We have fwsm v 2.3(3) and v2.3(1). We did not have to turn on ip unreachables in v2.3(1), but somehow v2.3(3) requires it. We know this because the error message come across (and after several days of headache). Is there a difference in how these two versions treat mtu size. This is critical as we may have to downgrade to make a host of this work. Any ideas ?