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Hello,

Thanks, 
The problem was related to MTU.
Actually, I have another installation which is configured to set 1450(1500 - 50 VxLAN header length) for guest VM interfaces.
That setup runs in 'regular' network environments with 1500 MTU on host interfaces  and use linuxbridge.

There is a reson why I didn't looked at that at first thing for the current case:

The hosts private network interfaces  has set to MTU 9000 
Open vSwitch is used to connect private(self service) network.
OVS bridges have 1500 MTU ( kolla configured it in this way )

I've identified that  1480  MTU for guest VM fix ssh issue  in my current case, but not sure I understand why ...
20 bytes is the shortest IP header size...

So there are 2 another questions:
1. What's and why adding 20 bytes ? 
2. I've not found a configuration settings in kolla-ansible which allows to configure bridges interfaces MTU - any ideas how to do that properly ?

Thanks,
Regards,
Serge.


06.04.2018, 20:57, "Brian Haley" <haleyb.dev at gmail.com>:
> On 04/06/2018 01:28 PM, s serge wrote:
>>  Hello,
>>
>>  I'm evaluating an installation and everything from networking side was looking good
>>  until I tried to reach a VM host via private network from another VM via ssh.
>>
>>  In short:
>>  1. Spawn a VM
>>  2. Associate a floating IP
>>  3. Logon to VM via ssh on public network
>>  4. Spawn another VM
>>  5. Try to reach 1st VM via ssh private network IP - FAIL.
>>  6. ICMP to 1st VM IP via private network works well.
>>
>>  Looks pretty weird for me as according to logs everything looks fine,
>>  both VM got assigned a private IP and fetches metadata info.
>>
>>  Some notes about setup:
>>  Separate interfaces for management, private(VXLAN) and external network.
>>  Dozen of similar servers.
>>
>>  I'll continue to debug the issue, but appreciate any relevant feedback.
>
> I would check two things:
>
> 1. Security groups are allowing port 22
> 2. MTU is set correctly, should probably be 1450 if you're using VXLAN,
> which should have been set via the DHCP reply
>
> -Brian