Packet Mirroring in CB-PE Stacking Systems to Prevent Broadcast Loops
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Solution Overview
Problem
In data center networks, the integration of 10-Gigabit and Gigabit servers creates complexity in network structure and management, leading to issues like network congestion and packet loss, particularly due to the lack of effective methods for handling non-unicast packets in Top of Rack (ToR) access devices.
Innovation Solution
A method for packet forwarding in a Core Backbone (CB)-Port Extender (PE) stacking network that uses a switch module with a packet buffering chip to manage traffic by mirroring non-unicast packets and preventing them from being forwarded through certain ports, thereby avoiding broadcast loops and network congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-unicast packets are forwarded through all ports in a stacking system, then network coverage is improved, but broadcast loops and network congestion occur
Solution Approach 1:
The patent segments the stacking system into different levels (first-level stacking ports connecting CB devices, second-level stacking ports connecting PE devices). By segmenting the forwarding rules according to packet ingress port type, the system achieves both wide coverage and loop prevention. Unicast packets from CB devices are forwarded through all first-level stacking ports for wide coverage, while non-unicast packets from PE devices are restricted to specific ports to prevent broadcast loops.
Solution Approach 2:
The patent applies different forwarding qualities to different packet types and ingress ports. Packets entering through first-level stacking ports receive full forwarding treatment to all ports, while packets entering through second-level stacking ports receive restricted forwarding treatment. This local differentiation of forwarding quality enables the system to optimize for both coverage and reliability in different network contexts.
2Device complexity
If packet forwarding is simplified in stacking systems, then management complexity is reduced, but packet loss increases due to inadequate traffic management
Solution Approach 1:
The patent implements preliminary action by pre-configuring forwarding rules based on packet ingress port identification. Before packets are forwarded, the system determines the ingress port type (first-level or second-level stacking port) and applies the appropriate forwarding rule set. This preliminary classification enables simplified management while ensuring reliable packet delivery, as the correct forwarding behavior is predetermined for each packet type.
3Adaptability or versatility
If mixed Gigabit and 10-Gigabit servers are deployed, then network adaptability is improved, but network structure complexity increases
Solution Approach 1:
The patent implements universality by creating a unified forwarding mechanism that handles multiple server types (Gigabit and 10-Gigabit) through a single stacking system architecture. The CB-PE stacking system provides multi-functional support for different server speeds and packet types using consistent forwarding rules, eliminating the need for separate management systems for different server types and thereby reducing overall network structure complexity.
Data Source
AI summary
A CB device receives a first packet sent from another device through a stacking port. In response to determining, based on source port information carried in the first packet, that the first packet entered the stacking system from a PE device and the first packet is a non-unicast packet, the switch module performs mirroring processing to the first packet to obtain a mirrored packet, and transmits the first packet and the mirrored packet to a packet buffering module of the CB device. In response to determining that a second packet from the packet buffering module entered the stacking system from the PE device and the second packet is the non-unicast packet, the second packet is forbidden from being forwarded through a first-level stacking port of the CB device.