AT&T 7100 series, 7500 series, 2500 series, 7200 series, 7400 series, 7300 series manual Lan

Communication Between the LAN and Outside DTEs

LAN nodes must be intelligent enough to understand and regenerate LAN protocols. Therefore, network nodes are most often PCs or other hosts. Outside terminals usually access the LAN through a circuit- switched, dialed-up connection. The connection links the terminal with a gateway PC that is both a LAN node and an extension on the communications system. The gateway must be executing software that can translate messages between the LAN’s protocol and the outside terminal’s protocol.

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LOCAL AREA NETWORK CONNECTIONS 8-15

—It can give outside users access to the LAN and the hardware and software resources that reside there.

—It can provide LAN users with access to the lines and trunks attached to communications system.

∙Second, it can let LAN nodes communicate with nodes in other networks.

∙Third, for LAN nodes, the communications system can provide switched access to the LAN server when direct access through the usual LAN links is blocked.

		S75/S85/G1/G2		GATEWAY
				PC
	D
7400B	C	E
	P	I	ADU	LAN
		A
OUTSIDE PC
(ON-PREMISES)
	A	D
	N
		C	7400A
	A
		P
MODEM	L
	O
	G
OUTSIDE PC
(OFF-PREMISES)
		MODEM
		POOL

Figure 8-6.Outside DTE Access to LAN

The general configuration for communication between the LAN and outside DTEs is shown in figure 8-6.The configuration can be applied to the connection of any outside terminal to a StarLAN, Ethernet, or token ring LAN. However the software that runs on the gateway PC to provide access for outside terminals varies with the type of LAN and the operating system it uses. The following table lists some packages that run on the gateway PC to provide access for outside terminals. Note that any of the operating systems shown in the table can run a StarLAN, token ring, or Ethernet LAN.

Table 8-4.Gateway PC Software

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