LLDP Packet Fragmentation for Ethernet Frame Limits
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Solution Overview
Problem
In data center environments, the increased number of type-length-values (TLVs) in Link Layer Discovery Protocol (LLDP) packets often exceeds the maximum Ethernet frame size, leading to frame drops or data loss, particularly due to large Ethernet port densities and virtualization applications requiring many physical I/O connections, and modifying the LLDP state machine may compromise backward compatibility.
Innovation Solution
The method involves fragmenting LLDP packets into multiple fragments, each containing a fragmentation TLV for reassembly, allowing peer devices to process them as a single instance once all fragments are received, ensuring compatibility with devices that do not support fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of TLVs in LLDP packets is increased to accommodate more network device information, then the information exchange capability is improved, but the packet size exceeds the maximum Ethernet frame size of 1522 bytes causing frame drops
Solution Approach 1:
The patent divides a large LLDP packet containing multiple TLVs into multiple smaller fragments, each fitting within the 1522-byte Ethernet frame limit. The fragmentation process creates separate transmissible units that can be reliably delivered across the network without exceeding frame size constraints.
Solution Approach 2:
The patent embeds fragmentation control information (fragmentation TLV fields including fragment number, total fragment count, and sequence identifiers) within each packet fragment itself. This nested structure allows receiving devices to automatically reassemble the fragments into the complete original packet without external coordination.
2Quantity of substance
If LLDP packets are fragmented into multiple packets to transmit larger information, then the information transmission capacity is improved, but the device complexity increases due to fragmentation handling requirements
Solution Approach 1:
The patent implements self-service fragmentation handling where each packet fragment contains embedded control information (fragmentation TLV fields) that enables receiving devices to automatically identify, sort, and reassemble fragments without requiring complex external coordination or additional processing infrastructure.
Solution Approach 2:
The fragmentation TLV fields serve multiple functions simultaneously: they identify fragment sequence, indicate total fragment count, enable reassembly validation, and maintain compatibility with standard LLDP processing. This multi-functionality reduces the need for separate specialized handling mechanisms.
3Adaptability or versatility
If new fragmentation fields are added to LLDP packets to enable fragment identification and reassembly, then the packet functionality is improved, but the packet size increases and may exceed frame limits
Solution Approach 1:
The patent uses compact fragmentation TLV fields that provide only the essential minimum information needed for fragmentation handling (fragment number, total count, sequence identifiers). This partial information approach avoids adding excessive overhead while maintaining full fragmentation functionality.
Solution Approach 2:
The patent modifies existing LLDP packet structure by introducing new TLV field types specifically designed for fragmentation control. These parameter changes enable fragment identification and reassembly capabilities while keeping the added overhead minimal through efficient data encoding.
Data Source
AI summary
Described are methods of communicating network device information between network devices. A communication is established between a first network device and a second network device according to a link layer discovery protocol (LLDP). The method further comprises an LLDP advertisement message is output in the communication from the second network device to the first network device. The first network device determines whether the second network device processes fragmented packets by searching the LLDP advertisement message for a fragmentation time length value (TLV) field. The second network device outputs to the first network device a plurality of packet fragments in response to a determination that the LLDP advertisement message includes the fragmentation TLV field.