2
I am currently struggling with a very strange problem. I have a Linux Ubuntu 16.04 machine with two interfaces (eth1 and eth2). I set up a bridge between these two interfaces with bridge-utils for the following simple setup:
laptop1 → bridge → laptop2
where the bridge is the Ubuntu computer with the stated interfaces.
On laptop2 there is an openssh server running. When I now try to ssh from laptop1 to laptop2 it is not working. The bridge itself works, cause pinging and stuff works.
I also used wireshark to examine the problem. The SSH handshake just works fine but after some packets the transmission gets stuck in a TCP retransmission flow until it times out or terminates. I spent a few hours on online research but nobody seems to have this problem.
The only hint I found was disabling the LRO feature. But that did not solve my problem. Maybe I am missing something else.
Maybe someone has a hint or clue to solve my problem.
user3429251
Posted 2016-11-09T19:22:44.550
Reputation: 21
2decrease the mtu – Ipor Sircer – 2016-11-09T19:26:09.113
1I came here to write what @IporSircer said 6 seconds earlier - it may be that the 1 laptop is using jumbo frames (bigger then 1500 bytes). MTU issues can cause the types of problem described. – davidgo – 2016-11-09T19:28:07.940
I checked the laptop settings. The interface uses mtu = 1500. And no jumbo frames. What i don't understand is why the bridge should not work with the interfaces set to mtu 1500 as well. – user3429251 – 2016-11-09T19:54:38.957
Are you using ethernet-to-USB adapters, by chance? – MariusMatutiae – 2016-11-10T05:25:08.687
Yes indeed. I use usb ethernet adapters. Is there a problem with USB Adapters? – user3429251 – 2016-11-10T08:44:27.930