Operation; Conformance Criteria; Flow Control (Pause); Reliability And Performance - GE Mark VIeS System Manual

3.5 Operation

The performance of a level 1 Ethernet switch is mainly centered on the ability to buffer packets. When a level 1 switch has a
continuous stream of incoming broadcast or multicast packets, the switch must in turn send those packets out upon complete
reception. A single incoming stream should require enough space to buffer one packet or at the most one packet per port.
When the switch has multiple incoming streams, it is only able to relieve one of the incoming streams and must buffer the rest
for later transmission.

3.5.1 Conformance Criteria

The packet traffic can be synchronized by IEEE 1588 timing and triggered to initiate within a 1-microsecond packet start
window. The switch's capability and conformance is tested to meet the following four criteria:
• Initiation of the required Multicast packet load on one port, without IEEE 802.3x flow control negotiated
• Initiation of the required Multicast packet load on one port, with IEEE 802.3x flow control negotiated
• Initiation of the required Multicast packet load distributed across all ports, packet count per port must average required
per number of switch ports with no IEEE 802.3x flow control
• Initiation of the required packet Multicast load distributed across all ports, packet count per port must average 200 per
number of switch ports with IEEE 802.3x flow control negotiated on half the ports

3.5.2 Flow Control (Pause)

The switch supports flow control between switches. It uses IEEE defined pause packets to receive and honor pause packets.
The switch only sends the pause packets if it needs flow control on a port.

3.5.3 Reliability and Performance

Because high reliability is critical to any controls solutions business, the switch exceeds 4 million hours Mean Time Between
Failures (MTBF) at 35°C (95 °F) ambient temperature, ground fixed controlled environment. The switch also meets the
following performance criteria:
Feature
Switch latency
Switch architecture
Inrush current
88 GEH-6855_Vol_II
Performance Criteria
Description
Switch packet latency does not exceed required application limits.
The switch supports store and forward architecture, providing high data confidence.
The switch provides soft start capability that limits inrush current to less than 200% of the
normal operating current.
GEH-6855_Vol_II Mark VIeS Functional Safety Systems Volume II
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