64 gigabit fibre channel speed negotiation and transmitter training

Patent metadata

Field	Value
Publication number	US-10523405-B2
Application number	US-201715659791-A
Country	US
Kind code	B2
Filing date	Jul 26, 2017
Priority date	Aug 1, 2016
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

Link speed negotiation for 64 Gbps is done at 32 Gbps to allow only two speeds to be used during link state negotiation. The desire for 64 Gbps operation is indicated in a field shared during link state negotiation. After link speed negotiation is completed at 32 Gbps, a determination is made whether 32 or 64 Gbps operation is desired. If 32 Gbps operation is desired, procedures continue as in the prior operations. If 64 Gbps operation is desired, a new procedure is performed. The new procedure provides time for the optical transceiver to changeover from the PAM2 (pulse amplitude modulation) or binary operation used in 32 Gbps operation to the PAM4 multi-level operation used in 64 Gbps operation. After determining that the optical transceiver is ready to transmit, transmitter training is performed, with increased handshaking to provide improved granularity. After transmitter training is complete, conventional link initialization is performed.

First claim

What is claimed is:

1. A method, performed by a processor, comprising the steps of:
performing link speed negotiation for a port at one end of a Fibre Channel link using an optical transceiver capable of operating at three different speeds but having only one speed selection pin by performing link speed negotiation at only two of the three different speeds and selecting the third speed of the three different speeds by reviewing a bit setting in a Control Field in a Training Frame in a Transmitting Training Signal;
determining if the negotiated speed requires a change from the modulation type used during link speed negotiation;
proceeding directly to transmitter training when no change in modulation type is determined and performing transmitter training;
setting the changed modulation type in the optical transceiver when a change in modulation type is determined;
determining that the optical transceiver is ready to operate using the changed modulation type by monitoring a Ready bit in an addressable memory location of a memory in the optical transceiver, wherein the optical transceiver operates according to a small form factor (SFF) specification;
proceeding to changed modulation type transmitter training when it is determined that the optical transceiver is ready to operate using the changed modulation type; and
performing changed modulation type transmitter training.

2. The method of claim 1 , wherein the two speeds used for link speed negotiation are the lowest speed and the middle speed and wherein the bit setting indicates the highest speed.

3. The method of claim 2 , wherein the three speeds are 16 Gigabits per second (Gbps), 32 Gbps and 64 Gbps.

4. The method of claim 1 , wherein performing changed modulation type transmitter training includes:
determining if the optical transceiver has achieved frame lock;
setting a receiver frame lock bit in a Status Field in the Training Frame in the Transmitting Training Signal when it is determined that the optical transceiver has achieved frame lock;
determining that far end receive frame lock has been achieved by monitoring received bits in the Status Field in the Training Frame in the Transmitting Training Signals; and
commencing coefficient training when it is determined that the optical transceiver has achieved frame lock and that the far end frame lock has been achieved.

5. The method of claim 1 , further comprising the steps of:
independently performing the steps of claim 1 for ports at one end of three additional Fibre Channel links which are parallel with the Fibre Channel link;
determining, after speed negotiation and transmitter training, if the ports at one end of each of the four parallel connected Fibre Channel links are capable of operating as parallel lanes;
determining, after speed negotiation and transmitter training, if each of the ports at one end of the four parallel connected Fibre Channel links has indicated capability of operation at four times the rate of an individual link;
determining, after speed negotiation and transmitter training, if each of the four parallel connected Fibre Channel links has independently negotiated for operation at an equal speed which allows four parallel connected Fibre Channel links to be combined for operation at four times the rate of an individual link; and
determining, after speed negotiation and transmitter training, if each of the four parallel connected Fibre Channel links has independently negotiated for operation at an equal speed which allows four parallel connected Fibre Channel links to be combined for operation at four times the rate of an individual link; and
configuring each of the ports at one end of the four parallel connected Fibre Channel links for operation at four times the rate of an individual link upon determining that the ports at one end of each of the four parallel connected Fibre Channel links are capable of operating as parallel lanes, that each of the ports at one end of each of the four parallel connected Fibre Channel links has indicated capability of operation at four times the rate of an individual link and that each of the four parallel connected Fibre Channel links has independently negotiated for operation at an equal speed which allows four parallel connected Fibre Channel links to be combined for operation at four times the rate of an individual link.

6. One or more non-transitory processor-readable storage media encoding computer executable instructions for executing a method on a computer system, the method comprising the steps of:
performing link speed negotiation for a port at one end of a Fibre Channel link using an optical transceiver capable of operating at three different speeds but having only one speed selection pin by performing link speed negotiation at only two of the three different speeds and selecting the third speed of the three different speeds by reviewing a bit setting in a Control Field in a Training Frame in a Transmitting Training Signal;
determining if the negotiated speed requires a change from the modulation type used during link speed negotiation;
proceeding directly to transmitter training when no change in modulation type is determined and performing transmitter training;
setting the changed modulation type in the optical transceiver when a change in modulation type is determined;
determining that the optical transceiver is ready to operate using the changed modulation type by monitoring a Ready bit in an addressable memory location of a memory in the optical transceiver, wherein the optical transceiver operates according to a small form factor (SFF) specification;
proceeding to changed modulation type transmitter training when it is determined that the optical transceiver is ready to operate using the changed modulation type; and
performing changed modulation type transmitter training.

7. The one or more non-transitory processor-readable storage media of claim 6 , wherein the two speeds used for link speed negotiation are the lowest speed and the middle speed and wherein the bit setting indicates the highest speed.

8. The one or more non-transitory processor-readable storage media of claim 7 , wherein the three speeds are 16 Gigabits per second (Gbps), 32 Gbps and 64 Gbps.

9. The one or more non-transitory processor-readable storage media of claim 6 , wherein performing changed modulation type transmitter training includes:
determining if the optical transceiver has achieved frame lock;
setting a receiver frame lock bit in a Status Field in the Training Frame in the Transmitting Training Signal when it is determined that the optical transceiver has achieved frame lock;
determining that far end receive frame lock has been achieved by monitoring received bits in the Status Field in the Training Frame in the Transmitting Training Signals; and
commencing coefficient training when it is determined that the optical transceiver has achieved frame lock and that the far end frame lock has been achieved.

10. The one or more non-transitory processor-readable storage media of claim 6 , wherein the method further comprises the steps of:
independently performing the steps of claim 6 for ports at one end of three additional Fibre Channel links which are parallel with the Fibre Channel link;
determining, after speed negotiation and transmitter training, if the ports at one end of each of the four parallel connected Fibre Channel links are capable of operating as parallel lanes;
determining, after speed negotiation and transmitter training, if each of the ports at one end of the four parallel connected Fibre Channel links has indicated capability of operation at four times the rate of an individual link;
determining, after speed neg

Assignees

• Avago Tech Int Sales Pte Lid

Inventors

• Mehta Anil
• Kipp Scott
• Slavick Jeffrey A

Classifications

• H04L49/357

  Fibre channel switches · CPC title

• H04L49/30

  Peripheral units, e.g. input or output ports · CPC title

• H04L49/352

  Gigabit ethernet switching [GBPS] · CPC title

• H04L41/0681

  Configuration of triggering conditions · CPC title

• H04L5/1438 Primary

  Negotiation of transmission parameters prior to communication (modified according to link quality H04L1/0001) · CPC title