# Line Modules, I/O Modules, and IOAs

A range of line modules, I/O modules, and I/O adapters (IOAs) are available for the router. On the ERX14xx models, ERX7xx models, and the ERX310 router, most line modules pair with a corresponding I/O module. On the E120 and E320 routers, a single line module pairs with all available IOAs.

I/O modules and IOAs provide the input and output connections from the network to the router. Line modules connect to their corresponding I/O modules or IOAs through a passive midplane. A line module receives packets through its I/O module or IOA and processes those packets. The router then routes the packets out to the network through the designated I/O module or IOA.

Each line module, I/O module, and IOA has a label on its faceplate. In this documentation, these modules are identified by that label. For example, the high-density Gigabit Ethernet line module has two ports, and is called the GE-HDE line module. Its corresponding I/O modules are the GE-HDE I/O module and the GE-2 SFP I/O module.

When we refer to a related set of line modules, I/O modules, or IOAs, the generic information from the module labels is used in this documentation. For example, the term “ OCx/STMx line modules” refers to both the OCx/STMx ATM and the OCx/STMx POS line modules. Similarly, the term “ GE I/O modules” refers to both the GE Multimode I/O module and the GE Single Mode I/O module.

For a complete list of the line modules and I/O modules available for ERX14xx models, ERX7xx models, and the ERX310 router, see ERX Module Guide, Table 1, Module Combinations. For more information about line modules and IOAs available with the E120 and E320 routers, see E120 and E320 Module Guide, Table 1, Modules and IOAs.

For more information about managing these modules, see Managing Modules.