YD/T 4499-2023
Technical requirements for carrier-grade NAT64 equipment (English Version)

Standard No.

YD/T 4499-2023

Language

Chinese, Available in English version

Release Date

2023

Published By

Professional Standard - Post and Telecommunication  CN  /  YD

Latest

YD/T 4499-2023

Introduction

Standard Background and Technology Evolution

As the IPv4 address exhaustion problem intensifies, the core goal of this standard is to standardize the technical requirements of NAT64 equipment in the operator's network and realize seamless access of pure IPv6 terminals to IPv4 resources. This technology is derived from the IETF RFC 6146 standard and has been localized and adapted by the China Communications Standards Association (CCSA) to form an enhanced specification for operator networks.

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Analysis of core functional modules

Module	Functional requirements	Performance indicators
NAT64 translator	Bidirectional address mapping, protocol conversion (TCP/UDP/ICMP), session state persistence	Support 100,000+/second session establishment
DNS64 server	AAAA record synthesis, prefix management (default 64:FF9B::/96), recursive query	Response delay <50ms

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Detailed explanation of key technical requirements

5.1 Address mapping mechanism

The standard stipulates that a dual-stack address pool must be maintained:

• IPv6 address pool: Prefix64::/n prefix, used to synthesize IPv4-converted IPv6 addresses
• IPv4 address pool: Supports port multiplexing (PAT), a single IPv4 address can map 65,535 sessions

5.2 Protocol conversion specification

Actual deployment case: A provincial operator uses the Huawei NE40E device to implement:

1. Processing of Flow Label field during IPv6 header conversion
2. ICMPv6→ICMPv4 type code mapping table
3. Fragment reassembly strategy when MTU does not match

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Device form factor comparison

Type	Stand-alone device	Plug-in device
Deployment mode	Physically separated, requiring additional rack space	Integrated in router service card
Redundancy solution	Active-Standby dual-machine hot standby	1:N card-level backup
Applicable scenarios	Large core node	Edge access node

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Implementation recommendations

Deployment architecture selection

It is recommended to adopt a layered deployment mode:

1. Core layer: independent NAT64 cluster to process cross-domain traffic
2. Aggregation layer: plug-in device to achieve local traffic offloading

Logging and tracing

Must meet the following requirements

• Syslog complies with RFC5424 standard
• Session logs are saved for ≥90 days
• Support Radius extended attribute tracing

Energy efficiency optimization

Refer to YD/T 1148-2005 requirements, it is recommended to:

• Use dynamic power management technology
• Automatic sleep of idle boards
• The heat dissipation design meets TIA-942 Tier III Standards

YD/T 4499-2023 history

• 2023 YD/T 4499-2023 Technical requirements for carrier-grade NAT64 equipment

Standard and Specification