For TBF implement overhead parameter parsing.

index c7b4f0f..3bdce5a 100644
@@ -26,7 +26,8 @@
 static void explain(void)
 {
 	fprintf(stderr, "Usage: ... tbf limit BYTES burst BYTES[/BYTES] rate KBPS [ mtu BYTES[/BYTES] ]\n");
-	fprintf(stderr, "               [ peakrate KBPS ] [ latency TIME ]\n");
+	fprintf(stderr, "               [ peakrate KBPS ] [ latency TIME ] ");
+	fprintf(stderr, "[ overhead BYTES ]\n");
 }
 
 static void explain1(char *arg)

@@ -45,6 +46,7 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 	__u32 ptab[256];
 	unsigned buffer=0, mtu=0, mpu=0, latency=0;
 	int Rcell_log=-1, Pcell_log = -1;
+	unsigned short overhead=0;
 	struct rtattr *tail;
 
 	memset(&opt, 0, sizeof(opt));

@@ -130,6 +132,15 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 				return -1;
 			}
 			ok++;
+		} else if (matches(*argv, "overhead") == 0) {
+			NEXT_ARG();
+			if (overhead) {
+				fprintf(stderr, "Double \"overhead\" spec\n");
+				return -1;
+			}
+			if (get_u16(&overhead, *argv, 10)) {
+				explain1("overhead"); return -1;
+			}
 		} else if (strcmp(*argv, "help") == 0) {
 			explain();
 			return -1;

@@ -170,7 +181,8 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 		opt.limit = lim;
 	}
 
-	opt.rate.mpu = mpu;
+	opt.rate.mpu      = mpu;
+	opt.rate.overhead = overhead;
 	if (tc_calc_rtable(&opt.rate, rtab, Rcell_log, mtu) < 0) {
 		fprintf(stderr, "TBF: failed to calculate rate table.\n");
 		return -1;

@@ -178,7 +190,8 @@ static int tbf_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 	opt.buffer = tc_calc_xmittime(opt.rate.rate, buffer);
 
 	if (opt.peakrate.rate) {
-		opt.peakrate.mpu = mpu;
+		opt.peakrate.mpu      = mpu;
+		opt.peakrate.overhead = overhead;
 		if (tc_calc_rtable(&opt.peakrate, ptab, Pcell_log, mtu) < 0) {
 			fprintf(stderr, "TBF: failed to calculate peak rate table.\n");
 			return -1;

@@ -252,6 +265,10 @@ static int tbf_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 	}
 	fprintf(f, "lat %s ", sprint_time(latency, b1));
 
+	if (qopt->rate.overhead) {
+		fprintf(f, "overhead %d", qopt->rate.overhead);
+	}
+
 	return 0;
 }