Contents

BRAS services overview·· 1

BRAS network· 1

BRAS components· 2

BRAS services· 2

BRAS services overview

A broadband remote access server (BRAS) is an access gateway for broadband network applications. It provides a basic access approach to the backbone network and management features for the broadband access network.

BRAS network

Figure 1 describes the location of the BRAS device in a campus network.

Figure 1 BRAS device in a campus network

BRAS components

Figure 2 BRAS components

Figure 3 Introduction to BRAS components

BRAS services

User access

This component provides the following services:

·          Portal—Portal authentication, also referred to as Web authentication, controls user access to networks. Portal authenticates a user by the username and password the user enters on a portal authentication page. Portal authentication provides a flexible access control method without the installation of client software. It is deployed on the access layer and vital data entries.

An unauthenticated user is required to visit a specific authentication website with free access to services on that page. To access other network resources, the user has to perform authentication on the authentication website. Users that pass portal authentication are allowed to access authorized network resources. For more information, see portal configuration in BRAS Services Configuration Guide.

·          IPoE—IP over Ethernet (IPoE) is a IPoX access method. In IPoE, a BRAS receives IP packets from Ethernet users and authenticates users based on their access location or packet characteristics. The AAA server authorizes users that pass authentication with corresponding access rights. For more information, see IPoE configuration in BRAS Services Configuration Guide.

·          PPPoE—Point-to-Point Protocol over Ethernet (PPPoE) extends PPP by transporting PPP frames encapsulated in Ethernet over point-to-point links. PPPoE provides Internet access for the hosts in an Ethernet through a remote access device and implements access control, authentication, and accounting on a per-host basis. Integrating the low cost of Ethernet and scalability and management functions of PPP, PPPoE gained popularity in various application environments, such as residential access networks. For more information, see PPPoE configuration in BRAS Services Configuration Guide.

·          L2TP—The Layer 2 Tunneling Protocol (L2TP) is a Virtual Private Dialup Network (VPDN) tunneling protocol. L2TP sets up point-to-point tunnels across a public network (for example, the Internet) and transmits encapsulated PPP frames (L2TP packets) over the tunnels. With L2TP, remote users can access the private networks through L2TP tunnels after connecting to a public network by using PPP. For more information, see L2TP configuration in BRAS Services Configuration Guide.

AAA management

Authentication, Authorization, and Accounting (AAA) provides a uniform framework for implementing network access management. This feature specifies the following security functions:

·          Authentication—Identifies users and verifies their validity.

·          Authorization—Grants different users different rights, and controls the users' access to resources and services. For example, you can permit office users to read and print files and prevent guests from accessing files on the device.

·          Accounting—Records network usage details of users, including the service type, start time, and traffic. This function enables time-based and traffic-based charging and user behavior auditing.

AAA has various implementations, including RADIUS, HWTACACS, and LDAP. RADIUS is most often used. For more information, see AAA configuration in BRAS Services Configuration Guide.

Address assignment

This component provides the following address assignment methods:

·          Static address—For more information about configuring a static IPv4 address and a static IPv6 address, see IP addressing configuration and IPv6 basics configuration in Layer 3—IP Services Configuration Guide.

·          DHCP—The Dynamic Host Configuration Protocol (DHCP) provides a framework to assign configuration information to network devices. For more information, see DHCP configuration in BRAS Services Configuration Guide.

·          DHCPv6—DHCPv6 provides a framework to assign IPv6 prefixes, IPv6 addresses, and other configuration parameters to hosts. For more information, see DHCPv6 configuration in BRAS Services Configuration Guide.

·          Stateless address autoconfiguration—A node automatically generate an IPv6 global unicast address based on the address prefix information contained in the RA message. For more information, see IPv6 basics configuration in Layer 3—IP Services Configuration Guide.

Service management

The device provides various service management functions and service support for users.

Table 1 Managing access services

Table 2 Managing value-added services