1

IPv6 Address Space Management Report of IPv6 Registry Simulation

Policy SIG1 Sept 2004

APNIC18, Nadi, FijiGeoff Huston

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IPv6 Address structure

Interface Identifier

64 bits64 bits

Minimum LIR Allocation

16 bits29 bits

20 bits 9 bits

RIR Allocation Unit

Customer SiteSubnet

FormatPrefix

3 bits 16 bits45 bits

Global Routing Prefix

Aggregate Provider Prefix

Routing Entry Prefix

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IPv6 Address structure

Interface Identifier

64 bits

CustomerSubnet

16 bits

FormatPrefix

3 bits

ISP Allocation

Global Routing Prefix

16 bits29 bits/64

/48/32

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IANA to RIR Allocation size parameters

• Ensuring address aggregation outcomes within the parameters of:• Profile of IPv6 LIR / ISP requests• Chosen Host Density metric• Allocation address block lifetime• Reverse space management• Adopted RIR address pool management technique

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IANA to RIR Allocation size20 bits 9 bits

RIR Allocation Block

9 bits 20 bits

RIR Allocation Block

5 bits 23 bits

RIR Allocation Block

/23 Allocation: Each allocation supports up to 512 /32 allocations

3 bits

3 bits

3 bits

/12 Allocation: Each allocation supports up to 1M /32 allocations

/8 Allocation: Each allocation supports up to 17M /32 allocations

/23

/12

/8

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IPv6 Registry simulation exercise

• Use recent RIR IPv4 allocation data to create a demand model of an IPv6 address registry

• Assume a sequence of IPv6 transactions based on a demand model derived from the sequence of recorded IPv4 allocations

• Convert IPv4 to IPv6 allocations by assuming an equivalence of an IPv4 end-user-assignment of a /32 with an IPv6 end-user-assignment of a /48

• IPv4 uses a constant host density of 80% while IPv6 uses a HD-Ratio of 0.8

• Use a minimum IPv6 ISP allocation unit of a /32• Assume new LIR applications at 20%• Assume IPv4 allocation timeframe mean of 12

months

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IPv4 / IPv6 Allocation equivalence table

End Customer Size IPv4 Allocation IPv6 Allocation205 /24 /32410 /23 /32819 /22 /32

1638 /21 /323277 /20 /327131 /18 /32

12416 /18 /3121618 /17 /3037640 /16 /2965536 /15 /28

114104 /14 /27198668 /14 /26345901 /13 /25602248 /12 /24

1048576 /11 /231825676 /10 /223178688 /10 /215534417 /9 /209635980 /8 /19

16777216 /7 /18

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Allocation size simulation results

IPv6 Allocation Size

12

16

20

24

28

32

0 6 12 18 24 30 36

Months

Pre

fix

Siz

e LACNICRIPENCCARINAPNICALL

9

Simulation with NATs factored in

IPv6 Allocation Size(NAT Factor at 2:1)

12

16

20

24

28

32

0 6 12 18 24 30 36

Months

Pre

fix

Siz

e LACNICRIPENCCARINAPNICALL

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Management algorithm simulation

• Three algorithms have been compared• Sequential

• Comparable to current IPv4 system, where each new allocation window is drawn from the remaining free pool in sequence

• Sparse• Each new allocation subdivides the largest allocation

window in half

• Rate-Sparse• Each new allocation subdivides a window in half, where the

selected window is the slowest growing allocation

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Management Algorithm Simulation

0

100

200

300

400

500

600

700

800

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Rate-Sparse

Sparse

Sequential

Block Occupancy levelNu

mb

er

of

Frag

men

ted

Allo

cati

on

s

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IANA to RIR Address block size

• /20 block is smaller than the allocation window of some individual allocations

• /16 block has an anticipated lifetime of 36 months of RIR allocations using current allocation framework

• /16 would have a lifetime of < 12 months assuming an IPv4 NAT ratio of 2:1

• /12 block has an anticipated lifetime of 36 months with minimal fragmentation under rate-managed sparse allocation, with NATless deployments

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Thank you!

• Questions

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HD Ratio Variation

HD Ratio

0.00

0.20

0.40

0.60

0.80

1.00

0 500 1000 1500 2000 2500 3000 3500 4000 4500Millions

Size

Rat

io (

HD

: S

ize)

0.99

0.98

0.97

0.80323130291

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HD Ratio Variation

HD Ratio

0.00

0.20

0.40

0.60

0.80

1.00

1 10 100 1000 10000 100000 1000000 10000000 100000000 1000000000 10000000000

Size

Rat

io (

HD

: S

ize)

0.99

0.98

0.97

0.80322881 12 16 20 244

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Higher HD-Ratio

IPv6 Allocation Size(NAT Factor at 2:1, HD-Ratio at 0.95)

12

16

20

24

28

32

0 6 12 18 24 30 36

Months

Pre

fix

Siz

e LACNICRIPENCCARINAPNICALL

17

Reduced Subnet ID Length

IPv6 Allocation Size(NAT Factor at 2:1, Subnet-ID length at 8 bits)

12

16

20

24

28

32

0 6 12 18 24 30 36

Months

Pre

fix

Siz

e LACNICRIPENCCARINAPNICALL