IBM SG24-4817-00 manual Atm

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Using a similar analysis, we can see in Table 11 on page 79, the bandwidth improvement possible for a constrained Ethernet environment of 40 users and 4 servers. In this scenario, we have added an 8285 switch with an 3-slot 8271 ATM/LAN Switch Module as shown in Figure 31 on page 79. In this case, however, rather than move our secondary servers to full-duplex Ethernet, we will go directly to 100base-Tx, providing each secondary server with 100 Mbps of dedicated bandwidth.

Figure 31. Relieving Ethernet Congestion with LAN Switching Module

Note

The choice of 100Base-Tx in this scenario is merely to demonstrate the versatility of the LAN Switch modules in conjunction with the 8285 switch. For the purposes of the example, we could have just as easily moved all of the servers to ATM directly, providing 155 Mbps to each server. Or we could have connected a shared 100Base-Tx segment to the LAN switch module to access resources on that segment and to provide ATM access to the 100Base-Tx users.

Table 11 illustrates the before and after results of our changes.

Table 11 (Page 1 of	2). Bandwidth Improvement with Ethernet LAN Switch Module
Device	Maximum Bandwidth Available (Kbps)				Bandwidth
					Improvement
	Server	ATM	Micro-	ATM25
					Ratio￿2￿
	Offload	Server	segment	Offload
			-ation￿1￿
Primary Server	100000	155000	155000	155000	682x
Secondary Server	100000	100000	100000	100000	440x

Chapter 4. IBM 8285 ATM Modules 79