IPv6 has lower ping than IPv4 with my Jamulus server

[corrados]

When my Jamulus server was moved to a new location, I did some tests with IPv6 and observed something interesting. Here is a ping and a Jamulus screen shot using IPv4:

ping anygenre1.jamulus.io
PING jamulusanygenre1.fischvolk.de (82.153.225.55) 56(84) bytes of data.
64 bytes from 82.153.225.55: icmp_seq=1 ttl=57 time=18.3 ms
64 bytes from 82.153.225.55: icmp_seq=2 ttl=57 time=18.2 ms
64 bytes from 82.153.225.55: icmp_seq=3 ttl=57 time=17.6 ms

So I get around 18 ms ping.

Connecting the exact same server but now using "Jamulus -6" and the IPv6 address, I get:

ping6 2a09:9340:1801:43::a
PING 2a09:9340:1801:43::a (2a09:9340:1801:43::a) 56 data bytes
64 bytes from 2a09:9340:1801:43::a: icmp_seq=1 ttl=57 time=15.8 ms
64 bytes from 2a09:9340:1801:43::a: icmp_seq=2 ttl=57 time=14.9 ms
64 bytes from 2a09:9340:1801:43::a: icmp_seq=3 ttl=57 time=14.8 ms

which is approx. 3 ms faster!

I did not expect such a behavior. Maybe some IPv4 tunneling introduces delay?
Have other Jamulus users experienced similar ping gains? Would be interesting to now.

[rdica]

@corrados All my servers also have IPv6 connectivity, with two of them having slightly better routing via IPv6 than legacy.
Like you, I see 2-5ms lower pings in the client over IPv6.

My residential ISP in the US has the largest IPv6 deployment to residential customers in the country, and it appears they have decent peering with other network backbones throughout North America. This affords me the ability to run servers in different geographic regions where I can play, mostly using IPv6 connectivity. With the addition of SRV DNS support this gives me an easy-to-use dualstack option I provide to my regular users/players.

[corrados]

Thanks for your feedback. So you use "-6" option for all of your Jamulus servers?

Up to now I have not used that flag for my anygenre1.jamulus.io server. The question for me is if someone wants to use the URL like "anygenre1.jamulus.io" to connect to the server but wants to use IPv6. Do you know if this is possible?

[rdica]

Yes, I use -6 option on my servers and clients.
It is possible! :)
My server hostnames resolve in both IPv6 (AAAA) and legacy (A) DNS space. IPv6 enabled clients attempting direct connections to the server hostname will by default try IPv6 first as this is the design of IPv6.

There is no requirement to have a single hostname resolve in both DNS spaces. Some choose to use a separate IPv6-specific hostname because of fears of client machines having faulty IPv6 stacks that cause connectivity issues. "Happy Eyeballs" technology was developed to address this shortcoming but its not a one-size-fits-all solution given the many different networking/router configurations, and maturity of network stacks in use by an OS. On this subject I thought I had asked in a previous discussion about "Happy Eyeballs" implementation in Jamulus, if any, but cannot find the thread at the moment.

Something to consider before enabling IPv6 connectivity on your directory server:
Servers with IPv6 enabled will try to connect to --directoryaddress hostname:port via IPv6 if the hostname resolves in both DNS spaces. Currently this prevents the registration of a server as there's no apparent "Happy Eyeballs" implementation that would have a server try legacy IP when IPv6 fails.
I learned this when I stood up my directory server, and had to have it listen on legacy IP only so servers could successfully register.

[corrados]

Thanks again for your detailed description. Since "anygenre1.jamulus.io" server is the main Jamulus directory server, I then will not risk any registration issues caused by my IPv6 experiments. But for my private Jamulus server, I'll definitely use IPv6 to get the lowest possible ping times :-).

[ann0see]

I then will not risk any registration issues caused by my IPv6 experiments.

IPv6 is currently not supported for directories (yet). Only a direct connection would use IPv6.