Is it possible DISCOVERY on multicast disabled LTE network?

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Is it possible DISCOVERY on multicast disabled LTE network?

RTI Context DDS is perfectly working on our LAN network with WiFi, and we are tring to make it work on LTE(5G further). And as I know, our LTE carrier disabled multicast function on LTE to descrese wireless bandwidth and performance.

So my question is "Is it possible AUTO-DISCOVERY on multicast disabled LTE network?"

 

I considered some approaches:

1. Make a VPN tunnel which is multicast supported.

2.Tring Routing Service Function from RTI.

 

Thanks,

Jason

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Hi Jason,

So, what project are you working on?  Does it have a support contract with RTI?  If so, you probably should just direct your questions to RTI's support team...you'll get more attention and the support team is there to help you do what you need to do.  This community forum is not guaranteed to answer your questions...while sometimes RTI folks like myself will take a look and answer what we can, it generally depends on other non-RTI forum members to help each other.

Fundamentally, configuration-less and efficient "auto-discovery" requires the use of multicast.  There ain't no magic.  You can also have "auto-discovery" by configuring all of the IP addresses of all of the possible nodes that may be communicating with each other using the Initial Peers QOS or the NDDS_DISCOVERY_PEERS environment variable.  But this means you do need to know about the IP addresses and keep that list up-to-date and in addition, each application will be constantly "pinging" every address on the list in case applications that weren't started earlier have been started.

Yes, running a VPN that allows multicast on your LTE network would certain make the network idiosyncrasies transparent to DDS...make a look like a local LAN subnet with multicast.

If you use RTI Routing Service, you eliminate the "automatic discovery" issues for your own applications, but the RTI Routing Services have to discover each other across the LTE network...so all you did was shift the problem to the Routing Service, which is fundamentally just another DDS application.

Finally, on LTE networks, do you even know your IP address and is all IP addresses "ping"-able from all nodes on the network?  LTE networks usually give a private address to each client, so NAT routers are used and you can't actually connect to a host using it's IP address, since that address is private and not routable.

There are various ways around the problem, including some optional products like RTI's Cloud Discovery Service and the use of TCP instead of UDP over a network.  But fundamentally, NAT'ed routers make it quite difficult to have configurationless autodiscovery.  Some amount of address configuration and maintenance thereof will be needed.  You can read about some of this in these chapters of the Connext Users Manual: https://community.rti.com/static/documentation/connext-dds/6.0.1/doc/manuals/connext_dds/html_files/RTI_ConnextDDS_CoreLibraries_UsersManual/index.htm#UsersManual/PartWAN.htm#partwan_2465258880_919195%3FTocPath%3DPart%25205%253A%2520RTI%2520Secure%2520WAN%25C2%25A0Transport%7C_____0 and https://community.rti.com/static/documentation/connext-dds/6.0.1/doc/manuals/connext_dds/html_files/RTI_ConnextDDS_CoreLibraries_UsersManual/index.htm#UsersManual/PartTCP.htm#parttcp_3522674191_920452%3FTocPath%3DPart%25208%253A%2520RTI%2520TCP%25C2%25A0Transport%7C_____0

 

 

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Thank you very much.

I make a VPN tunnel to have rtiddsping worked.But auto-discovery in VPN is still a question.

 

I am working on a early research project for verifying whether DDS features could be used in our production environment before purchasing RTI Context DDS.

How can I contact local support for early technical questions like RTI Context DDS could or not do something and how to do.

 

Thanks!

Jason

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Hi Jason,

You may also want to tale a look at the RTI Cloud Discovery Service.  This service acts helps appliations discover each othen when they are running on a network that does not have multicast. All you need to do is point the individual applications to the Address where you are running the Clold Discovery Service.

The  Clold Discovery Service is included with the latest Connext installations. Use the RTI Launcher, go to the "Labs" tab and you should see it there.

Gerardo

 

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Dear Jason,

When you ran rtiddsping on VPN did you have to set an IP address in NDDS_DISCOVERY_PEERS or through the command line for it to work?  When on VPN, are both hosts IPs in the same subnet?

And then, can you confirm that the VPN is able to transfer multicast packets (can use wireshark to see if multicast packets sent on one host is received by another).

Finally, if you can tell me which company you work for and your location, I can get a local team to support you.

Best regards,

--Howard

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Hi Howard,

1. NDDS_DISCOVERY_PEERS was not set, just set  dds.transport.UDPv4.builtin.parent.allow_interfaces_list property.And both hosts IPs are in the same VPN subnet.

2.Theoretically, OpenVPN in TAP mode supports transfering multicast packets.

3.Is there any manual describing the transport evironment(e.g. UDP) required by RTI Connext DDS?

 

May I send email to you including some detail of our project?

 

Thanks,

Jason

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Hi Jason,

You can use howard@rti.com.  Please let me know the name of your company, where you are located and the details of your project.

If discovery is not completing with the default settings, then it's possible

1) multicast traffic is not being passed between hosts, again, if you run wireshark, you should easily be able to verify this...Connext DDS will send a multicast packet once every 30 seconds by default and multiple on startup

2) if you do see multicast packets successfully received but discovery is still not competing, then my guess is that you're running in a Windows environment and the Network Profile that Windows is using for your VPN connection is "Public" instead of "Private" or "Domain".   The Windows firewall is configured differently if the network profile is "Public" and prevents DDS discovery from completing.

If this is the case, then you either have to change your Network Profile for the VPN connection (on both hosts) to be "Private", or you have to disable the Windows firewall for the VPN connection (on both hosts).

Best regards,

--Howard