This document provides information about the CS352 course on Internetworking Protocols. It discusses the topics that will be covered in Unit III, including IPv6 transition issues, IPsec, addressing, extension headers, routing, autoconfiguration, and more. It lists the course instructor and their details. It then provides background on problems with IPv4 and advantages of IPv6. Several sections define IPv6 headers and addressing, describing the fixed header, extension headers, address notation, and network/node addressing splits.

1. Course Code: CS352
COURSE NAME: XVI / Internetworking Protocols
UNIT - III: IPV6:
IPv6 Transition issues, IP Security Protocol (Ipsec), Protocol basics, IPv6 Addressing, IPv6
Options and Extension Headers, IPv6 Multicast, IPv6 Anycast, IPv6 Internet Control
Message Protocol (ICMPv6), Neighbor Discovery, Routing, Quality of Service, Auto
configuration, Mobile IPv6, Multicast Listener Discovery (MLD), IPv6 and DNS, Next
Generation Protocols.
Course Instructor:
Dr. M. Ambika, Assistant Professor / CSE.

2. Problems with IPv4
 The imminent exhaustion of the IPv4 addressing space.
 The imminent collapse of the Internet routing structure due to explosive growth of the nondefault
routing table.
 The problem of end-to-end interoperability across routing domains in which IP addresses may not
be globally unique.
IPV6 OFFERS THREE ADVANTAGES OVER IPV4
1. Plentiful Addresses
2. Routing Scalability
3. Easier End-to-End Support
4. better performance as a result of streamlined headers, no fragmentation, and no header checksums.

4. Some of the issues that IPv6 promoters point to include the following.
 Security - IPv6-enabled nodes support the IP Security Protocol (IPsec)
 Autoconfiguration – IPv6 includes a feature called stateless autoconfiguration that lets users plug-and-play in
networks without prior contact with the network administrator.
 Mobility - improved handling of mobile IP nodes,
 Performance
 Cost – will reduce costs in various ways, including the reduced costs of administration, improved security,
better performance, and lower cost for actual registration of IP addresses.

6. IPv6 - Headers
 An IPv6 address is 4 times larger than IPv4, but surprisingly, the header of an IPv6 address is only
2 times larger than that of IPv4.
 IPv6 headers have one Fixed Header and zero or more Optional (Extension) Headers.
 All the necessary information that is essential for a router is kept in the Fixed Header.
 The Extension Header contains optional information that helps routers to understand how to
handle a packet/flow.
 IPv6 fixed header is 40 bytes long and contains the following information.

7. Fixed Header

9. S.N. Field & Description
1 Version (4-bits): It represents the version of Internet Protocol, i.e. 0110.
2 Traffic Class (8-bits): These 8 bits are divided into two parts. The most significant 6 bits
are used for Type of Service to let the Router Known what services should be provided to
this packet. The least significant 2 bits are used for Explicit Congestion Notification (ECN).
3 Flow Label (20-bits): This label is used to maintain the sequential flow of the packets
belonging to a communication. The source labels the sequence to help the router identify
that a particular packet belongs to a specific flow of information. This field helps avoid re-
ordering of data packets. It is designed for streaming/real-time media.
4 Payload Length (16-bits): This field is used to tell the routers how much information a
particular packet contains in its payload. Payload is composed of Extension Headers and
Upper Layer data. With 16 bits, up to 65535 bytes can be indicated; but if the Extension
Headers contain Hop-by-Hop Extension Header, then the payload may exceed 65535 bytes
and this field is set to 0.

10. 5 Next Header (8-bits): This field is used to indicate either the type of Extension Header, or
if the Extension Header is not present then it indicates the Upper Layer PDU. The values
for the type of Upper Layer PDU are same as IPv4’s.
6 Hop Limit (8-bits): This field is used to stop packet to loop in the network infinitely. This
is same as TTL in IPv4. The value of Hop Limit field is decremented by 1 as it passes a
link (router/hop). When the field reaches 0 the packet is discarded.
7 Source Address (128-bits): This field indicates the address of originator of the packet.
8 Destination Address (128-bits): This field provides the address of intended recipient of
the packet.

11. Extension Headers
 In IPv6, the Fixed Header contains only that much information which is necessary, avoiding those
information which is either not required or is rarely used.
 All such information is put between the Fixed Header and the Upper layer header in the form of
Extension Headers.
 Each Extension Header is identified by a distinct value.
 When Extension Headers are used, IPv6 Fixed Header’s Next Header field points to the first
Extension Header. If there is one more Extension Header, then the first Extension Header’s ‘Next-
Header’ field points to the second one, and so on. The last Extension Header’s ‘Next-Header’ field
points to the Upper Layer Header.
 Thus, all the headers points to the next one in a linked list manner.
 If the Next Header field contains the value 59, it indicates that there are no headers after this
header, not even Upper Layer Header.

12. The following Extension Headers must be supported as per RFC 2460:

13. The following IPv6 extension headers are currently defined.
Routing Header– Extended routing, like IPv4 loose source route
Fragmentation Header – Fragmentation and reassembly
Authentication Header– Integrity and authentication, security
Encapsulation Security Payload Header (ESP)– Confidentiality
Hop-by-Hop Option Header– Special options that require hop-by-hop processing
Destination Options Header– Optional information to be examined by the destination node

14. The sequence of Extension Headers should be:
Extension Headers are arranged one after another in a linked list manner, as depicted in the following diagram:

15. IPv6 Header Format
IPv6
IPv4: 20 Bytes + Options IPv6: 40 Bytes + Extension Header
Fragment
Offset
Flags
Total Length
Type of
Service
IHL
Padding
Options
Destination Address
Source Address
Header Checksum
Protocol
Time to Live
Identification
Version
IPv4 Header
Next
Header
Hop Limit
Flow Label
Traffic
Class
Destination Address
Source Address
Payload Length
Version
IPv6 Header

16. IPv4 Packet Size Limits
IPv4 packet size is restricted by a number of factors, including the following.
 Total length field This IPv4 header field is 16 bits, restricting the total size of any IPv4 packet to 65,575 octets or
fewer.
 Up to 576 octets The IPv4 specification in RFC 791 requires that all nodes be capable of accepting packets of
any size up to 576 octets. Thus, although there is an upper bound on packet size, very small packets (even
packets with no payloads) are permitted. Packets with a maximum-sized IPv4 header (60 octets) are thus able
to carry a 512 octet payload, that number of octets representing a manageable block of data (512 = 29 octets).
 Over 576 octets RFC 791 recommends that datagrams larger than 576 octets only be sent if the source is
assured that the destination will accept larger datagrams.
• While IPv4 packets are limited based on the length of the entire packet, IPv6 packets are limited on the payload
length.
• When IPv6 extension headers are present, the packet header can be considerably longer than the standard IPv6
header length (40 octets)—but the header extensions are considered to be part of the payload when calculating
payload length.

17. IP Address
o An Ipv6 address uses 128 bits as opposed to 32 bits in IPv4.
o IPv6 addresses are written using hexadecimal, as opposed to dotted decimal in IPv4.
o Because an hexadecimal number uses 4 bits this means that an IPv6 address consists of 32 hexadecimal
numbers.
o These numbers are grouped in 4’s giving 8 groups or blocks. The groups are written with a : (colon) as
a separator.
group1:group2: ……etc…. :group8
Here is an IPv6 address example:

18. IP Address
• For example, given below is a 128 bit IPv6 address represented in binary format and divided into
eight 16-bits blocks:
0010000000000001 0000000000000000 0011001000111000 1101111111100001 0000000001100011
0000000000000000 0000000000000000 1111111011111011
• Each block is then converted into Hexadecimal and separated by ‘:’ symbol:
2001:0000:3238:DFE1:0063:0000:0000:FEFB
The above address can be represented as follows using some rules
2001:0000:3238:DFE1:63:0000:0000:FEFB
[In Block 5, 0063, the leading two 0s can be omitted, such as (5th block)]
2001:0000:3238:DFE1:63::FEFB
[If two of more blocks contain consecutive zeroes, omit them all and replace with double colon sign
::, such as (6th and 7th block)]
2001:0:3238:DFE1:63::FEFB
[zeroes in the address, they can be shrunk down to a single zero, such as (2nd block):]

19. IPv6 Addressing 19
IPv6 Address Notation: Example
128.91.45.157.220.40.0.0.0.0.252.87.212.200.31.255

21. Network And Node Addresses
• In IPv4 an address is split into two components a network component and a node component.
• This was done initially using Address classes and later using subnet masking.
• In IPv6 we do the same. The first step is to split the address into two parts.
• The address is split into 2 64 bit segments the top 64 bits is the network part and the lower 64 bits the node
part:
• The upper 64 bits are used for routing.
• The lower 64 bits identify the address of the interface or node, and is derived from the actual physical or MAC
address using IEEE’s Extended Unique Identifier (EUI-64) format.
• If we look at the upper 64 bits in more detail we can see that it is split into 2 blocks of 48 and 16 bits respectively
• The lower 16 bits are used for subnets on an internal networks, and are controlled by a network administrator.
• The upper 48 bits are used for the global network addresses and are for routing over the internet.

23. GLOBAL ROUTING PREFIX AND SUBNET ID
• The IPv6 address can be in any of the defined formats, and the prefix length is the number of bits used
in the address as the global routing prefix, in decimal.
• Prefix length is stated in classless inter-domain routing (CIDR) notation.
• CIDR notation is a slash at the end of the address that is followed by the prefix length in bits.
ipv6-address/prefix-length
• The site prefix of an IPv6 address occupies up to 48 of the leftmost bits of the IPv6 address.
• For example, the site prefix of the IPv6 address
2001:db8:3c4d:0015:0000:0000:1a2f:1a2b/48 is contained in the leftmost 48 bits
2001:db8:3c4d.
You use the following representation, with zeros compressed, to represent this prefix:
2001:db8:3c4d::/48

24. You can also specify a subnet prefix, which defines the internal topology of the network to
a router. The example IPv6 address has the following subnet prefix.
2001:db8:3c4d:15::/64
The subnet prefix always contains 64 bits.
These bits include 48 bits for the site prefix, in addition to 16 bits for the subnet ID.
The following prefixes have been reserved for special use:
2002::/16 - Indicates that a 6to4 routing prefix follows.
fe80::/10 - Indicates that a link-local address follows.
ff00::/8 - Indicates that a multicast address follows.

25. IPv6 Address Scope
IPv6
Link-local: The scope is the local link (nodes on the same subnet)
Not Routed internally or externally.
Unique-local: The scope is the organization (private site addressing)
but Not routed on Internet
Global: The scope is global (IPv6 Internet addresses). Routed on Internet

27. Link Local
• These are meant to be used inside an internal network, and again they are not routed on the Internet.
• It is equivalent to the IPv4 address 169.254.0.0/16 which is allocated on an IPv4 network when no DHCP
server is found.
• Link local addresses start with fe80
• They are restricted to a link and are not routed on the Internal network or the Internet.
• Link Local addresses are self assigned i.e. they do not require a DHCP server.
• A link local address is required on every IP6 interface even if no routing is present.
Unique Local
• Unique Local are meant to be used inside an internal network.
• They are routed on the Internal network but not routed on the Internet.
• They are equivalent to the IPv4 addresses are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16
• The address space is divided into two /8 spaces:
• fc00::/8 for globally assigned addressing, and
• fd00::/8 for locally assigned addressing.
• For manually assignment by an organisation use the fd00 prefix.

28. Link Local
• These are meant to be used inside an internal network, and again they are not routed on the Internet.
• It is equivalent to the IPv4 address 169.254.0.0/16 which is allocated on an IPv4 network when no DHCP
server is found.
• Link local addresses start with fe80
• They are restricted to a link and are not routed on the Internal network or the Internet.
• Link Local addresses are self assigned i.e. they do not require a DHCP server.
• A link local address is required on every IP6 interface even if no routing is present.
Unique Local
• Unique Local are meant to be used inside an internal network.
• They are routed on the Internal network but not routed on the Internet.
• They are equivalent to the IPv4 addresses are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16
• The address space is divided into two /8 spaces:
• fc00::/8 for globally assigned addressing, and
• fd00::/8 for locally assigned addressing.
• For manually assignment by an organisation use the fd00 prefix.

29. IPv6 Address Representation: Link Local
IPv6
Hosts on the same link (the same subnet) use these automatically configured addresses to
communicate with each other.
Auto-configured IPv6 address is known as Link-Local address.
This address always starts with FE80.
The first 16 bits of link-local address is always set to 1111 1110 1000 0000 (FE80).
The next 48-bits are set to 0, thus:
Neighbor Discovery provides address resolution.
The prefix for link-local addresses is FE80::/64.
The following illustration shows the structure of a link-local address.
• These addresses are not routable, so a Router never forwards these addresses outside the link.

30. IPv6 Address Representation: Link Local
IPv6
Remaining 54 bits
Mandatory address for communication between two IPv6 devices
Automatically assigned by router as soon as IPv6 is enabled

31. IPv6 Address Representation: Unique Local
IPv6
IPv6 unicast unique-local addresses are similar to IPv4 private addresses.
The scope of a unique-local address is the internetwork of an organization’s
site. (You can use both global addresses and unique-local addresses in your
network)
The prefix for unique-local addresses is FC00::/8.

32. Unique-Local Address
This type of IPv6 address is globally unique, but it should be used in local communication. The second half of
this address contain Interface ID and the first half is divided among Prefix, Local Bit, Global ID and Subnet ID
Prefix is always set to 1111 110. L bit, is set to 1 if the address is locally assigned. So far, the meaning of L
bit to 0 is not defined. Therefore, Unique Local IPv6 address always starts with ‘FD’.

33. IPv6 Address Representation: Global Unicast
IPv6
Global unicast and anycast addresses are defined by a global routing prefix, a
subnet ID, and an interface ID.

34. Global Unicast Address
This address type is equivalent to IPv4’s public address. Global Unicast addresses in IPv6 are globally
identifiable and uniquely addressable.
Global Routing Prefix: The most significant 48-bits are designated as Global Routing Prefix which is
assigned to specific autonomous system. The three most significant bits of Global Routing Prefix is
always set to 001.

35. Network And Node Addresses
• In IPv4 an address is split into two components a network component and a node component.
• This was done initially using Address classes and later using subnet masking.
• In IPv6 we do the same. The first step is to split the address into two parts.
• The address is split into 2 64 bit segments the top 64 bits is the network part and the lower 64 bits the node
part:
• The upper 64 bits are used for routing.
• The lower 64 bits identify the address of the interface or node, and is derived from the actual physical or MAC
address using IEEE’s Extended Unique Identifier (EUI-64) format.
• If we look at the upper 64 bits in more detail we can see that it is split into 2 blocks of 48 and 16 bits respectively
• The lower 16 bits are used for subnets on an internal networks, and are controlled by a network administrator.
• The upper 48 bits are used for the global network addresses and are for routing over the internet.

36. How this interface or node ID is derived?
• The lower 64 bits identify the address of the interface or node, and is derived from the actual
physical or MAC address using IEEE’s Extended Unique Identifier (EUI-64) format.
Lowest-order 64-bit field of unicast address may be assigned in several different ways:
• auto-configured from a 64-bit EUI-64, or expanded from a 48-bit MAC
address (e.g., Ethernet address)
• auto-generated pseudo-random number (to address privacy concerns)
• assigned via DHCP
• manually configured
• possibly other methods in the future

37. • IPv6 has three different types of Unicast Address scheme.
• The second half of the address (last 64 bits) is always used for Interface ID.
• The MAC address of a system is composed of 48-bits and represented in Hexadecimal.
• MAC addresses are considered to be uniquely assigned worldwide.
• Interface ID takes advantage of this uniqueness of MAC addresses.
• A host can auto-configure its Interface ID by using IEEE’s Extended Unique Identifier (EUI-64)
format.
• First, a host divides its own MAC address into two 24-bits halves.
• Then 16-bit Hex value 0xFFFE is sandwiched into those two halves of MAC address, resulting in
EUI-64 Interface ID.

38. Conversion of EUI-64 ID into IPv6 Interface Identifier
To convert EUI-64 ID into IPv6 Interface Identifier, the most significant 7th bit of EUI-64 ID is complemented. For
example:

39. IPv6 Address Representation EUI 64
IPv6
IPv6 uses the extended universal identifier (EUI)-64 format to do stateless
autoconfiguration.
This format expands the 48-bit MAC address to 64 bits by inserting “FFFE” into
the middle 16 bits.
To make sure that the chosen address is from a unique Ethernet MAC address,
the universal/local (U/L bit) is set to 1 for global scope (0 for local scope).

40. IPv6 Address Representation EUI 64
IPv6

42. IPv6 Addressing 42
IPv6 Address Types

43. IPv6 Address Types
IPv6
Unicast
Address is for a single interface.
A packet sent to a unicast address is delivered to the interface identified by that address.
IPv6 has several types (for example, global and IPv4 mapped).
Multicast
One-to-many
An identifier for a set of interfaces
A packet sent to a multicast address is delivered to all interfaces identified by that address.
Uses a larger address range
Anycast
One-to-nearest (allocated from unicast address space).
Multiple devices share the same address.
All anycast nodes should provide uniform service.
Source devices send packets to anycast address.
Routers decide on closest device to reach that destination.
Suitable for load balancing and content delivery services.

44. Unicast address
• The unicast address specifies a single interface.
• A packet sent to a unicast address destination travels from one host to the destination host.
• The two regular types of unicast addresses include:
• Link-local addressLink-local addresses are designed for use on a single local link (local network).
Link-local addresses are automatically configured on all interfaces. The prefix used for a link-local
address is fe80::/10. Routers do not forward packets with a destination or source address
containing a link-local address.
• Global addressGlobal addresses are designed for use on any network. The prefix used for a global
address begins with binary 001.
• There are two special unicast addresses defined:
• Unspecified addressThe unspecified address is 0:0:0:0:0:0:0:0. You can abbreviate the address
with two colons (::). The unspecified address indicates the absence of an address, and it can never
be assigned to a host.
• It can be used by an IPv6 host that does not yet have an address assigned to it.
• For example, when the host sends a packet to discover if an address is used by another node, the
host uses the unspecified address as its source address.
• Loopback addressThe loopback address is 0:0:0:0:0:0:0:1. You can abbreviate the address as ::1.
The loopback address is used by a node to send a packet to itself.
https://www.computernetworkingnotes.com/networking-tutorials/ipv6-unicast-addresses-
explained.html

45. The following types of addresses are unicast IPV6 addresses −
Global unicast − Global unicast addresses are similar to public IPV4 addresses. It can be aggregated or
summarized to produce an efficient routing infrastructure.
Link-local − Nodes use link-local addresses when communicating with neighbouring nodes on the same
link, and are also called as a subnet.
Loopback − In loopback an address not assigned to any physical interface which can be used for a host to
send an IPv6 packet to itself.
Unspecified address − It is used only as a source address and represents the absence of an IPv6 address.
Unique local − It is similar to a private address in IPv4 and not intended to be routable in the IPv6
Internet.
IPv4 embedded − An IPv6 address which carries an IPv4 address in the low-order 32 bits of the address.

46. What’s the Difference Between Types of IPv4 and IPv6 Addresses?
The IPv4 address has three types:
• Unicast
• Multicast
• Broadcast
On the other hand, the IPv6 address has the following three types:
• Unicast
• Multicast
• Anycast
As you can see, the broadcast type is missing in the IPv6 version of the IP address. But IPv6 can still
broadcast a message. The broadcasting is done by Multicast in the IPv6 address.
• Note: There is no concept of classes in the IPv6 address, unlike the IPv4 address which has 5
classes.

49. 1. Unicast
• When a computer that is the source wants to communicate with another computer which is the
destination, it uses the unicast address as a destination. Therefore, the unicast address refers to a
single/individual host.
• The unicast is used to send data to a single destination. It communicates one to one.
• The range for the unicast address is 2001::/16.

50. Types of Unicast Address:
The unicast addresses are of three types:
• Global address
• Link-local address
• Unique local address or site Local
• Unspecified address
• Loopback address
• IPv4 embedded
A. Global Address:
 Global IP Address is similar to the public IP address in Class A of iPv4 address. If you don’t know,
public IP allows you to communicate with the Internet.
 It is also called the Global Unicast Address.
 So, if you want to send someone a public IP that is routable, you can use the Global Unicast Address.
 The global registries are assigned a range of 2001::/16.
 The initial 3 bits cannot be changed in the unicast address.
 IANA has assigned only 2000::/3 addresses to the global pool.
 2001:db8::/32 - is reserved range of addresses for documentation.

51. This 128 bits unicast address are made up of 3 main parts:
Global Routing Prefix:
RFC 3587 states that out of 128 bits, the leftmost three bits must be permanently fixed as 001.
Subnet IP:
You can also do the subnetting of the network which could be of 16 bits. Therefore, you can make
65,536 subnets.
Interface ID:
The interface ID is made up of 64 bits.
The following image represents the IPv6 Global Address anatomy.
Global Unicast address use – 3-1-1 Rule

52. Ranges from 2000: 0010 0000 0000 0000:
to 3FFF: 0011 1111 1111 1111:
Ie: 2000 ::/64 to 3FFF:FFF:FFF:FFF::/64
With 64 bits interface ID = 18 Quintillion devices / subnet
With 16 bits subnet ID = 65,536 subnets
Global Unicast address use – 3-1-1 Rule

53. B. Link-Local Address:
• The link-local address is made to be used for addressing a single link for purposes such as automatic address
configuration, neighbor discovery, or when there is no router present.
• The link-local address is a private IP. Therefore, it is not routable.
• It is generated in a computer when IPv6 is working in a small segment of 10-20 computers.
• Therefore, the IP is auto-generated on its own when IPv6 is enabled.
• The range of the link-local address is FE80::/10.
• These addresses are not routable.
Note: Link-local address is used in an ethernet segment or within a LAN.
The following image shows the link-local address anatomy.
It consists of 2 parts:
Network ID
Interface ID (host)

54. C. Unique Local Address:
It is also called Unicast Local Address.
It is routable except on the public Internet.
It is similar to the private IP in IPv4 address.
This IP is used in scenarios where you want to communicate in a building using a Local Area Network (LAN).
The address range is FC00::/7.
The first half of the address FC00::/8 is fixed for assignment by a global authority.
The following is the anatomy of the unique local address.
It consists of the following parts:
Global ID:
It is made up of 40 bits and is changeable.
Subnet ID:
It is made up of 16 bits and is used for subnetting.
Interface ID:
It is made up of 64 bits.

55. Unspecified address
• The unspecified address is 0:0:0:0:0:0:0:0.
• You can abbreviate the address with two colons (::).
• The unspecified address indicates the absence of an address, and it can never be assigned to a host.
• An interface uses the unspecified address as a source address only if a valid address is not assigned to the
interface.
• The unspecified address is never assigned to an interface or used as a destination address.
• Routers never forward an IPv6 packet with a source address of unspecified.
• Interfaces usually use the unspecified address to learn their own unique addresses.
.
Loopback address
• The loopback address is 0:0:0:0:0:0:0:1.
• You can abbreviate the address as ::1.
• The loopback address is used by a node to send a packet to itself.
IPv4 embedded − An IPv6 address which carries an IPv4 address in the low-order 32 bits of the address.

56. 2. Multicast
• A multicast address is used to deliver a package to a group of destinations.
• Therefore, a single source is able to communicate with many other destination hosts.
• The packet sent by the multicast address is delivered to every host that is a part of that specific group.
• The multicast has a one-to-many relationship.
• One – sender
• Multiple Receiver.
• Example: TV Channels.
• The source node have unicast address.
• Multicast can only be the destination.
• The range for the multicast address is FF00::/8.
• There is no need to make a different range for broadcasting a message. The multicast can broadcast the
message.
• The broadcasting is done by using special multicast groups – all IPv6 devices and a solicited-node multicast
address.
• The multicast address delivers the received packets to many interfaces.

58. Multicast address format
Binary 11111111 at the start of the address identifies the address as being a multicast address.
Multicast addresses have the following format:
Flags in multicast address
The 3 high-order flags are reserved, and must be initialized to 0.
T = 0 indicates a permanently-assigned (well-known) multicast address, assigned by the Internet Assigned
Number Authority (IANA).
T = 1 indicates a non-permanently assigned (transient) or dynamic multicast address.

59. Representation IPv6 Multicast Address
Preferred ff00:0000:0000:0000:0000:0000:0000:0000/8
Leading 0s omitted ff00:0:0:0:0:0:0:0/8
Compressed ff00::/8
IPv6 Multicast Address Representations

60. • It is of two types:
• Assigned or Reserved or Well Known Node multicast address
• Solicited Node multicast address
Well-Known Multicast Addresses
• Well-known multicast addresses have the prefix ff00::/12.
• the Flag field, is always set to 0 and scope is set to 2.
• Well-known multicast addresses are predefined or reserved multicast addresses for assigned groups of
devices.
• These addresses are equivalent to IPv4 well-known multicast addresses in the range 224.0.0.0 to
239.255.255.255.
• Some examples of IPv6 well-known multicast addresses include the following:
ff02::1 - All IPv6 devices or noted
ff02::2 - All IPv6 routers
ff02::5 - All OSPFv3 routers
ff02::a - All EIGRP (IPv6) routers

61. Solicited-node multicast address:
• The solicited-node multicast address is a special kind of IPv6 multicast.
• It is formed by low-order 24 bits of an address (unicast or anycast) and joining those bits to the
prefix FF02:0:0:0:0:1:FF00::/104 creates a multicast address.

62. 3. Anycast
• One-to-nearest
• The anycast address is identical to the multicast address.
• Multiple devices can have the same anycast address.
• In other words, an anycast address is assigned to more than one interface or a group of interfaces.
• A packet sent to an anycast address is routed to the “nearest” interface having that address, according to the
router’s routing table.
For example, if you live in India, the router sends your request to the Indian servers of Google.
• Therefore, assigning a unicast address to more than one interface makes a unicast address an anycast
address.
• Anycast address delivers packets to its nearest interface or node based on no.of hops, distance so on,
• There is no special prefix for an IPv6 anycast address.
• An IPv6 anycast address uses the same address range as global unicast addresses.
• Each participating device is configured to have the same anycast address.
• For example, servers A, B, and C in Figure could be DHCPv6 servers with a direct Layer 3 connection into the
network. These servers could advertise the same /128 address using OSPFv3. The router nearest the client
request would then forward packets to the nearest server identified in the routing table.

65. Check your IPV6 address…..

66. IPv4-COMPATIBLE ADDRESSES
• When IPv4 addresses are encapsulated within IPv6 addresses, a “mixed” format is allowed, in which the IPv4 portion
of the address can be represented in standard dotted quad form, while the rest of the address is formatted as a
standard IPv6 address, resulting in this form.
XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:ddd.ddd.ddd.ddd
• These addresses were originally defined to fall into two categories.
• IPv4-compatible IPv6 address The IPv6 transition mechanisms (seeRFC 2893, “Transition Mechanisms for IPv6 Hosts
and Routers”) include a technique for hosts and routers to dynamically tunnel IPv6 packets over IPv4 routing
infrastructure. IPv6 nodes that use this technique are assigned special IPv6 unicast addresses that carry a global IPv4
address in the low-order 32 bits.
• IPv4-mapped IPv6 address A second type of IPv6 address that holds an embedded IPv4 address is also defined. This
address type is used to represent the addresses of IPv4 nodes as IPv6 addresses.