[Bug 1626826] Comment bridged from LTC Bugzilla

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------- Comment From yeqi at cn.ibm.com 2016-09-30 05:04 EDT-------
Hello,

Thanks for the information.  Regarding your questions. First of all,
single nic is not mandatory. It happened I only have OSA port available
at that time. I got another OSA port afterwards.  But I still have the
same issue with the 2nd nic.

Below was exactly what I did.

1. I used below commands to create bridge.  The nic was not assigned an
IP address.

brctl addbr br0
brctl addif br0 enc3030

2. Issued brctl show, I can see the bridge info looks OK.

3. Define a VM on KVM. Dump the network device part. And the VM was using an IP address that can be accessed in a corporate LAN.
<interface type='bridge'>
<mac address='52:54:00:58:98:c1'/>
<source bridge='br0'/>
<model type='virtio'/>
<address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0001'/>
</interface>

4. After started the VM, I could see a port attached the bridge.
Something like tap8e806d7c-d9.

5. But I couldn't ping the VM successfully from a server out side of KVM
host.

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https://bugs.launchpad.net/bugs/1626826

Title:
  KVM guest cannot use br0 created by brctl on Ubuntu16.04

Status in Ubuntu on IBM z Systems:
  New
Status in bridge-utils package in Ubuntu:
  Incomplete

Bug description:
  == Comment: #0 - QI YE  - 2016-09-22 06:01:59 ==
  ---Problem Description---
  Ubuntu16.04. Created a bridge br0 on enc100 via brctl.  enc100 is the only external accessible nic. Defined a ubuntu guest to use br0 and assigned an IP to the guest in the same subnet as br0. After started the guest, couldn't access external servers or internet from the guest. 
   

  ---uname output---
  Linux ntc170 4.4.0-38-generic #57-Ubuntu SMP Tue Sep 6 15:47:15 UTC 2016 s390x s 390x s390x GNU/Linux
   
  Machine Type = 2827 (z Systems EC12) 
   
  ---Debugger---
  A debugger is not configured
   
  ---Steps to Reproduce---
   1. define br0 on enc100 via brctl command (IP on br0 is 192.168.1.170 for example)
  2. update /etc/network/interfaces
  3. create a guest on KVM and use br0 for it's nic
  4. Start guest via virsh command and assign an IP, e.g. 192.168.1.171.  After installation, cannot access external systems via KVM host.

  == Comment: #2 - QI YE  - 2016-09-22 09:53:58 ==
  attached sosreport file

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