1. IP Version 6 (IPv6)

2. IPv4 Limitations Address space limitations Performance
IPv4 uses 32-bit addresses (enough to address over 4 billion nodes in theory)
Impossible to achieve 100% address utilization even with subnetting and CIDR
Address space will be exhausted well before reaching the four billion mark
Bigger address space will eventually be needed
Performance
IPv4 is efficient and robust, Still there is room for improvement.
IPv6 handles many issues like MTU, checksum, IP headers, IP options more efficiently

3. IPv4 Limitations (cont’d)
Security
IPv4 does not provide any security
Application layer can provide security (Ex: HTTPS). But sniffers can still find out processes and systems involved.
Transport layer can provide security (SSL operates along with transport layer). Better than application layer security, but it requires applications be rewritten to support SSL.
VPN software and hardware products
Take one stream of IP datagrams and encrypt
Each encrypted IP datagram becomes the payload of another IP datagram with different addressing information on it
Known as tunneling
Moderately well security, but hampered by lack of standard
Extra overhead

4. IPv4 Limitations (cont’d)
Autoconfiguration (ability of hosts to automatically configure themselves)
Under IPv4, DHCP allows systems to rely on servers for IP configuration.
Hosts depend on a single point of connection to the network
IPv6 can allow hosts to detect the nearest gateway for connection and configure automatically

5. IPv6 Header Fields Simplification of Header Quality of Service
Version (6)
Traffic Class (related to QoS)
Flow Label (related to Qos)
Payload Length
Next Header 8-bit selector. Identifies the type of header immediately following the IPv6 header. Uses the same values as the IPv4 Protocol field
Hop Limit
Source Address
Destination Address
Simplification of Header
Some IPv4 header fields have been dropped or made optional
Quality of Service
New capability added to label packets for special handling
Enhanced support for options
Flexible header options allow more efficient forwarding

6. IPv6 Header Format Version 4 bits TrafficClass 4 bits Flow Label
Payload Length
16 bits
Next Header
8 bits
Hop Limit
8 bits
Source address
128 bits
Destination address
128 bits

7. IPv6 Extension Headers
Accommodate some of the occasionally needed missing fields
Provide extra information for security, authentication, routing, etc.
Hop-by-Hop Options Header
Routing Header
Fragment Header
Authentication Header
Encapsulation Security Payload Header
Destination Options Header

8. IPv6 Extension Headers (cont’d)
Hop-by-Hop option header
Identified by a Next Header value of 0 in the IPv6 header
Must be examined by every node along a packet's delivery path
Used for resource reservation (RSVP, QOS, etc)
Routing header
identified by a Next Header value of 43 in the immediately preceding header
used by an IPv6 source to list one or more intermediate nodes to be "visited" on the way to a packet's destination
Very similar to IPv4's Source Route options
Fragment header
identified by a Next Header value of 44 in the immediately preceding header
used by an IPv6 source to send packets larger than would fit in the path MTU to their destinations
unlike IPv4, fragmentation in IPv6 is performed only by source nodes, not by routers along a packet's delivery path

9. IPv6 Extension Headers (cont’d)
Authentication header
Identified by a Next Header value of 51 in the immediately preceding header
Encapsulation Security Payload Header (payload type 50)
Destination Options Header
identified by a Next Header value of 60 in the immediately preceding header
Used to carry optional information that need be examined only by a packet's destination node(s)
No Next header
Value 59 in the Next Header field of an IPv6 header or any extension header indicates that there is no header following that header

10. IPv6 Fragmentation Extension Header
Next Header
8 bits
Reserved
8 bits
Offset
13 bits
RES
2 bits M
1 bit
Ident
Similar to IPv4 fragmentation fields
Fragmentation/reassembly executed only by source/destination hosts

11. Authentication Header in IPv6
Hosts establish a standards-based security association that is based on the exchange of secret keys
Before each packet is sent, IPv6 authentication creates a checksum based on the key and the entire packet content (using SHA or MD5)
Receiving side does the same for verification
SPI is an arbitrary 32-bit value that, in combination with the destination IP address and security protocol (AH), uniquely identifies the Security Association for this datagram.
Next Header
Length
Reserved
Security Parameters Index (SPI)
Sequence Number
Authentication Data
(variable number of 32-bit words)

12. Encapsulating Security Payload Protocol
Used to encrypt and encapsulate the transport layer payload or the entire IP packet
Sender side does encryption and receiver side does decryption
Extra padding can hide actual data size
Precise format of payload depends on encryption algorithm
Security Parameters Index (SPI)
Initialization Vector
Payload Area
Padding
Pad Length
Payload Type

13. Comments on Security
Authentication header protocol provides data origin authentication services and connectionless data integrity services
Encapsulating security payload protocol provides data confidentiality services and partial traffic flow confidentiality services
IPSec protocols suite is mandatory for IPv6
Will have widespread use
Currently used by VPNs
Encryption and authentication work together to create a flexible , yet powerful security solution

14. IPv6 Addresses 128 bits long
Addresses are assigned to individual interfaces on nodes
Three categories
Unicast
Anycast: An identifier for a set of interfaces
a packet sent to an anycast address is delivered to one of the interfaces identified by that address (possibly nearest one)
Used to deliver a packet to any node in a group of nodes via a single address
Example: anycast address could refer to the group of routers associated with a particular provider or subnet
Multicast: An identifier for a set of interfaces
packet sent to a multicast address is delivered to all interfaces identified by that address

15. IPv6 Address Representation
Basic form
X:X:X:X:X:X:X:X
Where X is a four-digit hexadecimal number (or 16-bit binary number)
Examples of valid IPv6 addresses
47CD:1234:4422:AC02:0022:1234:A456:0124
1030:0:0:0:C9B4:FF12:48AA:1A2B
2000:0:0:0:0:0:0:1
Contiguous 0s can be omitted:
47CD:0000:0000:0000:0000:0000:A456:0124 is same as
47CD::A456:0124
Embedded IPv4 address (special form)
::FFFF:

16. IPv6 Addressing Model
IP addresses are assigned to network interfaces rather than nodes
A unicast address is associated with only one network interface
But a network interface can be associated with more than one unicast address
In IPv4, all network interfaces, including point-to-point links that connect a node with a router requires a dedicated IP address
In IPv6, specific addresses are unnecessary for the endpoints of point-to-point links if the nodes at either end of the link are not originating or receiving
In IPv6, multiple network interfaces can share a single IPv6 address if the hardware is able to appropriately share the network load across those multiple interfaces.

17. IPv6 Address Space Prefix Use 0000 0000 Reserved 0000 0001 Unassigned
NSAP allocation
IPX allocation
0000 1
0001
001
Aggregatable Global Unicast Addresses
Prefix
Use
010
011
100
101
110
1110
1111 0
Unassigned
Link local use addresses
Site local use addresses
Multicast addresses

18. Address Space Allocation
IPv6 addresses do not have classes, but leading bits specify different uses of the IPv6 address
Aggregatable Global Unicast addresses (001 prefix)
Important chunk of address space
Like classless IPv4 addresses, only much longer
1/8th of the total address space
Large chunks of address space have been left unassigned for future growth and new features
Support for two other encoding of address schemes
NSAP (Network Service Access Point) addresses (used by ISO protocols)
IPX addresses (used by Novell’s network layer protocol
“Link local use” addresses
Used for addressing on a single link or network
Cannot be integrated into global addressing scheme
Example use includes auto address configuration and neighbor discovery

19. Address Space Allocation (cont’d)
“Site local use” addresses
Designed for local use but formatted in such a way that can be integrated into the global address scheme later
Multicast addresses
Similar to IPv4
Allow discovery of routers and hosts in a multicast group
Reserved address space
For some special types of addresses
One example: loopback address 0:0:0:0:0:0:0:1
Can be used to accommodate IPv4 addresses

20. Aggregatable Global Unicast Addresses
001
RegistryID
ProviderID
SubscriberID
SubnetID
InterfaceID
Registry ID
Identifies the registration authority, which assigns the provider portion of the address
Provider ID
An Internet service provider, which assigns the subscriber portion of the address
Subscriber ID
Distinguishes among multiple subscribers in the provider’s address space
Subnet ID
Identifies a topologically connected group of nodes within the subscriber network
Interface ID
Identifies a single node interface among group of interfaces identified by the subnet prefix
Note: At present, there is no fixed length assigned to any field yet.

21. Autoconfiguration Plug-and-play feature
Autoconfiguration is possible for IPv4 through a DHCP server which provides IP config. info. to DHCP clients
Longer address format in IPv6 provides a new form of autoconfiguration
Called stateless autoconfiguration
Does not require a server
Makes use of the hierarchical address scheme of IPv6 unicast addresses
Two parts
Interface ID and Prefix
Interface ID can be a physical address (ethernet address, for example) making it a unique link-level address
Prefix for the subnet (padded with enough zeros to make the entire address 128 bits long)
A router serving the link broadcast network prefix periodically