Unit 18
Chapter 12
IPv6 Basics and Address Notation
IPv6 addresses are 128 bits long
Link Local Addresses
Strictly for LAN communication.
Replaces MAC address for local addressing!
Neighbor Discovery Protocol replaces arp.
‘How To “arp -a” In IPv6’
https://www.practicalcodeuse.com/how-to-arp-a-in-ipv6
https://oswalt.dev/2011/10/neighbor-solicitation-ipv6s-replacement-for-arp/
IPv6 ‘arp’ For Windows:
netsh int ipv6 show neigh
IPv6 ‘arp’ For Linux:
ip -6 neigh
Link Local addresses always start with:
fe80:0000:0000:0000
The second half is the Host ID, eg.:
0001:0002:0003:0004
The full Link Local address is like:
fe80:0000:0000:0000:0001:0002:0003:0004
External IPv6 Addresses
The first half is the Network Number, given by the nearest router upon boot.
They start with a number in the 2000s:
2004:1234:5678:90ab
The second half is the Host ID:
0001:0002:0003:0004
The full address is like:
2004:1234:5678:90ab:0001:0002:0003:0004
Address Shortening Rules
1. Leading zeros can be dropped, eg. :0223: becomes :223:
2. Continuous groups of four zeros can be abbreviated as :: , eg. :0000:0000:0000: becomes ::
3. But you can only use that abbreviation once.
4. All CIDRs are /64
5. IPv6 loopback is ::1
Multicast
No more broadcast in IPv6. You can multicast to all nodes (think all computers) at
ff02::1
or all routers at
ff02::2
This is the address our NIC cries out to, to find a router and join an IPv6 network.
Anycast
There’s not much like it in IPv4. In IPv6, it allows several systems scattered over large distances to share the same address. Thus anyone anywhere can ask for that address, and automatically connect to the nearest system. Think of Google or Youtube: you just need the closest server, not any particular server.
RIRs
DHCP
DNS
Tunneling
4to6
6in4
Teredo, Miredo
ISATAP