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network/cgnat_allocation_analysis.md
Graham McIntire 177a560cba
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2026-05-08 17:47:42 -05:00

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CGNAT Allocation Analysis

This report analyzes the CGNAT (100.64.x.x) subnet allocations across all network sites to identify which sites use /22 allocations versus other sizes.

Summary

Sites Using /22 Allocations

  1. Climax - 100.64.4.0/22 (100.64.4.0 - 100.64.7.255)
  2. Culleoka - 100.64.24.0/22 (100.64.24.0 - 100.64.27.255)
  3. Site 982 - 100.64.32.0/22 (100.64.32.0 - 100.64.35.255)
  4. New Hope - 100.64.16.0/22 (100.64.16.0 - 100.64.19.255)
  5. Site 380 - 100.64.8.0/22 (100.64.8.0 - 100.64.11.255)

Sites Using /20 Allocations

  1. Site 494 - 100.64.160.0/20 (100.64.160.0 - 100.64.175.255)
  2. Lowry Crossing - 100.64.144.0/20 (100.64.144.0 - 100.64.159.255)

Detailed Site Information

/22 Allocations (1,024 addresses each)

Site CGNAT Subnet Router IP Interface
Climax 100.64.4.0/22 100.64.7.254/22 climax-bridge
Culleoka 100.64.24.0/22 100.64.27.254/22 ether2-netonix
Site 982 100.64.32.0/22 100.64.35.254/22 982
New Hope 100.64.16.0/22 100.64.19.254/22 sfp-sfpplus1-edgepoint
Site 380 100.64.8.0/22 100.64.11.254/22 combo1-380

/20 Allocations (4,096 addresses each)

Site CGNAT Subnet Router IP Interface
Site 494 100.64.160.0/20 100.64.175.254/20 494
Lowry Crossing 100.64.144.0/20 100.64.159.254/20 lowrycrossing

Key Observations

  1. Allocation Size Pattern:

    • 5 sites use /22 allocations (1,024 addresses)
    • 2 sites use /20 allocations (4,096 addresses)

  2. Larger Sites: Sites 494 and Lowry Crossing have 4x larger CGNAT allocations compared to the other sites, suggesting they either serve more customers or were allocated larger blocks for future growth.

  3. Address Usage: The /22 sites can support up to 1,022 customer connections (excluding network and broadcast addresses), while the /20 sites can support up to 4,094 customer connections.

  4. Sequential Allocation: The /22 allocations appear to be somewhat sequential:

    • 100.64.4.0/22 (Climax)
    • 100.64.8.0/22 (Site 380)
    • 100.64.16.0/22 (New Hope)
    • 100.64.24.0/22 (Culleoka)
    • 100.64.32.0/22 (Site 982)

  5. Separate Range for /20s: The /20 allocations are in a different part of the CGNAT space:

    • 100.64.144.0/20 (Lowry Crossing)
    • 100.64.160.0/20 (Site 494)