CCNA Networking · Quick Reference

Module 12 — IPv6 Addressing Cheat Sheet

CCNA Networking

In one line: IPv4 uses 32-bit addresses, which provides roughly 4.3 billion unique addresses. That sounded enormous in 1981 when IPv4 was designed — but with billions of phones, laptops, ser...

Key Ideas

1IPv4 Limitations. IPv4 uses 32-bit addresses, which provides roughly 4.3 billion unique addresses. That sounded enormous in 1981 when IPv4 was designed — but with billions of phones, la...

2IPv6 Address Representation. An IPv6 address is written as eight groups of four hexadecimal digits, separated by colons. Each group represents 16 bits, for a total of 128 bits (8 × 16 = 128).

3IPv6 Address Types. IPv6 defines three types of communication, similar in concept to IPv4 but with one key difference: IPv6 has no broadcast. Its role is filled by multicast instead.

4GUA and LLA Static Configuration. IPv6 addresses can be configured manually on a Cisco router, just like IPv4 — using ipv6 address instead of ip address. The prefix length is always specified with a sl...

5Dynamic Addressing for IPv6 GUAs. IPv6 hosts can obtain a Global Unicast Address automatically, without manual configuration, through three different methods — each offering a different balance of auto...

Code Examples

Full (unabbreviated) IPv6 address:
2001:0db8:0000:0000:0000:ff00:0042:8329

Each of the 8 groups = 16 bits (4 hex digits)
Total: 8 × 16 = 128 bits

Original:    2001:0db8:0000:0000:0000:ff00:0042:8329
Step 1 — drop leading zeros in each group:
             2001:db8:0:0:0:ff00:42:8329
Step 2 — compress the contiguous all-zero run with ::
             2001:db8::ff00:42:8329

! Both addresses below ...

! Configure a static Global Unicast Address (GUA)
R1(config)# interface GigabitEthernet0/0
R1(config-if)# ipv6 address 2001:db8:acad:1::1/64
R1(config-if)# no shutdown

! Configure a custom static Link-Local Address (optional — auto-generated by defaul...