ERX System Modules
The system supports an SRP module and a selection of line modules. You can use any line module for access or uplink. Access line modules receive traffic from low-speed circuits, and the system routes the traffic onto higher-speed uplink line modules and then to the core of the Internet.
Each module connects to a corresponding I/O module via a passive midplane. See Figure 1-7.
The front panel of each system module contains a collection of status LEDs (light-emitting diodes). See Figure 1-8. For information about how to interpret the LEDs, see Chapter 8, Troubleshooting.
The SRP module (see Figure 1-8) is a two-board assembly; both boards connect to the system's midplane and to each other:
- The fabric board is a switch fabric server that queues packets for the line modules. The fabric server houses a flexible hardware queuing resource that empowers IP QoS for each physical and logical interface, providing weighted scheduling for preferential packet delivery.
- The system processor board is the dedicated processor that boots the system, manages diagnostics, and supports routing protocol processing.
An SRP module must be present for the system to boot. For details about installing SRP modules, see Chapter 3, Installing ERX Modules. For specifications of SRP modules, see Appendix B, Module Specifications.
Caution: Do not remove the SRP module while the system is running.
You can install two SRP modules of the same type in the system. If you do, the first SRP module serves as the primary; the second as a redundant module, which enhances the system's reliability. See Redundancy Features, later in this chapter.
The PCMCIA slot on the front of the SRP module holds a Type II PCMCIA nonvolatile storage (NVS) card. This card retains the system's configuration and software. See Figure 1-8. The PCMCIA card is factory installed.
SRP I/O Module
A single corresponding input/output module called the SRP I/O module interfaces with one or two SRP modules through the system's midplane. The same SRP I/O works with all models of the SRP module. This I/O module is two slots wide. See Figure 1-2 and Figure 1-4.
The SRP module provides standard craft management interfaces, including:
- 10/100Base-T - a port for Ethernet management
- RS-232 - a port for VT100 management access
- External timing inputs - ports for external timing sources
For details about installing the SRP I/O module, see Chapter 3, Installing ERX Modules.
Line modules process data from different types of network connections. For information about the available line modules and which SRP modules support specific line modules, see Appendix B, Module Specifications.
Figure 1-9 shows a representative line module. For details about installing line modules, see Chapter 3, Installing ERX Modules.
Each line module supports packet classification on ingress. A classification engine on the line module matches specific fields (such as source and destination IP address, source and destination port, and protocol), the ingress IP interface, layer 2 fields, or some combination of these against user-configured filters at wire speed.
Most line modules have a corresponding input/output (I/O) module that provides the physical interconnection to the network. Insert each I/O module in the back of the system, directly behind its corresponding line module. For information about which line modules pair with which I/O modules, see Appendix B, Module Specifications. For details about installing I/O modules, see Chapter 3, Installing ERX Modules.