This patch populate faq about datapath-id.
Author: Tao YunXiang <[email protected]>
Signed-off-by: Tao YunXiang <[email protected]>
---
Documentation/faq/configuration.rst | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/Documentation/faq/configuration.rst
b/Documentation/faq/configuration.rst
index 4a98740c5..fd5d2e005 100644
--- a/Documentation/faq/configuration.rst
+++ b/Documentation/faq/configuration.rst
@@ -281,3 +281,24 @@ the sense of OFPP_LOCAL)
A: Open vSwitch does not support such a configuration. Bridges always have
their local ports.
+
+Q: Why the datapath-id choose the minimum non-local MAC address among all of
+the ports in bridge?
+
+ A: The reason that this happens is to keep the MAC address of the bridge
+ steady.
+
+ Here's the use case it was designed to address. It started with
+ XenServer, but other hypervisors work similarly. Each physical NIC that
+ might have VMs on it gets put into a bridge, and then the IP address for
+ that NIC (if any) gets migrated from the pnic to the bridge device. You
+ want the bridge device to have the same MAC address as the physical NIC,
+ so taking the minimum MAC address does that. Adding virtual NICs doesn't
+ change it because OVS ignores random MACs.
+
+ If you want a stable MAC and datapath-id, you could set your own MAC
+ by ``hwaddr`` in ``other_config`` of bridge.
+
+ ::
+
+ ovs-vsctl set bridge br-int other_config:hwaddr=3a:4d:a7:05:2a:45
--
2.17.1
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