1. IPv6 (Internet Protocol V. 6)
W.lilakiatsakun

2. IPv6 Overview
IPv6 was first formally described in Internet standard document RFC 2460
Initial motivation: 32-bit address space soon to be completely allocated.
Additional motivation:
header format helps speed processing/forwarding
header changes to facilitate QoS
IPv6 datagram format:
fixed-length 40 byte header
no fragmentation allowed

3. IPv4 Header Vs IPv6 Header

4. IPv6 Header
Traffic Class (Priority): identify Class of traffic (priority) among datagrams in flow
Flow Label: identify datagrams in same “flow.”
(concept of “flow” is defined in RFC 3697)
Next header: identify upper layer protocol for data

5. Other changes
Checksum: removed entirely to reduce processing time at each hop
Options: allowed, but outside of header, indicated by “Next Header” field
ICMPv6: new version of ICMP
additional message types, e.g. “Packet Too Big”
multicast group management functions

6. Summary of IPv6 Header (1)
New fields:
Flow label
Traffic class
Modified fields:
Total length becomes Payload length
TTL becomes Hop Limit
Protocol becomes Next Header (indicates extension header)

7. Summary of IPv6 Header (2)
Eliminated fields:
Header length -> not necessary since IPv6 header is fixed length
Header checksum -> reduce processing time at each hop
ID, Flag, Segmentation, Protocol, Options, Padding -> moved to “extended header”

8. Traffic Class Field
The 8-bit Traffic Class field in the IPv6 header is available for use by originating nodes and/or forwarding routers to identify and distinguish between different classes or priorities of IPv6 packets.
It is used to provide “Differentiated Service” that defines in RFC 2474

9. Flow Label
The 20 bits field Flow classifiers had been based on 5-tuple:
Source/destination address
protocol type
Source/destination port numbers
Flow label value of 0 used when no special QoS requested (the common case today)

10. Next Header Field
Extension headers are daisy-chained by the “next header” field
The order is fixed

11. Example of Next Header Value (1)
Hop-by-Hop header (0)
Destination options header (w/ routing header) (60)
Routing header (43)
Fragment header (44)
Authentication header (51)
ESP header (50)

12. Example of Next Header Value (2)
ESP header (50)
Mobility header (135)
Destination options header (60)
ICMPv6 (58)
No Next header (59)
Upper-layer header (Varies—TCP=6, UDP=17)

13. IPv6 Addressing IPv6 address has 128 bits
2128 = 3.4x1038 addresses!!!!
340,282,366,920,938,463,463,374,607,431,768,211,456
4.3x1020 addresses per square inch on earth
Enough address for every grain of sand on earth!

14. Addressing Format (1)

15. Addressing Format (2) Representation Abbreviations are possible
16-bit hexadecimal numbers
Numbers are separated by (:)
Hex numbers are not case sensitive
Abbreviations are possible
Leading zeros in contiguous block could be represented by (::)
Example:
2001:0db8:0000:130F:0000:0000:087C:140B
2001:0db8:0:130F::87C:140B
Double colon only appears once in the address

16. Addressing Format (3) Rule 1: Leading zeros can be removed
Rule 2: 0000 can be written as 0
Rule 3: Use “::” for all zeros in one or more group of 16-bit number

17. Example of IPv6 Address

18. Prefix Representation
In this representation you attach the prefix length like IPv4 address:
/16
IPv6 address is represented the same way:
2001:db8:12::/48
Only leading zeros are omitted. Trailing zeros are not omitted
2001:0db8:0012::/48 = 2001:db8:12::/48
2001:db8:1200::/ :db8:12::/48

19. IPv6 Addressing Model Interface “expected” to have multiple addresses
Addresses have scope
Link Local
Unique Local
Global
Addresses have lifetime
Valid and preferred lifetime

20. Address Type (1) Unicast Multicast Anycast No more broadcast addresses
Address of a single interface. One-to-one delivery to single interface
Multicast
Address of a set of interfaces. One-to-many delivery to all interfaces in the set
Anycast
Address of a set of interfaces. One-to-one-of-many delivery to a single interface in the set that is closest
No more broadcast addresses

21. Address Type (2) Unicast Global start with 2 or 3
2000::/3
3FFE:85B:1F1F::A9:1234
Link Local start with FE8x – FEBx
Site-Local (Deprecated) start with FECx – FEFx
Unique Local (ULA) start with FC00: FD00
IPv4 Compatible start with 0 – 96 bits
Anycast Address is allocated from unicast prefix

22. Address Type (3)

23. Global Unicast Address
Global Unicast Addresses Are:
Addresses for generic use of IPv6
Structured as a hierarchy to keep the aggregation

24. Unique Local Unique-Local Addresses Used for: Local communications
Inter-site VPNs
Not routable on the Internet

25. Link Local Link-Local Addresses Used for:
Mandatory Address for Communication between two IPv6 device (like ARP but at Layer 3)
Automatically assigned by Router as soon as IPv6 is enabled. Only Link Specific scope
Remaining 54 bits could be Zero or any manual configured value

26. IP Multicast Address IP multicast address has a prefix FF00::/8
( ); the second octet defines the lifetime and scope of the multicast address

27. Multicast Mapping over Ethernet
Mapping of IPv6 multicast address to Ethernet
address is:
33:33:<last 32 bits of the IPv6 multicast address>

28. Solicited-Node Multicast Address (1)
For each unicast and anycast address configured there is a corresponding solicited-node multicast
This is specially used for two purpose, for the replacement of ARP, and DAD (Duplicate Address Detection)
Used in neighbor solicitation messages

29. Solicited-Node Multicast Address (2)
Multicast address with a link-local scope
Solicited-node multicast consists of prefix + lower 24 bits from unicast, FF02::1:FF:XXXXXX

30. Anycast Address (1)
Anycast allows a source node to transmit IP datagrams to a single destination node out of a group destination nodes with same subnet id based on the routing metrics
Only routers should respond to anycast addresses
Routers configured to respond to anycast packets will do so when they receive a packet send to the anycast address

31. Anycast Address (2)

32. Prefix Allocation Generally subdivide 48 bits for site prefix
80 bits for internal site numbering
16 bits for subnet number
64 bits for host number on subnet
Host address can use EUI-64 (MAC-based)
Guarantee uniqueness
No need for manual or DHCP assignment

33. Subnet Organizations assign subnets (similar to IPv4)
Obtain 48-bit site prefix from ISP
Combine with each 16-bit subnet number
Produces 64-bit prefix for every link
Configure prefix in all routers attached to link
Configure router advertisements
Routers will distribute prefix info to hosts
Hosts configure their own addresses

34. Host ID (Interface ID)(1)
The Interface ID can be configured manually or auto-configured by any of the following methods:
Using a randomly generated number
Using DHCPv6
Using the Extended Unique Identifier (EUI-64) format.

35. Host ID (Interface ID)(2)
This format expands the device interface
48-bit MAC address to 64 bits by inserting FFFE into the middle 16 bits.
Cisco commonly uses the EUI-64 host ID format to do stateless auto-configuration for Cisco IP Phones, gateways, routers, and so forth.

36. Host ID (Interface ID)(3)
Extended Unique Identifier (EUI-64)

37. Host Address Assignment
IPv6 provides the following mechanisms for assigning address to IPv6 devices:
Manual Configuration
IPv6 Stateless Address Auto-Configuration (RFC2462)
DHCP for IPv6
Stateless DHCP
Stateful DHCP

38. Manual Configuration
An IPv6 address can be configured statically by a human operator. This can be an appropriate method of assigning addresses for router interfaces and static network elements and resources.
However, manual assignment is open to errors and operational overhead due to the 128-bit length and hexadecimal attributes of the addresses.

39. IPv6 Stateless Address Auto-Configuration (1)
Stateless address auto-configuration (SLAAC) provides a convenient method to assign IP addresses toIPv6 nodes.
If you want to use IPv6 SLAAC on an IPv6 node, then it is important to connect that IPv6 node to a network with at least one IPv6 router.
This router is configured by the network administrator and sends out Router Advertisement (RA) announcements onto the link.

40. IPv6 Stateless Address Auto-Configuration (2)
With SLAAC, the node uses the IPv6 network prefix advertised in the link-local router's RAs and creates the IPv6 host ID by using the phone's MAC address and the EUI-64 format for host IDs.

41. Neighbor Discovery (1)
Replaces ARP, ICMP (redirects, router discovery)
Reachability of neighbors
Hosts use it to discover routers, auto configuration of addresses
Duplicate Address Detection (DAD)

42. Neighbor Discovery (2)
Neighbor discovery uses ICMPv6 messages, originated from node on link local with hop limit of 255
Five neighbor discovery messages
1. Router solicitation (ICMPv6 type 133)
2. Router advertisement (ICMPv6 type 134)
3. Neighbor solicitation (ICMPv6 type 135)
4. Neighbor advertisement (ICMPv6 type 136)
5. Redirect (ICMPV6 type 137)

43. Router Solicitation and Advertisement
Router solicitations (RS) are sent by booting nodes to request RAs for configuring the interfaces
Routers send periodic Router Advertisements (RA) to the all-nodes multicast address

44. Neighbor Solicitation and Advertisement
The Neighbor Solicitation message allows a device to check that a neighbor exists and is reachable, and to initiate address resolution.
The Neighbor Advertisement message confirms the existence of a host or router, and also provides layer-two address information when needed.

45. Redirect

46. Why DHCPv6
Stateless auto-configuration only configures addresses;not “other configuration” information (DNS servers,domain search list)
Stateless auto-configuration is “one-size fits all”
Addresses can not be selectively assigned
Policies can not be enforced about clients allowed addresses

47. DHCP v6 (1)
DHCP Process is same as in IPv4
If a client wishes to receive configuration parameters,it will send out a request on the attached local network to detect available DHCPv6 servers. This is done through the Solicit and Advertise messages
DHCP Solicit message is sent to the All-DHCP-Agents multicast address
Using the link-local address as the source address

48. DHCP v6 (2) Multicast addresses used:
FF02::1:2 = All DHCP Agents (servers or relays, Link-local scope)
FF05::1:3 = All DHCP Servers (Site-local scope)
DHCP Messages: Clients listen UDP port 546; servers and relay agents listen on UDP port 547

49. DHCP Operation
The default gateway has two configurable bits in its Router Advertisement (RA)
available for this purpose:
• O bit — When this bit is set, the client can use DHCPv6 to retrieve other configuration parameters (for example, TFTP server address or DNS server address) but not the client's IP address.
• M bit — When this bit is set, the client can use DHCPv6 to retrieve a managed IPv6 address and other configuration parameters from a DHCPv6 server.

50. Stateless DHCPv6 (RFC 3736)
When a router sends an RA with the O bit set but does not set the M bit, the client can use Stateless Address Auto-Configuration (SLAAC) to obtain its IPv6 address and use DHCPv6 to obtain additional information (such as TFTP server address or DNS server address).
This mechanism is known as Stateless DHCPv6 because the DHCPv6 server does not have to keep track of the client address bindings.

51. Stateful DHCP (RFC 3315)
When a router sends an RA with the M bit set, this indicates that clients should use DHCP to obtain their IP addresses.
When the M bit is set, the setting of the O bit is irrelevant because the DHCP server will also return "other" configuration information together with the addresses.
This mechanism is known as Stateful DHCPv6 because the DHCPv6 server does keep track of the client address bindings.

52. DHCPv6 & DHCPv4