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Method and Apparatus for Obtaining Deterministic and Managed Assignment of Port Addresses in a Fibre Channel Network

IP.com Disclosure Number: IPCOM000126454D
Original Publication Date: 2005-Jul-18
Included in the Prior Art Database: 2005-Jul-18
Document File: 3 page(s) / 60K

Publishing Venue

IBM

Abstract

An improved method of acquiring multiple Fibre Channel N_Port identifiers (N_Port IDs) is disclosed. Additional information is provided during the N_Port ID-acquisition process that gives the fabric information about the number of additional N_Port IDs that will be requested, and that gives the N_Port information about the number of additional N_Port IDs that the fabric will be able to assign. This additional information enables the fabric to more efficiently allocate the resources for managing the upcoming requests, and it enables the N_Port to make informed decisions about whether or not subsequent requests for additional N_Port IDs will be accepted.

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Method and Apparatus for Obtaining Deterministic and Managed Assignment of Port Addresses in a Fibre Channel Network

This invention defines new functions to be used in conjunction with processing the Common Service Parameters field of the FLOGI extended link service. (See [1].) These new functions include explicit indications from the requestor (i.e. the N_Port), and grantor (i.e. the fabric) of each one's intentions regarding additional N_Port address acquisitions that are to subsequently occur. Using this invention, the N_Port specifies whether it expects to request further N_Port ID assignments and (if so) how many, and the fabric specifies whether it is capable of granting additional N_Port ID assignments and (if so) how many it expects to be able to grant.

     The new parameters added to the Common Service Parameters field of the FLOGI request are shown below. Bit 30 of word 1 and bits 15-0 of word 2 of the FLOGI request are used since they are currently reserved in the Fibre Channel standard [1]. Word 1:
Bit 30 = 1: The requesting N_Port desires to acquire at least one additional N_Port ID. Bit 30 = 0: The requesting N_Port does not desire to acquire additional N_Port IDs. Word 2:
Bits 15-0: Contains a binary number specifying the number of additional N_Port IDs that the N_Port expects to require. (Additional N_Port IDs are requested by sending FDISC requests subsequent to completion of the FLOGI extended link service. See [1] for additional information.)

     The new parameters added to the Common Service Parameters field of the FLOGI response are shown below.

Word 1: Bit 30 = 1 The responding fabric supports NPIV Bit 29 = 1 The responding fabric currently has sufficient resources to assign the number of additional N_Port IDs indicated in word 2. (See below.) This bit is not set to 1 unless Bit 30 of the request was set to one by the N_Port, indicating that the N_Port expects to request additional N_Port addresses.

Word 2: Bits 15-0: If the N_Port indicated in the FLOGI request that it desires to acquire additional N_Port addresses, this field specifies the number of additional N_Port addresses that the fabric has the resources to grant. The value of this field may be less than or equal to the number of additional N_Port addresses that the N_Port indicated it expected to require. If the N_Port indicated in the FLOGI request that it does not desire to acquire additional N_Port IDs, then this field is set to zero.

A summary of the settings of bits 29 and 30 of word 1 of the FLOGI common service parameters is shown below:

If bit 30 is set to 1 in the FLOGI Request (indicating that the N_Port expects to request additional N_Port addresses), then bits 29-30 of word 1 of the Common Service Parameters field in the FLOGI Response are set as follows:

1

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Bit 29 Bit 30

0 0 Fabric does not support NPIV (Bits 15-0 of word 2 are set to zero)

0 1 Fabric supports NPIV but is unable to assign any additional N_Port IDs at this time. (Bits 15...