Broadcast Question

Hi all,
I have setup a boardcast between two traccar servers using one single SQL database. I added the following code to the configuration of both servers and opened port 7001 on both instances.

<entry key='broadcast.interface'>ens5</entry>
<entry key='broadcast.address'>172.26.15.255</entry> <!-- I calculated the IP based on the private IP on my interface(s). -->
<entry key='broadcast.port'>7001</entry> <!-- Open on both server. -->

As I could not find any further information in the documentation and the forum, let me ask here.

1.) Does this config make any sense?
2.) What to look for in the log file to see whether the multicasting is working or how else can I validate that the multcasting is working as it should?
3.) When a device sends data to server 1 is server 2 updating the device as well (e.g. live routes?) without refreshing the page?

I am using a loadbalancer to balance the traffic between both servers. The devices are sending their data to either server 1 or server 2. At the moment it appears that when device 1 sends data to server 1, server 2 only updates the device on page refresh. Is this correct or am I missing something.

Thanks,
Chris

This config doesn't make sense. You have to use a multicast address.

Hi Anton,

Thanks, yes, that was not correct. My bad. Made changes as follows. I retrieved the address running the command ip maddr show.

ubuntu@abc:~$ ip maddr show
1:      lo
        inet  224.0.0.1
        inet6 ff02::1
        inet6 ff01::1
2:      ens5
        link  01:00:5e:00:00:01
        link  33:33:00:00:00:01
        link  33:33:ff:6b:e0:e9
        link  01:80:c2:00:00:00
        link  01:80:c2:00:00:03
        link  01:80:c2:00:00:0e
        link  33:33:ff:7f:32:a7
        inet  224.0.0.1 <- Should be this address as it is within the multicast range, correct?
        inet6 ff02::1:ff7f:32a7
        inet6 ff02::1:ff6b:e0e9
        inet6 ff02::1 users 2
        inet6 ff01::1

     <!-- Multicast -->
    <entry key='broadcast.interface'>ens5</entry>
    <entry key='broadcast.address'>224.0.0.1</entry>
    <entry key='broadcast.port'>7001</entry>

That is better, but I think that address is reserved for system use, so I wouldn't recommend using it.

Thanks Anton. I was doing some research on how to add / use a multicast address on a specific multicast enabled interface on Ubuntu. Stuck at this point. Can I just pick any address from the wide multicast range or do I need to config the interface to use a specific multicast address?

I think you can just pick any address.

Hi again Anton. Not sure what I might be missing. I'll continue tomorrow with my testing. At this moment server 2 does not get any push from server 1 once a device status changes. Server 2 needs a page refresh to see the latest device updates.

Both servers now use:

    <!-- Multicast -->
    <entry key='broadcast.interface'>ens5</entry>
    <entry key='broadcast.address'>224.0.0.250</entry>
    <entry key='broadcast.port'>7001</entry> 

But no success right now.

Server two private IP: 172.26.4.143
Server one private IP: 172.26.13.192

Could that be an issue that both are not in the same IP range?

Well, on the other hand both servers actually do use the same broadcast IP.

broadcast 172.26.15.255

What's the network mask?

netmask 255.255.240.0 

Looks like they're in the same network range then.

Is there any other way to investigate the root cause as I am still not able to get multicast to work. Here a complete set-up overview.

Server 1 interface seems fine:

ens5: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9001
        inet 172.26.13.192  netmask 255.255.240.0  broadcast 172.26.15.255
        inet6 2a05:d014:b0b:e800:c7ed:cb0f:dd7f:32a7  prefixlen 128  scopeid 0x0<global>
        inet6 fe80::51:ebff:fe6b:e0e9  prefixlen 64  scopeid 0x20<link>
        ether 02:51:eb:6b:e0:e9  txqueuelen 1000  (Ethernet)
        RX packets 8152951  bytes 2153004450 (2.1 GB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9093193  bytes 3294217163 (3.2 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Server 2 interface seems in the same range:

ens5: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9001
        inet 172.26.4.143  netmask 255.255.240.0  broadcast 172.26.15.255
        inet6 fe80::9:f3ff:fe72:5381  prefixlen 64  scopeid 0x20<link>
        inet6 2a05:d014:b0b:e800:b852:70af:8f8f:c10  prefixlen 128  scopeid 0x0<global>
        ether 02:09:f3:72:53:81  txqueuelen 1000  (Ethernet)
        RX packets 107775  bytes 14741216 (14.7 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 155668  bytes 64582864 (64.5 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Both interfaces are multicast enabled ->> UP,BROADCAST,RUNNING,MULTICAST

The corresponding config entry in the traccar config file (server 1 and server 2 both use the same):

    <!-- Multicast -->
    <entry key='broadcast.interface'>ens5</entry>
    <entry key='broadcast.address'>224.0.0.250</entry>
    <entry key='broadcast.port'>7001</entry>  

Further:

1.) Firewall port 7001 UDP is open (TCP too just for debugging)
2.) Both servers connect to the same mySQL database on a managed mySQL server on AWS

Besides the config in the traccar.xml file, is there any other setting I might be missing? Seems like the current configuration should work but in fact it actually does not appear to perform as it should. Any further hints? Can the log help?

Thanks,
Chris

The config looks correct.

Hi Anton. Thanks for validating the config. What else may I need to look for?

If you don't see any warnings in logs, it means that synchronization messages are sent successfully. Maybe you have some network issues? You can probably use Wireshark or something like that to verify that data is sent and/or received.