ICND2 – Chapter 19 – IPv6


1. Address Assignment Features – Allows easier renumbering, dynamic allocation, and recovery of addresses
2. Aggregation – Blocks are easier to aggregate vs. IPv4
3. No Need for NAT/PAT
4. IPSec required – more secure
5. Header improvements – no need to recalculate Checksums – Flow label to easily identify packets belonging to same connection
6. Transition Tools –

Public IPv6 addresses are grouped by major geographical region.

Inside each region, the address space is further divided to ISPs in that region.

Each ISP in a region further divides their range to customers.

ICANN assigns one or more IPv6 address ranges to each RIR (Regional Internet Registry)

IPv6 uses 32 HEXADECIMAL numbers organized into 8 quartets that are separated by a : (colon).

Each hex digit represents 4 digits.

Leading 0s can be eliminated in a quartet.

One and only 1 string of consecutive 0s (even crossing quartets) can be represented with a :: (double colon).

IPv6 addresses use / (slash) notation for subnet masks.

Address Types:

Global Unicast – Same as IPv4 public addresses
Prefix 2000::/3 (Can be easily identified as it starts with a 2 or 3)

Unique Local – Private IP addresses
Prefix FD00::/8 (Can easily be identified as it starts with FD)

Link Local – For packets sent on a local subnet
Prefix: FE80::/10 (Easily identified as starting with FE8, FE9, FEA, and FEB)

Multicast – Multicasts that stay on local subnet
Prefix: FE2::/16 (Easily identified as it starts with FF02)

Special Addresses:

FF02::1 – All nodes on the link
FF02::2 – All routers on the link
FF02::12 – Used by hosts to send to a DHCPv6 inquiry

DHCPv6 servers can either be stateful or stateless.

The use of the zero-subnet or broadcast subnet is a non-issue with IPv6.


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