Reviewing And Setting The Subnet Mask And Default Gateway - Fluke 2680A User Manual

2680A/2686A
Users Manual

Reviewing and Setting the Subnet Mask and Default Gateway

If communication between the host computer and the 2680 Series passes through a
router or gateway, you must set the subnet mask and default gateway address on
both the host computer and the instrument. Get this information from your network
administrator.
For more information on the purpose of the subnet mask and default gateway
address, see Network Considerations in Appendix H.
Perform the procedure in Table 2-14 to review or set the instrument network
gateway parameters. The network gateway parameters include turning the default
gateway feature on or off, setting a subnet mask, and setting an IP address for the
gateway attached to the local network.
Set the IP address of the instrument before setting gateway
parameters. The 2680 Series instrument checks the gateway IP
address for validity by using the instrument IP address.
•
Default Gateway Parameters If the 2680 Series instrument and host PC are
on different subnets and must communicate through a gateway (router), turn
the default gateway feature ON and enter the subnet mask and IP address of
the gateway, as supplied by your network administrator. If you do not require
a gateway, turn the default gateway feature OFF.
•
Subnet Mask The subnet mask is a 32-bit binary number expressed as four 3
digit segments, like an IP address. The subnet mask, when masked with the
instrument IP address, determines what the network number is. For example, if
the IP address is 129.196.180.93 and the subnet mask is 255.255.255.0, the
network number is 129.196.180.0.
The subnet mask contains a consecutive set of bits, starting at the highest order
bit, forming a binary mask value. For example, 255.255.0.0 (binary value
FFFF0000 hex) is a valid mask, but 255.255.10.0 (binary value FFFF0A00
hex) is not a valid mask, because the bits are not consecutive. 0.255.255.0
(binary value 00FFFF00 hex) is also not a valid mask, because the bits do not
begin at the highest order bit.
The subnet mask must also contain a minimum number of bits depending on
the class of the instrument IP address. The minimum number of bits for a class
A address is 255.0.0.0, class B is 255.255.0.0 and class C is 255.255.255.0.
For example, if the IP address is 129.196.180.93, a class B address, a subnet
mask of 255.0.0.0 is not valid, because there are too few subnet mask bits set.
•
Default Gateway IP Address The default gateway IP address is the IP
address of a gateway (router) attached to the same network as the instrument.
When the instrument detects that a host PC is not on the same network (using
2-42
Note