Differences between version 6 and previous revision of DestinationHostUnreachable.
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| Newer page: | version 6 | Last edited on Thursday, April 12, 2007 3:12:02 pm | by BenStaz | Revert |
| Older page: | version 5 | Last edited on Thursday, April 12, 2007 3:08:44 pm | by BenStaz | Revert |
@@ -1,5 +1,5 @@
[ICMP] reason subcode 0x1, used with [ICMP] reason code 0x3 to explain why a DestinationUnreachable message was sent.
-If
a packet
is to be
forwarded to a host on a network that
is directly connected
to the router
(i.e.
, the router is
the last-
hop router) and the router has ascertained that there is no path
to the destination
host then
the router MUST generate
a Destination Unreachable, Code 1 (
Host Unreachable) ICMP
message.
+When
a datagram
is being
forwarded, and reaches a router attached
to the network
a destination
host is to be found on
(i.e, the last hop router),
and the route
to the host is down,
the host is not responding or does not respond on the service port in question,
a Host Unreachable message is sent back
.
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).
