BSCI – Chapter 1

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This lesson starts by introducing the network as the platform for the Information age. p g

Th Ci i i f h f I t lli t I f ti N t k (IIN) dThe Cisco vision of the future Intelligent Information Network (IIN) andthe Service-Oriented Network Architecture (SONA) are thenintroduced, followed by the Cisco Enterprise Architectures and howthey align with the Cisco Enterprise Composite Network Modelthey align with the Cisco Enterprise Composite Network Model(ECNM).

Next, the key characteristics of scalable internetworks, traffic patternsi d t k d h ti t l fit i t th d lin converged networks, and how routing protocols fit into these modelsare discussed.

This module also introduces the topology of the International Travelp gyAgency (ITA), on which the labs exercises are based.

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Technological Revolution CyclesSince the late 1700s, there have been five technology revolutions. Each of thesetechnology revolutions lasted about half a century.

The five technological revolutions are:The five technological revolutions are:

First Industrial Revolution

Second Industrial RevolutionSecond Industrial Revolution

Age of Steel, Electricity, and Heavy Engineering

Age of Oil Automobiles and Mass ProductionAge of Oil, Automobiles, and Mass Production

Age of Information and Telecommunications

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The Intelligent Information Network (IIN)IIN encompasses these features:

•Integration of networked resources and information assetsIntegration of networked resources and information assetsthat have been largely unlinked.

•Intelligence across multiple products and infrastructureIntelligence across multiple products and infrastructurelayers.

•Active participation of the network in the delivery of servicesActive participation of the network in the delivery of servicesand applications.

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The Intelligent Information Network (IIN)

The IIN technology vision offers an evolutionaryapproach that consists of three phases in whichfunctionality can be added to the infrastructure asfunctionality can be added to the infrastructure asrequired:

Phase 1: Integrated systems/transport

Phase 2: Integrated services

Phase 3: Integrated applications (Application-Oriented Networking (AON))

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Oriented Networking (AON))

The SONA FrameworkThe Cisco SONA framework outlines how enterprises can evolve to anIIN. Cisco SONA leverages Cisco and Cisco partner solutions, services,and experience working with enterprises across industries to deliverp g pproven, scalable business solutions to help enterprises achieve theirbusiness goals.

It addresses new IT challenges such as the deployment of serviceIt addresses new IT challenges, such as the deployment of service-oriented architectures (SOA), Web services, and virtualization. The CiscoSONA framework provides the following advantages:

Outlines the path toward the IINIllustrates how to build integrated systems across a fully converged IINImproves flexibility and increases efficiency, which results in optimizedapplications processes and resourcesapplications, processes, and resources

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The SONA Framework

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Cisco Enterprise Architectures

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The Hierarchical Network ModelThe hierarchical network model divides networks or their modular blocks into the access,distribution, and core layers, with these features:

Access layerAccess layer

Distribution layer

Core layer (also referred to as the backbone)y ( )

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The Hierarchical Network Model

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The Enterprise Composite Network ModelSince the Intelligent Network Service, security is critically important to all network planningand implementation. For this reason, Cisco has developed a set of best practices for security.These best practices constitute a blueprint. This blueprint is called Security Architecture forEnterprise (SAFE).

SAFE includes the Enterprise Composite Network Model (ECNM) (also called the EnterpriseComposite Model [ECM]), which network professionals can use to describe and analyze anymodern enterprise network.

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The Enterprise Composite Network ModelVarious modules form an integrated converged network that supports business processes.The campus consists of six modules:

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Routing and Routing ProtocolsThe focus of this course is on selecting planning implementing tuning andThe focus of this course is on selecting, planning, implementing, tuning, andtroubleshooting IP advanced routing protocols. All the models and tools describedpreviously are important in the initial part of this process (selecting and planning).

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The three-layer hierarchical design model

At the same time layered models can be difficult to comprehend becauseAt the same time, layered models can be difficult to comprehend becausethe exact composition of each layer varies from network to network.

Each layer of the three-tiered design model may include the following:

A routerA switchA link

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A linkA combination of these

The three-layer hierarchical design model

The Core Layer Optimized and reliable transport structure by forwarding traffic at very high p p y g y gspeeds. Switches packets as fast as possible.

Devices at the core layer should not be burdened with any processes that stand inDevices at the core layer should not be burdened with any processes that stand in the way of switching packets at top speed.

Core devices:

No Access-list checking

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No Access-list checking

No Data encryption

No Address translation

The three-layer hierarchical design model

The Distribution LayerP id b d d fi iti i li t d th filt t li it h t tProvides boundary definition using access lists and other filters to limit what gets into the core.

Defines policy for the network.

A policy is an approach to handling certain kinds of traffic, including the following:–Routing updates –Route summaries

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–VLAN traffic –Address aggregation

The three-layer hierarchical design model

The Access LayerThe access layer supplies traffic to the network and performs networkThe access layer supplies traffic to the network and performs network entry control. End users access network resources by way of the access layer. Acting as the front door to a network, the access layer employs access lists designed to prevent unauthorized users from gaining entry.

The access layer can also give remote sites access to the network by

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y g yway of a wide-area technology, such as Frame Relay, ISDN, or leased lines.

The three-layer hierarchical design model

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Router function in the hierarchy

Core layer – 12000, 7500, 7200, and 7000 series routers.

Distribution layer – 4500, 4000, and 3600/3800 series routers.

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Access layer – 2600/2800, 2500, 1700/1800, and 1600 series routers.

Core layer example

Core routing is done without access lists, address translation, or other packetmanipulation.

The most powerful Cisco routers serve the core because they have the fastestswitching technologies and the largest capacity for physical interfaces.

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Distribution layer example

Distribution layer routers bring policy to the network by using a combination of the y g p y y gfollowing:

Access lists Route summarizationRoute summarization Distribution lists Route maps

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Other rules to define how a router should deal with traffic and routing updates

Many of these techniques are covered later in the course.

Access layer example

Routers at the access layer permit users to access to the network.Access routers generally offer fewer physical interfaces than distribution and core routers.

Access routers generally connect to access switches for user access to

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Access routers generally connect to access switches for user access to the network.

Five characteristics of a scalable network

•Reliable and available

•Responsive•Responsive

•Efficient

•Adaptable

•Accessible but secure•Accessible but secure

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Making the network reliable and available

A reliable and available network provides users with 24 hour a day, seven day a week access. In a highly reliable and available network fault tolerance and redundancyIn a highly reliable and available network, fault tolerance and redundancymake outages and failures invisible to the end user.These features include the following:

–Support for scalable routing protocols–Alternate paths–Load balancing

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g–Protocol tunnels–Dial backup

Making the network responsive

Networks must be configured to meet the needs of all applications, especially time delay sensitive applications such as voice and video.

The IOS supports four methods of queuing, as described in the following sections: –First-in, first-out (FIFO) queuing–Priority queuing–Custom queuing –Weighted fair queuing (WFQ)

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Note: All the queuing methods will also be discussed in Note: All the queuing methods will also be discussed in BCMSN and ONT.BCMSN and ONT.

Making the network efficient

An efficient network should not waste bandwidth, especially over costly WANlinks. Optimize a WAN connection:

Access listsSnapshot routing - Snapshot routing allows routers using distance vectorprotocols to exchange their complete tables during an initial connection and thenwaits until the next active period on the line before again exchanging routinginformation

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information.

Compression over WANs

Making the network efficient

Bandwidth optimization features:

Dial-on-demand routing (DDR)

Route summarization

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Incremental updates

Making the network adaptable

An adaptable network will handle the addition and coexistence of multiple routedand routing protocols.and routing protocols.EIGRP is an exceptionally adaptable protocol because it supports routinginformation for many routed protocols:

–IP–IPX–AppleTalk–The IOS also supports route redistribution

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Making the network accessible but secure

Accessible networks let users connect easily over a variety oftechnologiestechnologies.

These services include all of the following:–Dialup or circuit-switched networks–Dedicated or leased lines–Packet-switched networks

Ci it it h d t k di l hil l d li th t

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Circuit-switched networks are dialup while leased lines that arededicated.

Security PAP, CHAP, VPNs, AAA, etc.

Fast Switching and Process SwitchingLoad sharing or Load balancing allo s ro ters to takeLoad sharing or Load balancing allows routers to takeadvantage of multiple paths to the same destination.

Equal-cost load balancing:Equal cost load balancing:–Distributes packets equally among multiple paths with equal metrics–RIP, IGRP, EIGRP, OSPF, IS-IS and BGP

Unequal-cost load balancing:–Distributes packets among multiple paths with different metrics,inversely proportional to the cost of the routes.inversely proportional to the cost of the routes.

–EIGRP

Load sharing can be either:–Per Destination (Fast Switching)–Per Packet (Process Switching)

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Fast Switching – Per Destination Load BalancingRouter(config if)# ip route cache

ping 10.0.0.1ping 10.0.0.2

Router(config-if)# ip route-cache

The default for most interfaces is Fast Switching.

L d b l i i di t ib t d di t th d ti ti IP ddLoad balancing is distributed according to the destination IP address.Given two paths to the same network, all packets for one destination IP address willtravel over the first path, all packets for a second destination will travel over thesecond path all packets for the third destination will again travel over the first pathsecond path, all packets for the third destination will again travel over the first path,and so on.

To enable fast switching:Router(config-if)# ip route-cache

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Router(config if)# ip route cache

To enable distributed or process switching:Router(config-if)# no ip route-cache

Process Switching – Per Packet Load BalancingRouter(config-if)#no ip route-cache

ping 10.0.0.1ping 10.0.0.2

( g )# p

Process SwitchingGi l t th k t l d h i th t k t tGiven equal cost paths, per packet load sharing means that one packet to adestination is sent over one link, the next packet to the same destination is sentover the next link, and so on.

If the paths are unequal cost the load balancing may be one packet over theIf the paths are unequal cost, the load balancing may be one packet over thehigher-cost link for every three packets over the lower-cost link, or similar ratio.

With process switching, for every packet, the router performs a route tablelookup and selects an interface, and looks up the data-link information.

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To enable distributed or process switching:Router(config-if)# no ip route-cache

Which one?

ping 10 0 0 1i 10 0 0 2ping 10 0 0 1

Fast Switching Process Switching

ping 10.0.0.1ping 10.0.0.2ping 10.0.0.1ping 10.0.0.2

Router(config-if)#no ip route-cacheRouter(config-if)# ip route-cache

Fast Switching or Process Switching

Process switching (per packet load balancing) has a price, load balancing may be distributed more evenly but the lower switching

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balancing may be distributed more evenly but the lower switching time and processor utilization of fast switching are lost.

Using debug ip packet withFast Switching and Process SwitchingFast Switching and Process Switching Router# debug ip packetIP: s=192.168.3.2 (FastEthernet0), d=10.0.0.1 (Serial0/0),

g=192.168.1.2, forward IP: s=192 168 3 2 (FastEthernet0) d=10 0 0 1 (Serial0/1)IP: s=192.168.3.2 (FastEthernet0), d=10.0.0.1 (Serial0/1),

g=192.168.2.2, forward IP: s=192.168.3.2 (FastEthernet0), d=10.0.0.1 (Serial0/0),

g=192.168.1.2, forward IP: s=192 168 3 2 (FastEthernet0) d=10 0 0 1 (Serial0/1)IP: s=192.168.3.2 (FastEthernet0), d=10.0.0.1 (Serial0/1),

g=192.168.2.2, forward

debug ip packet can be used to observe packets sent and received and the interfaces that are involved.

IMPORTANT: The debug ip packet command allows only process switched packets to be observed. Fast switch packets are not displayed (except for the first

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p p y ( ppacket in the flow).

Standard IP Switching OverviewStandard IP Switching Overview

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Ci IOS Pl tf S it hi M h iCisco IOS Platform Switching MechanismsProcess switching, or routing table-driven switching:

Full lookup is performed at every packet

Fast switching, or cache-driven switching:M t t d ti ti t d i th hMost recent destinations are entered in the cacheFirst packet is always process-switched

Topology driven switching:Topology-driven switching:CEF (prebuilt FIB table) CEFCEF

CEFCEF

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Cisco Express Forwarding

CEF Switching OverviewCEF Switching Overview

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The International Travel Agency

The labs in this course reference the fictitious International Travel Agency(ITA) hich maintains a global data net ork(ITA), which maintains a global data network.

The ITA business scenario provides a tangible, real-world application of theconcepts introduced in the labs.

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Use the diagram of the ITA WAN topology to become familiar with thecompany and its network.

Summary

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© 2006 Cisco Systems, Inc. All rights reserved.