diff --git a/src/net/tcp.c b/src/net/tcp.c
index 1c48769a..987cb63e 100644
--- a/src/net/tcp.c
+++ b/src/net/tcp.c
@@ -16,6 +16,7 @@
 #include <ipxe/uri.h>
 #include <ipxe/netdevice.h>
 #include <ipxe/profile.h>
+#include <ipxe/process.h>
 #include <ipxe/tcpip.h>
 #include <ipxe/tcp.h>
 
@@ -107,6 +108,8 @@ struct tcp_connection {
 	struct list_head tx_queue;
 	/** Receive queue */
 	struct list_head rx_queue;
+	/** Transmission process */
+	struct process process;
 	/** Retransmission timer */
 	struct retry_timer timer;
 	/** Shutdown (TIME_WAIT) timer */
@@ -166,6 +169,7 @@ static struct profiler tcp_rx_profiler __profiler = { .name = "tcp.rx" };
 static struct profiler tcp_xfer_profiler __profiler = { .name = "tcp.xfer" };
 
 /* Forward declarations */
+static struct process_descriptor tcp_process_desc;
 static struct interface_descriptor tcp_xfer_desc;
 static void tcp_expired ( struct retry_timer *timer, int over );
 static void tcp_wait_expired ( struct retry_timer *timer, int over );
@@ -273,6 +277,7 @@ static int tcp_open ( struct interface *xfer, struct sockaddr *peer,
 	DBGC ( tcp, "TCP %p allocated\n", tcp );
 	ref_init ( &tcp->refcnt, NULL );
 	intf_init ( &tcp->xfer, &tcp_xfer_desc, &tcp->refcnt );
+	process_init_stopped ( &tcp->process, &tcp_process_desc, &tcp->refcnt );
 	timer_init ( &tcp->timer, tcp_expired, &tcp->refcnt );
 	timer_init ( &tcp->wait, tcp_wait_expired, &tcp->refcnt );
 	tcp->prev_tcp_state = TCP_CLOSED;
@@ -369,6 +374,7 @@ static void tcp_close ( struct tcp_connection *tcp, int rc ) {
 		pending_put ( &tcp->pending_flags );
 
 		/* Remove from list and drop reference */
+		process_del ( &tcp->process );
 		stop_timer ( &tcp->timer );
 		stop_timer ( &tcp->wait );
 		list_del ( &tcp->list );
@@ -497,7 +503,7 @@ static size_t tcp_process_tx_queue ( struct tcp_connection *tcp, size_t max_len,
  * will have been started if necessary, and so the stack will
  * eventually attempt to retransmit the failed packet.
  */
-static int tcp_xmit ( struct tcp_connection *tcp ) {
+static void tcp_xmit ( struct tcp_connection *tcp ) {
 	struct io_buffer *iobuf;
 	struct tcp_header *tcphdr;
 	struct tcp_mss_option *mssopt;
@@ -517,7 +523,7 @@ static int tcp_xmit ( struct tcp_connection *tcp ) {
 
 	/* If retransmission timer is already running, do nothing */
 	if ( timer_running ( &tcp->timer ) )
-		return 0;
+		return;
 
 	/* Calculate both the actual (payload) and sequence space
 	 * lengths that we wish to transmit.
@@ -537,7 +543,7 @@ static int tcp_xmit ( struct tcp_connection *tcp ) {
 
 	/* If we have nothing to transmit, stop now */
 	if ( ( seq_len == 0 ) && ! ( tcp->flags & TCP_ACK_PENDING ) )
-		return 0;
+		return;
 
 	/* If we are transmitting anything that requires
 	 * acknowledgement (i.e. consumes sequence space), start the
@@ -553,7 +559,7 @@ static int tcp_xmit ( struct tcp_connection *tcp ) {
 		DBGC ( tcp, "TCP %p could not allocate iobuf for %08x..%08x "
 		       "%08x\n", tcp, tcp->snd_seq, ( tcp->snd_seq + seq_len ),
 		       tcp->rcv_ack );
-		return -ENOMEM;
+		return;
 	}
 	iob_reserve ( iobuf, TCP_MAX_HEADER_LEN );
 
@@ -620,16 +626,19 @@ static int tcp_xmit ( struct tcp_connection *tcp ) {
 		DBGC ( tcp, "TCP %p could not transmit %08x..%08x %08x: %s\n",
 		       tcp, tcp->snd_seq, ( tcp->snd_seq + tcp->snd_sent ),
 		       tcp->rcv_ack, strerror ( rc ) );
-		return rc;
+		return;
 	}
 
 	/* Clear ACK-pending flag */
 	tcp->flags &= ~TCP_ACK_PENDING;
 
 	profile_stop ( &tcp_tx_profiler );
-	return 0;
 }
 
+/** TCP process descriptor */
+static struct process_descriptor tcp_process_desc =
+	PROC_DESC_ONCE ( struct tcp_connection, process, tcp_xmit );
+
 /**
  * Retransmission timer expired
  *
@@ -1272,8 +1281,16 @@ static int tcp_rx ( struct io_buffer *iobuf,
 	/* Dump out any state change as a result of the received packet */
 	tcp_dump_state ( tcp );
 
-	/* Send out any pending data */
-	tcp_xmit ( tcp );
+	/* Schedule transmission of ACK (and any pending data).  If we
+	 * have received any out-of-order packets (i.e. if the receive
+	 * queue remains non-empty after processing) then send the ACK
+	 * immediately in order to trigger Fast Retransmission.
+	 */
+	if ( list_empty ( &tcp->rx_queue ) ) {
+		process_add ( &tcp->process );
+	} else {
+		tcp_xmit ( tcp );
+	}
 
 	/* If this packet was the last we expect to receive, set up
 	 * timer to expire and cause the connection to be freed.