BSCI Chapter 1
This lesson starts by introducing the network as the platform for the Information age. The Cisco vision i of the future Intelligent t Information Network (IIN) and the Service-Oriented Network Architecture (SONA) are then introduced, followed by the Cisco Enterprise Architectures and how they align with the Cisco Enterprise Composite Network Model (ECNM). Next, the key characteristics of scalable internetworks, traffic patterns in converged networks, and how routing protocols fit into these models are discussed. This module also introduces the topology of the International Travel Agency (ITA), on which the labs exercises are based.
Technological Revolution Cycles Since the late 1700s, there have been five technology revolutions. Each of these technology revolutions lasted about half a century. The five technological revolutions are: First Industrial Revolution Second Industrial Revolution Age of Steel, Electricity, and Heavy Engineering Age of Oil, Automobiles, and Mass Production Age of Information and Telecommunications
The Intelligent Information Network (IIN) IIN encompasses these features: Integration of networked resources and information assets that have been largely unlinked. Intelligence across multiple products and infrastructure layers. Active participation of the network in the delivery of services and applications.
The Intelligent Information Network (IIN) The IIN technology vision offers an evolutionary approach that consists of three phases in which functionality can be added to the infrastructure as required: Phase 1: Integrated systems/transport Phase 2: Integrated services Phase 3: Integrated applications (Application- Oriented Networking (AON))
The SONA Framework The Cisco SONA framework outlines how enterprises can evolve to an IIN. Cisco SONA leverages Cisco and Cisco partner solutions, services, and experience working with enterprises across industries to deliver proven, scalable business solutions to help enterprises achieve their business goals. It addresses new IT challenges, such as the deployment of serviceoriented architectures (SOA), Web services, and virtualization. The Cisco SONA framework provides the following advantages: Outlines the path toward the IIN Illustrates how to build integrated systems across a fully converged IIN Improves flexibility and increases efficiency, which results in optimized applications, processes, and resources
The SONA Framework
Cisco Enterprise Architectures
The Hierarchical Network Model The hierarchical network model divides networks or their modular blocks into the access, distribution, and core layers, with these features: Access layer Distribution layer Core layer (also referred to as the backbone)
The Hierarchical Network Model
The Enterprise Composite Network Model Since the Intelligent Network Service, security is critically important to all network planning and 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 for Enterprise (SAFE). SAFE includes the Enterprise Composite Network Model (ECNM) (also called the Enterprise Composite Model [ECM]), which network professionals can use to describe and analyze any modern enterprise network.
The Enterprise Composite Network Model Various modules form an integrated converged network that supports business processes. The campus consists of six modules:
Routing and Routing Protocols The focus of this course is on selecting, planning, implementing, tuning, and troubleshooting IP advanced routing protocols. All the models and tools described previously are important in the initial part of this process (selecting and planning).
The three-layer hierarchical design model At the same time, layered models can be difficult to comprehend because the exact composition of each layer varies from network to network. Each layer of the three-tiered design model may include the following: A router Aswitch A link A combination of these
The three-layer hierarchical design model The Core Layer Optimized and reliable transport structure by forwarding traffic at very high speeds. Switches packets as fast as possible. Devices 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 No Data encryption No Address translation
The three-layer hierarchical design model The Distribution Layer Provides boundary definition iti using access lists and other filters to limit it 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 VLAN traffic Address aggregation
The three-layer hierarchical design model The Access Layer The 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 way of a wide-area technology, such as Frame Relay, ISDN, or leased lines.
The three-layer hierarchical design model
Router function in the hierarchy Core layer 12000, 7500, 7200, and 7000 series routers. Distribution layer 4500, 4000, and 3600/3800 series routers. 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 packet manipulation. The most powerful Cisco routers serve the core because they have the fastest switching technologies and the largest capacity for physical interfaces.
Distribution layer example Distribution layer routers bring policy to the network by using a combination of the following: Access lists Route summarization Distribution lists Route maps 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 the network.
Five characteristics of a scalable network Reliable and available Responsive Efficient Adaptable Accessible but secure
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 redundancy make outages and failures invisible to the end user. These features include the following: Support for scalable routing protocols Alternate paths Load balancing 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) Note: All the queuing methods will also be discussed in BCMSN and ONT.
Making the network efficient An efficient network should not waste bandwidth, especially over costly WAN links. Optimize a WAN connection: Access lists Snapshot routing - Snapshot routing allows routers using distance vector protocols to exchange their complete tables during an initial connection and then waits until the next active period on the line before again exchanging routing information. Compression over WANs
Making the network efficient Bandwidth optimization features: Dial-on-demand routing (DDR) Route summarization Incremental updates
Making the network adaptable An adaptable network will handle the addition and coexistence of multiple routed and routing protocols. EIGRP is an exceptionally adaptable information for many routed protocols: protocol because it supports routing IP IPX AppleTalk The IOS also supports route redistribution
Making the network accessible but secure Accessible networks let users connect easily over a variety of technologies. These services include all of the following: Dialup or circuit-switched networks Dedicated or leased lines Packet-switched networks Circuit-switchedit it networks are dialup while leased lines thatt are dedicated. Security PAP, CHAP, VPNs, AAA, etc.
Fast Switching and Process Switching Load sharing or Load balancing allows routers to take advantage of multiple paths to the same destination. 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. EIGRP Load sharing can be either: Per Destination (Fast Switching) Per Packet (Process Switching)
Fast Switching Per Destination Load Balancing Router(config-if)# if)# ip route-cache ping 10.0.0.2 ping 10.0.0.1 The default for most interfaces is Fast Switching. Load balancing is distributed ib t d according to the destination IP address. Given two paths to the same network, all packets for one destination IP address will travel over the first path, all packets for a second destination will travel over the second path, all packets for the third destination will again travel over the first path, and so on. To enable fast switching: Router(config-if)# if)# ip route-cache To enable distributed or process switching: Router(config-if)# no ip route-cache
Process Switching Per Packet Load Balancing Router(config-if)#no ip route-cache ping 10.0.0.2 ping 10.0.0.1 Process Switching Given equal cost paths, per packet load sharing means thatt one packet to a destination is sent over one link, the next packet to the same destination is sent over the next link, and so on. If the paths are unequal cost, the load balancing may be one packet over the higher-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 table lookup and selects an interface, and looks up the data-link information. To enable distributed or process switching: Router(config-if)# no ip route-cache
Which one? Fast Switching Process Switching ping 10.0.0.2 ping 10.0.0.10 0 1 ping 10.0.0.20 0 ping 10.0.0.10 0 1 Router(config-if)# ip route-cache Router(config-if)#no 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 time and processor utilization of fast switching are lost.
Using debug ip packet with Fast Switching and Process Switching Router# debug ip packet IP: s=192.168.3.2 (FastEthernet0), d=10.0.0.1 (Serial0/0), g=192.168.1.2, forward IP: s=192.168.3.2 168 2 (FastEthernet0), d=10.0.0.1 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=192.168.3.2 168 2 (FastEthernet0), d=10.0.0.1 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 p for the first packet in the flow).
Standard IP Switching Overview...
Cisco IOS Platform Switching Mechanisms Process switching, or routing table-driven switching: Full lookup is performed at every packet Fast switching, or cache-driven switching: Most recent destinations are entered in the cache First packet is always process-switched Topology-driven switching: CEF (prebuilt FIB table) CEF CEF CEF CEF Cisco Express Forwarding
CEF Switching Overview...
The International Travel Agency The labs in this course reference the fictitious International Travel Agency (ITA), which maintains a global data network. The ITA business scenario provides a tangible, real-world application of the concepts introduced in the labs. Use the diagram of the ITA WAN topology to become familiar with the company and its network.
Summary