| 4.1 |  | AAA Secure Network Access |
| 4.1.2 |  | AAA secures network architecture |

| The first step in the process of providing remote access of any kind is to provide a way to authenticate the user. AAA secures two types of remote access and remote management traffic. These are packet mode and character mode. In the remote client system, AAA technologies work with the network access server (NAS) and the security server to protect character-mode or packet-mode access to a NAS and other network equipment. The remainder of this section and module will focus primarily on character-mode traffic. However, it is important to have a general understanding of both character-mode and packet-mode traffic types.

AAA secures packet (interface) mode traffic
Traveling sales people, executives, remote office staff, and telecommuters all need to communicate by connecting to the main office LAN. Packet mode traffic is typically used when network users are trying to gain remote access to a network .

In order for a remote network connection to function, users must have the necessary application software, FTP or Telnet, protocol stacks, TCP/IP or IPX, and link-layer drivers installed on their machines. The application software and protocol stacks then encapsulate the higher-layer data and protocols in link-layer protocols such as Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP). The encapsulated packets, hence the packet-mode name, are transmitted across the dialup line in analog or digital form, depending on the type of telecommunication line used.

AAA secures character (line) mode traffic
As computer networks have become more complex, so has network administration. In geographically dispersed networks, it is necessary for network administrators to access network devices remotely. Most communication to control equipment takes place in character mode, such as Telnet. AAA can protect character-mode access to network equipment .

In Cisco routers, AAA secures character-mode traffic during login sessions via the line types shown in Figure .