diff --git a/src/include/ipxe/eth_slow.h b/src/include/ipxe/eth_slow.h
index f6d731b3b..754ea6e1f 100644
--- a/src/include/ipxe/eth_slow.h
+++ b/src/include/ipxe/eth_slow.h
@@ -190,6 +190,12 @@ struct eth_slow_lacp_entity_tlv {
  */
 #define LACP_STATE_EXPIRED 0x80
 
+/** LACP fast interval (1 second) */
+#define LACP_INTERVAL_FAST 1
+
+/** LACP slow interval (30 seconds) */
+#define LACP_INTERVAL_SLOW 30
+
 /** LACP collector TLV */
 struct eth_slow_lacp_collector_tlv {
 	/** TLV header */
diff --git a/src/net/eth_slow.c b/src/net/eth_slow.c
index 049c26cb3..41ce79fe0 100644
--- a/src/net/eth_slow.c
+++ b/src/net/eth_slow.c
@@ -27,6 +27,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <string.h>
 #include <byteswap.h>
 #include <errno.h>
+#include <ipxe/timer.h>
 #include <ipxe/iobuf.h>
 #include <ipxe/netdevice.h>
 #include <ipxe/if_ether.h>
@@ -148,9 +149,30 @@ static int eth_slow_lacp_rx ( struct io_buffer *iobuf,
 			      struct net_device *netdev ) {
 	union eth_slow_packet *eth_slow = iobuf->data;
 	struct eth_slow_lacp *lacp = &eth_slow->lacp;
+	unsigned int interval;
 
 	eth_slow_lacp_dump ( iobuf, netdev, "RX" );
 
+	/* If partner is not in sync, collecting, and distributing,
+	 * then block the link until after the next expected LACP
+	 * packet.
+	 */
+	if ( ~lacp->partner.state & ( LACP_STATE_IN_SYNC |
+				      LACP_STATE_COLLECTING |
+				      LACP_STATE_DISTRIBUTING ) ) {
+		DBGC ( netdev, "SLOW %s LACP partner is down\n", netdev->name );
+		interval = ( ( lacp->partner.state & LACP_STATE_FAST ) ?
+			     ( ( LACP_INTERVAL_FAST + 1 ) * TICKS_PER_SEC ) :
+			     ( ( LACP_INTERVAL_SLOW + 1 ) * TICKS_PER_SEC ) );
+		netdev_link_block ( netdev, interval );
+	} else {
+		if ( netdev_link_blocked ( netdev ) ) {
+			DBGC ( netdev, "SLOW %s LACP partner is up\n",
+			       netdev->name );
+		}
+		netdev_link_unblock ( netdev );
+	}
+
 	/* Build response */
 	memset ( lacp->reserved, 0, sizeof ( lacp->reserved ) );
 	memset ( &lacp->terminator, 0, sizeof ( lacp->terminator ) );