Campus IPv6 Subnetting Lab

Start from zero

An IP address is a number used to identify a device or network. IPv6 is longer than IPv4, so we write it in hexadecimal to keep the address readable.

Device address One interface 2001:db8:acad:102::25

Network prefix Many addresses 2001:db8:acad:102::/64

IPv4 octets, IPv6 hextets

IPv4 is usually written as 4 decimal octets. IPv6 is written as 8 hexadecimal groups. In IPv6 lessons, call those groups hextets or simply groups.

IPv4 4 octets 192.0.2.10

IPv6 8 hextets 2001:db8:acad:102::1

Bits first

A bit has only two values

Computers count with bits. A bit can be 0 or 1. Four bits make a nibble, and a nibble is exactly one hexadecimal digit.

1010

8on

4off

2on

1off

1010 means 8 + 2 = 10, and decimal 10 is hex a.

Binary to hex

Memorize the 4-bit map

4 bits = 1 hex digit

00000

00011

00102

00113

01004

01015

01106

01117

10008

10019

1010a

1011b

1100c

1101d

1110e

1111f

Build a hextet

Four hex digits make one IPv6 group

Each hex digit is 4 bits. A hextet has 4 hex digits, so one hextet is 4 x 4 = 16 bits.

20010

00000

10001

2001 is one hextet, and it represents 16 bits.

Address anatomy

Eight hextets make 128 bits

2001:0db8:acad:0102:0000:0000:0000:0001

Group 1200116 bits

Group 20db816 bits

Group 3acad16 bits

Group 40102subnet field

Group 50000host part

Group 60000host part

Group 70000host part

Group 80001host part

/48 campusFirst 3 groups stay the same.

/60 to /64 subnettingGroup 4 carries zone and LAN numbers.

Interface IDLast 4 groups identify the host on a /64 LAN.

Compression rule 1

Remove leading zeros inside a group

IPv6 lets you shorten each hextet by removing zeros at the beginning of that hextet. Do not remove zeros from the middle or end of a group.

0db8becomesdb8

0102becomes102

0001becomes1

2001stays2001

Compression rule 2

Use `::` for one run of zero groups

A long run of 0000 groups can become ::, but only once in the address. If you use :: twice, nobody can know how many zero groups belong in each gap.

Full2001:0db8:acad:0102:0000:0000:0000:0001

Drop leading zeros2001:db8:acad:102:0:0:0:1

Compress zero run2001:db8:acad:102::1

Prefix length

The slash tells you the network part

In 2001:db8:acad:102::/64, the first 64 bits identify the LAN. The remaining 64 bits identify devices on that LAN.

64 network bits 64 interface bits

2001:db8:acad:0102 0000:0000:0000:0001

1

Start with the parent prefix

The campus owns 2001:db8:acad::/48. The first three hextets stay fixed for every address in this lab.

2

Choose a block size

A /60 building block leaves 4 bits before /64, so each building gets 16 normal LANs.

3

Assign /64 LANs

Inside 0100::/60, LANs run from 0100 through 010f. Each user network gets one /64.

4

Summarize and validate

Advertise one building summary route, then check that new proposals do not overlap an existing range.

/48Institution allocation2001:db8:acad::/48

/60Zone or building block2001:db8:acad:0100::/60

/64Normal LAN or VLAN2001:db8:acad:0102::/64

/127Router-to-router link2001:db8:acad:ff01::/127

/128One device address2001:db8:acad:ff00::1/128

Subnetting step

From `/60` to `/64`

A /60 building block has 4 more bits before a normal /64 LAN. Four bits means 2^4 = 16 LAN choices.

0123 4567 89ab cdef

Administration block

`2001:db8:acad:0100::/60` contains 16 /64 LANs

0100010101020103...010f

Worked example

Administration block

Give Administration 2001:db8:acad:0100::/60. Because 64 - 60 = 4, the final hex digit can count from 0 to f.

/48campus2001:db8:acad::/48

/60building2001:db8:acad:0100::/60

/64LAN2001:db8:acad:0102::/64

Design ruleKeep blocks readable, separated, and easy to summarize.

Subnetting ruleMore prefix bits means a smaller network; fewer prefix bits means a larger network.

LAN ruleUse /64 for normal IPv6 LANs, /127 for router links, and /128 for loopbacks.

Warm-up Q&A

Think first, then reveal

These are not scored. They are here to tease the practice questions and make sure the basics feel steady.

What is binary 1010 in hex?

1010 is 8 + 2 = 10, and decimal 10 is hex a.

Why is 2001:0db8 often written 2001:db8?

IPv6 lets you remove leading zeros inside each hextet. The value does not change.

How many /64 LANs are inside one /60?

64 - 60 = 4 bits. 2^4 = 16, so one /60 contains 16 /64 LANs.

Start practice questions

Campus IPv6 Subnetting Lab

Start from zero

IPv4 octets, IPv6 hextets

A bit has only two values

Memorize the 4-bit map

Four hex digits make one IPv6 group

Eight hextets make 128 bits

Remove leading zeros inside a group

Use `::` for one run of zero groups

The slash tells you the network part

Start with the parent prefix

Choose a block size

Assign /64 LANs

Summarize and validate

From `/60` to `/64`

`2001:db8:acad:0100::/60` contains 16 /64 LANs

Administration block

Think first, then reveal

Answer the design questions

Question title

Design builder

Campus-zone allocations

Detailed assignments

Assessment checks

Start from zero

IPv4 octets, IPv6 hextets

A bit has only two values

Memorize the 4-bit map

Four hex digits make one IPv6 group

Eight hextets make 128 bits

Remove leading zeros inside a group

Use :: for one run of zero groups

The slash tells you the network part

Start with the parent prefix

Choose a block size

Assign /64 LANs

Summarize and validate

From /60 to /64

2001:db8:acad:0100::/60 contains 16 /64 LANs

Administration block

Think first, then reveal

Answer the design questions

Question title

Design builder

Campus-zone allocations

Detailed assignments

Assessment checks

Use `::` for one run of zero groups

From `/60` to `/64`

`2001:db8:acad:0100::/60` contains 16 /64 LANs