Heartbeat Messages

The Sequenced Unit Header message header with a Hdr Count field set to 0 will be used for heartbeat messages. During trading hours heartbeat messages will be sent from the Cboe One Server, GRP and all multicast addresses if no data has been delivered within 1 second. Heartbeat messages never increment the sequence number, but can be used to detect gaps on the real-time multicast channels during low update rate periods.

Heartbeats on the real-time multicast addresses during trading hours will have a Hdr Sequence value equal to the sequence of the next sequenced message to be sent. Heartbeats on gap multicast addresses will always have the Hdr Sequence field set to 0. All heartbeat messages sent to and from the Cboe One Server and GRP are considered un-sequenced and should have Hdr Sequence and Hdr Unit fields set to 0.

Outside of trading hours Cboe sends heartbeat messages on all real-time and gap channels with a sequence of 0 to help users validate multicast connectivity. Heartbeat messages may not be sent from 12:00 a.m. - 1:00 a.m. ET or during maintenance windows.

Cboe expects heartbeat messages to be sent to the Cboe One Server and GRP on live connections no less than every 5 seconds. Failure to receive two consecutive heartbeat messages will result in the termination of the user connection.