# ERX Modules

Each 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 network.

Each module connects to a corresponding I/O module via a passive midplane. See Figure 8.

The front panel of each module contains a collection of status LEDs (light-emitting diodes). For information about how to interpret the LEDs, see Troubleshooting.

Figure 8: Modules in ERX14xx Models

| Note: Some line modules require a minimum amount of memory to be used with JunosE Release 5.3.0 or a higher-numbered release. See the ERX Module Guide for line module specifications.

## SRP Module

Switch route processor (SRP) modules perform system management, routing table calculations and maintenance, forwarding table computations, statistics processing, configuration storage, and other control plane functions. Each SRP module is a PowerPC-based system with its own memory, nonvolatile disk storage, and power supply. (See Figure 9 and Figure 10.)

Figure 9: SRP Module for ERX7xx and ERX14xx Models

Figure 10: SRP Module for ERX310 Router

### Module Details

ERX7xx and ERX14xx models use up to two redundant SRP modules operating in an active/standby configuration. ERX310 router use only one SRP module. An SRP module must be present for any system to boot.

SRP modules ranging from 5 Gbps to 40 Gbps can be used in ERX7xx and ERX14xx models. Only a 10-Gbps SRP module (SRP-SE10G) can be used in ERX310 router. See the ERX Module Guide for complete information.

| Note: Because of different physical dimensions and switch fabric capabilities, SRP modules are not interchangeable between systems. For example, the 10-Gbps SRP module used in ERX7xx and ERX14xx models cannot be used in the ERX310 router, and vice versa.

| Caution: Do not remove the SRP module while the system is running.

| Note: Some SRP modules require a minimum amount of memory to be used with JunosE Release 5.3.0 or a higher-numbered release. See the ERX Module Guide for module specifications.

For details about installing SRP modules, see Installing Modules.

### SRP Module Redundancy

SRP module redundancy is available only for ERX7xx and ERX14xx models. See Redundancy Features

### Nonvolatile Storage

The PCMCIA slot on the front of the SRP module holds a Type II PCMCIA nonvolatile storage (NVS) card. (See Figure 9 and Figure 10.) This card is loaded with the system's software and configuration files. The PCMCIA card is factory installed.

| Caution: Although you can remove PCMCIA NVS (Flash) cards from a running router, we recommend that you do not do so. If you remove the card while data is being written to or copied from the NVS card, data can be lost or corrupted. Therefore, we strongly recommend that you shut down the router before removing a PCMCIA NVS card.

## SRP I/O Module

The SRP I/O module is a single corresponding input/output module that interfaces with the SRP modules through the system's midplane. The same SRP I/O module works with all SRP modules, but is router specific. The I/O module used in ERX7xx and ERX14xx models cannot be used in the ERX310 router, and vice versa. See Figure 2, Figure 4, and Figure 6 for locations.

### Module Details

The SRP I/O module provides standard craft management interfaces, including:

- 10/100Base-T—The port enables access to the ERX router for Ethernet management functions via CLI or SNMP, for example.
- RS-232—The port provides a serial connection for monitoring the system's hardware configuration through a PC (running terminal emulation software) or ASCII terminal. Allows direct CLI access.
- Alarm contacts—The contacts provide for remote indication of critical, major, and minor router alarms (ERX7xx and ERX14xx models only; currently not implemented)
- External timing inputs—The inputs provide a method of ensuring that the clock timing used by the router remains synchronized with the network's system clock. BNC connectors and wire wraps are available for ERX7xx and ERX14xx models only.

For details about installing the SRP I/O module, see Installing Modules.

## Line Modules

Line modules (LM) process data from different types of network connections. For information about available line modules and which SRP modules support specific line modules, see the ERX Module Guide.

Figure 11 shows a representative line module. For details about installing line modules, see Installing Modules.

Figure 11: Representative Line Module

### Packet Classification

Most line modules support packet classification on ingress; some non-ASIC line modules do not. 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.

## I/O Modules

Most line modules have a corresponding input/output (I/O) module that provides the physical interconnection to the network. Insert each I/O module into the back of the system, directly behind its corresponding line module.

For information about which line modules pair with which I/O modules, see the ERX Module Guide. See Figure 2, Figure 4, and Figure 6 for locations. For details about installing I/O modules, see Installing Modules.