diff --git a/input/grid5000/ipv6.yaml b/input/grid5000/ipv6.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..cd94bb7cb445ea43895d2c55f13fa6960970616c
--- /dev/null
+++ b/input/grid5000/ipv6.yaml
@@ -0,0 +1,10 @@
+ipv6:
+  site-indexes:
+    grenoble: 1
+    lille: 2
+    luxembourg: 3
+    lyon: 4
+    nancy: 5
+    nantes: 6
+    rennes: 7
+    sophia: 8
diff --git a/lib/refrepo/input_loader.rb b/lib/refrepo/input_loader.rb
index 55442113b30a78d1039c8a156a2b87c10e9ea2a7..fd88f0401de56402c6313b593536012f8bc7c627 100644
--- a/lib/refrepo/input_loader.rb
+++ b/lib/refrepo/input_loader.rb
@@ -107,17 +107,6 @@ def add_kavlan_ips(h)
   end
 end
 
-$ipv6_site_indexes = {
-  'grenoble' => 1,
-  'lille' => 2,
-  'luxembourg' => 3,
-  'lyon' => 4,
-  'nancy' => 5,
-  'nantes' => 6,
-  'rennes' => 7,
-  'sophia' => 8,
-}
-
 def add_ipv6(h)
   # for each node
   h['sites'].each_pair do |site_uid, hs|
@@ -132,7 +121,7 @@ def add_ipv6(h)
             if not ip4.nil?
               # compute and assign IPv6 based on IPv4
               ip6 = '2001:660:4406:'
-              ip6 += '%x' % $ipv6_site_indexes[site_uid]
+              ip6 += '%x' % h['ipv6']['site-indexes'][site_uid]
               ip6 += '00:'
               ip6 += '%x::' % ((ip4.split('.')[2].to_i & 0b1111) + 1)
               ip6 += '%x' % (ip4.split('.')[3].to_i)