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D-Link DVX-1000 User Manual
Appendix A - Appendix
Sending ICMP redirect messages
For the same reason as mentioned above, it is not advisable to send ICMP redirect messages.
Connections from IANA-reserved blocks
IANA has generated a list of reserved blocks of IP Address, from/to where the connection is not allowed.
ICMP Source Quench Messages
An ICMP source quench is generated by a gateway or the destination host and tells the sending end to ease up because
it cannot keep up with the speed at which it’s receiving the data. This service is allowed.
ICMP Parameter Problem Messages
The ICMP Parameter Problem message is sent to the source host for any problem not specifically covered by another
ICMP message. Receipt of a Parameter Problem message generally indicates some local or remote implementation
error. These messages are allowed.
ICMP Destination Unreachable/Service Unavailable Messages
The Destination Unreachable message is an ICMP message which is generated by the router to inform the client that the
destination host is unreachable, unless the datagram has a multicast address. Reasons for this message may include
the physical connection to the host does not exist (distance is infinite), the indicated protocol or port is not active, or
the data must be fragmented but the ‘don’t fragment’ flag is on.This message is allowed.
ICMP Time Exceeded Messages
The ICMP time exceeded message is generated when the gateway processing the datagram (or packet, depending on
how you look at it) finds the Time To Live field (this field is in the IP header of all packets) is equal to zero and therefore
must be discarded. The same gateway may also notify the source host via the time exceeded message.
ICMP Ping
ICMP echo request and echo reply messages are allowed, by default.