EMA C++ Configuration Guide : 3 Configuration Groups : 3.4 Channel Group : 3.4.8 Parameters for Use with Channel Type: RSSL_RELIABLE_MCAST
 
3.4.8 Parameters for Use with Channel Type: RSSL_RELIABLE_MCAST
In addition to the universal parameters listed in Section 3.4.2, you can use the following parameters to configure a channel whose type is RSSL_RELIABLE_MCAST.
Several of these parameters configure how the channel sends a Host Status Messages on the network, while others configure how the channel manages RRCP packet transmission. For further details on the Host Status Message (HSM) concept, on configuring HSMs, and on RRCP packet transmission, refer to the ADH Software Installation Manual.
Additionally several parameters are designed for use with an LSEG Real-Time Distribution System infrastructure tool called rrdump. rrdump is a monitoring utility available in the LSEG Real-Time Distribution System Infrastructure Tools package. For more information on rrdump, refer to ADH Software Installation Manual.
 
Table 13: Parameters for Channel Type: RSSL_RELIABLE_MCAST  
Parameter Name
Type
Default
Notes
DisconnectOnGap
UInt64
0
Specifies whether the underlying connection should be closed if a multicast gap situation is detected.
0 (false): 0 is the default value which means the underlying connection is not closed if a multicast gap situation occurs.
1 (true): Sets the underlying connection to close if a multicast gap situation occurs.
HsmInterface
EmaString
“”
Specifies the Host Status Message (HSM) interface.
By default, HsmInterface is set to the host machine’s default interface.
HsmInterval
UInt64
 
The interval (in seconds) over which HSM packets are sent. You can use rrdump to change the value of hsmInterval. Thus, after starting the application, you can stop and restart HSM publication as needed. The default interval is 0 (disabled) which suspends host status message publication.
HsmMultAddress
EmaString
“”
Specifies the multicast address over which this channel sends HSM packets. Enterprise Message API configuration allows for the use of defined aliases.
HsmPort
EmaString
“”
Specifies the multicast port to which this channel sends HSM packets.
ndata
UInt64
7
Specifies the maximum number of retransmissions to attempt for an unacknowledged point-to-point packet.
nmissing
UInt64
128
Specifies the maximum number of missed consecutive multicast packets, from a particular node, from which RRCP requests retransmits.
nrreq
UInt64
3
Specifies the maximum number of retransmit requests that can be sent for a missing packet.
PacketTTL
UInt64
5
Sets the lifespan (in hops) of the data packet through the multicast network, which can prevent the packet from circulating indefinitely. It has a range of 0 - 255.
0 means the message can be sent only to other applications on the same machine.
A value of 255 sets the message to travel through the network indefinitely.
pktPoolLimitHigh
UInt64
190000
Specifies the high-water mark for the RRCP packet pool. If this limit is reached, no further RRCP packets are allocated until usage falls below the low-water mark (as set by pktPoolLimitLow).
pktPoolLimitLow
UInt64
180000
Specifies the low-water mark for the RRCP packet pool. If RRCP packet allocation gets frozen (due to pktPoolLimitHigh having been reached), additional RRCP packets are allocated only when usage falls below the pktPoolLimitLow setting. pktPoolLimitLow should be greater than 3 * userQLimit.
RecvAddress
EmaString
“”
Specifies the multicast address to which this channel connects for receiving data.
RecvPort
EmaString
“”
Specifies the multicast port to which this channel connects for receiving data.
SendAddress
EmaString
“”
Specifies the multicast address to which this channel connects for sending data.
SendPort
EmaString
“”
Specifies the multicast port to which this channel connects for sending data.
tbchold
UInt64
3
Specifies the maximum time that RRCP holds a transmitted broadcast packet in case the packet needs to be retransmitted. tbchold is specified in RRCP clock ticks (100 milliseconds), so a value of 2 means 200 milliseconds.
tcpControlPort
EmaString
“”
Specifies the port to use for the RRCP tcpControlPort. This port is used when troubleshooting RRCP using the rrdump tool. A setting of -1 disables tcpControlPort.
tdata
UInt64
1
Specifies the time that RRCP waits before retransmitting an unacknowledged point-to-point data message. tdata is specified in RRCP clock ticks of 100 milliseconds, thus a value of 2 means 200 milliseconds.
tpphold
UInt64
3
Specifies the maximum time that RRCP holds a transmitted point-to-point packet in case the packet needs to be retransmitted. tpphold is specified in RRCP clock ticks (100 milliseconds), so a value of 2 means 200 milliseconds.
trreq
UInt64
4
Specifies the amount of time that RRCP waits before "resending" a retransmit request for a missed multicast packet. trreq is specified in RRCP clock ticks (100 milliseconds), so a value of 2 means 200 milliseconds.
twait
UInt64
3
Specifies the duration of time for which RRCP ignores additional retransmit requests for a data packet that it has already retransmitted. This time period starts with the receipt of the first request for retransmission. twait is specified in RRCP clock ticks (100 milliseconds), so a value of 2 means 200 milliseconds.
UnicastPort
EmaString
“”
Port to which this connection connects for unicast messages (i.e., ack/nak messages and any retransmit messages). This value also configures a TCP listening port for use with the rrdump tool.
userQLimit
UInt64
65535
Specifies the maximum backlog of messages allowed on an application's inbound message queue.
If userQLimit is exceeded, the RRCP protocol engine begins to discard messages for that application until the backlog decreases.