diff --git a/src/include/gpxe/retry.h b/src/include/gpxe/retry.h
new file mode 100644
index 00000000..8a9e2cf6
--- /dev/null
+++ b/src/include/gpxe/retry.h
@@ -0,0 +1,36 @@
+#ifndef _GPXE_RETRY_H
+#define _GPXE_RETRY_H
+
+/** @file
+ *
+ * Retry timers
+ *
+ */
+
+#include <gpxe/list.h>
+
+/** Effective maximum retry count for exponential backoff calculation */
+#define BACKOFF_LIMIT 5
+
+/** A retry timer */
+struct retry_timer {
+	/** List of active timers */
+	struct list_head list;
+	/** Base timeout (in ticks) */
+	unsigned int base;
+	/** Retry count */
+	unsigned int retries;
+	/** Expiry time (in ticks) */
+	unsigned long expiry;
+	/** Timer expired callback
+	 *
+	 * @v timer	Retry timer
+	 */
+	void ( * expired ) ( struct retry_timer *timer );
+};
+
+extern void start_timer ( struct retry_timer *timer );
+extern void reset_timer ( struct retry_timer *timer );
+extern void stop_timer ( struct retry_timer *timer );
+
+#endif /* _GPXE_RETRY_H */
diff --git a/src/net/retry.c b/src/net/retry.c
new file mode 100644
index 00000000..f00c178e
--- /dev/null
+++ b/src/net/retry.c
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stddef.h>
+#include <latch.h>
+#include <gpxe/list.h>
+#include <gpxe/process.h>
+#include <gpxe/init.h>
+#include <gpxe/retry.h>
+
+/** @file
+ *
+ * Retry timers
+ *
+ * A retry timer is a truncated binary exponential backoff timer.  It
+ * can be used to build automatic retransmission into network
+ * protocols.
+ */
+
+/** List of running timers */
+static LIST_HEAD ( timers );
+
+/**
+ * Reload timer
+ *
+ * @v timer		Retry timer
+ *
+ * This reloads the timer with a new expiry time.  The expiry time
+ * will be the timer's base timeout value, shifted left by the number
+ * of retries (i.e. the number of timer expiries since the last timer
+ * reset).
+ */
+static void reload_timer ( struct retry_timer *timer ) {
+	unsigned int exp;
+
+	exp = timer->retries;
+	if ( exp > BACKOFF_LIMIT )
+		exp = BACKOFF_LIMIT;
+	timer->expiry = currticks() + ( timer->base << exp );
+}
+
+/**
+ * Reset timer
+ *
+ * @v timer		Retry timer
+ *
+ * This resets the timer, i.e. clears its retry count and starts it
+ * running with its base timeout value.
+ *
+ * Note that it is explicitly permitted to call reset_timer() on an
+ * inactive timer.
+ */
+void reset_timer ( struct retry_timer *timer ) {
+	timer->retries = 0;
+	reload_timer ( timer );
+}
+
+/**
+ * Start timer
+ *
+ * @v timer		Retry timer
+ *
+ * This resets the timer and starts it running (i.e. adds it to the
+ * list of running timers).  The retry_timer::base and
+ * retry_timer::callback fields must have been filled in.
+ */
+void start_timer ( struct retry_timer *timer ) {
+	list_add ( &timer->list, &timers );
+	reset_timer ( timer );
+}
+
+/**
+ * Stop timer
+ *
+ * @v timer		Retry timer
+ *
+ * This stops the timer (i.e. removes it from the list of running
+ * timers).
+ */
+void stop_timer ( struct retry_timer *timer ) {
+	list_del ( &timer->list );
+}
+
+/**
+ * Single-step the retry timer list
+ *
+ * @v process		Retry timer process
+ */
+static void retry_step ( struct process *process ) {
+	struct retry_timer *timer;
+	struct retry_timer *tmp;
+	unsigned long now = currticks();
+
+	list_for_each_entry_safe ( timer, tmp, &timers, list ) {
+		if ( timer->expiry >= now ) {
+			timer->retries++;
+			reload_timer ( timer );
+			timer->expired ( timer );
+		}
+	}
+
+	schedule ( process );
+}
+
+/** Retry timer process */
+static struct process retry_process = {
+	.step = retry_step,
+};
+
+/** Initialise the retry timer module */
+static void init_retry ( void ) {
+	schedule ( &retry_process );
+}
+
+INIT_FN ( INIT_PROCESS, init_retry, NULL, NULL );