Siemens DataNET Hub (DNH) - Manual (Page 13)

2000585-001 Introduction •••• 5
DataNET Hub Operation, Continued
DataNET switching operates by dynamically and automatically learning
the topology of the network (i.e., which MAC/IP addresses are reachable
through which paths) as Ethernet frames are forwarded through the net-
work. The DataNET hubs require no static initialization of network data in
order to perform their switching function.
Each DNH can learn as many as 1200 IP addresses. This allows the hub
to accommodate up to 1000 instruments (analyzers, etc.), and still be
able to switch frames from another 200 devices (workstations, etc.).
DataNET switching accommodates any Ethernet-encapsulated protocol.
The hub will also “snoop” IP datagrams (RFC 894) and ARP messages
(RFC 826) to learn the locations of all devices using IP.
• MAC Address (Media Access Control). The “built-in” hardware ad-
dress of a device connected to a shared media.
• IP Address is a 32-bit address defined by the Internet Protocol. It is
usually represented in dotted decimal notation. Present address is
127.236.032.239
DataNET hubs operate as layer 2 Ethernet bridges. That is, hubs will
forward frames among connected Ethernet segments and DataNET de-
vices regardless of the upper layer protocols carried in those frames.
In the absence of hardware failures or network overload, the hub soft-
ware will deliver each Ethernet frame to its intended destination (all sta-
tions in the case of Ethernet broadcasts) in order and without duplication.
In normal operation, the network may deliver frames to additional desti-
nations (i.e., to stations whose MAC addresses do not match the frames’
destination address). End devices must be prepared to receive and ig-
nore frames whose destination addresses do not match their own MAC
addresses.
DataNET Switching
Definitions
Transparency