A

ABRs (area border routers), 362 access control, 446 access layer of hierarchical LAN architecture, 39-40 best practices, 86-87 access point modes (LWAPP), 122-123 access VPNs, 188 ACD, 511 global unicast addresses, 267 IPv4-compatible addresses, 267 link-local addresses, 267 loopback addresses, 266 multicast addresses, 268-269 site-local addresses, 268 unspecified addresses, 266 reserving subnets for VoIP devices, 239 address assignment methods for IPv6, 273 address classes (IPv4), 228-229...

Administrative Distance

On Cisco routers running more than one routing protocol, it is possible for two different routing protocols to have a route to the same destination. Cisco routers assign each routing protocol an administrative distance. When multiple routes exist for a destination, the router selects the longest match. For example, if to reach a destination of 170.20.10.1 OSPF has a route prefix of 170.20.10.0 24 and EIGRP has a route prefix of 170.20.0.0 16, the OSPF route is preferred because the 24 prefix is...

B

On VoIP networks, 527-528 WAN technology considerations, 169 BDRs (backup designated routers), 362-363 Beauty Things scenario, 577-579 Bellman-Ford algorithm, 295 best path selection BGP, 401 metrics, 300-301 bandwidth, 301 cost, 302-303 delay, 303 hop count, 301 load, 303 MTU, 304 reliability, 304 BGP (Border Gateway Protocol), 390 administrative distance, 396 attributes, 396 atomic aggregate, 399-400 community, 399 local preference, 397 MED, 398-399 next-hop, 397 origin, 398 weight, 400 best...

Best Practices for Hierarchical Layers

Each layer of the hierarchical architecture contains special considerations. The following sections describe best practices for each of the three layers of the hierarchical architecture access, distribution, and core. When designing the building access layer, you must take into consideration the number of users or ports required to size up the LAN switch. Connectivity speed for each host should be considered. Hosts might be connected using various technologies such as Fast Ethernet, Gigabit...

Binary Numbers

The binary number system uses two digits 1 and 0. Computer systems use binary numbers. IP addresses and MAC addresses are represented by binary numbers. The number of binary 1s or 0s is the number of bits, short for binary digits. For example, 01101010 is a binary number with 8 bits. An IP address has 32 bits, and a MAC address has 48 bits. As shown in Table B-2, IPv4 addresses are usually represented in dotted-decimal format therefore, it is helpful to know how to convert between binary and...

Campus Design Considerations

When designing for the Cisco Unified Wireless Network, you need to be able to determine how many LWAPs to place and how they will be managed with the WLCs. Table 4-4 summarizes campus design considerations. Table 4-4 WLAN Design Considerations Table 4-4 WLAN Design Considerations The design should have enough APs to provide full RF coverage for wireless clients for all the expected locations in the enterprise. Cisco recommends 20 data devices per AP and 7 g.711 concurrent or 8 g.729 concurrent...

Campus LAN Quality of Service Considerations

For the access layer of the campus LAN, you can classify and mark frames or packets to apply quality of service (QoS) policies in the distribution or at the Enterprise Edge. Classification is a fundamental building block of QoS and involves recognizing and distinguishing between different traffic streams. For example, you distinguish between HTTP HTTPS, FTP, and VoIP traffic. Without classification, all traffic would be treated the same. Marking sets certain bits in a packet or frame that has...

CCDA Official Exam Certification Guide Third Edition

Anthony Bruno, CCIE No. 2738 Steve Jordan, CCIE No. 11293 Copyright 2007 Cisco Systems, Inc. Published by Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclusion of brief quotations in a review. Printed in...

RIP and Eigrp Characteristics and Design 317

Do I Know This Already Quiz 317 Foundation Topics 320 RIPvl 320 RIPvl Forwarding Information Base 321 RIPvl Message Format 321 RIPvl Timers 322 Update Timer 322 Invalid Timer 323 Flush Timer 323 Holddown Timer 323 RIPvl Design 323 RIPvl Summary 324 RIPv2 324 MD5 Authentication 325 RIPv2 Forwarding Information Base 325 RIPv2 Message Format 326 RIPv2 Timers 327 RIPv2 Design 327 RIPv2 Summary 327 RIPng 328 RIPng Timers 328 Authentication 328 RIPng Message Format 329 RIPng Design 330 RIPng Summary...

Network Structure Models

Do I Know This Already Quiz 33 Foundation Topics 36 Hierarchical Network Models 36 Benefits of the Hierarchical Model 36 Hierarchical Network Design 37 Core Layer 38 Distribution Layer 38 Access Layer 39 Hierarchical Model Examples 40 Cisco Enterprise Architecture Model 42 Enterprise Campus Module 43 Enterprise Edge Module 45 E-Commerce 45 Internet Edge 46 VPN Remote Access 47 Enterprise WAN 48 Service Provider (SP) Edge Module 49 Remote Modules 50 Enterprise Branch Module 50 Enterprise Data...

WAN Technologies 151

Do I Know This Already Quiz 151 WAN Defined 154 WAN Connection Modules 155 WAN Comparison 156 Dialup 157 ISDN 157 Frame Relay 159 Time-Division Multiplexing 160 SONET SDH 160 Multiprotocol Label Switching 161 Other WAN Technologies 162 Digital Subscriber Line 162 Cable 163 Wireless 164 Dark Fiber 166 Dense Wave Division Multiplexing 166 Ordering WAN Technology and Contracts 166 WAN Design Methodology 167 Response Time 168 Throughput 168 Reliability 168 Bandwidth Considerations 169 Window Size...

Internet Protocol Version 6 257

Do I Know This Already Quiz 257 IPv4-Compatible IPv6 Addresses 263 IPv6 Prefix Representation 264 IPv6 Address Types and Address Allocations 264 IPv6 Unicast Address 265 IPv6 Anycast Address 265 IPv6 Multicast Address 265 IPv6 Address Allocations 265 Unspecified Address 266 Loopback Address 266 IPv4-Compatible IPv6 Address 267 Global Unicast Addresses 267 Link-Local Addresses 267 Site-Local Addresses 268 Multicast Addresses 268 IPv6 Mechanisms 270 ICMPv6 270 IPv6 Network Discovery (ND) Protocol...

Routing Protocol Selection Criteria 289

Do I Know This Already Quiz 289 Routing Protocol Characteristics 292 Static Versus Dynamic Route Assignment 292 Interior Versus Exterior Routing Protocols 294 Distance-Vector Routing Protocols 295 EIGRP 296 Link-State Routing Protocols 296 Distance-Vector Routing Protocols Versus Link-State Protocols 297 Hierarchical Versus Flat Routing Protocols 297 Classless Versus Classful Routing Protocols 298 IPv4 Versus IPv6 Routing Protocols 299 Administrative Distance 299 Routing Protocol Metrics and...

Characteristics and Design

This chapter reviews distance-vector routing protocols. It covers both versions of the Routing Information Protocol (RIP). Although RIPvl is no longer a test subject, it is included for reference and because it is still seen on some enterprise networks. This chapter also covers Cisco's Enhanced Interior Gateway Routing Protocol (EIGRP). Cisco's IGRP is also included although it is no longer a test subject. This chapter also covers the routing protocols for IPv6 RIPng and EIGRP for IPv6. The...

Cisco Enterprise Architecture Model

The Cisco Enterprise Architecture model facilitates the design of larger, more scalable networks. It represents the focused views of the Cisco Service-Oriented Network Architecture (SONA), which concentrates on each area of the network. SONA is covered in Chapter 1, Network Design Methodology. As networks become more sophisticated, it is necessary to use a more modular approach to design than just WAN and LAN core, distribution, and access layers. The architecture divides the network into...

Cisco IOS Packaging

Cisco IOS packaging involves consolidating and organizing the IOS software using consistent and standardized naming across all router platforms. The four base service categories are as follows IP Base Entry-level IOS supporting IP data IP Voice Supports converged voice and data Advanced Security Security features and VPN Enterprise Base Enterprise Layer 3 protocols and IBM support In addition, three additional premium packages offer new IOS software features that focus on more complex...

Comparing Hardware and Software

Table 6-4 compares the Cisco router and switch hardware platforms and their associated software families, releases, and functional descriptions. Table 6-4 Cisco Router Switch Platform and Software Comparison Table 6-4 Cisco Router Switch Platform and Software Comparison Cisco IOS T Releases 12.3, 12.4, 12.3T, and 12.4T Access routing platforms supporting fast and scalable delivery of data for enterprise applications. Delivers midrange routing services for the Enterprise and SP edge networks....

Converting Binary to Decimal

To convert a binary number to decimal, multiply each instance of 0 or 1 by the power of 2 associated with the position of the bit in the binary number. The first bit, starting from the right, is associated with 20 1. The value of the exponent increases by 1 as each bit is processed, working leftward. As shown in Table B-4, each bit in the binary number 10101010 has a decimal equivalent from 0 to 128 based on the value of the bit multiplied by a power of 2 associated with the bit position. This...

Converting Decimal to Hexadecimal

First things first memorize Table B-1. There are two ways to convert larger numbers. The first method is to convert decimal to binary and then convert binary to hex. The second method is to divide the decimal number by 16 the residual is the rightmost hexadecimal digit and then keep dividing until the number is not divisible anymore. For the first method, use the schemes described in later sections. For the second method, follow the examples described here. First, divide the decimal number by...

Dense Wave Division Multiplexing

Dense Wave Division Multiplexing (DWDM) increases fiber optic's bandwidth capabilities by using different wavelengths of light called channels over the same fiber strand. It maximizes the use of the installed base of fiber used by service providers and is a critical component of optical networks. DWDM allows for service providers to increase the services offered to customers by adding new bandwidth to existing channels on the same fiber. DWDM lets a variety of devices access the network,...

Determining the Network Portion of an IP Address

Given an address and mask, you can determine the classful network, the subnetwork, and the subnetwork's broadcast number. You do so with a logical AND operation between the IP address and subnet mask. You obtain the broadcast address by taking the subnet number and making the host portion all ls. Table 7-l4 shows the logical AND operation. Notice that the AND operation is similar to multiplying bit l and bit 2 if any 0 is present, the result is 0. Table 7-14 The AND Logical Operation Table 7-14...

Digital Subscriber Line

Digital Subscriber Line (DSL) is a technology that provides high-speed Internet data services over ordinary copper telephone lines. It achieves this by using frequencies that are not used in normal voice telephone calls. The term xDSL describes the various competing forms of DSL available today. Some of the DSL technologies available include asymmetric (ADSL), symmetric (SDSL), high bit rate (HDSL), very high bit rate (VDSL), rate-adaptive (RADSL) and IDSL (based on ISDN). Table 5-3 summarizes...

Distance Vector Routing Protocols

The first IGP routing protocols introduced were distance-vector routing protocols. They used the Bellman-Ford algorithm to build the routing tables. With distance-vector routing protocols, routes are advertised as vectors of distance and direction. The distance metric is usually router hop count. The direction is the next-hop router (IP address) toward which to forward the packet. For RIP, the maximum number of hops is 15, which can be a serious limitation, especially in large nonhierarchical...

Distance Vector Routing Protocols Versus Link State Protocols

When choosing a routing protocol, consider that distance-vector routing protocols use more network bandwidth than link-state protocols. Distance-vector protocols generate more bandwidth overhead because of the large periodic routing updates. Link-state routing protocols do not generate significant routing update overhead but do use more router CPU and memory resources than distance-vector protocols. Generally, WAN bandwidth is a more expensive resource than router CPU and memory in modern...

Do I Know This Already

The core layer of the hierarchical model is responsible for fast transport. 2. C. The Enterprise Edge consists of e-commerce, Internet connectivity, VPN remote access, and WAN modules. The Enterprise Edge modules connect to SPs. C. The distribution layer of the hierarchical model is responsible for security filtering, address and area aggregation, and media translation. D. HSRP provides default gateway redundancy. Hosts participating in RIP can find alternative gateways. F. The...

Do I Know This Already Quiz

The purpose of the Do I Know This Already quiz is to help you decide whether you need to read the entire chapter. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now. The eight-question quiz, derived from the major sections in the Foundation Topics portion of the chapter, helps you determine how to spend your limited study time. Table 2-1 outlines the major topics discussed in this chapter and the Do I Know This Already quiz questions that...

Dual Stack Backbones

In this model, all routers in the backbone are dual-stack, capable of routing both IPv4 and IPv6 packets. The IPv4 protocol stack is used between IPv4 hosts, and the IPv6 protocol stack is used between IPv6 hosts. This deployment model works for organizations with a mixture of IPv4 and IPv6 applications. Figure 8-8 shows a network with a dual-stack backbone. All the WAN routers run both IPv4 and IPv6 routing protocols. The disadvantages are that the WAN routers require dual addressing, run two...

E

E& M (Ear and Mouth) signaling, 503, 505 E.164 standard, 508 eBGP, 391 E-Commerce submodule (Enterprise Edge Module), 45 edge distribution module for campus LANs, 91 EGPs (exterior gateways protocols), 294 BGP. See BGP EIGRP (Enhanced IGRP), 296, 334 neighbor discovery and recovery, 335-336 network design, 340 packets, 339 protocol-dependent modules, 335 RTP, 336 timers, 337 encryption, 447 encryption keys, 447 enhanced features of IPv6, 260-261 Enterprise Branch architecture, 200 SONA...

EIGRP Components

EIGRP has four components that characterize it Neighbor discovery and recovery Reliable Transport Protocol (RTP) You should know the role of the EIGRP components, which are described in the following sections. EIGRP uses different modules that independently support IP, Internetwork Packet Exchange (IPX), and AppleTalk routed protocols. These modules are the logical interface between DUAL and routing protocols such as IPX RIP, AppleTalk Routing Table Maintenance Protocol (RTMP), and IGRP. The...

EIGRP for IPv4 Networks

Cisco Systems released EIGRP in the early 1990s as an evolution of IGRP toward a more scalable routing protocol for large internetworks. EIGRP is a classless protocol that permits the use of VLSMs and that supports CIDR for the scalable allocation of IP addresses. EIGRP does not send routing updates periodically, as does IGRP. EIGRP allows for authentication with MD5. EIGRP autosummarizes networks at network borders and can load-balance over unequal-cost paths. Packets using EIGRP use IP 88....

EIGRP for IPv4 Summary

The characteristics of EIGRP follow Hybrid routing protocol (a distance-vector protocol that has link-state protocol characteristics). Uses IP protocol number 88. Classless protocol (supports VLSMs). Default composite metric of bandwidth and delay. You can factor load and reliability into the metric. Sends route updates to multicast address 224.0.0.10. Sends partial route updates only when there are changes. Support for MD5 authentication and fast convergence. Uses DUAL for fast convergence and...

EIGRP Timers

EIGRP sets updates only when necessary and sends them only to neighboring routers. There is no periodic update timer. EIGRP uses hello packets to learn of neighboring routers. On high-speed networks, the default hello packet interval is 5 seconds. On multipoint networks with link speeds of T1 and slower, hello packets are unicast every 60 seconds. The holdtime to maintain a neighbor adjacency is 3 times the hello time 15 seconds. If a router does not receive a hello within the holdtime, it...

Enterprise Campus Module

The Enterprise Campus consists of the following submodules Figure 2-5 shows the Enterprise Campus model. The campus infrastructure consists of the campus core, building-distribution, and building-access layers. The campus core provides a high-speed switched backbone between buildings, to the server farm and to the enterprise distribution. This segment consists of redundant and fast convergence connectivity. The building-distribution layer aggregates all the closet access switches and performs...

Enterprise Data Center Infrastructure

Data centers (DC) contain different types of server technologies, including standalone servers, blade servers, mainframes, clustered servers, and virtual servers. Figure 3-14 shows the Enterprise DC. The DC access layer must provide the port density to support the servers, provide high-performance low-latency Layer 2 switching, and support dual and single connected servers. The preferred design is to contain Layer 2 to the access layer and Layer 3 on the distribution. Some solutions push Layer...

Enterprise Edge Module

As shown in Figure 2-6, the Enterprise Edge consists of the following submodules E-commerce networks and servers Internet connectivity and DMZ Figure 2-6 Enterprise Edge Module The e-commerce submodule provides highly available networks for business services. It uses the high-availability designs of the server farm module with the Internet connectivity of the Internet module. Design techniques are the same as those described for these modules. Devices located in the e-commerce submodule include...

Enterprise Teleworker Branch of One Design

At the remote edges of the network is another branch office called the Branch of One, also known as Enterprise Teleworkers. Organizations are continually trying to reduce costs and improve their employees' productivity. By working from home, employees can manage their work schedules more effectively and increase their productivity. This also results in greater job satisfaction and flexibility in the employees' work schedule. The work-from-home teleworker is an extension of the enterprise and...

Example of Layered Communication

Suppose that you use a Telnet application. Telnet maps to the top three layers of the OSI model. In Figure B-4, a user on Host 1 enables the Telnet application to access a remote host (Host 2). The Telnet application provides a user interface (application layer) to network services. As defined in RFC 854, ASCII is the default code format. No session layer is defined for Telnet (not an OSI protocol). Per the RFC, Telnet uses TCP for connectivity (transport layer). The TCP segment is placed in an...

F

Falcon Communications scenario, 579, 581 Fast EtherChannel, network design guidelines, 79 Fast Ethernet, network design rules, 74 100BASE-FX, 75 100BASE-T, 75 100BASE-T4, 75 100BASE-TX, 75 FHSS (frequency-hopping spread spectrum), 114 fields of IPv6 header, 261-262 firewalls as Cisco Self-Defending Network technology, 470 flat routing protocols, 297 floating static routes, 58 flooding, 82 flow control, 622 flush timer (RIP), 323 forwarding information base (RIPvl), 321 forwarding information...

Features of This Book

Do I Know This Already Quizzes Each chapter begins with a quiz that helps you determine how much time you need to spend studying that chapter. If you follow the directions at the beginning of the chapter, the Do I Know This Already quiz directs you to study all or particular parts of the chapter. Foundation Topics These are the core sections of each chapter. They explain the protocols, concepts, and configuration of the topics in that chapter. If you need to learn about the topics in a...

Foundation Summary

The Foundation Summary section of each chapter lists the most important facts from the chapter. Although this section does not list every fact from the chapter that will be on the CCDA exam, a well-prepared CCDA candidate should at a minimum know all the details in each Foundation Summary before taking the exam. This chapter covered the following topics that you will need to master for the CCDA exam IPv4 header Know each field of the IPv4 header. IPv4 addressing Know IPv4 address classes,...

Ground Start Signaling

Ground-start signaling is an analog signaling technique used to indicate on-hook and off-hook conditions. Ground-start is commonly used in switch-to-switch connections. The difference between ground-start and loop-start is that ground-start requires the closing of the loop at both locations. Ground-start is commonly used by PBXs. The standard way to transport voice between two telephone sets is to use tip and ring lines. Tip and ring lines are the twisted pair of wires that connect to your...

Hierarchical Model Examples

You can implement the hierarchical model by using either routers or switches. Figure 2-2 is an example of a switched hierarchical design in the enterprise campus. In this design, the core provides high-speed transport between the distribution layers. The building-distribution layer provides redundancy and allows policies to be applied to the building-access layer. Layer 3 links between the core and distribution switches are recommended to allow the routing protocol to take care of load...

Hierarchical Network Design

As shown in Figure 2-1, a traditional hierarchical LAN design has three layers The core layer provides fast transport between distribution switches within the enterprise campus. The distribution layer provides policy-based connectivity. The access layer provides workgroup and user access to the network. Figure 2-1 Hierarchical Network Design Has Three Layers Core, Distribution, and Access Each layer provides necessary functionality to the enterprise campus network. You do not need to implement...

Hierarchical Network Models

Hierarchical models enable you to design internetworks that use specialization of function combined with a hierarchical organization. Such a design simplifies the tasks required to build a network that meets current requirements and can grow to meet future requirements. Hierarchical models use layers to simplify the tasks for internetworking. Each layer can focus on specific functions, allowing you to choose the right systems and features for each layer. Hierarchical models apply to both LAN...

Hierarchical Versus Flat Routing Protocols

Some routing protocols require a network topology that must have a backbone network defined. This network contains some, or all, of the routers in the internetwork. When the internetwork is defined hierarchically, the backbone consists of only some devices. Backbone routers service and coordinate the routes and traffic to or from routers not in the local internetwork. The supported hierarchy is relatively shallow. Two levels of hierarchy are generally sufficient to provide scalability. Selected...

How This Book Is Organized

This book is divided into the following parts Part I General Network Design (Chapters 1 and 2) Part II LAN and WAN Design (Chapters 3 through 6) Part III The Internet Protocol and Routing Protocols (Chapters 7 through 12) Part IV Security, Convergence, and Network Management (Chapters 13 through 16) Part V Comprehensive Scenarios (Chapter 17) Part VI Appendixes (Appendixes A and B) The CCDA Exam Topics section describes the design topics that are covered on the CCDA exam. Before you begin...

Identifying Customer Requirements

To obtain customer requirements, you need to not only talk to network engineers, but also talk to business unit personnel and company managers. Networks are designed to support applications you want to determine the network services that you need to support. The steps to identify customer requirements are as follows Step 1 Identify network applications and services. Step 2 Define the organizational goals. Step 3 Define the possible organizational constraints. Step 4 Define the technical goals....

Intelligent Information Network and Service Oriented Network Architecture

Cisco has developed a strategy to address the increasing demands placed on today's networks. Beyond just basic connectivity, the network plays a crucial role because it touches many components of the infrastructure end users, servers, middleware, and applications. As demands for networks grow, the network can become complex and difficult to scale and manage. Many applications are not visible to network managers on a limited scale, hampering capacity planning and service performance....

IP Multicast

Table 12-4 summarizes IP multicast protocols. Internet Group Management Protocol. Used by IP hosts to report their multicast group memberships to routers. Cisco Group Management Protocol. Used to control multicast traffic at Layer 2. Another method used to control multicast traffic at Layer 2. Protocol Independent Multicast. IP multicast routing protocol. Distance-Vector Multicast Routing Protocol. Primary multicast routing protocol used in the MBONE. Table 12-5 summarizes IP multicast...

Pv4 Header

The best way to understand IPv4 is to know the IPv4 header and all its fields. Segments from TCP or the User Datagram Protocol (UDP) are passed on to IP for processing. The IP header is appended to the TCP or UDP segment. The TCP or UDP segment then becomes the IP data. The IPv4 header is 20 bytes in length when it uses no optional fields. The IP header includes the addresses of the sending host and destination host. It also includes the upper-layer protocol, a field for prioritization, and a...

Pv6 Address Types and Address Allocations

This section covers the major types of IPv6 addresses. IPv4 addresses are unicast, multicast, or broadcast. IPv6 maintains each of these address functions, except that the IPv6 address types are defined a little differently. A special all-nodes IPv6 multicast address handles the broadcast function. IPv6 also introduces the anycast address type. Also important to understand are the IPv6 address allocations. Sections of the IPv6 address space are reserved for particular functions, each of which...

Pv6 Multicast Address

The IPv6 multicast (one-to-many) address identifies a set of hosts. The packet is delivered to all the hosts identified by that address. This type is similar to IPv4 multicast (Class D) addresses. IPv6 multicast addresses also supersede the broadcast function of IPv4 broadcasts. You use an all-nodes multicast address instead. FF01 0 0 0 0 0 0 1 Indicates all-nodes address for interface-local scope. FF02 0 0 0 0 0 0 2 All-routers address for link-local.

Pv6 Multicast Addresses

IPv6 retains the use and function of multicast addresses as a major address class. IPv6 prefix FF00 8 is allocated for all IPv6 multicast addresses. IPv6 multicast addresses are described in RFC 2373. EIGRP for IPv6, OSPFv3, and RIPng routing protocols use multicast addresses to communicate between router neighbors. The format of the IPv6 multicast address is described in Chapter 8, Internet Protocol Version 6. The common multicast addresses are repeated in Table 12-3. Table 12-3 Well-Known...

ISIS Operation and Design

This subsection discusses IS-IS areas, designated routers, authentication, and the NET. IS-IS defines areas differently from OSPF area boundaries are links and not routers. IS-IS has no BDRs. Because IS-IS is an OSI protocol, it uses a NET to identify each router. To configure the IS-IS routing protocol, you must configure a NET on every router. Although configuring NET is not a CCDA test requirement, this information is included for extra credit. Although you can configure IS-IS to route IP,...

Large Building LANs

Large-building LANs are segmented by floors or departments. The building-access component serves one or more departments or floors. The building-distribution component serves one or more building-access components. Campus and building backbone devices connect the data center, building-distribution components, and the Enterprise Edge-distribution component. The access layer typically uses Layer 2 switches to contain costs, with more expensive Layer 3 switches in the distribution layer to provide...

Layer 3 to Layer 2 Mapping

Multicast-aware Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI) network interface cards use the reserved IEEE 802 address 0100.5e00.0000 for multicast addresses at the MAC layer. This includes Fast Ethernet and Gigabit Ethernet. Notice that for the address, the highorder byte 0x01 has the low-order bit set to 1. This bit is the Individual Group (I G) bit. It signifies whether the address is an individual address (0) or a group address (1). Hence, for multicast addresses, this...

Link State Routing Protocols

Link-state routing protocols address some of the limitations of distance-vector protocols. When running a link-state routing protocol, routers originate information about themselves (IP addresses), their connected links (the number and types of links), and the state of those links (up or down). The information is flooded to all routers in the network as changes in the link state occur. Each router makes a copy of the information received and forwards it without change. Each router independently...

Loop Start Signaling

Loop-start signaling is an analog signaling technique used to indicate on-hook and off-hook conditions in the network. It is commonly used between the telephone set and the CO, PBX, or FXS module. As shown in Figure 15-3, with loop-start the local loop is open when the phone is on-hook. When the phone is taken off-hook, a -48 direct current (DC) voltage loops from the CO through the phone and back. Loop-start signaling is used for residential lines.

Lwapp

Lightweight Access Point Protocol (LWAPP) is a draft Internet Engineering Task Force (IETF) standard for control messaging for setup, authentication, and operations between access points (AP) and wireless LAN controllers (WLC). With Cisco's UWN Split-MAC operation, the control and data messages are split. Lightweight Access Points (LWAP) communicate with the WLCs using control messages over the wired network. LWAPP data messages are encapsulated and forwarded to and from wireless clients. The...

Media Redundancy

In mission-critical applications, it is often necessary to provide redundant media. In switched networks, switches can have redundant links to each other. This redundancy is good because it minimizes downtime, but it can result in broadcasts continuously circling the network, which is called a broadcast storm. Because Cisco switches implement the IEEE 802.1d spanning-tree algorithm, you can avoid this looping in Spanning Tree Protocol (STP). The spanning-tree algorithm guarantees that only one...

Multicast Addresses

Multicast addressing uses Class D addresses from the IPv4 protocol. Class D addresses range from 224.0.0.0 to 239.255.255.255. IANA manages multicast addresses. Routing protocols (RIPv2, EIGRP, and OSPF) use multicast addresses to speak to their neighbors. For example, OSPF routers use 224.0.0.6 to speak to the designated router (DR) in a multiaccess network. Class D multicast addresses range from 224.0.0.0 to 239.255.255.255. Multicast addresses in the range of 224.0.0.1 to 224.255.255.255 are...

Multi Tier Design

The multi-tier design is the largest of the branch profiles, supporting between 100 and 1000 users. This design profile is similar to the dual-tier design in that it also provides dual-access routers in the WAN edge. In addition, dual ASAs are used for firewall filtering, and dual distribution switches provide the multilayer switching component. The WAN services use an MPLS deployment model with dual WAN links into the WAN cloud. Because there are dual routers, the typical redundancy services...

Network Audit Tools

When performing a network audit, you have three primary sources of information Existing network management software New network management tools After gathering the existing documentation, you must obtain access to the existing management software. The client may already have CiscoWorks tools from which you can obtain hardware models and components and software versions. You can also obtain the existing router and switch configurations. The network audit should provide the following information...

OSPFv2

RFC 2328 defines OSPFv2, a link-state routing protocol that uses Dijkstra's shortest path first (SPF) algorithm to calculate paths to destinations. OSPFv2 is used in IPv4 networks. OSPF was created for its use in large networks where RIP failed. OSPF improved the speed of convergence, provided for the use of VLSMs, and improved the path calculation. In OSPF, each router sends link-state advertisements about itself and its links to all other routers in the area. Note that it does not send...

OSPFv2 Summary

Memorize the characteristics of OSPFv2, as listed here Link-state routing protocol. Classless protocol (supports VLSMs and CIDR). Metric is cost (based on interface bandwidth by default). Fast convergence. Uses link-state updates and SPF calculation. Reduced bandwidth use. Sends partial route updates only when changes occur. Routes are labeled as intra-area, interarea, external Type 1, or external Type 2. Support for authentication. Uses the Dijkstra algorithm to calculate the SPF tree. Default...

OSPFv3 Link State Advertisements

OSPFv3 retains the LSA types used by OSPFv2 with some modifications and introduces two new LSAs Link LSA and Intra-Area-Prefix. All LSAs use a common 20-byte header that indicates the LS type, the advertising router, and the sequence number. Figure 11-7 shows the format of the LSA header. The LS age indicates the time in seconds since the LSA was generated. The LS type indicates the function performed by this LSA. This field includes a U bit and S2 and S1 bits. When the U bit is set to 0, the...

OSPFv3 Summary

The characteristics of OSPFv3 follow Link-state routing protocol for IPv6. Metric is cost (based on interface bandwidth by default). Sends partial route updates only when changes occur. Routes are labeled as intra-area, interarea, external Type 1, or external Type 2. Uses IPv6 for authentication. Uses the Dijkstra algorithm to calculate the SPF tree. Default administrative distance is 110. Uses multicast address FF02 5 (ALLSPFRouters). Uses multicast address FF02 6 (ALLDRouters). Recommended...

P

See LSAs packet-switched WANs, 185 partial-mesh topologies, 187 passwords, 445 PAT (port address translation), 232 path MTU discovery, 272 PBR (policy-based routing), 402 PBXs, 500 Q.SIG, 506 PCM (Pulse Code Modulation), 520 PDIOO lifecycle, 13, 167-168 Design phase, 14 top-down design process, 21-22 Implement phase, 14 Operate phase, 14 Optimize phase, 15 Plan phase, 14 Prepare phase, 14 PE (provider edge) routers, 161 Pearland Hospital scenario, 569-571, 573 peer-to-peer VPNs,...

Comprehensive Scenarios

This chapter covers four comprehensive scenarios that draw on several design topics covered in this book Scenario One Pearland Hospital Scenario Two Big Oil and Gas Scenario Three Beauty Things Store Scenario Four Falcon Communications The case studies and questions in this chapter draw on your knowledge of CCDA exam topics. Use these exercises to help master the topics as well as to identify areas you still need to review for the exam. Understand that each scenario presented encompasses...

PBX and PSTN Switches

Traditional switches and PBXs route voice using TDM technology and use 64-kbps circuits. The CCDA must understand some of the differences between these devices. The PBX, as its name states, is used in a private network and uses proprietary protocols. The PBX is located in the enterprise's data center. Each PBX may scale up to 1000 phones. Companies deploy PBX networks to obtain enterprise features and to prevent PSTN long-distance charges. PBXs are customer-owned voice switches. Enterprise...

Prepare Plan Design Implement Operate and Optimize Phases

Cisco has formalized a network's life cycle into six phases Prepare, Plan, Design, Implement, Operate, and Optimize. These phases are collectively known as PPDIOO. The PPDIOO life cycle It lowers the total cost of ownership by validating technology requirements and planning for infrastructure changes and resource requirements. It increases network availability by producing a sound network design and validating the network operation. It improves business agility by establishing business...

PSTN Numbering Plan

The PSTN uses the ITU E.164 standard for public network addressing. The E.164 standard uses a maximum of 15 digits and makes each phone unique in the PSTN. Examples of E.164 addresses are the residential, business, IP phones, and cell phones that you use every day. Each country is assigned a country code to identify it. The country codes can be one to three digits in length. Table 15-4 shows some examples of country codes. The ITU website that lists country codes is located at e164_763.html....

Qa

As mentioned in the Introduction, you have two choices for review questions here in the book or the exam questions on the CD-ROM. The answers to these questions appear in Appendix A. For more practice with exam format questions, use the exam engine on the CD-ROM. 1. What is the maximum data rate of IEEE 802.11g 2. What is the typical data rate of IEEE 802.11n 3. What are some difficulties with having to manage hundreds of standalone access points 4. What standard does IEEE 802.11i use for...

QoS Mechanisms for VoIP Networks

Cisco provides different QoS tools that you should use on edge and backbone routers to support VoIP networks. This section covers several QoS mechanisms and their impact on VoIP networks Priority Queue-WFQ (PQ-WFQ) CRTP was covered in an earlier section. It compresses the IP UDP RTP headers from 40 bytes to 2 or 4 bytes. It is configured on a link-to-link basis. Cisco recommends using CRTP for links lower than 768 kbps. Do not configure CRTP if the router CPU is above 75 percent utilization....

References and Recommended Readings

CCIE Routing and Switching Exam Certification Guide. Indianapolis Cisco Press, 2002. Doyle, J. Routing TCP IP, Volume I. Indianapolis Cisco Press, 1998. Enhanced IGRP. Enhanced Interior Gateway Routing Protocol. Hedrick, C. RFC 1058, Routing Information Protocol. Available from http www.ietf.org rfc. Implementing EIGRP for IPv6. Malkin, G. RFC 1723, RIP Version 2 - Carrying Additional Information. Available from http www.ietf.org rfc. Malkin, G. RFC 2453, RIP Version 2. Available from...

Remote Modules

The remote modules of the Cisco Enterprise Architecture model are the Enterprise Branch, Enterprise Data Center, and Enterprise Teleworker modules. The Enterprise Branch normally consists of remote offices or sales offices. These branch offices rely on the WAN to use the services and applications provided in the main campus. Infrastructure at the remote site usually consists of a WAN router and a small LAN switch, as shown in Figure 2-12. Instead of MPLS or Frame Relay, it is common to use...

RIPv1 Design

New networks should not be designed using RIPv1. It does not support VLSMs and CIDR. The IP addressing scheme with RIPv1 requires the same subnet mask for the entire IP network, a flat IP network. As shown in Figure 10-2, when you use RIPv1, all segments must have the same subnet mask. RIPvl has low scalability. It is limited to 15 hops therefore, the network diameter cannot exceed this limit. RIPvl also broadcasts its routing table every 30 seconds. RIP's slow convergence time prevents it from...

RIPv1 Forwarding Information Base

The RIPvl protocol keeps the following information about each destination IP address IP address of the destination host or network Gateway The first gateway along the path to the destination Interface The physical network that must be used to reach the destination Metric The number of hops to the destination Timer The amount of time since the entry was last updated The database is updated with the route updates received from neighboring routers. As shown in Example 10-1, the show ip rip...

RIPv1 Message Format

The RIPvl message format is described in RFC 1058 and is shown in Figure 10-1. The RIP messages are encapsulated using User Datagram Protocol (UDP). RIP uses the well-known UDP port 520. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 IP address (2nd route entry - up to 25) Command Describes the packet's purpose. The RFC describes five commands, two of which are obsolete and one of which is reserved. The two used commands are Request Requests all or part of the responding...

RIPv1 Timers

The Cisco implementation of RIPv1 uses four timers RIPv1 sends its full routing table out all configured interfaces. The table is sent periodically as a broadcast (255.255.255.255) to all hosts. The update timer specifies the frequency of the periodic broadcasts. By default, the update timer is set to 30 seconds. Each route has a timeout value associated with it. The timeout gets reset every time the router receives a routing update containing the route. When the timeout value expires, the...

RIPv2 Forwarding Information Base

RIPv2 maintains a routing table database as in Version l. The difference is that it also keeps the subnet mask information. The following list repeats the table information of RIPvl IP address The IP address of the destination host or network, with subnet mask Gateway The first gateway along the path to the destination Interface The physical network that must be used to reach the destination Metric A number indicating the number of hops to the destination Timer The amount of time since the...

RIPv2 Message Format

The RIPv2 message format takes advantage of the unused fields in the RIPvl message format by adding subnet masks and other information. Figure 10-3 shows the RIPv2 message format. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 IP address (2nd route entry - up to 25) Command Indicates whether the packet is a request or response message. The request message asks that a router send all or a part of its routing table. Response messages contain route entries. The router sends the...

Roaming and Mobility Groups

The primary reason to have wireless networks is the ability to access network resources from common areas and in areas difficult to run cables. End clients might want to move from one location to another. Mobility allows users to access the network from several locations. Roaming occurs when the wireless client changes association from one access point to another. The challenge is to scale the wireless network to allow client roaming. Roaming can be intracontroller or intercontroller....

Scenario Four Answers

The current Falcon network is not scalable. It is a flat network architecture using Layer 2 links in the core with no hierarchy. It does not have core, distribution, and access layers. 2. Recommend inserting a distribution layer to create a hierarchy between the core and access layers. Use Layer 3 links instead of Layer 2 links to prevent spanning-tree loop broadcast storms. 3. All hubs need to be replaced with switches. All switches should be replaced with PoE switches to provide power to...

Scenario Four Falcon Communications

Falcon Communications has requested an assessment of its current network infrastructure. You are given the diagram shown in Figure 17-5. The current infrastructure contains three 6500 Catalyst switches connected using Layer 2 links. Building access switches, WAN routers, Internet firewalls, the mainframe, and Windows servers all connect to the 6500 switches. Some Fast Ethernet hubs are used on the network. The IT manager mentions that they experience sporadic network outages several times...

Scenario One Answers

The hospital needs to provide access to patient records, prescriptions, and information from patient rooms. 2. No cost restrictions were discussed. 3. The technical requirements are as follows WLAN access from rooms on floors 6 through 10 Redundant access to servers in the data center Fast switching between LAN segments 4. The technical constraint is as follows Servers must be located in the first floor data-center rooms. 5. Figure 17-1 shows the logical diagram of the current network. Figure...

Scenario One Pearland Hospital

Robertson, the IT director at Pearland Hospital, is responsible for managing the network. Mr. Robertson has requested your help in proposing a network solution that will meet the hospital's requirements. The hospital is growing, and the management has released funds for network improvements. The medical staff would like to be able to access medical systems using laptops from any of the patient rooms. Doctors and nurses should be able to access patient medical records, x-rays, prescriptions,...

Security Policy and Process

To provide the proper levels of security and increase network availability, a security policy is a crucial element in providing secure network services. In addition, it is important to understand that network security is built around a security policy that is part of a system life cycle. In terms of network security in the system life cycle, business needs are a key area to consider. Business needs define what the business wants to do with the network. Risk assessment is another part of the...

Server Farm Module

The server-farm or data-center module provides high-speed access to servers for the campus networks. You can attach servers to switches via Gigabit Ethernet or 10 Gigabit Ethernet. Some campus deployments might need EtherChannel technology to meet traffic requirements. Figure 3-13 shows an example of a server-farm module for a small network. Servers are connected via Fast Ethernet or Fast EtherChannel. The server-farm switches connect via redundant uplink ports to the core switches. The largest...

Service Set Identifier SSID

WLANs use an SSID to identify the WLAN's network name. The SSID can be 2 to 32 characters long. All devices in the WLAN must have the same configured SSID to communicate. It is similar to a VLAN identifier in a wired network. The difficulty in large networks is configuring the SSID, frequency, and power settings for hundreds of remotely located access points. Cisco addresses this problem with the Cisco Wireless Control System (WCS). WCS is covered in more detail in the Cisco UWN Architecture...

Single Tier Design

The single-tier design is recommended for branch offices that do not require hardware redundancy and that have a small user base of up to 50 users. This profile consists of an access router providing WAN services and connections for the LAN services. The access router can connect the Layer 2 switch ports in one of three ways Using an ISR that has an optional EtherSwitch module that provides 16 to 48 Ethernet ports for client connections. Trunking to an access switch that aggregates the Ethernet...

Sona

SONA is an architectural framework that guides the evolution of enterprise networks to IIN to support new IT strategies. With SONA, distributed applications and services are centrally managed over a common, unified platform. An integrated system allows access to networked applications and services from all locations with greater speed and service quality. Figure 1-1 shows the SONA framework and the offerings included at each layer. SONA networks are based on a three-layer design that...

Sparse Versus Dense Multicast Routing Protocols

IP multicast traffic for a particular (source, destination group) multicast pair is transmitted from the source to the receivers using a spanning tree from the source that connects all the hosts in the group. Each destination host registers itself as a member of interesting multicast groups through the use of IGMP. Routers keep track of these groups dynamically and build distribution trees that chart paths from each sender to all receivers. IP multicast routing protocols follow two approaches....

Static Versus Dynamic Route Assignment

Static routes are manually configured on a router. They do not react to network outages. The one exception is when the static route specifies the outbound interface If the interface goes down, the static route is removed from the routing table. Because static routes are unidirectional, they must be configured for each outgoing interface the router will use. The size of today's networks makes it impossible to manually configure and maintain all the routes in all the routers in a timely manner....

Token Ring Design Rules

Token Ring is not a CCDA test subject but this section is included for reference because you might find Token Ring on existing networks. IBM developed Token Ring in the 1970s. In the 1980s, Token Ring and Ethernet competed as the preferred medium for LANs. The IEEE developed the IEEE 802.5 specification based on the IBM Token Ring specifications. The 802.5 working group is now inactive. The most recent specification is IEEE 802.5-1998. You can find more information at http www.8025.org. Table...

Top Down Approach

Top-down design simply means starting your design from the top layer of the OSI model and working your way down. Top-down design adapts the network and physical infrastructure to the network application's needs. With a top-down approach, network devices and technologies are not selected until the applications' requirements are analyzed. Figure 1-3 shows a top-down structure design process. The design process begins with the applications and moves down to the network. Notice that SONA's Network...

Traffic Shaping and Policing

Traffic shaping and policing are mechanisms that take an action based on the traffic's characteristics, such as DSCP or IP precedence bits set in the IP header. Traffic shaping slows down the rate at which packets are sent out an interface by matching certain criteria. Traffic shaping uses a token bucket technique to release the packets into the output queue at a preconfigured rate. Traffic shaping helps eliminate potential bottlenecks by throttling back the traffic rate at the source. Policing...

Trust and Identity Management

Trust and Identity Management is part of the Cisco Self-Defending Network, which is crucial for the development of a secure network system. It defines who and what can access the network, as well as when, where, and how that access can occur. Access to the business applications and network equipment is based on the user level rights granted to users. Trust and Identity Management also attempts to isolate and keep infected machines off the network by enforcing access control. The three main...

Using EoIP Tunnels for Guest Services

Basic solutions use separate VLANs for guest and corporate users to segregate guest traffic from corporate traffic. The guest SSID is broadcast, but the corporate SSID is not. All other security parameters are configured. Another solution is to use Ethernet over IP (EoIP) to tunnel the guest traffic from the LWAPP to an anchor WLC. As shown in Figure 4-12, EoIP is used to logically segment and transport guest traffic from the edge AP to the anchor WLC. There is no need to define guest VLANs in...

VLSMs

VLSMs are used to divide a network into subnets of various sizes to prevent wasting IP addresses. If a Class C network uses 255.255.255.240 as a subnet mask, 16 subnets are available, each with 14 IP addresses. If a point-to-point link needs only two IP addresses, 12 IP addresses are wasted. This problem scales further with Class B and Class A address space. With VLSMs, small LANs can use 28 subnets with 14 hosts, and larger LANs can use 23 or 22 masks with 510 and 1022 hosts, respectively....