IPv6 Address Format

From 32 bits to 128

• IPv4
  • 192.168.100.1 /24
  • 192.168.100.001 /24
• IPv6
  • 2001:ABCD:1002:DCBA:: /64
  • 2001:ABCD:1002:DCBA:0000:0000:0000:0000: /64

64 bit networks

• /64 is the new /24
  • Ubiquitous
  • M2M Factory or point-to-point link
• 64 bit network definition
  • 2600:ABCD:4321:1234
    • 16 bit sections divided by colons.
    • 16:16:16:16
• 64 bit host identification
  • 443:8080:80:4444
• 128 bit IPv6 address
  • 2600:ABCD:4321:1234:443:8080:80:4444

IPv6 Header

• There are fewer fields
  • No checksums
  • No fragmentations
  • To keep header as small as possible
  • IT is still has twice as big as an IPv4 thogn, because we haev to store the whole IP.

• Instead of "protocol" we say "Next Header"
• Instead of time to live we say "Hop Limit"
• Traffic class is what we use for Quality of Service

IPv6 Real world

• /48 is a common assignable block size
  • /32 is also available
• There are service providers that can give you IPvv6 space by building a trunk, they will allocate you some space.
• 2600:ABCD:4321::/48
  • Each subnet would be built in the 4th block
  • 2600:ABCD:4321:0000 - 2600:ABCD:4321:FFFF
  • 1 subnet per VLAN typically

IPv6 address shortening

• We can reduce consecutive bytes of 00's.
  • 2001:ABCD:4321:DCBA:0000:0000:0000:0001
  • 2001:ABCD:4321:DCBA::1
• Reducing 00's to :: can only happen once!
  • 2001:ABCD:0000:0000:3201:0000:0000:0001
• Right
  • 2001:ABCD::3201:0:0:1
  • 2001:ABCD:0:0:3201::1
• Wrong
  • 2001:ABCD::3201::1

IPv6 Real World continues

• Site prefix 2600:ABCD:4321:: /48
• My first VLAN (1)
  • 2600:ABCD:4321:0001::/64
• My tenth VLAN (10)
  • 2600:ABCD:4321:000A::/64

IPv6 VLAN 10

• It is really important to have DNS working properly.

Ports of IPv6

• Because they are so large you probably do not have to worry about variable portions of an address.

Additional IPv6 concepts:

• SLAAC
• NDP

Practice Question (IPv4 subnetting)

• Find the network address for the following IP address and subnet mask:10.0.0.143 /25
  • 10.0.0.0
  • 10.0.0.128
  • 10.0.0.136
  • 10.0.0.140