Retry-on-error responses, Retry-on-error responses –14 – Altera SerialLite II IP Core User Manual

Page 37

3–14

Chapter 3: Parameter Settings

Link Layer Configuration

SerialLite II MegaCore Function

January 2014

Altera Corporation

User Guide

6. If the timer expires three times in succession, a link error is declared and the link is

restarted. You can control the Timeout limit in the SerialLite II parameter editor,
and it is good practice not to set the time-out to be too long so the system does not
have to wait too long for such situations to resolve. However, do not set the
Timeout

to be too short because then the system always times out and the link

never remains up. The time-out value is based primarily on the round trip latency
(that is, from the time a packet is sent to when the ACK is returned to that
transmitter). The exact value of the round trip latency is undetermined, pending
device characterization, but a value of 1,024 columns is recommended.

Implementation of the retry-on-error mechanism is optional for the priority port. If
the Retry-on-error parameter is turned off, no segment acknowledgments are
generated or expected, and all segments are transmitted without any
acknowledgements from the receiver.

Table 3–4

shows the retry-on-error options for the priority data port.

Retry-on-error Responses

Table 3–5

summarizes the response to various transmission errors.

Table 3–4. Retry-on-error Options (Priority Data Port Only)

Option

Description

Turned on

Logic is created to acknowledge segments and retransmit segments when errors
occur. Eight transmit segment buffers are created. Available only if the priority
data port is enabled.

Turned off

Logic is not created to acknowledge segments. Available only if the priority data
port is enabled. This is the default setting.

Table 3–5. Retry-on-error Responses

Error

Response

Invalid 8b/10b codes groups