Virtual Identifiers for Physical Switches in Virtual Chassis
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Solution Overview
Problem
The existing virtual chassis systems are limited by the number of packet forwarding engines (PFEs) and physical switches due to the constraints of global addressing, which restricts the scalability of the network.
Innovation Solution
The implementation of a virtual chassis architecture that uses a control module to associate virtual identifiers with local identifiers across multiple switches, allowing for a larger number of PFEs and physical switches to be interconnected as a single logical entity, enabling increased scalability by differentiating between local and virtual identifiers for efficient packet forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a global address is assigned to each PFE in multiple physical switches to form a virtual chassis, then the PFEs can be managed as a unified network element, but the number of PFEs and physical switches is limited by the number of bits in the global address
Solution Approach 1:
The patent segments the addressing scheme into two parts: a global identifier (32 bits) that identifies the virtual chassis and a local identifier (32 bits) that identifies the PFE within the chassis. This segmentation allows the system to support a much larger number of PFEs (up to 4 billion) while maintaining manageable addressing complexity through hierarchical organization.
Solution Approach 2:
The patent transitions from a flat global addressing scheme to a two-dimensional addressing structure by introducing the concept of a virtual chassis as an intermediate dimension. The global address space is divided into multiple virtual chassis identifiers, each containing multiple local PFE identifiers, effectively adding a hierarchical dimension to the addressing scheme.
2Productivity
If link-state routing protocol is used to decide shortest cost path between PFEs, then routing efficiency is improved, but the scalability is restricted by global address limitations
Solution Approach 1:
The patent changes the addressing parameter from a single 32-bit global address to a composite structure with a 32-bit global identifier and a 32-bit local identifier. This parameter change enables the routing protocol to scale to much larger virtual chassis configurations while maintaining the efficiency of link-state routing through proper routing table organization and forwarding decisions.
Data Source
AI summary
In some embodiments, an apparatus includes a first switch having an egress port configured to be coupled to a second switch to collectively to define a single logical entity having a set of virtual identifiers. A first set of virtual identifiers from the set of virtual identifiers is associated with the first switch, a second set of virtual identifiers from the set of virtual identifiers is associated with the second switch. The first switch is configured to receive a forwarding table associating a first set of destination addresses with a set of identifiers local to the first switch and associating a second set of destination addresses with a set of identifiers local to the second switch. Each identifier from the first set of identifiers is uniquely associated the first set of virtual identifiers. Each identifier from the set of identifiers is uniquely associated the second set of virtual identifiers.