CCNA ITN: Module 12

IPv4 address exhaustion

due to 4.3 billion address limit

IPv6 address space

128-bit with 340 undecillion possible addresses

IPv6 adoption

driven by mobile providers, ISPs, IoT needs

Dual stack

allows IPv4 and IPv6 to run together

Tunneling

encapsulates IPv6 in IPv4 to travel over IPv4 networks

Translation

NAT64 translates between IPv4 and IPv6 packets

IPv6 address format

128-bit written as 8 hextets of hex digits

Omitting leading 0s

leading 0s in hextets can be omitted

Double colon (::)

replaces one group of all-0 hextets

Double colon rules

only used once per address, use on longest 0 string

Unicast address

identifies a single IPv6 interface

Multicast address

targets a group of devices

Anycast address

sent to nearest device with the address

No IPv6 broadcast

replaced by all-nodes multicast

Prefix notation

slashed format (e.g., /64)

Global Unicast Address (GUA)

globally routable, like public IPv4

Link-local address (LLA)

used within a local link, not routable

Unique local address (ULA)

private IPv6, fc00::/7 to fdff::/7

Subnet-Router anycast

all-0s host portion in subnet

LLA range

fe80::/10, required for all IPv6 devices

ipv6 address command

assigns GUA or LLA manually

Stateless Autoconfig (SLAAC)

device creates IPv6 address from RA message

Stateful DHCPv6

device receives full config from server

Link-local manual config

use ipv6 address … link-local

Router Advertisement (RA)

sent by routers every 200 sec or on RS

ipv6 unicast-routing

enables IPv6 routing on Cisco routers

SLAAC

client builds GUA from RA prefix and interface ID

Stateless DHCPv6

adds DNS info to SLAAC

Stateful DHCPv6

full config from server, default GW from RA

EUI-64 address

builds interface ID using MAC + FFFE + flipped bit

Random interface ID

alternative to EUI-64

Windows SLAAC/LLA

same interface ID process for both

Cisco dynamic LLA

LLAs auto-generated using EUI-64 (Ethernet) or MAC (Serial)

Static LLA on routers

common for readability and management

show ipv6 interface brief

command shows LLA and GUA

show ipv6 route / ping

verify IPv6 routing and reachability

IPv6 multicast prefix

ff00::/8

FF02::1

all-nodes multicast (like IPv4 broadcast)

FF02::2

all-routers multicast group

Solicited-node multicast

used for efficient NIC filtering

IPv6 subnetting

designed into protocol, uses dedicated subnet ID

IPv6 subnetting method

increment subnet ID hextet in hex

65,536 subnets

admins should plan a logical scheme

IPv6 conservation

no need to conserve due to huge address space