diff --git a/app/models/switch.rb b/app/models/switch.rb
index 3c808c41611..f3a48b87127 100644
--- a/app/models/switch.rb
+++ b/app/models/switch.rb
@@ -3,6 +3,7 @@ class Switch < ApplicationRecord
   include CustomActionsMixin
 
   belongs_to :host, :inverse_of => :host_virtual_switches
+  has_one :ext_management_system, :through => :host
 
   has_many :host_switches, :dependent => :destroy
   has_many :hosts, :through => :host_switches
diff --git a/spec/models/switch_spec.rb b/spec/models/switch_spec.rb
new file mode 100644
index 00000000000..b0c7cd974a3
--- /dev/null
+++ b/spec/models/switch_spec.rb
@@ -0,0 +1,9 @@
+RSpec.describe Switch do
+  let(:ems)    { FactoryBot.create(:ext_management_system) }
+  let(:host)   { FactoryBot.create(:host, :ext_management_system => ems) }
+  let(:switch) { FactoryBot.create(:switch, :host => host) }
+
+  it "#ext_management_system" do
+    expect(switch.ext_management_system).to eq(ems)
+  end
+end