Westermo MR Series - Manual (Page 87)

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Web Interface and Command Line Reference Guide www.westermo.com
MAC address filtering:
When this parameter is enabled, a received frame will only be sent up the stack if the source
MAC address or matching part thereof exists in the MAC filter table. It is possible to allow a
range of addresses by specifying only the significant portion of the MAC address in the filter
table to allow packets from other units.
MTU
This parameter is used to set the Maximum Transmit Unit for the specified interface. The default
value is 0 meaning that the MTU will either be 1504 (for units using a Kendin Ethernet device)
or 1500 (for non-Kendin devices). The non-zero, values must be greater than 128 and not more
than the default value. Values must also be multiples of 4 and the unit will automatically adjust
invalid values entered by the user. So, if the MTU is set to 1000, the largest IP packet that the
unit will send is 1000 bytes.
QOS:
This parameter is used to turn QOS “On” or “Off” for this Ethernet port.
Remote access options:
The Remote access options parameter can be set to “No restrictions”, “Disable management”,
“Disable return RST”, “Disable management & return RST”. When set to “No restrictions”,
users on this interface can access the unit’s Telnet, FTP and web services for the purpose of
managing the unit.
When set to “Disable management”, users on this interface are prevented from managing the
unit via Telnet, FTP or the web interface.
Disable return RST - whenever a unit receives a TCP SYN packet for one of its own IP address-
es with the destination port set to an unexpected value, i.e. a port that the unit would normally
expect to receive TCP traffic on, it will reply with a TCP RST packet. This is normal behaviour.
However, the nature of internet traffic is such that whenever an internet connection is estab-
lished, TCYP SYN packets are to be expected. As the router’s PPP inactivity timer is restarted
each time the unit transmits data (but not when it receives data), the standard response of the
unit to SYN packets i.e. transmitting an RST packet, will restart the inactivity timer and prevent
the unit from disconnecting the link even when there is no “genuine” traffic. This effect can be
prevented by using the appropriate commands and options within the firewall script. However,
where you are not using a firewall, the same result can be achieved by selecting this option, i.e.
when this option is selected the normal behaviour of the unit in responding to SYN packets
with RST packets is disabled. The option will also prevent the unit from responding to unsolic-
ited UDP packets with the normal ICMP destination unreachable responses.
The “Disable management & return RST” option prevents users from managing the unit via the
Telnet, FTP and web interfaces and also disables the transmission of TCP RST packets as above.
RIP version:
RIP (Routing Information Protocol), is used by routers to determine the best route to any desti-
nation. There are several different versions that can be enabled or disabled using this parameter.
When RIP version is set to Off, RIP is disabled and no RIP packets transmitted out this inter-
face. When RIP version is set to “V1” or “V2”, the unit will transmit RIP version 1 or 2 packets
respectively (version 2 packets are sent to the “all routers” multicast address 224.0.0.9). When
RIP Version is set to “V1 Compat”, the unit will transmit RIP version 2 packets to the subnet
broadcast address. This allows “V1” capable routers to act upon these packets.
When RIP is enabled, RIP packets are transmitted when the Ethernet instance first becomes
active, and at intervals specified by the RIP interval parameter on the Configure > General
page.
RIP destination IP address list:
RIP packets are normally sent out on a broadcast basis or to a multi-cast address. This parame-
ter may be used to force RIP packets to be sent to a specified IP address. It is particularly useful
if you need to route the packets via a VPN tunnel.