2018-11-14 - 17:09
OSADL Projects

OSADL Realtime QA Farm

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Real-time Ethernet (TSN) synchronization analysis (star topology)

Star topology with one PTP grandmaster and two slaves via PTP-capable switch
Star topology with one PTP grandmaster and two slaves via PTP-capable switch

Peer-to-peer - Star topology

One of the Linux real-time test systems (rack #9, slot #3 at shadow position) serves as PTP grandmaster while receiving global time information via NTP in the same way as all other systems. This PTP server is connected to an industrial Cisco switch (type IE 3000-4TC) that is capable of handling PTP packets in layer 2 and is configured to transparently forward them in an end-to-end mode. This switch is, in turn, connected to two real-time test systems (rack #b, slot #6 at primary and shadow position) that serve as PTP test clients and are equipped with continuous PTP jitter and system time jitter monitoring. They receive time information uniquely from the PTP link. Thus, the three peers, one PTP grandmaster and two PTP clients, share the same time information with the below depicted jitter and can send SO_TXTIME flagged packets such as implemented in an OPC UA PubSub scenario across the peers with a predictable arrival time at the destination peer. The three computer systems, one PTP grandmaster and the two PTP slaves, are equipped with an Intel I210 network controller.

PTP grandmaster: Jitter analysis from system time to network adapter by week

Last update 13 minutes ago

Jitter analysis of time synchronization to the network adapter
Please note that the recorded values of this and of all below plots represent the maximum of subsequent 5-min intervals. Thus, from the given numerical values below the plot the only meaningful value is the one in the column labeled "Max:".

 

PTP client #1: Jitter analysis from network to network adapter and from network adapter to system by week

Last update 13 minutes ago

Jitter analysis of the network adapter
Jitter analysis from network to network adapter

Jitter analysis of the system
Jitter analysis from network adapter to system time

 

PTP client #2: Jitter analysis from network to network adapter and from network adapter to system by week

Last update 18 minutes ago

Jitter analysis of the network adapter
Jitter analysis from network to network adapter

Jitter analysis of the system
Jitter analysis from network adapter to system time