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Many virtual machines on one host - do not see each other

Posted: Tue Oct 09, 2018 3:49 pm
by pkroliszewski
Hello,

Here is my setup.
I have a two physical machines A and B that runs kvm (qemu) on linux. On that machines i have a set of virtual machines
A1:10.9.8.100
A2:10.9.8.50
B1:10.9.8.101

On the router (mikrotik g750) i have a gateway set on 10.9.8.1 - this is used for all virtual machines to reach the internet.

A1 uses macvtap0 interface of host A
A2 uses macvtap1 interface of host A
B1 uses macvtap0 inteface of host B

All virtual hosts have access to internet,
Ping:
A1-> B1 works (the same in opposite direction)
A2 ->B1 as above
A1-> 10.9.8.1 (gateway set up on router) works
A2 -> 10.9.8.1 works
B1 -> 10.9.8.1 works

A1->A2, A2->A1 NOT WORKS ...

This is related to mode used by kvm for macvtap - VEPA, and should be resolved by hairpin on router. But... how to do that? Maybe someone here could point me into right direction?

Re: Many virtual machines on one host - do not see each other

Posted: Wed Oct 10, 2018 10:58 pm
by Vooray
Hey!

Dont have kvm knowledge, but i can definitely say that communication between hosts on the same subnet does not involve routing (and router).