diff --git a/src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlock.kt b/src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlock.kt
index 4aef5e1..8c9d700 100644
--- a/src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlock.kt
+++ b/src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlock.kt
@@ -14,6 +14,8 @@ import net.shadowfacts.phycon.block.BlockWithEntity
  */
 abstract class DeviceBlock<T: DeviceBlockEntity>(settings: Settings): BlockWithEntity<T>(settings), NetworkComponentBlock {
 
+	abstract override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction>
+
 	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
 		return getBlockEntity(world, pos)!!
 	}
diff --git a/src/main/kotlin/net/shadowfacts/phycon/network/block/netswitch/SwitchBlockEntity.kt b/src/main/kotlin/net/shadowfacts/phycon/network/block/netswitch/SwitchBlockEntity.kt
index e51943f..51d0d51 100644
--- a/src/main/kotlin/net/shadowfacts/phycon/network/block/netswitch/SwitchBlockEntity.kt
+++ b/src/main/kotlin/net/shadowfacts/phycon/network/block/netswitch/SwitchBlockEntity.kt
@@ -36,9 +36,8 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 		return interfaces.find { it.side == side }!!
 	}
 
-	private fun handle(frame: EthernetFrame, fromItf: Interface) {
-		val itfSide = (fromItf as SwitchInterface).side
-		macTable[frame.source] = itfSide
+	private fun handle(frame: EthernetFrame, fromItf: SwitchInterface) {
+		macTable[frame.source] = fromItf.side
 
 		if (frame is PacketFrame && frame.packet is ItemStackPacket) {
 			val packet = frame.packet as ItemStackPacket
@@ -54,10 +53,10 @@ class SwitchBlockEntity: BlockEntity(PhyBlockEntities.SWITCH),
 
 		if (frame.destination.type != MACAddress.Type.BROADCAST && macTable.containsKey(frame.destination)) {
 			val dir = macTable[frame.destination]!!
-			println("$this ($itfSide, ${fromItf.macAddress}) forwarding $frame to side $dir")
+			println("$this (${fromItf.side}, ${fromItf.macAddress}) forwarding $frame to side $dir")
 			interfaceForSide(dir).send(frame)
 		} else {
-			println("$this ($itfSide, ${fromItf.macAddress}) flooding $frame")
+			println("$this (${fromItf.side}, ${fromItf.macAddress}) flooding $frame")
 			flood(frame, fromItf)
 		}
 	}