er.print_output("/sbin/route -6 add default 2001:db8::1")
+
+        import scapy.all as sp
+
+        pkt = sp.Ether(dst=gw_mac) \
+            / sp.IPv6(dst="64:ff9b::198.51.100.2", hlim=1) \
+            / sp.SCTP(sport=1111, dport=2222) \
+            / sp.SCTPChunkInit(init_tag=1, n_in_streams=1, n_out_streams=1, \
+                a_rwnd=1500, params=[])
+        s = DelayedSend(pkt, sendif=ifname)
+
+        found = False
+        packets = sp.sniff(iface=ifname, timeout=5)
+        for r in packets:
+            print("Reply packet:")
+            r.show()
+
+            ip6 = r.getlayer(sp.IPv6)
+            icmp6 = r.getlayer(sp.ICMPv6TimeExceeded)
+            if not ip6 or not icmp6:
+                continue
+            assert ip6.src == "2001:db8::1"
+            assert ip6.dst == "2001:db8::2"
+            assert icmp6.type == 3 # Time exceeded
+            assert icmp6.code == 0 # hop limit exceeded in transit
+            found = True
+        assert found
+
     @pytest.mark.require_user("root")
     @pytest.mark.require_progs(["scapy"])
     def test_ttl_zero(self):