[Samba] Samba multi channel route configuration on same subnet

[Christian Samsel]

So i was playing around with Samba multi channel and it was not working as 
i originally expected it.

I have two hosts:
my workstation running up to date Windows 10 with 2 interfaces
my server running Gentoo with Samba 4.5.4 with 2 interfaces 
(all connected to the same network)
workstation has IPs 192.168.2.114, 192.168.2.115
server has 192.168.2.16(enp2s0f0),192.168.2.17(enp2s0f1)

i'm connecting to .16 using my workstation and i can send at 2x linespeed
devided to both .16 and .17 as expected.

But when i'm receiving Samba sends over .16 and only over .16 to both 
.114 and .115 at half line speed. It's because .16 has the default route. 
Adding single target routes to the two workstation IPs via different
interfaces works, but i expected Samba to handle this internally. Windows 
handles this nicely without further work. What is the best practice? Am i
suppose to add routes for all clients or place different interfaces in 
different subnets. Both seems ugly. 

Thanks for reading,
Christian


More info: 

server # ip route
default via 192.168.2.1 dev enp2s0f0
192.168.2.0/24 dev enp2s0f0  proto kernel  scope link  src 192.168.2.16
192.168.2.0/24 dev enp2s0f1  proto kernel  scope link  src 192.168.2.17

server ~ # ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 brd 127.255.255.255 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether f8:b1:56:c1:3a:6b brd ff:ff:ff:ff:ff:ff
3: enp2s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:15:17:a0:0e:56 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.16/24 brd 192.168.2.255 scope global enp2s0f0
       valid_lft forever preferred_lft forever
4: enp2s0f1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:15:17:a0:0e:57 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.17/24 brd 192.168.2.255 scope global enp2s0f1
       valid_lft forever preferred_lft forever

server # lspci | grep Ether
00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I217-LM (rev 04) ###(not active)
02:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit Ethernet Controller (rev 06)
02:00.1 Ethernet controller: Intel Corporation 82571EB Gigabit Ethernet Controller (rev 06)


PS C:\WINDOWS\system32> Get-SmbMultichannelConnection

Server Name  Selected Client IP     Server IP    Client Interface Index Server Interface Index Client RSS Capable Client RDMA Capable
-----------  -------- ---------     ---------    ---------------------- ---------------------- ------------------ -------------------
192.168.2.16 True     192.168.2.115 192.168.2.17 20                     4                      False              False
192.168.2.16 True     192.168.2.114 192.168.2.16 8                      3                      False              False





working route configuration:

server # ip route 
default via 192.168.2.1 dev enp2s0f0
192.168.2.0/24 dev enp2s0f0  proto kernel  scope link  src 192.168.2.16
192.168.2.0/24 dev enp2s0f1  proto kernel  scope link  src 192.168.2.17
192.168.2.114 dev enp2s0f0  scope link
192.168.2.115 dev enp2s0f1  scope link