KSZ9567R_V01 datasheet(51/233 Pages) MICROCHIP

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DS00002329E-page 51

KSZ9567R

4.5.2

IEEE 1588 PTP MESSAGING PROCESSING

The device supports IEEE 1588 PTP time synchronization when 1588 PTP mode and message detection are enabled.

Different operations will be applied to PTP packet processing based on the setting of P2P or E2E in transparent clock

mode, master or slave in ordinary clock mode, one-step or two-step clock mode, and if the domain checking is enabled.

For the IPv4/UDP egress packet, the checksum can be updated by either re-calculating the two-bytes or by setting it to

zero. For the IPv6/UDP egress packet, the checksum is always updated.

4.5.3

IEEE 1588 PTP EVENT TRIGGERING AND TIMESTAMPING

An event trigger output signal can be generated when the target and activation time matches the IEEE1588 PTP system

clock time. Likewise, an event timestamp input can be captured from an external event input signal and the correspond-

ing time on the IEEE1588 PTP system clock will be captured. Both the output event block and the input timestamp block

can be programmed to generate interrupts.

4.6

Audio Video Bridging and Time Sensitive Networks

AVB defines a set of features and protocols for ensuring high QoS for time-sensitive traffic such as audio and video

streams. The device provides the necessary hardware features for implementation of AVB: gPTP timing synchronization

features (802.1AS, based on 1588 PTP), prioritized queuing, and credit-based traffic shapers (802.1Qav). Ports sup-

porting AVB must operate at 1000 or 100 Mbps at full-duplex. 10 Mbps and/or half-duplex are not compatible with AVB.

Non-AVB devices are not allowed to participate in an AVB network, but non-AVB traffic is allowed to occupy available

bandwidth unused by the AVB traffic. Protocols are defined for network discovery, path setup, and bandwidth reservation

across the network.

AVB defines Stream Reservation (SR) traffic classes, which are given a high priority for queuing and egress scheduling.

With up to four egress queues per port, the device can accommodate up to two SR traffic classes. Ingress AVB traffic

packets are typically VLAN tagged. If not, the device can assign them a customizable VLAN tag on a port-by-port basis.

The information in this tag, including the 3-bit PCP priority field, is used to map the packets to the appropriate high pri-

ority queue. At least one queue must be reserved for non-SR traffic classes, in order to accommodate regular “best

effort” network traffic.

FIGURE 4-9:

PTP SYSTEM CLOCK OVERVIEW

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