Extended link-training time negotiated on link start-up
Examples described herein relate to link training between network connected devices. In some examples, an amount to extend link training is determined. The amount to extend link training can be determined by: receiving, by a receiver in a first device, signals over a lane from a transmitter in a second device, the signals indicating capability to extend link training time and amount to extend link training time; determining, at the first device, a link training time based on a default link training time and an amount to extend link training time; and performing link training based on the determined link training time. In some examples, the determined amount is highest common denominator of the received identified capability and transmitted indicated capability. In some examples, if the received communication indicates no ability to extend link training time, the link training time is a default link training time. In some examples, the signals indicating capability to extend link training time and amount to extend link training time comprise an IEEE 802.3 compatible Next Page.
1. An apparatus comprising:
a first device comprising a transmitter and receiver associated with a lane of a communications link, wherein:
the first device is to receive one or more communication signals identifying capability to extend link training time beyond a first link training time;
the first device is to transmit one or more other communication signals indicating a capability to extend link training time; and
the first device is to determine an amount to extend link training time based on the received identified capability and transmitted indicated capability.
2. The apparatus of claim 1 , wherein the first link training time comprises a default link training time.
3. The apparatus of claim 1 , wherein the determined amount is a lesser of the received identified capability and transmitted indicated capability.
4. The apparatus of claim 1 , wherein if the one or more received communication signals indicate no ability to extend link training time, the link training time is a default link training time.
5. The apparatus of claim 1 , wherein the one or more received communication signals comprises an Institute of Electrical and Electronics Engineers (IEEE) 802.3 compatible Next Page.
6. The apparatus of claim 1 , wherein to determine an amount to extend link training time based on the received identified capability and transmitted indicated capability, the first device is to engage in an exchange phase to advertise non-IEEE compatible capabilities.
7. The apparatus of claim 1 , wherein the first device is to:
advertise one or more capabilities and
select an operating mode for the lane, wherein the one or more capabilities comprise one or more of link speed, forward error correction (FEC) capabilities, or pause capabilities.
8. The apparatus of claim 1 , wherein the first device is a link partner with a second device and the first and second devices are to engage in a link-training phase for link training time plus the determined amount to extend link training time.
9. The apparatus of claim 8 , wherein the link-training phase comprises:
request changes in the second device's transmit equalizer settings,
monitor an effect on link quality at a receiver of the first device to determine received signal characteristics, and
selectively request additional changes in the second device's transmit equalizer settings based on the received signal characteristics.
10. The apparatus of claim 9 , wherein the received signal characteristics comprises one or more of bit error rate (BER), eye size, signal to noise ratio (SNR), or link errors, wherein link errors comprise one or more of: uncorrectable and correctable forward error correction (FEC) errors, pseudorandom bit sequence (PRBS) errors, or physical coding sublayer (PCS) errors.
11. The apparatus of claim 1 , comprising one or more of: a server, rack, or data center and wherein the first device is provided in one or more of: the server, rack, or data center.
12. A method to determine an amount to extend link training, the method comprising:
receiving, by a receiver in a first device, signals over a lane from a transmitter in a second device, the signals indicating capability to extend link training time and amount to extend link training time;
determining, at the first device, a link training time based on a default link training time and an amount to extend link training time; and
performing link training based on the determined link training time.
13. The method of claim 12 , wherein the determined amount is highest common denominator of the received identified capability and transmitted indicated capability.
14. The method of claim 12 , wherein if the received signals indicate no ability to extend link training time, the link training time is a default link training time.
15. The method of claim 12 , wherein the signals indicating capability to extend link training time and amount to extend link training time comprise an IEEE 802.3 compatible Next Page.
16. The method of claim 12 , comprising:
advertising, by the first device, one or more capabilities;
receiving, from a link partner, one or more capabilities; and
selecting an operating mode for the lane, wherein the one or more capabilities comprise one or more of link speed, forward error correction (FEC) capabilities, or pause capabilities.
17. The method of claim 12 , wherein the first device is a link partner with a second device and comprising:
engaging in a link-training phase with the second device for a link training time plus the determined amount to extend link training time.
18. The method of claim 17 , wherein the link-training phase comprises:
requesting changes in the second device's transmit equalizer settings,
monitoring an effect on link quality at a receiver of the first device to determine received signals characteristics, and
selectively requesting additional changes in the second device's transmit equalizer settings based on the received signals characteristics.
19. The method of claim 18 , wherein the received signals characteristics comprise one or more of bit error rate (BER), eye size, signal to noise ratio (SNR), or link errors, wherein link errors comprise one or more of: uncorrectable and correctable forward error correction (FEC) errors, pseudorandom bit sequence (PRBS) errors, or physical coding sublayer (PCS) errors.
20. A non-transitory computer-readable medium comprising instructions stored thereon, that if executed by one or more processors, cause the one or more processors to be configured for performance of operations comprising:
engage in a link training wherein:
the one or more processors are to receive one or more communication signals identifying capability to extend link training time;
the one or more processors are to cause transmission of one or more other communication signals indicating including a capability to extend link training time; and
the one or more processors are to determine an amount to extend link training time based on the received identified capability and transmitted indicated capability.
21. The non-transitory computer-readable medium of claim 20 , wherein the determined amount is a lesser of the received identified capability and transmitted indicated capability.
22. The non-transitory computer-readable medium of claim 20 , wherein if the one or more received communication signals indicate no ability to extend link training time, the link training time is a default link training time.