Cisco Router 7204 Installation And Configuration Manual page 23

Chapter 1 Product Overview
Network processing engines have the same functionality; however, their performance differs because of
the microprocessor type and the type of memory for packet data (SRAM and DRAM, or SDRAM) each
network processing engine provides.
The Cisco 7204 supports all versions of the network processing engine except the NPE-300; therefore,
Note
the NPE-300 is not explained in this publication. (The NPE-300 is keyed so that it can only be installed
in Cisco 7200 VXR routers.) For information about the NPE-300 and its use in the Cisco 7200 VXR
routers, refer to the Cisco 7200 VXR Installation and Configuration Guide publication.
The NPE-100, NPE-150, and NPE-200 consist of the following components:
• Reduced instruction set computing (RISC) microprocessor
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–
• System controller that uses direct memory access (DMA) to transfer data between DRAM and
packet SRAM on the network processing engine.
• DRAM for storing routing tables, protocols, network accounting applications, packets of
information in preparation for process switching, and packet buffering for SRAM overflow. The
standard configuration is 32 megabytes (MB), with up to 128 MB available through single in-line
memory module (SIMM) upgrades.
• Packet SRAM for storing packets of information in preparation for fast switching.
–
–
–
Unified cache SRAM that functions as the secondary cache for the microprocessor. (The primary
•
cache is within the microprocessor.)
Two environmental sensors for monitoring the cooling air as it leaves the Cisco 7204 chassis.
•
Boot ROM for storing sufficient code for booting the Cisco IOS software. (This component is only
•
available on the NPE-200.)
The network processing engines perform the following system management functions:
Sending and receiving routing protocol updates
•
Managing tables, caches, and buffers
•
• Monitoring interface and environmental status
• Providing Simple Network Management Protocol (SNMP) management and the console/Telnet
interface
• Accounting and switching of data traffic
• Booting and reloading images
• Managing port adapters (recognition and initialization during OIR)
Figure 1-4
OL-5101-02
The NPE-100 and the NPE-150 have an R4700 microprocessor that operates at an internal clock
speed of 150 megahertz (MHz).
The NPE-200 has an R5000 microprocessor that operates at an internal clock speed of
200 MHz.
The NPE-100 does not have SRAM.
The NPE-150 has 1 MB of SRAM.
The NPE-200 has 4 MB of SRAM.
shows the NPE-100, Figure 1-5 shows the NPE-150, and Figure 1-6
Cisco 7204 Installation and Configuration Guide
Physical Description
shows the NPE-200.
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