Advantages of IOS internetwork operating system

Connectivity

The IOS supports a variety of data link layer technologies for the LAN and WAN environments, including copper and fiber wiring as well as wireless.

Scalability

The IOS supports both fixed and modular chassis platforms, enabling you to purchase the appropriate hardware for your needs, yet still allowing you to leverage the same IOS CLI to reduce your management costs.

Reliability

To ensure that your critical resources are always reachable, Cisco has developed many products and IOS features to provide network redundancy.

Security

With the IOS, you can strictly control access to your network and networking devices in accordance with your internal security policies.

Naming Conventions for IOS Images

c1841-advipservicesk9-mz.124-6.T7.bin ( this name is used to expalation)

·         c1841
The c1841 refers to the name of the platform on which the image will run. This is important because different router models have different processors, and an image compiled for one processor or router model will typically not run on a different model.

·         advipservicesk9
The advipservicesk9 refers to the features included in this IOS version, commonly referred to as the feature set. In this example, the IOS is the advanced IP services and the k9 refers to the inclusion of encryption support.

·         mz or z
The mz or z means that the image is compressed and must be uncompressed before loading/running. If you see l (the letter l, not the number 1) here, this indicates where the IOS image is run from. The l indicates a relocatable image and that the image can be run from RAM. Remember that some images can run directly from flash, depending on the router model.

·         124-6.T7 
The 124-6.T7 indicates the software version number of the IOS. In this instance, the version is 12.4(6)T7. Images names with T indicate new features, and without the T the mainline (only bug fixes are made to it).

·         .bin
The .bin at the end indicates that this is a binary image.

An IOS filename is broken down into four parts:

·         Platform

·         Feature set

·         Run location and compression

·         Version

Memory Locations

Code	Location
F	Image runs in flash
M	Image runs in Random Access Memory (RAM)
R	Image runs in Read Only Memory (ROM)
L	Image will be relocated at runtime

·         Compression Identifiers

Code	Compression
Z	Image is Zip compressed
X	Image is Mzip compressed
W	Image is Stac compressed

Connections

Cisco's networking products support two types of external connections:
ports (referred to as lines) and interfaces.

Out-of-band management (which you do by console ports) does not affect the bandwidth flowing through your network, while in-band management(which is done by interface) does

Console Port

Almost every Cisco product has a console port. This port is used to establish an out of- band connection in order to access the CLI to manage your Cisco device. Most console connections to Cisco devices require an RJ-45 rollover cable and an RJ-45-to-DB9 terminal adapter.
The rollover cable pins are reversed on the two sides.

Com port setting
Speed	9600 bps
Data bits	8
Stop bits	1
Parity & Flow Control	None

Cabling Devices

A straight-through cable is used for DTE-to-DCE connections.

·         A hub to a router, PC, or file server

·         A switch to a router, PC, or file server

Crossover cables should by used when you connect a DTE to another DTE or a DCE to another DCE.

·         A hub to another hub

·         A switch to another switch

·         A hub to a switch

·         A PC, router, or file server to another PC, router, or file server