LINK AGGREGATION (IEEE 802.1AX / 802.3ad) – OFFICIAL TECHNICAL OVERVIEW & HARDWARE DATASHEET

EXECUTIVE SUMMARY

Link Aggregation, formally defined under IEEE 802.1AX (formerly 802.3ad), is a method of parallelizing multiple physical Ethernet links into a single logical link, known as a Link Aggregation Group (LAG) or Port Channel. This technology delivers two primary network infrastructure advantages: linear increase in aggregate throughput and physical link redundancy with sub-second failover. This document specifies the implementation architecture, hardware requirements, and operational parameters for enterprise and carrier-grade switching platforms supporting up to 128 member links per aggregate interface.

HARDWARE ARCHITECTURE & SILICON

The forwarding plane for Link Aggregation resides within the switch’s packet processor or ASIC (Application-Specific Integrated Circuit). A Link Aggregation Control Protocol (LACP) state machine runs either in hardware (for line-rate decisions) or CPU-managed control plane. The hash-based distribution algorithm selects an egress physical member port using a configurable hash key comprised of fields such as:
– MAC source/destination addresses
– IP source/destination addresses
– TCP/UDP port numbers

The hardware maintains a hash-to-member lookup table, ensuring all frames of a given flow are forwarded on the same physical link to prevent reordering. Non-hash-based round-robin distribution is not supported in compliance with IEEE 802.1AX frame ordering requirements.

KEY FEATURES & ROUTING LOGIC

– LACP PROTOCOL SUPPORT: Active/Passive negotiation modes with 1-second (fast) or 30-second (slow) heartbeat timers.
– STATIC LAG: Manual configuration without LACP negotiation for legacy interoperability.
– LOAD BALANCING ALGORITHMS: Layer 2, Layer 3, Layer 4, or mixed hashing; per-platform configurable via CLI.
– LINK PROTECTION: Automatic member link removal upon signal loss, CRC errors, or carrier loss; automatic restoration.
– MULTI-CHASSIS LAG (MLAG) OPTION: Extend LAG across two physical switches for node-level redundancy.
– MAX MEMBERS: Up to 32 active links per LAG (vendor-specific scaling to 128 on high-end line cards).

COMPLIANCE & STANDARDS

– IEEE 802.1AX-2020 (Link Aggregation)
– IEEE 802.3ad (Original specification, superseded)
– Link Aggregation Control Protocol (LACP) mandatory compliance
– Frame ordering preservation per standard clause 5.2.1
– Marker Protocol for link failure diagnosis

TECHNICAL SPECIFICATIONS

– AGGREGATION METHODS: LACP (Active/Passive) or Static configuration
– MAXIMUM LAG GROUPS PER SYSTEM: Hardware dependent — typically 256 to 2048 groups
– MEMBER PORTS PER LAG: 2 to 32 (128 on modular chassis with fabric oversubscription ratio 1:1)
– FAILOVER TIME: Parameter Specification

Form Factor 1RU Fixed / 4RU Modular Chassis (per SKU) Switching Capacity Up to 12.8 Tbps (full line-rate LAG) Power Supply Dual Hot-Swappable Redundant AC: 100-240V or DC: -48V Max LAG Groups 2048 groups / system Member Ports / LAG 32 (hardware max) LACP Fast Timer 1 second heartbeat, 3 second timeout, Operating Temperature 0°C to 45°C (32°F to 113°F) MTBF 284,000 hours (Telcordia SR-332) Hash Buckets 1024 per LAG Minimum Link Requirement 1 (fallback mode) to 2 (standard operation)

ORDERING SKU INFORMATION (MODULAR INTERFACE CARDS WITH LACP HARDWARE OFFLOAD)

– SKU: AGM-8X25G-LAG | 8-port 25GbE SFP28 | Max LAG: 8 member ports | LACP Hardware offload | 1RU blade
– SKU: AGM-4X100G-LAG | 4-port 100GbE QSFP28 | Max LAG: 4 member ports | MLAG ready | 0.5RU blade
– SKU: AGC-32X10G-LAG | 32-port 10GbE SFP+ | Max LAG: 32 member ports | Full line-rate | 1RU fixed chassis
– SKU: AGC-48X1G-LAG | 48-port 1000BASE-T | Max LAG: 16 member ports | PoE++ optional | 1RU fixed chassis
– SKU: AGM-128X1G-LAG | 128-port FE/GE | Distributed LAG (DLAG) | 4RU modular line card