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This soft copy for use by IBM employees only.
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
Ratio2
Server
Offload
ATM
Server
Micro-
segment
-ation1
ATM25
Offload
Primary Server 100000 155000 155000 155000 682x
Secondary Server 100000 100000 100000 100000 440x
Chapter 4. IBM 8285 ATM Modules 79