
Chapter 1 Product Overview
Route Processors
1-16
Cisco 12404 Internet Router Installation and Configuration Guide
OL-11636-01
Flash Memory or SIMM
A single online memory module (SIMM) is a Flash memory card that allows you
to remotely load and store multiple Cisco IOS software and microcode images.
You can download a new image over the network or from a local server and then
add the new image to Flash memory or replace the existing files. You can then
boot the routers either manually or automatically from any of the stored images.
Flash memory also functions as a trivial file transfer protocol (TFTP) server to
allow other servers to boot remotely from stored images or to copy them into their
own Flash memory.
Read-Only Memory
Read-only memory (ROM), computer memory on which data has been
prerecorded. Once data has been written onto a ROM chip, it cannot be removed
and can only be read.
Unlike main memory (RAM), ROM retains its contents even when the computer
is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile.
The PRP provides two dedicated PCMCIA card slots. Either
slot can support a
Flash memory card or an input/output (I/O) device, as long as the device requires
only +5 VDC. The PRP supports Type 1 and Type 2 devices. Each PCMCIA slot
has an ejector button for ejecting the card from its slot.
PRP LEDs
The light emitting diodes (LEDs) located on the PRP show the status of the PRP,
system error messages, or when reprogrammed, the PRP LEDs show the
user-defined status/error messages. The two types of system status LEDs used on
the PRP are:
•
2 PCMCIA LEDs go on when the slot is accessed.
•
4 RJ-45 Ethernet port activity LEDs (labeled LINK, EN, TX and RX) these
LEDs are used in conjunction with the RJ-45 Ethernet connector. When on,
the 4 RJ-45 LEDs indicate:
–
Link activity (LINK)
–
Port enabled (EN)
–
Data transmission (TX)
–
Data reception (RX)
todd.book Page 16 Tuesday, November 27, 2007 6:02 PM