How to load a different congestion control algorithm in Mac OS X?

Question

I found an alternative opensource TCP implementation for Mac OS X [1] which use LEDBAT as congestion control, instead of NewReno.

Since I'm not so familiar with that OS, could you please suggest me how to build that source file and load it into the system?

(for instance I was wondering if there is a way to do so as in Linux, for which there are some implementation [2] that can be easily built, then plugged as a module into the kernel and loaded runtime:

make; make install
modprobe tcp_ledbat
sysctl -w net.ipv4.tcp_congestion_control=ledbat

)

[1] http://opensource.apple.com/source/xnu/xnu-1699.22.81/bsd/netinet/tcp_ledbat.c

[2] http://perso.telecom-paristech.fr/~valenti/pmwiki/pmwiki.php?n=Main.LEDBAT#howtokernel

Thank you

I see a vote for migration to SuperUser, but this seems more like something a IT pro would need which suggests ServerFault. On the other hand, it's mac specific so perhaps Apple.SE. @Dynamiq: you could flag it for moderator if you have a preference. — dmckee --- ex-moderator kitten, Dec 16 '11 at 23:04
***Aside:*** You should be able to just build stuff *after* you have installed the Developer Tools (you got a DVD with the machine). — dmckee --- ex-moderator kitten, Dec 16 '11 at 23:05
Thank you **dmckee** for the suggestions. I'll try to play with xCode then! — Dynamiq, Dec 20 '11 at 15:57

score 3 · Answer 1 · edited Jun 06 '20 at 03:42

The LEDBAT congestion control algorithm is built into OSX Lion (10.7.X) and does not need to be compiled separately. I don't think it would be possible to use LEDBAT in an earlier version of OSX without alot of work. LEDBAT provides for 'background' transfers and may be selected on a socket by setting the following socket option - setsocketopt(sock, SOL_SOCKET, SO_TRAFFIC_CLASS, SO_TC_BK, sizeof(int)). It also seems that the socket's traffic class may affected by the DSCP value in the IP header.

Additionally OSX has had the facility to load kernel modules for other network protocols for some time using their Network Kernel Extensions (NKE) - for example there is an NKE module that has been developed for the SCTP protocol.

These constants are no longer defined in system headers as of macOS 10.15; possibly the replacement is supposed to be `SO_NET_SERVICE_TYPE` and `NET_SERVICE_TYPE_BK`, but I can't find any docs about it. — the paul, Jun 06 '20 at 03:41

How to load a different congestion control algorithm in Mac OS X?

1 Answers1