Statically configure a Firewall to let OMG DDS Traffic through

Jan 19, 2021

DDS端口

The ports (and multicast addresses) used by DDS implementations (such as RTI Connext DDS) are specified by the OMG DDS Interoperability Wire Protocol Specification (DDS-RTPS).By default, each DomainParticipant opens 4 UDP/IP ports: Two of those ports are multicast ports which are shared among all domain participants in the same DomainId. The other two are unicast ports which are different for each participant within a computer. The multicast IP address used for discovery is 239.255.0.1 by default consistent which the DDS-RTPS specification.

默认情况下，每个DomainParticipant打开4个UDP/IP端口

2个组播端口：同一个domainId下所有participants共享
2个单播端口：每个participant都不同

用作发现的组播IP地：239.255.0.1

The ports used are given by a formula that depends on the DDS domainId and the number of participants that are already running on the same operating system instance (computer or virtual machines):

端口分配依赖DmainId和participant数量

Multicast Ports (common to all applications on a domainId):
DiscoveryMulticastPort  =   PB + DG * domainId + d0
UserMulticastPort	=   PB + DG * domainId + d2
Unicast Ports (different for each participant running on a single operating system instance. Computer or VM):
DiscoveryUnicastPort    =   PB + DG * domainId + d1 + PG * participantId
UserUnicastPort         =   PB + DG * domainId + d3 + PG * participantId
These formulas are depend on two variables: domainId and participantId
domainId      - Is the DDS domainId
participantId - Is an integer starting at 0 that enumerates each participant 
                that runs on a given operating system instance (computer 
                or virtual machine). 
                The first participant will be 0, the second 1, etc.
The formulas are parameterized by the constants d0, d1, d2, d3, PB, DG, and PG which are all defined in the OMG DDS Interoperability Wire Protocol Specification (DDS-RTPS) as follows:
d0  (builtin_multicast_port_offset)    = 0
d2  (user_multicast_port_offset)       = 1 
d1  (builtin_unicast_port_offset)      = 10
d3  (user_unicast_port_offset)         = 11
PB  (port_base)             = 7400
DG ( domain_id_gain)        = 250
PG  (participant_id_gain)   = 2

公式中使用的常数是DDS协议编译的默认值。

可以通过DomainParticipantQos里面的WireProtocolQosPolicy改变端口映射。

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