Important notes

Receiver operators, including RoceReceiverOp and LinuxReceiverOperator specifications include:

• Always return the most recently received video frame. This operator will never return a video frame older than 1 frame time. If the pipeline is busy and is unavailable to accept incoming video frames, older frame data is replaced with newer frame data. If the frame request occurs while another frame is being received, this operator returns the last completed video frame.

• Never return the same video frame twice. If the pipeline is faster than a video reception time, the pipeline will block until the next incoming frame is complete.

• PTP timestamps, sent by HSB on both the start-of-frame and the end-of-frame condition, are available by looking at received metadata. When PTP is properly configured, this provides a reliable mechanism for determining the actual latency for processing or this displaying this data. Note that PTP is only supported for IGX configurations.

RoceReceiverOp uses RDMA with special caveats that are likely to change in future versions:

• There is no protection against rewriting the video buffer while the pipeline is using it. The current implementation allocates enough GPU memory to receive two video frames, and the transmitter is configured to alternate between these two buffers. Video pipelines usually start by copying the data from the receiver buffer into another region of memory (via CsiToBayerOp)–this minimizes the time during which an overwrite hazard can occur–but scheduling these operations is dependent on CPU availability. CudaCRCOp can be used to verify that received data has not been corrupted; as long as it computes the same value that’s found in the receiver metadata, then you’ve proven that the memory contents have not been updated.

For systems where the 192.168.0.0/24 network is unavailable, you can use the hololink set-ip command to reconfigure sensor bridge IP addresses. Sensor bridge devices transmit enumeration messages based on the BOOTP protocol; the host can reply with a request to set the IP address to a specific value. Programs in the Holoscan sensor bridge host software all accept a --hololink=<IP-address> command line parameter to look for the device with the given IP address instead of the default 192.168.0.2.

First, locate the MAC ID and local interface that the sensor bridge port is connected to with the hololink enumerate command. Within the demo container:

            

            
$ hololink enumerate
INFO:root:mac_id=48:B0:2D:EE:03:8E cpnx_version=0X2402 clnx_version=0XFFFF ip_address=192.168.0.2 serial_number=10040032828115 interface=eth0
INFO:root:mac_id=48:B0:2D:EE:03:8F cpnx_version=0X2402 clnx_version=0XFFFF ip_address=192.168.0.3 serial_number=10040032828115 interface=eth1
INFO:root:mac_id=48:B0:2D:EE:03:8E cpnx_version=0X2402 clnx_version=0XFFFF ip_address=192.168.0.2 serial_number=10040032828115 interface=eth0
INFO:root:mac_id=48:B0:2D:EE:03:8F cpnx_version=0X2402 clnx_version=0XFFFF ip_address=192.168.0.3 serial_number=10040032828115 interface=eth1
        

This configuration has two network ports, with MAC ID 48:B0:2D:EE:03:8E connected to the local eth0 device; 48:B0:2D:EE:03:8F is connected to eth1. These connect to the same sensor bridge device, as shown by the common serial number. Note that these messages will be observed by the local system regardless of the IP addresses of local network devices.

For our example, we’ll set up this configuration:

• Host eth0 will be configured to 192.168.200.101/24

• Host eth1 will be configured to 192.168.200.102/24

• Sensor bridge port 48:B0:2D:EE:03:8E will use IP address 192.168.200.2

• Sensor bridge port 48:B0:2D:EE:03:8F will use IP address 192.168.200.3

• Explicit routes are added with eth0 to 192.168.200.2 and eth1 to 192.168.200.3

First, follow the setup instructions to configure the host IP addresses and routes for your expected configuration– replace the references to 192.168.0.x with the addresses you expect to use. Then, use the hololink set-ip command to reconfigure the sensor bridge device ports. To configure the target IP address examples above, in the demo container,

            

            
$ hololink set-ip 48:B0:2D:EE:03:8E 192.168.200.2 48:B0:2D:EE:03:8F 192.168.200.3
INFO:root:Running in daemon mode; run with '--one-time' to exit after configuration.
INFO:root:Updating mac_id='48:B0:2D:EE:03:8E' from peer_ip='192.168.0.2' to new_peer_ip='192.168.200.2'
INFO:root:Updating mac_id='48:B0:2D:EE:03:8F' from peer_ip='192.168.0.3' to new_peer_ip='192.168.200.3'
INFO:root:Found mac_id='48:B0:2D:EE:03:8E' found using peer_ip='192.168.200.2'
INFO:root:Found mac_id='48:B0:2D:EE:03:8F' found using peer_ip='192.168.200.3'
        

hololink set-ip accepts a list of MAC ID and IP address pairs. Because the sensor bridge IP address configuration is not stored in nonvolatile memory, hololink set-ip runs as a daemon, and must be running whenever this configuration is desired. When hololink set-ip sees an enumeration message from a device with a listed MAC ID but a different IP address, it will reply with a request to set the desired IP address– this accommodates IP address reverting on power cycle or reset. Following this, pinging the target IP address now works:

            

            
$ ping 192.168.200.2
PING 192.168.200.2 (192.168.200.2) 56(84) bytes of data.
64 bytes from 192.168.200.2: icmp_seq=1 ttl=64 time=0.215 ms
64 bytes from 192.168.200.2: icmp_seq=2 ttl=64 time=0.352 ms
64 bytes from 192.168.200.2: icmp_seq=3 ttl=64 time=0.365 ms
^C
...
$ ping 192.168.200.3
PING 192.168.200.3 (192.168.200.3) 56(84) bytes of data.
64 bytes from 192.168.200.3: icmp_seq=1 ttl=64 time=0.218 ms
64 bytes from 192.168.200.3: icmp_seq=2 ttl=64 time=0.323 ms
64 bytes from 192.168.200.3: icmp_seq=3 ttl=64 time=0.281 ms
^C
        

Note that the routing must be set up correctly for the ping commands to work as expected. Here is more specific information on sensor bridge IP address reconfiguration.

Please use one of the following cables to connect the sensor bridge SPF+ to the IGX devkit QSFP port:

1. Fiber optic cable with optick to SFP+ and SFP+ to QSFP adapters

2. Copper SFP+ to SFP+ with an additional SFP+ to QSFP adapter

Please use the following cables to connect the sensor bridge SFP+ to the Jetson AGX Orin devkit 10G Ethernet port:

1. RJ45 Ethernet cable with RJ45 to SFP+ adapter

All Cables and adapters are available for purchase online - please note that the links above are only for demonstration purposes and should not be considered as a purchase recommendation.