diff --git a/recipes-bsp/init-ifupdown/init-ifupdown-master/sysmocom-idu/interfaces b/recipes-bsp/init-ifupdown/init-ifupdown-master/sysmocom-idu/interfaces
index 2bf920b..f7a1fca 100644
--- a/recipes-bsp/init-ifupdown/init-ifupdown-master/sysmocom-idu/interfaces
+++ b/recipes-bsp/init-ifupdown/init-ifupdown-master/sysmocom-idu/interfaces
@@ -8,6 +8,17 @@ iface lo inet loopback
 # in the future we will use VLANs to use individual switch ports as
 # break-out interfaces.  For now we simply do DHCP.
 
+# Note: when inmarsat is available, its route should have a stronger metric
+# than iridium (the route installed by linkmon). For the "inactive" routes, the
+# metrics should be reversed, because iridium is more likely to be available
+# than inmarsat (as an emergency/fallback measure).
+#
+# transport    "active" metric    "inactive" metric
+# GSM          10                 140
+# WIFI         20                 130
+# Inmarsat     30                 120
+# Iridium      40                 110
+
 # VLAN 2000: The iridium openport satellite modem attached to
 # port 1 of the IES-3080
 auto eth0.2000
@@ -16,7 +27,7 @@ iface eth0.2000 inet static
 	netmask 255.255.255.0
 	network 192.168.0.0
 	post-up ip r add 10.6.1.0/24 via 192.168.0.1
-	post-up ip r add 5.9.81.48/32 via 192.168.0.1 metric 100
+	post-up ip r add 5.9.81.48/32 via 192.168.0.1 metric 110
 
 # VLAN 2001: Reserved for a future C-Band satellite modem
 # attached to port 8 of the IES-3080
@@ -34,7 +45,7 @@ iface eth0.2002 inet static
         # Switch off rp_filter
         post-up /sbin/sysctl net.ipv4.conf.eth0/2002.rp_filter=2
         # Set a route with high metric nr so a ping -I on this iface will work:
-        post-up ip r add 5.9.81.48/32 via 10.156.136.97 metric 101
+        post-up ip r add 5.9.81.48/32 via 10.156.136.97 metric 120
         # Once sob-idu-linkmon sees pings working, it will install a route
         # with lower metric.
 
diff --git a/recipes-bsp/init-ifupdown/init-ifupdown/sysmocom-idu/interfaces b/recipes-bsp/init-ifupdown/init-ifupdown/sysmocom-idu/interfaces
index 2bf920b..f7a1fca 100644
--- a/recipes-bsp/init-ifupdown/init-ifupdown/sysmocom-idu/interfaces
+++ b/recipes-bsp/init-ifupdown/init-ifupdown/sysmocom-idu/interfaces
@@ -8,6 +8,17 @@ iface lo inet loopback
 # in the future we will use VLANs to use individual switch ports as
 # break-out interfaces.  For now we simply do DHCP.
 
+# Note: when inmarsat is available, its route should have a stronger metric
+# than iridium (the route installed by linkmon). For the "inactive" routes, the
+# metrics should be reversed, because iridium is more likely to be available
+# than inmarsat (as an emergency/fallback measure).
+#
+# transport    "active" metric    "inactive" metric
+# GSM          10                 140
+# WIFI         20                 130
+# Inmarsat     30                 120
+# Iridium      40                 110
+
 # VLAN 2000: The iridium openport satellite modem attached to
 # port 1 of the IES-3080
 auto eth0.2000
@@ -16,7 +27,7 @@ iface eth0.2000 inet static
 	netmask 255.255.255.0
 	network 192.168.0.0
 	post-up ip r add 10.6.1.0/24 via 192.168.0.1
-	post-up ip r add 5.9.81.48/32 via 192.168.0.1 metric 100
+	post-up ip r add 5.9.81.48/32 via 192.168.0.1 metric 110
 
 # VLAN 2001: Reserved for a future C-Band satellite modem
 # attached to port 8 of the IES-3080
@@ -34,7 +45,7 @@ iface eth0.2002 inet static
         # Switch off rp_filter
         post-up /sbin/sysctl net.ipv4.conf.eth0/2002.rp_filter=2
         # Set a route with high metric nr so a ping -I on this iface will work:
-        post-up ip r add 5.9.81.48/32 via 10.156.136.97 metric 101
+        post-up ip r add 5.9.81.48/32 via 10.156.136.97 metric 120
         # Once sob-idu-linkmon sees pings working, it will install a route
         # with lower metric.