ICMP reason subcode 0x1, used with ICMP reason code 0x3 to explain why a DestinationUnreachable message was sent.
It is usally generated by a gateway when it does not have a route for the destination specified in the IP packet that caused the error. Often this reason is used when a router cannot contact the next hop router specified in it's routing table (ie. The next hop router is not responding to ARP requests).
2 pages link to DestinationHostUnreachable:
