| Rev | Author | # | Line |
|---|---|---|---|
| 1 | MattBrown | 1 | [ICMP] reason subcode 0x4, used with [ICMP] reason code 0x3 to explain why a DestinationUnreachable message was sent. |
| 2 | |||
| 3 | It is generated by a router when it cannot forward a packet because the [MTU] of the outgoing interface is smaller than the packet's size and the packet has the DF (Don't Fragment) bit set. |
