Router Interfaces | Components of Router Hardware and Memory

Router Interfaces | Components of Router Hardware and Memory 

This article is an introduction of Router Interfaces, its Components of Router Hardware and Memory. In first part of this article we will discus the main components of router. Like other network devices, routers have the following main parts:

1. Input / Output Devices
2. CPU : to execute the OS instructions (Cisco routers use IOS as the operating system).
3. Memory (RAM, ROM, NVRAM and Flash) : A router has access to volatile and non-volatile memory storage, the latter needs constant energy to conserve information.

Router Memory Table.

Memory	Volatile / Nonvolatile	Store
RAM (SDRAM)	Volatile	• IOS running  • Configuration file running  • IP routing and ARP tables  • Packet buffer
ROM	Non volatile	• Startup instructions  • Basic diagnostic software  • IOS limited
NVRAM	Non volatile	• Startup configuration file
Flash	Non volatile	• IOS (Internetworking Operating System)  • Other system files

Hardware components of Router:

Although there are different types and models of routers, they all have the same general hardware components.

1. Power supply
2. Fan
3. Protection for WAN (WIC) or high-speed WIC (HWIC) interface card
4. Dynamic synchronous RAM (SDRAM) that is used to keep the configuration running and routing tables.
5. Non-volatile RAM (NVRAM) and boot flash memory used to store the ROMMON boot code and NVRAM data.
6. CPU
7. The connection of the advanced integration module (AIM) that downloads functions that demand a lot from the processor, such as encryption from the main CPU.
8. Protection for WAN (WIC) or high-speed WIC (HWIC) interface card

A network professional must know and understand the function of the main internal components of a router, rather than the exact location of these within a specific router.

Router Interfaces or Ports:

Routers have different types of interfaces or ports to support connections. Different router model have the different router interfaces according to their type and need. Following are the main types of router interfaces :

Console ports : 

Console port is used to access the administration of the initial configuration and the command line interface (CLI). There are two ports available, the most frequently used port (common RJ-45 port) and a new type B USB connector (USB mini-B). However, the console can only be accessed for one port at a time.

USB interfaces : 

Ports with the USB 0 and USB 1 label to provide additional storage space, similar to flash memory.

Gigabit Ethernet : 

Interfaces with the GE0 / 0 and GE0 / 1 label. Generally, they are used to provide LAN access by connecting with switches and users, or to interconnect to another router.

Auxiliary (AUX): 

An RJ-45 port for remote administration access, similar to the console port. It is now considered an old port, as it was used to support dial up modems.

Slots for enhanced high-speed WAN interface cards (eHWIC) : 

with the eHWIC 0 and eHWIC 1 label to provide modularity and flexibility by allowing the router to support different types of interface modules, including serial, digital subscriber line (DSL) , switch port and wireless technology.

CompactFlash slots : 

with the CPC and CF1 label to provide a larger amount of storage space in expandable Hash memory with CompactFlash cards up to 4 GB per slot. By default, the CFO slot has a 256 MB CompactFlash card and is the default boot location.

The connections of a Cisco router can be grouped into two categories: In-band router interfaces and management ports.

• Management Ports : (purple) These include the console and auxiliary ports used to configure, manage and troubleshoot the router. Unlike the LAN and WAN network interfaces, the management ports are not used for sending user traffic packets.
• In-band router interfaces : (orange) These are the LAN (i.e. Gigabit Ethernet) and WAN (i.e., enhanced high-speed WAN interface cards) interfaces configured with the assignment of IP addresses to transport traffic of users. Ethernet interfaces are the most frequent LAN connections, while common WAN connections include serial and DSL interfaces.

IN-BAND ROUTER INTERFACES

• Serial WAN interfaces (left) : which are added to the eHWIC0 and have the labels Serial 0 (i.e., S0 / 0/0) and Serial 1 (ie, S0 / 0/1). Serial interfaces are used to connect routers to an external WAN network. Each serial WAN interface has its own IP address and subnet mask, which identify it as a member of a specific network.

• LAN Ethernet network interfaces (right) : with the GE 0/0 (ie G0 / 0) and GE 0/1 (ie G0 / 1) labels. Ethernet interfaces are used to connect to other devices with Ethernet enabled, including switches, routers, firewalls, etc. Each LAN network interface has its own IPv4 address and subnet mask, or an IPv6 address and prefix, which identify it as a member of a specific network.