IPv6 Review: Simplified

In IPv6, the address size has moved from 32 bit IPv4 to 128 bit IPv6.

This provides huge amounts of addresses...trillions and trillions.

To make addresses more manageable, the IPv6 address is divided into 8 groups of 4 HEX characters each:
    2001:0050:0000:0000:0000:0AB4:1EA2:89AA

Each group is 16 bits.  Example, in 2001:..
                20 = 8 bits
                01 = 8 bits

Rules of IPv6:

RULE 1: Eliminate groups of consecutive zeros:
    Address above would be:
    2001:0050::0AB4:1EA2:89AA

RULE 2: Drop leading ZEROS:
    Address above would be:
    2001:50::AB4:1EA2:89AA

Types of Communication and Addresses in IPv6:

1. There is no broadcast in ipv6.
2. Unicast: one to one
3. Multicast: one to many
4. Anycast: one to closest

5. Link-local scope address:  layer 2 domain address.
6. Unique / Site-local scope address:  Organization address
7. Global scope address:  Internet / Public Address

Link-local scope address:

•  Assigned automatically as an ipv6 host comes online.    
•  Similar to the 169.254.x.x addresses of ipv4.  In ipv6 is a good thing. 
• Always begin with "FE80" (First 10 bits: 1111 1110 10...) followed by 54 bits of ZEROS.
• Last 64 bits is the 48 bit MAC ADDRESS with "FFFE" squeezed in the middle. 

            MAC ADDRESS:  0011.A123.DEF1
            fe80::0011:A1FF:FE23:DEF1  == notice FF.FE

Unique / Site-local scope address:

    - Was supposed to be similar to private addresses in ipv4.  The standard was later revised to be taken out of the RFC.

    - The ipv6 standard now don't use this scope.

Global scope address:

    - Have their high level 3 bits set to 001 (2000::/3)

    - N bits(global routing prefix 001..) - 64-BITS(SUBNET ID) -- 64 BITS HOST OR INTERFACE ID.
        The global routing prefix will be assigned to the ISPs.
            The ISPs will assign the subnets to its customers.
                The customers can further subnet it further and includes the hosts.

    - Global routing prefix is 48 bits or less.

    - Subnet ID is comprised of whatever bits are left over after the Global Routing Prefix.

    - The primary addresses expected to comprise the ipv6 internet are from the 2001::/16 subnet.

Google IPv6 BGP looking glass to see the available ipv6 out there that companies are using.

Configuring IPv6 OSPF example in Cisco:

router(config)# ipv6 unicast-routing
router(config)# ipv6 router ospf 1
router(config-router)# router-id 192.168.10.1
router(config)# interface f0/0 ==== ipv6 runs on the interface.
router(config-if)# ipv6 ospf 1 area 0

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