AP Networking

Moving forward: designing for reliability and growth

IPv4 was designed in the early 1980s for a much smaller network. As billions of devices joined the internet, a new addressing standard became necessary. IPv6 solves the address exhaustion problem while improving efficiency. And for networks that need to stay up, redundancy and monitoring turn potential outages into manageable events.

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What this topic covers

› 4.6.A — IPv6: structure, compression, and why it was created
› 4.6.B — Redundancy strategies, monitoring, security, and patch management to improve availability

Why IPv6?

IPv4 uses 32-bit addresses — about 4.3 billion (2³²) possible values. That seemed like plenty in the 1980s, but the rapid growth of internet-connected devices caused IPv4 address exhaustion. IPv6 was created to solve this problem, using 128-bit addresses with 2¹²⁸ possible values — enough to give every device on Earth a globally unique, routable address.

IPv6 address structure (4.6.A)

Format

› 128 bits total
› Written as 8 hextets — groups of 16 bits each
› Hextets are written in hexadecimal and separated by colons
› Every device can have a globally unique and routable address

Full format example

2001:0DB8:0000:0000:0000:0000:0000:1234

↑ 8 hextets separated by colons

each hextet is 4 hex digits (16 bits)

IPv6 address compression

IPv6 addresses can be shortened using two rules applied together:

Rule 1: Remove leading zeros

Each hextet can have leading zeros dropped: 0DB8 → DB8, 000A → A, 0000 → 0

Rule 2: Collapse consecutive all-zero hextets

One or more consecutive hextets that are all zeros can be replaced with :: — but only once per address

Full address	Compressed
2003:AB00:CDEF:000A:0000:0000:0000:0001	2003:AB00:CDEF:A::1
2001:0DB8:0000:0000:0000:0000:0000:1234	2001:DB8::1234
FE80:0000:0000:0000:01FF:FE23:4567:890A	FE80::1FF:FE23:4567:890A

Reliability and availability strategies (4.6.B)

Redundancy strategies

Redundancy ensures backup solutions are available when a primary system fails:

› Backup power: UPS or generators keep devices running during outages
› Secondary routers and switches: take over if a primary device fails
› Mobile or satellite internet: provides connectivity during primary ISP outages
› Regular data backups: protect against data loss

Monitoring, security, and patching

› Monitoring and alerting: enables rapid detection of failures or suspicious activity
› Security controls: firewalls, IPS, and access controls reduce the risk of outages caused by attacks or misconfigurations
› Patch management: applying and documenting software updates reduces the risk of failure and reduces recovery time when an outage does occur