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CCNP Practical Studies: Using DSL to Access a Central Site

Chapter Description

This sample chapter focuses on Digital Subscriber Line (DSL) technology, one of the most popular broadband access methods and a new topic on the CCNP exam.

Cisco 6400 UAC Overview

This section provides an overview of 6400 Universal Access Concentrator (UAC) hardware components (see Figure 8-3). Functional descriptions are provided for each component. How all the components work together within the system is also described.

Figure 3Figure 8-3 Cisco 6400 UAC Hardware Component

The 6400 is a broadband concentrator that supports Cisco's ATM services, PPP termination, and tunneling. The Cisco 6400 combines ATM switching and routing in a modular and scalable platform.

The 6400 UAC comprises three major functional components:

  • Node Line Card (NLC)—A half-height line card. It features two OC-3 ATM interfaces and supports SONET APS 1+1 redundancy.

  • Node Switch Processor (NSP)—The centerpiece of the 6400 system. It performs ATM switching and per-flow queuing for the ATM virtual circuits.

  • Node Route Processor (NRP)—Based on the Cisco 7200 series router. It supports a variety of configurations, including PPP over ATM and RFC 1483 bridging. It is a full-height line card.

Figure 8-4 illustrates how these components work together.

Figure 4Figure 8-4 Typical Traffic Flow for the Cisco 6400 UAC

The NLC receives traffic from the DSLAM or other ATM network. The NLC sends this traffic to the NSP. The NSP acts as an ATM switch. The ATM cells must be sent from the NSP to the NRP. The NRP handles routing functions for the 6400. The NRP reassembles the ATM cells into data packets and determines where the data needs to be sent. Direct data connections can be made via a Fast Ethernet port on the NRP. Other data packets are sent back through the NSP to the NLC, where these packets may be routed through the ATM network.

Understanding interface numbering is also important before you configure the 6400. The interface slot/subslot/port convention is used for both NLC and NRP. For NLC, the valid subslot and port number are 0 and 1. Because NRP is a full-height card, the subslot and port are always 0. In Example 8-6, NRP is installed in slot 1 and NLC is installed in slot 8, subslot 1.

Example 8-6 Cisco 6400 UAC Interface Numbering

interface atm 1/0/0  NRP in slot 1
interface atm 8/1/0  NLC in slot 8, sub-slot 1, port 0

All line cards are connected to the ATM backplane to the NSP. This interface is known as interface ATM0/0/0 and can be thought of as the interface to the NSP from an NLC or NRP card's perspective. Example 8-7 shows information about the NSP's ATM backplane.

Example 8-7 Internal Connection to the CPU Card

lab-6400NSP#show interface atm 0/0/0
ATM0/0/0 is up, line protocol is up
 Hardware is CPU card
 MTU 4470 bytes, sub MTU 4470, BW 155520 Kbit, DLY 0 usec,
   reliability 255/255, txload 1/255, rxload 1/255
 Encapsulation ATM, loopback not set
 Keepalive not supported
 4096 maximum active VCs, 0 current VCCs
 VC idle disconnect time: 300 seconds
 Signalling vc = 35, vpi = 0, vci = 16
 UNI Version = 3.0, Link Side = user

To create an ATM PVC on the Cisco 6400, you can use the following command syntax:

interface atm slot/subslot/port
atm pvc vpi vci interface atm slot/subslot/port vpi vci

Example 8-8 shows you how to create an ATM PVC. From the NSP, to create PVC 1/100 coming from NLC 8/0/0 to NRP 1/0/0, the 6400 commands are as shown.

Example 8-8 Creating an ATM PVC from the NLC to the NRP

interface atm 8/0/0
atm pvc 1 100 atm1/0/0 1 100
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