MAC Address Table: Table Size Up to 128K entries

Q: What happens when a MAC address table is full?

When the MAC address table reaches capacity, the switch may stop learning new addresses or employ aging algorithms to remove stale entries, potentially causing increased flooding and reduced network efficiency.

Q: How does a MAC address table differ from a routing table?

A MAC address table operates at layer 2 (data link layer) using MAC addresses for switching within a broadcast domain, while a routing table operates at layer 3 (network layer) using IP addresses for routing between different networks.

Component Specifications

Definition

The MAC address table, also known as a Content Addressable Memory (CAM) table, is a critical component within a switching ASIC that stores learned MAC addresses and their associated switch ports. It enables layer 2 switching by allowing the ASIC to make forwarding decisions based on destination MAC addresses, reducing network collisions and improving data transmission efficiency in Ethernet networks.

Working Principle

The MAC address table operates by learning source MAC addresses from incoming frames and associating them with the ingress port. When a frame arrives, the ASIC checks the destination MAC address against the table. If a match is found, the frame is forwarded only to the corresponding port; if not, it is flooded to all ports except the ingress port. This process uses hardware-based lookup mechanisms for high-speed operation.

Materials

Integrated into silicon ASIC; typically uses SRAM or TCAM (Ternary Content Addressable Memory) cells for storage, fabricated with CMOS technology on semiconductor wafers.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Aging Time	Configurable, typically 300 seconds
Table Size	Up to 128K entries
Memory Type	TCAM/SRAM hybrid
Lookup Speed	Nanosecond range
Learning Rate	Millions of addresses per second

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEEE 802.1D, IEEE 802.1Q

Parent Products

This component is used in the following industrial products

Switching ASIC

A specialized integrated circuit for data packet switching and routing in network equipment.

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Engineering Analysis

Risks & Mitigation

Table overflow leading to performance degradation
MAC address spoofing attacks
Aging timer misconfiguration causing network instability

FMEA Triads

Trigger: Memory corruption in TCAM/SRAM cells
Failure: Incorrect MAC address mappings causing packet loss or misrouting
Mitigation: Implement error-correcting codes (ECC) and periodic table validation routines

Trigger: Excessive broadcast traffic
Failure: Table thrashing and reduced switching performance
Mitigation: Configure broadcast storm control and optimize network segmentation

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

MAC address learning accuracy >99.99%, lookup latency <100ns

Test Method

RFC 2889 benchmarking for LAN switching devices, including address caching capacity and forwarding rate tests

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

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Manufacturers of MAC Address Table

Manufacturer profiles associated with MAC Address Table.

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Frequently Asked Questions

What happens when a MAC address table is full?