Data Communications Networking Devices - 4th Ed.pdf

584 ________________________________________________ LAN INTERNETWORKING DEVICESthumb is to add another downstream PU in the form of an additional gateway forevery 32 workstations on a local area network.Ethernet connectivityIn Figure 5.26 we illustrated how a Token-Ring network could be connected to anSNAnetwork through a 3174 control unit Token-Ring adapter. Asimilar mixtureof hardware and software can be used to connect an Ethernet/IEEE 802.3 networkto an SNAnetwork. By examining how this is accomplished we can note some ofthe numerous vendor gateway construction options available for connectingdifferent types of LANs into an SNA network.Figure 5.27 Using a control unit TRA to interconnect an Ethernet network. Through theinstallation of a Token-Ring adapter and an Ethernet card and appropriate software, thegateway PC provides a connection from a 10BASE-T network to the mainframe via aToken-Ring network