MAC Frame Flooding Reduction via Group ID Lookup
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Solution Overview
Problem
In virtual local area networks (VLANs), existing methods like GARP and IGMP snooping are inefficient for reducing flooding of MAC frames, especially in high-speed provider networks serving multiple customers, as they require complex control protocols and heavy load processing, leading to bandwidth compression and disturbance of communications between terminals with narrower bandwidths.
Innovation Solution
A method and apparatus for reducing MAC frame flooding in a backbone network by using edge bridges with destination group ID look-up tables and backbone port look-up tables to determine which ports should transmit MAC frames, eliminating unnecessary transmissions and avoiding the need for complex control protocols or upper-layer routing information snooping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If GARP or IGMP snooping is used to reduce flooding, then unnecessary MAC frame transmissions are reduced, but device complexity and processing load increase
Solution Approach 1:
The invention extracts the flooding control function from complex control protocols (GARP, IGMP snooping) and implements it through a simple destination group ID lookup mechanism in the bridge's forwarding table. This separates the essential function (determining whether to forward a frame) from the complex protocol overhead, achieving flood reduction without requiring bridges to participate in complex inter-bridge attribute exchange or upper-layer routing snooping.
Solution Approach 2:
The bridge independently determines whether to forward a MAC frame by looking up the destination group ID in its own forwarding table, without requiring coordination with other bridges or upper-layer protocols. Each bridge serves itself by using locally stored forwarding information to make forwarding decisions, eliminating the need for complex distributed control protocols.
2Loss of energy
If IGMP snooping is implemented in high-speed bridges, then flooding is reduced, but processing load becomes heavy
Solution Approach 1:
The invention replaces the complex mechanical process of IGMP snooping (snooping upper-layer routing information, exchanging attributes between bridges) with a simpler database lookup mechanism. The bridge uses a forwarding table storing destination group ID to port mappings to quickly determine forwarding decisions, substituting complex protocol processing with efficient table lookup operations that do not burden the bridge's processing capabilities.
3Loss of energy
If flooding reduction settings are installed in bridges, then unnecessary traffic is reduced, but transfer process becomes heavy load
Solution Approach 1:
The bridge pre-establishes forwarding tables mapping destination group IDs to outgoing ports before actual frame transmission occurs. When a frame arrives, the bridge simply looks up the destination group ID in the pre-built table to determine forwarding decisions, rather than performing complex real-time analysis. This preliminary preparation of forwarding information eliminates the need for heavy processing during the actual transfer process.
Data Source
AI summary
In receiving a MAC (media access control) frame whose destination address is any of a broadcast address, an unknown multicast address and an unknown unicast address, the flooding is reduced by broadcasting the received MAC frame to all the other ports than one that has received the MAC frame. An output control that attains this object is realized by using a destination group identifier (ID) look-up table (2-T1) which enables a look-up of a destination group ID by using, as a key, any one or combination of header information of the MAC frame, a port which received the MAC frame and a service VLAN (virtual local area network) ID corresponding to the MAC frame and a backbone port look-up table (2-T2) which enables a look-up of at least one backbone port which is to transmit or at least one backbone port which is not to transmit by using the destination group ID as a key.