IPV6 (Internet Protocol Version 6)

What is IPv6?

• Internet protocol version 6 (also called as IPng- IP next generation)

What are IPv6 address? And how they are used?

• IPv6 address are 128 bit address that help in forming networks.
• They are also logical address just like IPv4 address.
• IPv6 address are used to route data from one IPv6 network to another IPv6 network.

Why IPv6 addresses came?

• IPv4 addressing scheme has 4.3 billion (4294967296) IP addresses.
• IPv4 addresses are not enough in future with internet evolution.
• Internet architects knew that IPv4 addresses will get finished with the growth of the internet, and this was the motivation for them to come up with a different IP scheme, which is IPv6 addressing scheme.
• IPv6 is introduced as the IPv4 addresses are being saturated.

What is the motivation for us to move to IPv6?

• It has very large address space.  (2^128)
• IPv6 encapsulation is simpler than IPv4, providing faster forwarding rates by routers and better routing efficiency. No checksum is included in IPv6 header.
• There is no broadcast concept in IPv6.
• There are techniques apart from DHCP to automatically assign IPv6 addresses to the end devices.
• Automatic configuration of default gateway occurs on the end devices without the use of protocols like DHCP.
• IPv6 is a plug and play protocol.
• IPsec is in built into IPv6. Two devices can dynamically negotiate security parameters and built a secure tunnel between them with no user intervention.

Differences between IPv4 and IPv6

IPv4	IPv6
Internet protocol version 4	Internet protocol version 6
32 bit valve	128 bit value
There are 4 octets.	IPv6 addresses have 8 fields.
Each octet is made up of 8 bits.	Each field is made up of 16 bits.
Each octet is separated using a dot.	Each field is separated using a colon.  ( : )
2^32 IP addresses (4.3 billion)	2^128 IP addresses
Dotted decimal notation	Represented in Hexadecimal notation
192.168.2.1	2000:58ab:0000:0000:12cd:0011:8901:13fd
Uses Unicast, Multicast, and Broadcast.	Uses Unicast, Multicast, any cast.
Classified into A B C D E classes	No classification

How IPv6 address look like.

• IPv6 address has 128 bits in total.
• IPv6 address have 8 fields.
• Each field of an IPv6 address there are 4 hexadecimal characters.
• So the total number of hexadecimal characters in an IPv6 address are 32.
• Each hexadecimal character is of 4 bits.

IPv6 addressing scheme – simplification:

There are some rules using which you can shorten the length of the IPv6 addresses:

1. The leading zeros in a field can be eliminated.
   • Example:
     • 1200:5600:0028:afcd:0004:0589:0009:ca39
     • 1200:5600:28:afcd:4:589:9:ca39

• If all the hexadecimal characters are zero within a field, then the whole field can be represented by a single zero.
  • Example: 
    • 2000:0001:0000:0000:0000:000c:00ea:0000
    • 2000:1:0:0:0:c:ea:0

• If two or more consecutive fields are all zero, then they can be represented by a double colon.
  • Example: 
    • 2000:0001:0000:0000:0000:000c:00ea:0000
    • 2000:1::c:ea:0

• We can only have a single double colon within an IPv6 address. If :: used more than once, it leads to confusion to identify set of zeros.

Reserved addressees in IPv6:

1. Global unicast addresses:
   • These are IPv6 public addresses.
   • These are provided by the service providers.
   • 
2. Multicast addresses:
   • 
   • EIGRP (IPv4): 224.0.0.10
   • EIGRP (IPv6): FF02::A
   • OSPF v2 : 224.0.0.5, 224.0.0.6
   • OSPF v3 : FF02::5, FF02::6
   • RIP v2 : 224.0.0.9
   • RIP v6(ng) : FF02::9
3. Unique local address:
   • These are private IPv6 addresses.
   • 
4. Link local addresses:
   • These are very similar to IPv4’s APIPA addresses.
   • With these addresses the device cannot communicate out of their networks.
   • But in IPv6 link local addresses perform a lot more functionality than APIPA addresses in IPv4.
   • 
5. Unspecified addresses:
   • ::              0:0:0:0:0:0:0:0 (since it contains all zeros)
6. Loopback addresses:
   • ::1            0:0:0:0:0:0:0:1

Configuring IPv6 on cisco router:

• Configuring IPv6 addresses on the interface of the router:
  1. Manual configuration of IPv6 address on an interface  (static IP)
  2. Stateless auto configuration    ( EUI-64 )
  3. Statefull configuration   (through DHCP server) (Dynamic IP)
• By default cisco routers do not route IPv6 data.
• By default routers route IPv4 data.
• In IPv6 by default routers acts as IPv6 hosts.
• To enable IPv6 routing on cisco router
  • R(config)#ipv6 unicast routing

Stateless auto configuration:

• In stateless configuration the first 64 bits (network portion) of the IPv6 network is sent by router within Router advertisement message, the next 64 bits are calculated using EUI-64 method
• Link local addresses is pre-configured on that interface when we enable IPv6 on that interface of router.
• Link local address :     FE80::/10
  • First 10 bits are network bits, the next 54 bits all are zeros and the last 64 bits           are calculated using EUI-64 method.
• Global unicast addresses are made up of two components
  1. Subnet ID (64 bits)
  2. Interface ID (EUI-64 bits)
• Subnet ID contains:
  1. The registry      (which is responsible for assigning it, such as IANA)
  2. The ISP prefix   (which ISP is associated with this address)
  3. The site prefix  (which company is associated with the address)
  4. The subnet prefix  (subnet within the site)

EUI-64 (Extended Unique Identifier – 64)

1. EUI-64 is obtained by inserting FF FE in between MAC address of the system to fulfil 64 bits.
   • EUI-64    (Extended unique identifier 64)
     • Step 1
       1. MAC address (48 bit value)
       2. FFFE (16 bit value)
     • Step 2
       1. Insert the FFFE value between the MAC address.
          • 48 bit MAC address
          • 24 bits     FFFE       24 bits
     • Step 3
       1. 7^th bit from the start is inverted.

Note: In the MAC address the following bits have some identification.

7^th bit: (G/L) (Global/Local)        8^th bit: (I/G) (Individual/Group)

IPv6 addressing scheme: