194)
    1981 ~ IPv4 Protocol Published
    1985 ~ 1/16 of Total Space
    1990 ~ 1/8 of Total Space
    1995 ~ 1/3 of Total Space
    2000 ~ 1/2 of Total Space
    2001.5 ~ 2/3 of Total Space
  • IPv6 is a powerful enhancement to IPv4. There are several features in IPv6 that offer functional improvements. What IP developers learned from using IPv4 suggested changes to better suit current and foreseeable network demands:
    Larger address space: Larger address space includes several enhancements: improved global reachability and flexibility; the aggregation of prefixes that are announced in routing tables; multihoming to several Internet service providers (ISPs); autoconfiguration that can include link-layer addresses in the address space; plug-and-play options; and public-to private readdressing end to end without address translation; and simplified mechanisms for address renumbering and modification.
    Simpler header: A simpler header offers several advantages over IPv4: better routing efficiency for performance and forwarding-rate scalability; no broadcasts and thus no potential threat of broadcast storms; no requirement for processing checksums; simpler and more efficient extension header mechanisms; and flow labels for per-flow processing with no need to open the transport inner packet to identify the various traffic flows.
  • Mobility and security: Mobility and security help ensure compliance with mobile IP and IPSec standards functionality. Mobility enables people to move around in networks with mobile network devices—with many having wireless connectivity.
    Mobile IP is an Internet Engineering Task Force (IETF) standard available for both IPv4 and IPv6. The standard enables mobile devices to move without breaks in established network connections. Because IPv4 does not automatically provide this kind of mobility, you must add it with additional configurations.
    In IPv6, mobility is built in, which means that any IPv6 node can use it when necessary. The routing headers of IPv6 make mobile IPv6 much more efficient for end nodes than mobile IPv4.
    IPSec is the IETF standard for IP network security, available for both IPv4 and IPv6. Although the functionalities are essentially identical in both environments, IPSec is mandatory in IPv6. IPSec is enabled on every IPv6 node and is available for use. The availability of IPSec on all nodes makes the IPv6 Internet more secure. IPSec also requires keys for each party, which implies a global key deployment and distribution.
    Transition richness: There are multiple ways to incorporate existing IPv4 capabilities with the added features of IPv6:
    One approach is to have a dual stack with both IPv4 and IPv6 configured on the interface of a network device.
    Another technique—called “IPv6 over IPv4” or “6to4” tunneling—uses an IPv4 tunnel to carry IPv6 traffic. This newer method (RFC 3056) replaces an older technique of IPv4-compatible tunneling (RFC 2893). Cisco IOS Software Release 12.3(2)T (and later) also allows protocol translation (NAT-PT) between IPv6 and IPv4. This translation allows direct communication between hosts speaking different protocols.
  • IPv6 increases the number of address bits by a factor of 4, from 32 to 128. This factor enables a very large number of addressable nodes; however, as in any addressing scheme, not all the addresses are used or available.
    Current IPv4 protocol address use is extended by applying techniques such as NAT and temporary address allocations. But the manipulation of data payload by intermediate devices challenges (or complicates) the advantages of peer-to-peer communication, end-to-end security, and quality of service (QoS).
    IPv6 gives every user multiple global addresses that can be used for a wide variety of devices, including cell phones, personal digital assistants (PDAs), and IP-enabled vehicles. Quadrupling the available 32-bit IPv4 address space to 128 bits, IPv6 addresses the need for always-on environments. These addresses are reachable without using IP address translation, pooling, and temporary allocation techniques.
    Increasing the number of bits for the address also increases the IPv6 header size. Because each IP header contains a source and a destination address, the size of the header fields that contains the addresses is 256 bits for IPv6 compared to 64 bits for IPv4.
    Note: For more IETF information on IPv6 addressing details, refer to RFC 3513.
  • The IP version 4 (IPv4) header contains 12 basic header fields, followed by an options field and a data portion (usually the transport layer segment). The basic IPv4 header has a fixed size of 20 octets. The variable-length options field increases the size of the total IP header. IPv6 contains 5 of the 12 IPv4 basic header fields. The IPv6 header does not require the other seven fields.
  • Streamlined
    Fragmentation fields moved out of base header
    IP options moved out of base header
    Header Checksum eliminated
    Header Length field eliminated
    Length field excludes IPv6 header
    Alignment changed from 32 to 64 bits
    Revised
    Time to Live  Hop Limit
    Protocol  Next Header
    Precedence and TOS  Traffic Class
    Addresses increased 32 bits  128 bits
    Extended
    Flow Label field added
    The IPv6 header has 40 octets in contrast to the 20 octets in IPv4. IPv6 has a smaller number of fields, and the header is 64-bit aligned to enable fast processing by current processors. Address fields are four times larger than in IPv4.
    The IPv6 header contains these fields:
    Version: A 4-bit field, the same as in IPv4. It contains the number 6 instead of the number 4 for IPv4.
    Traffic Class: An 8-bit field similar to the type of service (ToS) field in IPv4. It tags the packet with a traffic class that it uses in differentiated services (DiffServ). These functionalities are the same for IPv6 and IPv4.
    Flow Label: A completely new 20-bit field. It tags a flow for the IP packets. It can be used for multilayer switching techniques and faster packet-switching performance.
    Payload Length: Similar to the Total Length field of IPv4.
    Next Header: The value of this field determines the type of information that follows the basic IPv6 header. It can be a transport-layer packet, such as TCP or UDP, or it can be an extension header. The next header field is similar to the Protocol field of IPv4.
    Hop Limit: This field specifies the maximum number of hops that an IP packet can traverse. Each hop or router decreases this field by one (similar to the Time to Live [TTL] field in IPv4). Because there is no checksum in the IPv6 header, the router can decrease the field without recomputing the checksum. On IPv4 routers the recomputation costs processing time.
    Source Address: This field has 16 octets or 128 bits. It identifies the source of the packet.
    Destination Address: This field has 16 octets or 128 bits. It identifies the destination of the packet.
    Extension Headers: The extension headers, if any, and the data portion of the packet follow the eight fields. The number of extension headers is not fixed, so the total length of the extension header chain is variable.
  • There are many types of extension headers. When multiple extension headers are used in the same packet, the order of the headers should be as follows:
    IPv6 header: This header is the basic header described in the previous figure.
    Hop-by-hop options header: When this header is used for the router alert (Resource Reservation Protocol [RSVP] and Multicast Listener Discovery version 1 [MLDv1]) and the jumbogram, this header (value = 0) is processed by all hops in the path of a packet. When present, the hop-by-hop options header always follows immediately after the basic IPv6 packet header.
    Destination options header (when the routing header is used): This header (value = 60) can follow any hop-by-hop options header, in which case the destination options header is processed at the final destination and also at each visited address specified by a routing header. Alternatively, the destination options header can follow any Encapsulating Security Payload (ESP) header, in which case the destination options header is processed only at the final destination. For example, mobile IP uses this header.
    Routing header: This header (value = 43) is used for source routing and mobile IPv6.
    Fragment header: This header is used when a source must fragment a packet that is larger than the MTU for the path between itself and a destination device. The fragment header is used in each fragmented packet.
    Authentication header and Encapsulating Security Payload header: The authentication header (value = 51) and the ESP header (value = 50) are used within IPsec to provide authentication, integrity, and confidentiality of a packet. These headers are identical for both IPv4 and IPv6.
    Upper-layer header: The upper-layer (transport) headers are the typical headers used inside a packet to transport the data. The two main transport protocols are TCP (value = 6) and UDP (value = 17).
  • Routers handle fragmentation in IPv4, which causes a variety of processing issues. IPv6 routers no longer perform fragmentation. Instead, a discovery process is used to determine the optimum maximum transmission unit (MTU) to use during a given session.
    In the discovery process, the source IPv6 device attempts to send a packet at the size that is specified by the upper IP layers, for example, the transport and application layers.
    If the device receives an “ICMP packet too big” message, it retransmits the MTU discover packet with a smaller MTU and repeats the process until it gets a response that the discover packet arrived intact. Then it sets the MTU for the session.
    The “ICMP packet too big” message contains the proper MTU size for the pathway. Each source device needs to track the MTU size for each session. Generally, the tracking is done by creating a cache that is based on the destination address; however, it can also be done by using the flow label. If source-based routing is performed, the tracking of the MTU size can be done by using the source address.
    The discovery process is beneficial because, as routing pathways change, a new MTU might be more appropriate. When a device receives an “ICMP packet too big” message, it decreases its MTU size if the Internet Control Message Protocol (ICMP) message contains a recommended MTU that is less than the current MTU of the device.
    A device performs an MTU discovery every 5 minutes to see whether the MTU has increased along the pathway. Application and transport layers for IPv6 accept MTU reduction notifications from the IPv6 layer.
    If they do not accept the notifications, IPv6 has a mechanism to fragment packets that are too large; however, upper layers are encouraged to avoid sending messages that require fragmentation.
    Link-layer technologies already perform checksum and error control. Because link-layer technologies are relatively reliable, an IP header checksum is considered to be redundant. Without the IP header checksum, the upper-layer optional checksums, such as User Datagram Protocol (UDP), are now mandatory.
  • Transcript

    • 1. Module 8 Introducing IPv6 and Defining IPv6 Addressing Postgraduate Programme BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1
    • 2. Objectives  Explain the need for IPv6 address space.  Explain how IPv6 deals with the limitations of IPv4.  Describe the features of IPv6 addressing.  Describe the structure of IPv6 headers in terms of format and extension headers.  Show how an IPv6 address is represented.  Describe the three address types used in IPv6. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2
    • 3. Introducing IPv6 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 3
    • 4. Why Do We Need a Larger Address Space?  Internet population Approximately 973 million users in November 2005 Emerging population and geopolitical and address space  Mobile users PDA, pen-tablet, notepad, and so on Approximately 20 million in 2004  Mobile phones Already 1 billion mobile phones delivered by the industry  Transportation 1 billion automobiles forecast for 2008 Internet access in planes – Example: Lufthansa  Consumer devices Sony mandated that all its products be IPv6-enabled by 2005 Billions of home and industrial appliances BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 4
    • 5. IP Address Allocation History In 1981, IPv4 Protocol was published. In 1985, about 1/16 of the total IPv4 address space was in use. By mid-2001, about 2/3 of the total IPv4 address space was in use. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 5
    • 6. IPv6 Advanced Features Larger address space Simpler header  Global reachability and flexibility  Routing efficiency  Aggregation  Performance and forwarding rate scalability  Multihoming  No broadcasts  Autoconfiguration  No checksums  Plug-and-play  Extension headers  End to end without NAT  Flow labels  Renumbering BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 6
    • 7. IPv6 Advanced Features (Cont.) Mobility and security Transition richness  Mobile IP RFC-compliant  Dual stack  IPSec mandatory (or native) for IPv6  6to4 tunnels BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved.  Translation Cisco Public 7
    • 8. Defining IPv6 Addressing BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 8
    • 9. Larger Address Space IPv4  32 bits or 4 bytes long ~ = 4,200,000,000 possible addressable nodes IPv6  128 bits or 16 bytes: four times the bits of IPv4 ~ = ~ = ~ = BSCI Module 8 Lessons 1 and 2 3.4 * 1038 possible addressable nodes 340,282,366,920,938,463,374,607,432,768,211,456 5 * 1028 addresses per person © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 9
    • 10. Address Representation  128-bit IPv6 addresses are represented by breaking them up into eight 16-bit segments.  Each segment is written in hexadecimal between 0x0000 and 0xFFFF, separated by colons.  An example of a written IPv6 address is 3ffe:1944:0100:000a:0000:00bc:2500:0d0b BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 10
    • 11. Rule 1: Leading 0’s  Two rules for reducing the size of written IPv6 addresses.  The first rule is:  The leading zeroes in any 16-bit segment do not have to be written; if any 16-bit segment has fewer than four hexadecimal digits, it is assumed that the missing digits are leading zeroes. Example 3ffe : 1944 : 0100 : 000a : 0000 : 00bc : 2500 : 0d0b 3ffe : 1944 : d0b BSCI Module 8 Lessons 1 and 2 100 : © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public a : 0 : bc : 2500 : 11
    • 12. Rule 1: Leading 0’s Practice 3ffe : 0404 : 0001 : 1000 : 0000 : 0000 : 0ef0 : bc00 3ffe : 0000 : 010d : 000a : 00dd : c000 : e000 : 0001 ff02 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0005 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 12
    • 13. Rule 1: Leading 0’s Practice 3ffe : 0404 : 0001 : 1000 : 0000 : 0000 : 0ef0 : bc00 3ffe : 404 : 1 : 1000 : 0 : 0 : ef0 : bc00 3ffe : 0000 : 010d : 000a : 00dd : c000 : e000 : 0001 3ffe : 0 : 10d : a : dd : c000 : e000 : 1 ff02 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0005 ff02 : BSCI Module 8 Lessons 1 and 2 0 : © 2006 Cisco Systems, Inc. All rights reserved. 0 : Cisco Public 0 : 0 : 0 : 0 : 5 13
    • 14. Rule 1: Leading 0’s  Notice that only leading zeroes can be omitted; trailing zeroes cannot, because doing so would make the segment ambiguous.  You would not be able to tell whether the missing zeroes belonged before or after the written digits. 3ffe : 1944 : 100 : a : 0 : bc : 2500 : d0b Correct Original Address 3ffe : 1944 : 0100 : 000a : 0000 : 00bc : 2500 : 0d0b OR Wrong, Ambiguous Original Address 3ffe : 1944 : 1000 : a000 : 0000 : bc00 : 2500 : d0b0 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 14
    • 15. Rule 2: Double colon :: equals 0000… 0000  The second rule can reduce this address even further:  Any single, contiguous string of one or more 16-bit segments consisting of all zeroes can be represented with a double colon. ff02 : 0000 : 0000 : 0000 : 0000 : 0000 : 0000 : 0005 ff02 : 0 : 0 : 0 : BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. ff02::5 Cisco Public 0 : 0 : 5 : ff02 : 0 : 5 15
    • 16. Rule 2: Double colon :: equals 0000… 0000  Only a single contiguous string of all-zero segments can be represented with a double colon.  Example: Both of these are correct 2001 : 0d02 : 0000 : 0000 : 0014 : 0000 : 0000 : 0095 2001 : d02 :: 14 : 0 : 0 : 95 2001 : d02 : 0 : 0 : 14 :: 95 2001 : 0d02 : 0000 : 0000 : 0014 : 0000 : 0000 : 0095 2001 : d02 :: 14 : 0 : 0 : 95 OR 2001 : BSCI Module 8 Lessons 1 and 2 d02 : 0 : © 2006 Cisco Systems, Inc. All rights reserved. 0 : Cisco Public 14 :: 95 16
    • 17. Rule 2: Double colon :: equals 0000… 0000  Using the double colon more than once in an IPv6 address can create ambiguity. Example 2001:d02::14::95  Illegal because the length of the two all-zero strings is ambiguous; it could represent any of the following IPv6 addresses: 2001:0d02:0000:0000:0014:0000:0000:0095 2001:0d02:0000:0000:0000:0014:0000:0095 2001:0d02:0000:0014:0000:0000:0000:0095 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 17
    • 18. Network Prefixes  IPv4, the prefix—the network portion of the address —can be identified by a dotted decimal or hexadecimal address mask or a bitcount. 255.255.255.0 or /24  IPv6 prefixes are always identified by bitcount.  The address is followed by a forward slash and a decimal number indicating how many of the first bits of the address are the prefix bits. 3ffe:1944:100:a::/64 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 18
    • 19. All 0’s IPv6 Address  An IPv6 address consisting of all zeroes can be written simply with a double colon. Default address, as discussed previously, "Default Routes and OnDemand Routing," in which the address is all zeroes and the prefix length is zero: 0:0:0:0:0:0:0:0 Equals :: IPv6’s Loopback address: (The Equivalent 127.0.0.1 in IPv4) 0:0:0:0:0:0:0:1 Equals ::1 BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 19
    • 20. Simple and Efficient Header A simpler and more efficient header:  The header in IPv6 has half the fields, aligned to only 64-bits  Hardware-based, efficient processing  Improved routing efficiency and performance  Faster forwarding rate with better scalability BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 20
    • 21. IPv4 and IPv6 Header Comparison IPv4 Header Version IHL Type of Service Identification Time to Live IPv6 Header Total Length Flags Protocol Fragment Offset Header Checksum Version Traffic Class Payload Length Flow Label Next Header Hop Limit Source Address Destination Address Legend Options BSCI Module 8 Lessons 1 and 2 Padding Source Address Field’s Name Kept from IPv4 to IPv6 Fields Not Kept in IPv6 Name and Position Changed in IPv6 Destination Address New Field in IPv6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 21
    • 22. IPv6 Extension Headers Simpler and more efficient header means:  IPv6 has extension headers.  IPv6 handles the options more efficiently.  IPv6 enables faster forwarding rate and end nodes processing. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 22
    • 23. MTU Issues  Routers handle fragmentation in IPv4, which causes a variety of processing issues.  IPv6 routers do not perform fragmentation.  Instead, a discovery process determines the optimum maximum transmission unit (MTU) to use during a given session.  In the discovery process, the source IPv6 device attempts to send a packet at the size that is specified by the upper layers, such as the transport or application layer.  If the device receives an “ICMP packet too big” message, it retransmits the MTU discover packet with a smaller MTU and repeats the process until it gets a response that the discover packet arrived intact.  Then it sets the MTU for the session BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 23
    • 24. Three types of IPv6 The three types of IPv6 address follow: 1. Unicast 2. Anycast 3. Multicast  Unlike IPv4, there is no IPv6 broadcast address.  There is, however, an "all nodes" multicast address, which serves essentially the same purpose as a broadcast address. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 24
    • 25. Global Unicast Addresses  A unicast address is an address that identifies a single device.  A global unicast address is a unicast address that is globally unique.  Global unicast addresses, we mean an address with global scope.  That is, an address that is globally unique and can therefore be routed globally with no modification. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 25
    • 26. Global Unicast Addresses  The host portion of the address is called the Interface ID.  The reason for this name is that a host can have more than one IPv6 interface, and so the address more correctly identifies an interface on a host than a host itself.  But that subtlety only goes so far: A single interface can have multiple IPv6 addresses, and can have an IPv4 address in addition. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 26
    • 27. Global Unicast Addresses  Most striking difference between IPv4 addresses and IPv6 addresses, (aside from their lengths): location of the Subnet Identifier  Subnet Identifier is part of the network portion of the address rather than the host portion. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 27
    • 28. Global Unicast Addresses  With very few exceptions: Interface ID is 64 bits long Subnet ID field is 16 bits provides for 65,536 separate subnets  The IANA and the Regional Internet Registries (RIRs) assign IPv6 prefixes—normally /32 or /35 in length—to the Local Internet Registries (LIRs).  The LIRs, which are usually large Internet Service Providers, then allocate longer prefixes to their customers. In the majority of cases, the prefixes assigned by the LIRs are /48. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 28
    • 29. Global Unicast Addresses Exceptions  If the customer is very large, a prefix shorter than /48 might be assigned.  If one and only one subnet is to be addressed, a /64 might be assigned.  If one and only one device is to be addressed, a /128 might be assigned. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 29
    • 30. Anycast Addresses  An anycast address represents a service rather than a device  The same address can reside on one or more devices providing the same service. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 30
    • 31. Anycast Addresses  A service is offered by three servers, all advertising the service at the IPv6 address 3ffe:205:1100::15.  The router, receiving advertisements for the address, does not know that it is being advertised by three different devices; instead, the router assumes that it has three routes to the same destination and chooses the lowest-cost route.  In this is the route to server C with a cost of 20. Preferred route BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 31
    • 32. Multicast Addresses  A multicast address identifies not one device but a set of devices—a multicast group.  A packet being sent to a multicast group is originated by a single device; therefore a multicast packet normally has a unicast address as its source address and a multicast address as its destination address.  A multicast address never appears in a packet as a source address.  IPv6 does not have a reserved broadcast address like IPv4, but it does have a reserved all-nodes multicast group. (FF02::1) BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 32
    • 33. Multicast Addresses BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 33
    • 34. Summary  IPv6 is a powerful enhancement to IPv4. Features that offer functional improvement include a larger address space, simplified header, and mobility and security.  IPv6 increases the number of address bits by a factor of four, from 32 to 128.  The IPv6 header has 40 octets and is simpler and more efficient than the IPv4 header.  IPv6 addresses use 16-bit hexadecimal number fields separated by colons (:) to represent the 128-bit addressing format.  The three types of IPv6 addresses are unicast, multicast, and anycast. BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 34
    • 35. Resources  IPv6 Addressing At-A-Glance http://cisco.com/application/pdf/en/us/guest/tech/tk872/c1550/cdccont_  IPv6 Extension Headers Review and Considerations http://cisco.com/en/US/partner/tech/tk872/technologies_white_paper09  IPv6 Headers At-A-Glance http://cisco.com/application/pdf/en/us/guest/tech/tk872/c1482/cdccont_ BSCI Module 8 Lessons 1 and 2 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 35

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