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Although LAN performance is measured in packets per second, WAN performance is more accurately measured by the amount of throughput on a link. To optimize performance on a WAN, you must optimize the WAN circuit.
As shown in Figure 6 , WAN circuits are made up of two components:
This topic contains the following sections:
Payload capacity is the speed at which data moves through a circuit. If your network is very large (over 4000 network segments and services) and uses only the Internetwork Packet ExchangeTM (IPXTM ) protocol and T1 (1.544-Mbps) connections, maximizing payload capacity can increase network performance significantly.
Because very large networks have minimal line overhead---for example, less than 5 percent of network capacity is associated with in-band maintenance traffic---decreasing line overhead does not significantly increase bandwidth. However, you can overcome transport protocol inefficiencies and increase capacity of a circuit by using data compression.
NOTE: If the link is not already fully using the line speed, adding data compression produces minimal performance improvement.
Line overhead contains the media's framing, routing protocol, and Network-layer protocol overhead. Line overhead is similar to an envelope in that it restricts the capacity of the system. To increase a circuit's capacity, you must minimize line overhead.
Reducing line overhead in a multiprotocol environment is critical because it increases circuit capacity for all protocols, not only the protocol being optimized. For example, reducing Service Advertising Protocol (SAP) traffic increases the available bandwidth for IPX, IP, and AppleTalk clients.
If your network is large (1000 network segments and services) and consists of small sites and branch offices connected by 64-Kbps or slower circuits, your line overhead can be at 25 percent or more of circuit capacity. In this case, reducing line overhead is critical. Without optimization of line overhead, circuits are saturated and payload optimization produces only minimal improvement.
By optimizing both the line overhead and the payload capacity, you can dramatically improve network throughput and transmit more user data over WAN connections. Novell® Internet Access Server 4.1 routing software provides several optimization tools.
For payload optimization, consider using the following:
For line optimization, consider using the following:
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