MPTCP on Gentoo kernel 4.10 : Dummy questions [SOLVED]

orion777 · Last edited by orion777 on Thu Mar 15, 2018 8:02 am; edited 1 time in total

I'm running gentoo 64 bit kernel 4.10 on Raspberry PI 3B (SAkakis' image https://forums.gentoo.org/viewtopic-p-8177442.html#8177442 ).
Now I wish to install MPTCP to get robust (redundant) network connection.
So, getting kernel sources and MPTCP patch for 4.10 into linux_mptcp:

orion777 · Posted: Fri Feb 09, 2018 7:34 am Post subject:

So, as I understood, nobody was/is using MPTCP on gentoo?

Hu · Moderator Joined: 06 Mar 2007 Posts: 21595

Nobody satisfies all of:

Reads and posts on the forums
Uses MPTCP on Gentoo
Can leverage #2 to help you

There might be MPTCP users who do not read the forums and have not seen this thread, or who use it, but lack the expertise to assist you.

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

Is there anything you need MPTCP for that you can't do using the simpler, built in multipath ip routing?

orion777 · Posted: Sat Feb 10, 2018 8:10 am Post subject:

Initially I was planning to use NetworkBonding to be able to send same packet thru different network cards simultaneously.
Due of the fact that I'm not experience user, I spend two months to get network configuration running (to understand interrelationship between NetworkManager, dhcpcd, dhclient and what is written in gentoo tutorial https://wiki.gentoo.org/wiki/Handbook:X86/Full/Networking ). And ONLY after that I understand that Network Bonding cannot be build using different network providers... (it was discussed and I was getting the answer here https://forums.gentoo.org/viewtopic-t-1074802.html . Also there is an advice to use two VPN connections to be able to bond them togehter, but I was not truing this solution yet)

So, to be able to send same packet over two different networks (in fact, two 3G/4G modems that emulates virtual ethernet cards) simultaneously I try to use mentioned here https://forums.gentoo.org/viewtopic-t-1060694-start-0.html MPTCP solution. But due of the fact that I'm dummy, I cant force it to work

What You means under built in multipath ip routing ?

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

Enaable CONFIG_IP_ROUTE_MULTIPATH and the kernel will automatically spread packets among routes that point to the same destination.

orion777 · Posted: Tue Feb 13, 2018 7:00 am Post subject:

Do You mean this?

bbgermany · Posted: Tue Feb 13, 2018 7:51 am Post subject:

Hi,

bonding of wan connections is possible, but your provider MUST support this. Usually they dont. Did you have a look at this: http://lartc.org/howto/lartc.rpdb.multiple-links.html

Since you are trying to "load balance" connections via your two 3G/4G interfaces, this could help you.

greets, bb
_________________
Desktop: Ryzen 5 5600G, 32GB, 2TB, RX7600
Notebook: Dell XPS 13 9370, 16GB, 1TB
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orion777 · Posted: Tue Feb 13, 2018 7:24 pm Post subject:

bbgermany · Posted: Wed Feb 14, 2018 7:27 am Post subject:

Thats quite easy:

if you get the ip address 192.168.0.1 ($IP1) from your provider on your first 3G/4G interface ($IF1). The fitting network ($P1_NET) could be 192.168.0.0. Gateways and mask and even the subnet is generated by the provider. You have to look it up via ifconfig.

greets, bb
_________________
Desktop: Ryzen 5 5600G, 32GB, 2TB, RX7600
Notebook: Dell XPS 13 9370, 16GB, 1TB
Server #1: Ryzen 5 Pro 4650G, 64GB, 16.5TB
Server #2: Ryzen 4800H, 32GB, 22TB

orion777 · Posted: Thu Feb 15, 2018 7:33 am Post subject:

So, here is my existing configs "by default"

bbgermany · Posted: Thu Feb 15, 2018 8:05 am Post subject:

I think you did it wrong a bit; You need to add a number for your routing as well:

orion777 · Posted: Fri Feb 16, 2018 7:22 am Post subject:

Yes, number and name, separated by "TAB", like echo "1 T1" >> /etc/iproute2/1rt_tables
But now I have two more problems..

bbgermany · Posted: Fri Feb 16, 2018 8:21 am Post subject:

orion777 · Posted: Fri Feb 16, 2018 7:11 pm Post subject:

bbgermany · Posted: Sat Feb 17, 2018 11:16 am Post subject:

Im very sorry, but I cannot help you with this, since I connot test it by myself. But I think, it could be related to the default gateways, your provider gives you, when you start up your connections.

greets, bb
_________________
Desktop: Ryzen 5 5600G, 32GB, 2TB, RX7600
Notebook: Dell XPS 13 9370, 16GB, 1TB
Server #1: Ryzen 5 Pro 4650G, 64GB, 16.5TB
Server #2: Ryzen 4800H, 32GB, 22TB

orion777 · Posted: Sun Feb 18, 2018 7:39 am Post subject:

I have two suggestions:
1) this solution cant work with network cards with different metrics
2) Both my cards gets IP by means of DHCP (dhclient, dhcpcd, NetworkManager). NetworkManager (as I understand) writes default gateway.. So maybe I cant override this default gateway settings?

orion777 · Posted: Thu Mar 15, 2018 8:02 am Post subject:

I have an answer.. and it is very simple! I found this in "options->default" description: 'default': This scheduler is the default one. It will first send data on subflows with the lowest RTT until their congestion-window is full. Then, it will start transmitting on the subflows with the next higher RTT. So, I can conclude that MPTCP uses TCP window as a measurement parameter to able to work. This means that MPTCP can work only with TCP. However, in my testing, I was using "ping", so ICMP packets. As I know, ICMP packets does not use windows, so maybe that why all my MPTCP tests were failed. Then I was trying to initiate TCP/IP data flow by wget something and both cards starts to work; also if one card is failed, down, on lost connection and stay live, second card takes all load automatically.

A few words about settings.
- First, you have to patch your kernel.
- Then it is necessary to enter additional routing settings. This can be done manually each time after system reboot or can be automated by various scripts (suggested gentoo script has mistakes and will not work. If someone know, please suggest me how to fix it ). All related info (manual and auto scripting) is here
- Default settings are specified during kernel make.
- Settings, those are set by default in kernel, can be overridden manually in live system thru sysctl
--- It is recommended to select default. In this mode MPTCP will use both network cards (not only one!) and your speed of connection will be doubled. Traffic balancing is fully flexible, based on
TCP window (as soon it is full - traffic is sent to the second network card and etc). Round-robin is not recommended because it is experimental,... seems that it has no flexibility and can work fine only with equal speed networks.