YOKOGAWA Vnet/IP User Manual

  3.Vnet/IPNetworkCongurationwithoutusingInformationNetwork
3-2
TI 30A10A05-01E
3.1 Bandwidth used for Open Communications
In Vnet/IP, bus 1 usually performs control communications and bus 2 performs open
communications. However, when bus 1 fails, bus 2 performs both control and open
communications. To ensure stable control communications, restrict the bandwidth of
open communications used in the Vnet/IP domain to 500 Mbps or less, which should
already include the 200 Mbps used for communication between Vnet/IP stations.
Therefore, you have to restrict the bandwidth used by other Ethernet communication
devicessuchasnetworkprintersorleserversto300Mbpsorless.
ToensurethatthebandwidthusedbyEthernetcommunicationdevicesdoesnotexceed
300Mbps,connectEthernetcommunicationdevicestolayer2switchesthroughlow
speed100MbpsHUBs.HUBsrestrictthecommunicationspeed,thusmaintainingthe
bandwidth used in Vnet/IP domains below the acceptable limit. On the other hand, you
can connect Vnet/IP interface cards to layer switches directly because Vnet/IP interface
cards can restrict the communication bandwidth.
When you connect multiple Vnet/IP domains and there is open communication coming from
Ethernet communication devices in other domains, restrict the total communication bandwidth
of all domains to 300 Mbps or less. The following gure shows an example of connecting
Ethernet communication devices to Vnet/IP domains through 100 Mbps HUBs used only for bus
2. In this example, there are three 100 Mbps HUBs used in the system to ensure that the total
communication bandwidth used by all Ethernet communication devices does not exceed 300
Mbps.
030101E.ai
L3SW
(1Gbps)
HUB
(100Mbps)
Ethernet peripheral
(ex. Network printer)
Ethernet peripheral
(ex. Network printer)
Ethernet peripheral
(ex. File server)
HIS
HUB
(100Mbps)
HUB
(100Mbps)
HIS
ENG
FCS
FCS
L2SW L2SW
Vnet/IP Domain 2Vnet/IP Domain 1
Figure ExampleofconnectingEthernetcommunicationdevicestoVnet/IPdomains(Bus2only)
Aug.19,2011-00

YOKOGAWA Vnet/IP Specifications

General

Brand	YOKOGAWA
Model	Vnet/IP
Category	Network Card
Language	English