Cisco 827 - 827 Router - EN Manual de usuario descargar pdf (Pagina 14)

Network Scenarios Pagina 14 di 35

http://www.cisco.com/univercd/cc/td/doc/product/access/acs_fix/827/827swcfg/ntwkscen.htm 14/02/2001

access-list 1 permit 192.168.1.0 0.0.0.255

end

Integrated Routing and Bridging

This network shows a user connecting to the Internet using integrated routing and bridging (IRB) to use

NAT across a bridged interface. This scenario might work for you if you want to add functionality to an

endpoint router without reconfiguring the central site. For example, you can provide an IP address and

NAT in a bridged network without having to reconfigure the central site for routing.

Exchanging the bridge with a router enables feature additions such as voice and Quality of Service

(QoS). IRB provides more secure control of the central site and more efficient use of the WAN link.

Figure 2-5 shows an IRB scenario.

Figure 2-5: IRB Internet Scenario

One side of the network (WAN in this scenario) is configured to act as a bridge. The Bridge-Group

Virtual Interface (BVI) is configured to act as a routed interface from the WAN bridge-group to the

nonbridged LAN interface. From the LAN, the network appears as a router. From the WAN, the

network appears as a bridge.

The ATM interface uses AAL5SNAP encapsulation, and the number of PVCs is set by default.

NAT (represented as the dashed line at the edge of the 827 routers) signifies two addressing domains

and the inside source address. The source list defines how the packet travels through the network.

The following configuration topics are covered in this section:

l Configuring the Default Gateway

l Configuring the Ethernet Interface and IRB

l Configuring the ATM Interface

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Cisco 827 - 827 Router - EN Manual de usuario Pagina 14