Packet Control Device Preventing Port Mirroring Loops
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Solution Overview
Problem
In existing port mirroring techniques, packets are repeatedly duplicated and transferred in loops, leading to increased processing loads and communication traffic, especially when virtual switches cannot accurately determine whether a packet is a mirror packet, particularly with broadcast or multicast packets.
Innovation Solution
A packet control device that refers to predetermined information to determine if a packet is a mirroring target and checks a specific area of the packet to assess if it has already been mirrored, generating a duplicate packet only when necessary and setting a value to indicate mirroring completion, thereby preventing loop duplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If port mirroring is implemented by duplicating packets, then monitoring capability is improved, but packet duplication loops occur causing increased processing load and network traffic
Solution Approach 1:
The patent uses bit inversion in the TOS field of IP packets as a marker to indicate whether a packet has been mirrored. By changing the state of specific bits (from 0 to 1 or vice versa), the system can track packet mirroring status and prevent duplicate mirroring, thus avoiding infinite loops while maintaining monitoring capability.
Solution Approach 2:
The patent introduces an intermediary mechanism (bit inversion marker) between the packet duplication process and the monitoring function. This marker acts as a mediator that carries information about packet mirroring status through the network, allowing virtual switches to make informed decisions about whether to duplicate packets without causing loops.
2Reliability
If port mirroring duplicates all packets including broadcast and multicast, then monitoring completeness is improved, but unnecessary network traffic increases
Solution Approach 1:
The patent implements a feedback mechanism where the inverted bit in the TOS field provides information back to subsequent virtual switches about the packet's mirroring history. This feedback allows downstream switches to determine whether a packet has already been mirrored and avoid redundant duplication, thereby reducing unnecessary network traffic while maintaining monitoring completeness.
Solution Approach 2:
The patent changes the state of specific parameters (bits in the TOS field) to encode mirroring information. By modifying these parameter values during the mirroring process, the system enables intelligent packet handling decisions at downstream switches, allowing them to filter out already-mirrored packets and reduce network traffic.
3Adaptability or versatility
If virtual switches cannot accurately determine mirror packets, then monitoring flexibility is improved, but packet duplication loops occur
Solution Approach 1:
The patent applies preliminary action by inverting the bit in the TOS field immediately when a packet is first mirrored. This preliminary marking occurs before the packet traverses the network, enabling subsequent virtual switches to accurately identify and avoid duplicating already-mirrored packets, thus preventing loops while maintaining monitoring flexibility.
Data Source
AI summary
A packet control device includes a processor that receives a first packet to be input or output through a port. The processor determines whether the first packet is to be mirrored. The processor determines, upon determining that the first packet is to be mirrored, whether the first packet has been mirrored, based on a value of an area of the first packet. Upon determining that the first packet has not been mirrored, the processor generates a second packet by duplicating the first packet, sets a first value indicating completion of mirroring to the area of the second packet, transfers the second packet to a transfer destination, and transmits the first packet to a transmission destination. Upon determining that the first packet has been mirrored, the processor sets a second value indicating incompletion of mirroring to the area of the first packet, and transmits the first packet to the transmission destination.