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Ethernet Connection, cont’d
CrossPoint / MAV Matrix Switchers • Ethernet Connection
A-6
Subnetting — A Primer
ItisnotthepurposeofthismanualtodescribeTCP/IPprotocolindetail.However,
someunderstandingofTCP/IPsubnetting(asubnetisasubset of a network — a
setofIPdevicesthathaveportionsoftheirIPaddressesincommon)isnecessary
inordertounderstandtheinteractionoftheCrossPointorMAVswitcherandthe
mail server gateway. To understand subnetting at the level required to install and
operatetheCrossPointorMAVswitcher,youmustunderstandtheconceptsofa
gateway,localandremotedevices,IPaddressesandoctets,andsubnetmasksand
octets.
Gateways
TheCrossPointorMAVswitchercancommunicatewiththee-mailserverthatthe
switcher uses for e-mail notification directly (if they are on the same subnet) or
the communication can be routed via a gateway (a computer that provides a link
between different subnets).
Local and remote devices
The local and remote devices are defined from the point of view of the function
beingdescribed.Inthismanual,subnettingisanissuewhenyouareusingthe
controllingPCtosetTCP/IPande-mailvaluesintheCrossPointorMAVswitcher
(see“IPSettings/Optionswindow” inchapter5,“MatrixSoftware”,and“Email
Settingspage”inchapter6,“HTMLOperation”).Whenyouaresettingupthe
variables for e-mail notification, which may include subnetting, the matrix switcher
is the local device and the e-mail server is the remote device.
IP addresses and octets
ValidIPaddressesconsistoffour1-,2-,or3-digitnumericsubelds,properlycalled
octets,separatedbydots(periods)(gureA-4).Eachoctetcanbenumberedfrom
000through255.Leadingzeroes,uptothreedigitstotalperoctet,areoptional.
Valuesof256andaboveareinvalid.
192.168.254.254Typical IP Address:
Octets
Figure A-4 — IP address and octets
Subnet masks and octets
The subnet mask (figure A-5) is used to determine whether the local and remote
devices are on the same subnet or different subnets. The subnet mask consists
of four numeric octets separated by dots. Each octet can be numbered from
000through255.Leadingzeroes,uptothreedigitstotalperoctet,areoptional.
Eachoctettypicallycontainseither255or0.Theoctetsdeterminewhetherornot
thesameoctetsoftwoIPaddresseswillbecomparedwhendeterminingiftwo
devices are on the same subnet.
255.255.0.0Typical Subnet Mask:
Octets
255 indicates that this octet will be
compared between two IP addresses.
0 indicates that this octet will not be
compared between two IP addresses.
Figure A-5 — Subnet mask and octets