6.1. Known Issues with Discovery (SPDP2)

The following known issues apply to the Simple Participant Discovery Protocol 2.0, which is an alternative version of the Simple Participant Discovery Protocol, designed for decreased bandwidth usage and improved reliability. See Simple Participant Discovery 2.0, in the RTI Connext Core Libraries User’s Manual for more information.

6.1.1. Features under future consideration for SPDP2

Note

RTI does not guarantee the following features for any release or timeline. If any of these enhancements is of interest to you, please provide that feedback through your account team.

The following features, which are not currently supported, are being considered for SPDP2 in future releases:

  • Use of SPDP2 with custom security plugins (for example, those implemented with the Security Plugins SDK), the Lightweight Security Plugins, or HMAC-Only mode. Only the RTI Security Plugins are supported in combination with SPDP2.

  • SPDP and SPDP2 compatibility mode. The compatibility mode will allow some DomainParticipants to simultaneously communicate with DomainParticipants that are using SPDP and SPDP2. DomainParticipants that are using the compatibility mode will be able to communicate with DomainParticipants that are using SPDP and other DomainParticipants that are using SPDP2. For now, you can use RTI Routing Service to achieve this communication; see this Knowledge Base article on the RTI Community Forum.

  • Improved configuration update behavior. Currently, when a DomainParticipant changes its configuration (partition, locators, etc.), it sends out:

    • If SPDP is enabled: a single Data(p) to all peers (matched or potential).

    • If SPDP2 is enabled: a single reliable message to matched peers, a single bootstrap message to unmatched initial peers. RTI will add an option to send multiple Data(p)s/bootstrap messages, since these messages are sent best-effort and can get lost, delaying configuration change updates in remote participants until the next periodic message.

[RTI Issue IDs CORE-12929, CORE-13884, and CORE-12930]

6.1.2. HMAC-Only mode and Lightweight Security Plugins not supported

DomainParticipants using SPDP2 cannot use HMAC-Only mode or Lightweight Security Plugins using only preshared keys. Participant discovery will not complete if these features are used. HMAC and preshared keys can be used if they are used in conjunction with the full Security Plugins.

[RTI Issue ID CORE-13385]

6.1.3. allow_unauthenticated_participants not supported in all scenarios

DomainParticipants using SPDP2 with allow_unauthenticated_participants set to TRUE will complete discovery with DomainParticipants that are not using security, but will not complete discovery with DomainParticipants that are using security but fail authentication.

[RTI Issue ID CORE-13383]

6.1.4. Participant discovery fails after re-authentication after asymmetric liveliness loss

If an asymmetric loss of liveliness occurs between two DomainParticipants, the DomainParticipants will attempt to perform re-authentication following the process described in Re-Authentication in the Security Plugins User’s Manual. However, communication between the DomainParticipants will not resume, regardless of the result of the re-authentication attempt. DomainParticipant communication will only resume if both DomainParticipants lose liveliness and begin participant discovery again.

[RTI Issue ID CORE-13870]