HIMA HIMax X-CPU 01, Руководство пользователя

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4 Start-up X-CPU 01
Page 34 of 52 HI 801 009 E Rev. 4.00
MAC Learning MAC Learning and ARP Aging Time are used to set how quick
the Ethernet switch should learn the MAC address.
The following settings are possible:
ƒ Conservative (recommended):
If the ARP cache already contains MAC addresses of
communication partners, these are locked and cannot be
replaced by other MAC addresses for at least one
ARP Aging
Time and a maximum of two ARP Aging Time periods. This
ensures that data packets cannot be intentionally or
unintentionally forwarded to external network participants
(ARP spoofing).
ƒ Tolerant:
When a message is received, the IP address contained in the
message is compared to the data in the ARP cache and the
MAC address stored in the ARP cache is immediately
overwritten with the MAC address from the message. The
Tolerant setting must be used if the availability of
communication is more important than the authorized access
to the controller.
Default setting: Conservative
IP Forwarding Allow a system bus module to operate as router and to forward
data packets to other network nodes.
Default setting: Deactivated
ICMP Mode The Internet Control Message Protocol (ICMP) allows the higher
protocol layers to detect error states on the network layer and
optimize the transmission of data packets.
Message types of Internet Control Message Protocol (ICMP)
supported by the processor module:
ƒ No ICMP Responses
All the ICMP commands are deactivated. This ensures a high
degree of safety against potential sabotage that might occur
over the network.
ƒ Echo Response
If Echo Response is activated, the node responds to a ping
command. It is thus possible to determine if a node can be
reached. Safety is still high.
ƒ Host Unreachable
Not important for the user. Only used for testing at the
manufacturer's facility.
ƒ All Implemented ICMP Responses
All ICMP commands are activated. This allows a more
detailed diagnosis of network malfunctions.
Default setting: Echo Response
Table 18: Configuration Parameters