Single Virtual Domain FCoE Fabric for Domain ID Exhaustion

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Solution Overview

Problem

Fibre Channel over Ethernet (FCoE) networks face Domain_ID exhaustion due to the large number of devices, leading to difficulties in existing Fibre Channel and FCoE fabrics, and previous solutions introduced issues related to failover and multipathing.

Innovation Solution

The entire FCoE fabric is treated as a single virtual domain with a unique Domain_ID, allowing multiple FCFs and FDFs to operate within subdomains, where one FCF is designated as the master for active-active configurations, enabling failover and multipathing while maintaining normal fabric configuration and routing using FSPF protocol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If each FCF is assigned a unique Domain_ID in conventional FCoE implementations, then device identification and fabric management are enabled, but Domain_ID exhaustion occurs due to the large number of devices

Engineering Contradiction:

Improvefabric managementVSAvoidDomain_ID availability

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The FCoE fabric is segmented into multiple virtual domains, each with its own Domain_ID. Instead of assigning unique Domain_IDs to all devices in a single domain, the system divides the fabric into virtual domain 0 and virtual domain 1 (or higher), allowing devices to be distributed across multiple domains. This segmentation resolves the Domain_ID exhaustion problem by expanding the available address space from 256 unique IDs to multiple domains with combined capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system adds a virtual domain dimension to the traditional single-domain Fibre Channel architecture. By introducing virtual domain IDs as an additional addressing dimension, the system can support more devices without increasing the complexity of individual Domain_ID assignments. Devices are identified by a combination of virtual domain ID and port ID, effectively adding another layer to the addressing hierarchy.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If FDFs are introduced to connect ENodes to FCFs, then Domain_ID exhaustion is addressed, but issues with failover and multipathing arise

Engineering Contradiction:

ImproveDomain_ID availabilityVSAvoidfailover and multipathing

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

FCFs in virtual domain 0 are configured to perform multiple functions: they act as principal switches for their own virtual domain, serve as edge switches for virtual domain 1, and participate in inter-domain routing. This multi-functionality eliminates the need for separate FDF devices, as FCFs themselves handle the routing and forwarding between virtual domains, thereby maintaining failover and multipathing capabilities without introducing additional single-function devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system merges the functions of FCFs and FDFs into a single FCF device. Instead of having FDFs as intermediate devices between ENodes and FCFs, the FCF directly performs both edge switching and principal switching functions across multiple virtual domains. This consolidation eliminates the FDF layer while preserving the ability to support failover and multipathing through virtual domain routing.

Inventive Principle:

Principle #5Merging (Combining)

3Quantity of substance

If a single virtual domain is created to alleviate Domain_ID exhaustion, then device capacity increases, but routing complexity and fabric configuration difficulty increase

Engineering Contradiction:

Improvedevice capacityVSAvoidrouting and configuration

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The fabric is segmented into multiple virtual domains with distinct Domain_IDs, and each FCF is assigned to a specific virtual domain. This segmentation allows routing tables to be organized by virtual domain, reducing the complexity of fabric-wide routing calculations. The FSPF protocol can be applied independently within each virtual domain, simplifying the routing computation compared to a single monolithic domain.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

FCFs in virtual domain 0 serve as intermediary devices that facilitate communication between virtual domain 0 and virtual domain 1. These FCFs maintain routing tables that map destinations in virtual domain 1 to appropriate interfaces, acting as mediators that simplify the routing complexity by providing a structured interface between domains rather than requiring all devices to understand the entire fabric topology.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9172590B2Single virtual domain fibre channel over ethernet fabric

Publication Date: 2015.10.27 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

The entire FCoE fabric is a single virtual domain, even though there may be multiple FCFs and FDFs. The virtual domain is a different Domain_ID than any of the FCFs. In certain embodiments there are multiple FCFs, of which one is selected as the master or designated FCF. The master FCF performs normal fabric configuration in conjunction with the Fiber Channel fabric. The master FCF assigns the virtual domain FC node IDs and controls development of subdomain IDs. Virtual links are instantiated between the master FCF and other FCFs, between top level FDFs and the FCFs and between the FDFs at each of various levels. FDFs connected to ENodes proxy the master FCF for most FIP operations. FIP FLOGI and FDISC operations are handled by the master FDF, but the FDFs convert the FIP FLOGI requests to VD_FLOGI requests, which include information about the FDF handling the transaction.