VLAN Tag Translation for Layer 2 Switching Interconnectivity
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Solution Overview
Problem
Current VLAN implementations in layer 2 switching do not allow for the expansion of broadcast or flooding domains and increase complexity in frame decoding due to the inability to change VLAN tags in incoming frames, limiting interconnectivity between VLANs.
Innovation Solution
The method involves translating VLAN tags in layer 2 frames, allowing for the association of member VLANs with a translation VLAN, which expands the broadcast and flooding domains while maintaining traffic separation and simplifying frame decoding by using a layer 2 forwarding table and output tag table to manage VLAN associations and translations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VLAN tag stacking is used to interconnect VLANs, then interconnectivity between VLANs is achieved, but device complexity and frame decoding complexity increase
Solution Approach 1:
The patent introduces translation VLANs as intermediary entities that mediate between member VLANs. Instead of stacking multiple VLAN tags which increases complexity, the translation VLAN acts as a mediator that receives frames from member VLANs and forwards them with appropriate VLAN tags, thereby achieving interconnectivity without increasing decoding complexity
Solution Approach 2:
The patent segments the VLAN interconnection function into two distinct parts: member VLANs that maintain their original tags and translation VLANs that handle the tag translation. This segmentation allows each component to have a specific role, preventing the need for complex multi-tag stacking while achieving the same interconnection goal
2Adaptability or versatility
If VLAN tag stacking is used to expand broadcast domain, then broadcast domain expansion is achieved, but device complexity increases
Solution Approach 1:
Translation VLANs serve as intermediaries that enable broadcast domain expansion without requiring multiple stacked tags. When a frame is received from a member VLAN, the translation VLAN forwards it to other member VLANs with appropriate tagging, achieving broadcast expansion while maintaining simple single-tag processing
Solution Approach 2:
The translation VLAN performs multiple functions: it acts as a broadcast domain expander, a tag translator, and a forwarding intermediary all in one. This multi-functionality eliminates the need for complex tag stacking mechanisms while achieving the same effects
3Adaptability or versatility
If VLAN tags are translated and replaced in outgoing frames, then interconnectivity and broadcast domain expansion are improved, but processing complexity may increase
Solution Approach 1:
The patent pre-establishes mapping relationships between member VLANs and translation VLANs in forwarding tables before operation. This preliminary configuration allows the switch to perform simple table lookups during frame forwarding rather than performing complex real-time tag translation logic, thereby reducing processing complexity
Data Source
AI summary
Methods and systems for associating and translating VLAN tags are disclosed. In one implementation, multiple different member VLAN tags are associated with a translation VLAN tag. When a frame addressed to an unknown MAC address and containing one of the member VLAN tags is received, the frame is flooded to the translation VLAN and to ports associated with the source member VLAN other than the originating port. In the copy sent to the translation VLAN, the VLAN tag is replaced with the tag of the translation VLAN, for tagged ports. For untagged ports, the input VLAN tag may simply be stripped from the frames. When a layer 2 frame addressed to an unknown MAC address and containing the translation VLAN tag is received, the layer 2 frame is flooded to each of the member VLANs and to ports of the translation VLAN other than the originating port. The VLAN tag in the frames forwarded to each of the member VLANs may be replaced with the VLAN tag corresponding to each member VLAN, for tagged ports. For untagged ports, the input VLAN tag may simply be stripped from the frames. MAC address learning for frames received from member VLANs extends to the translation VLAN but not to other member VLANs. MAC address learning for frames from the translation VLAN extends to the member VLANs.