VXLAN Gateway Pairing for Multi-Site Segment Mapping

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Solution Overview

Problem

Extending Virtual eXtensible Local Area Network (VXLAN) segments across multiple data center sites poses challenges such as coordinating unique Virtual Network Identifiers (VNIDs) across different administrative entities, scalability issues due to making VTEPs visible across sites, stability concerns with VM movements, inefficient multicast, and the need for avoiding control protocols between sites.

Innovation Solution

The solution involves establishing virtual trunk links between internal and external VXLAN gateways to facilitate segment mapping, using VLANs for inter-site connectivity, and employing a data path approach for segment pruning, thereby isolating sites and avoiding control protocol dependencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If VXLAN segments are extended across multiple data center sites, then network connectivity and versatility are improved, but coordination complexity and device complexity increase due to managing unique VNIDs across different administrative entities

Engineering Contradiction:
ImproveVXLAN segment connectivity across sitesVSAvoidcoordination complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces VXLAN gateway pairing as an intermediary mechanism between sites. Each gateway maintains a mapping of remote VNIDs to local VNIDs, acting as a mediator that translates between different administrative domains without requiring direct coordination between all entities. This resolves the contradiction by enabling cross-site connectivity while localizing the complexity management to gateway-level mappings.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the VNID coordination problem by allowing different VNID spaces in different sites. Instead of requiring a single global VNID space, each site can independently manage its own VNID allocations, with gateways handling the segmentation and mapping between them. This reduces coordination complexity while maintaining versatility.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If all VTEPs are made visible across sites for segment extension, then connectivity is improved, but scalability deteriorates due to the large number of VTEPs that must be tracked and managed

Engineering Contradiction:
ImproveVTEP visibility for connectivityVSAvoidscalability
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

VXLAN gateways act as intermediaries that aggregate VTEP information. Instead of making all VTEPs directly visible across sites, each gateway maintains a consolidated view of remote VTEPs and presents a simplified mapping to local VTEPs. This enables connectivity while improving scalability by reducing the visibility scope from all-to-all to gateway-mediated connections.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If head-end replication is used for multicast traffic, then connectivity is ensured, but efficiency deteriorates due to redundant packet duplication and increased network bandwidth consumption

Engineering Contradiction:
Improveconnectivity assuranceVSAvoidnetwork efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent uses selective copying at gateway boundaries rather than head-end replication. Instead of duplicating packets at the source for all possible destinations, gateways copy packets only when needed for specific remote segments. This maintains connectivity assurance while improving efficiency by eliminating redundant duplications.

Inventive Principle:
Principle #26Copying

4Measurement precision

If control protocols are used between sites for coordination, then management precision is improved, but device complexity and interoperability issues increase

Engineering Contradiction:
Improvecoordination precisionVSAvoidcontrol protocol complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements self-service coordination through data-plane mechanisms. VXLAN gateways automatically establish mappings and perform translations based on traffic patterns without requiring external control protocol coordination. This maintains management precision through automated learning and mapping while reducing device complexity by eliminating the need for control protocol implementations between sites.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3020164B1Support for virtual extensible local area network segments across multiple data center sites
Publication Date: 2017.09.06 CISCO TECHNOLOGY INC
  • EP3020164B1 patent drawingFigure 1
  • EP3020164B1 patent drawingFigure 2~5
  • EP3020164B1 patent drawingFigure 3

AI summary

A method is provided in one example embodiment and includes establishing a virtual trunk link (trunkl - trunkn) between a first network element (extGWl - extGWn) and a second network element (intGWl - intGWn). The first and second network elements are located in gateway element ISGW2 at a first site (site2), and the first site and a second site comprise at least a portion of an overlay network (SEGMENT 10010, SEGMENT 10020). The method further includes receiving data traffic at the first network element, which data traffic is associated with a segment of the overlay network, and mapping a first network identifier (SEGMENT 10010) allocated to the overlay network segment at the first network element to a virtual trunk link (trunkl- trunkn) and a VLAN ID. The method additionally includes forwarding the data traffic from the first network element to the second network element via the virtual trunk link with the VLAN ID. Preferably, two types of VXLAN gateways are thus connected, or paired, through virtual trunk links to facilitate VXLAN extension across multiple sites. In gateway element ISGW2, multiple VXLAN gateway virtual machines are deployed in pairs. They are categorized into two types, internal and external gateways. Internal VXLAN gateways connect to VXLAN tunnel endpoints (VTEPs) within the site and may run control protocols such as BGP or use internal Virtual Supervisor Module (VSM) to Virtual Ethernet Module (VEM) communication mechanism for VTEP and segment discovery within a site or for that matter multicast within that site. In contrast, external VXLAN gateways connect to gateways of other sites. The allocation of VLAN 20 to support segment ID mapping is a matter internal to to gateway element ISGW2. Scalable and stable multi-site connectivity can thus be provided.