Tài liệu Testkiller 640-503 Ed2 ppt

CISCO STUDY GUIDE Building Scalable Cisco Networks (BSCN) Exam 640-503 Edition 2 www.testkiller.com Congratulations!! You have purchased a Testkiller, Ltd Study Guide. This study guide is a selection of questions and answers similar to the ones you will find on the official CCNP 640-503 exam. Study and memorize the following concepts, questions and answers for approximately 15 to 20 hours and you will be prepared to take the exams. We guarantee it! Remember, average study time is 15 to 20 hours and then you are ready!!! GOOD LUCK! DISCLAIMER This study guide and/or material is not sponsored by, endorsed by or affiliated with Cisco Sys- tems, Inc. Cisco®, Cisco Systems®, CCDA™, CCNA™, CCDP™, CCNP™, CCIE™, CCSI™, the Cisco Systems logo and the CCIE logo are trademarks or registered trademarks of Cisco Sys- tems, Inc. in the United States and certain other countries. All other trademarks are trademarks of their respective owners . 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All Rights Reserved. www.testkiller.com Table of Contents Routing Principles . 1 Routing Metric 1 RIP Routing Metrics . 1 IGRP Routing Metrics 1 Classful Routes . 1 Classless Routing 1 Distance Vector Operation 1 Convergence . 1 EIGRP Convergence .1 OSPF Convergence . 2 IP Addresses 2 Current challenges in IP Addressing . 2 IP Addressing Solutions 2 Hierarchical Addressing 2 Variable Length Subnet Masks . 2 Route Summarization 2 CIDR . 3 Redistribution Implementation Guidelines . 3 NAT 3 Using IP Unnumbered Serial Interface . 3 Server Location . 3 OSPF . 3 Configuring OSPF in a Single Area 3 OSPF Operation in a Broadcast Multiaccess Topology . 4 OSPF Startup 4 OSPF over NBMA Topology . 4 NBMA Mode Neighborship . 5 Point-to-Multipoint Mode Neighborship 5 Interconnecting Multiple OSPF Areas 5 Multiple OSPF Areas 5 Types of Routers . 6 Types of Areas 6 Supporting Route Summarization . 6 EIGRP . 6 Configuring EIGRP 6 EIGRP Operation 6 EIGRP Packets 6 EIGRP Reliability . 7 Topology Table . 7 Configuring EIGRP 7 EIGRP Load Balancing . 7 EIGRP and WAN Links 7 EIGRP Link Utilization 7 www.testkiller.com Using EIGRP in a Scalable Network 7 BGP . 8 Configuring Basic Border Gateway Protocol . 8 BGP Use 8 When to use BGP 8 When not to use BGP 8 BGP Peers or Neighbors . 8 Policy-Based Routing . 8 Well Known Attributes .8 Optional Attributes 9 Defined BGP Attributes 9 BGP Synchronization 9 BGP Message Types .9 Implementing BGP in Scalable Networks 10 Route Reflectors 10 Policy Control and Prefix Lists . 10 Optimizing Routing Update Operation . 10 Redistribution 10 Policy-based Routing 10 Calculating cost for external routes 10 www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 1 Key Concepts Building Scalable Cisco Networks (BSCN) Routing Principles Routing is a relay process in which items are forwarded from one location to another. The mechanism of learning and maintaining awareness of the network topology is considered to be the routing function. Routing Metric In a routed network the routing process relies on the routing protocol to maintain a loop-free to- pology and to locate the best path to every destination network. RIP Routing Metrics RIP is a commonly used routing protocol in small to medium sized TCP/IP networks. IGRP Routing Metrics Cisco’s IGRP is a commonly used routing protocol in medium to large sized TCP/IP networks. IGRP uses a composite metric, based upon bandwidth, delay, reliability, load, and maximum transmission unit (MTU). Classful Routes Classful routing protocols, such as RIPv1 and IGRP, exchange routes to subnetworks within the same major Class (A, B or C) network. Classful routing is the result of subnet masks not being included in the routing advertisements generated by most distance vector routing protocols. Classless Routing Classless routing protocols can be considered second-generation protocols because they are de- signed to deal with some of the limitations of the earlier classful protocols. Distance Vector Operation The periodic routine routing updates generated by most distance vector routing protocols go only to directly connected routing devices. Convergence In a routed network, the routing process in each router must maintain a loop-free single path to each possible destination logical network. When all the routing tables are synchronized and each contains a usable route to each destination network, the network is converged. EIGRP Convergence A router running EIGRP uses reliable multicast messages when it sends queries and updates to other routers. www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 2 OSPF Convergence A router running OSPF uses a multicast address to propagate LSAs. LSA is state information about a link or a network. IP Addresses Current challenges in IP Addressing An IP address consists of a 32-bit number with two components: a network address and a node. The incredible growth of the Internet has resulted in following challenges: • IP address exhaustion • Routing table growth and manageability IP Addressing Solutions Solutions have been developed to slow the depletion of IP addresses and to reduce the number of Internet route table entries by enabling more hierarchical layers in an IP address. These solutions include the following: • Subnet masking • Address allocation for private internets • Network Address Translation (NAT) • Hierarchical addressing • Variable-length subnet masks (VLSMs) • Route summarization • Classless Interdomain Routing (CIDR) Hierarchical Addressing The benefits of hierarchical addressing are: • Reduced number of routing table entries • Efficient allocation of addresses Variable Length Subnet Masks The VLSMs are commonly used to maximize the number of possible addresses available for a network. The benefits if VLSMs are: • Even more efficient use of IP addresses • Greater capability to use route summarization Route Summarization Route summarization can reduce the number of routes that a router must maintain because it is a method of representing a series of network numbers in a single summary address. www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 3 Cisco routers manage route summarization in two ways: • Sending route summaries • Selecting routes from route summaries CIDR CIDR is a mechanism developed to help alleviate the problem of exhaustion of IP addresses and growth of routing tables. Redistribution Implementation Guidelines • Be familiar with your network and your network traffic • Do not overlap routing protocols • One-way redistribution • Two-way redistribution NAT Network Address Translation can be used to merge two large networks without having to re- address the whole network. Another function of NAT is overloading inside global addresses. This process allows several inside addresses to use a single IP address. NAT can also use a pool of addresses or multiple interfaces. Using IP Unnumbered Serial Interface To enable IP processing on a serial interface without assigning an explicit IP address to the inter- face, use the ip unnumbered type number interface configuration command. In the command type number indicates the type and number of another interface on which the router has an as- signed IP address. Server Location The server location is located in several ways: • A single server on a single remote medium • Multiple servers on a single remote medium, sometimes called a server farm • Multiple servers on multiple remote media OSPF Configuring OSPF in a Single Area OSPF is a link-state technology, as opposed to a distance vector technology such as Routing In- formation Protocol (RIP). The OSPF protocol performs the two primary functions of every rout- ing protocol algorithm: path selection and path switching. The OSPF addresses the following issues: www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 4 • Speed of convergence • Support for variable-length subnet masks (VLSMs) • Network Reachability • Use of bandwidth • Method for path selection Topologies found in OSPF are: • Broadcast multiaccess topologies • Point-to-point topologies • Nonbroadcast multiaccess (NBMA) topologies OSPF Operation in a Broadcast Multiaccess Topology Because OSPF topology is dependent on the status of a link between two routers, neighbor routers must recognize each other on the network before they can share information. This proc- ess is done using the Hello Protocol. The information contained in a Hello Packet is as follows: • Router ID • Hello and dead intervals • Neighbors • Area-ID • Router priority • DR and BDR IP address • Authentication password • Stub area flag The DR and BDR add value to the network in the following ways: • Reducing routing update traffic • Managing link-state synchronization OSPF Startup The steps involved when routers running OSPF come up on a network. 1. Exchange Process 2. Discovering Routes OSPF over NBMA Topology OSPF runs in two official modes in NBMA topologies: • Nonbroadcast Multiaccess (NBMA) • Point-to-Multipoint www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 5 NBMA Mode Neighborship Consider the following before using this mode: • Full mesh and direct communication • Stability of the network Point-to-Multipoint Mode Neighborship This mode has the following properties. • Does not require a fully meshed network • Does not require static neighbor configuration • Uses one IP subnet • Duplicates LSA packets Configuring OSPF over NBMA Topology • RFC –compliant Modes  NBMA Mode  Point-to-multipoint Mode • Cisco-defined Modes  Point-to-multipoint nonbroadcast mode  Broadcast mode  Point-to-point mode Interconnecting Multiple OSPF Areas Multiple OSPF Areas The following areas need to be addresses.  Frequent calculations of the shortest path first (SPF) algorithm  Large routing table  Large link-state table The hierarchical topology of OSPF has the following advantages.  Reduced frequency of SPF calculations  Smaller routing tables  Reduced link-state update (LSU) overhead www.testkiller.com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software. http://www.gfi.com/tt.shtml 6 Types of Routers 1. Internal Router 2. Backbone Router 3. Area Border Router 4. Autonomous System Boundary Router (ASBR) Types of Areas The characteristics that you assign an area control the type of route information that it receives. The possible area types include the following.  Standard area  Backbone area  Stub area  Totally stubby area  Not-so-stubby area Supporting Route Summarization Summarization is the consolidation of multiple routes into a single advertisement. With summa- rization, only summarized routes will propagate into the backbone. Two types of summarization exist, as follows: 1. Interarea route summarization 2. External route summarization EIGRP Configuring EIGRP EIGRP is a Cisco owned protocol that combines the advantages of link-state and distance vector routing protocols. This hybrid protocol has the following features:  Rapid convergence  Reduced bandwidth usage  Multiple network layer support EIGRP Operation Elements of EIGRP operation are:  EIGRP Packets  EIGRP neighbor relationship EIGRP Packets EIGRP uses the following five types of packets: [...]... the many variables that impact network scalability The amount of information exchanged between neighbors A topology change The depth of topology The number of alternative paths through the network 7 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... rules for routing is known as policy-based routing Well Known Attributes A well-known attribute is one that all BGP implementations must recognize These attributes are propagated to BGP neighbors 8 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... open message includes the following information: • • • • • Version My autonomous system Hold time BGP identifier (router ID) Optional parameters An update message may include the following fields 9 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... Quality of service Cost savings Load sharing Calculating cost for external routes You can configure the router to generate the following external packet types (the cost depends on the external type): 10 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... Intra-area route destinations are kept over inter-area routes 3 Type-5 destinations All routers, except those that are in a form of stub area, then calculate the paths to the AS external destinations 11 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... the “CCNP Keypoints” portion of this study guide We have identified important “KEYPOINTS” in this section Please ensure that you absolutely know and understand these prior to sitting for the exam 12 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... path to forward packets on a specific network 8 Route summarization uses hierarchical routing to allow one route update to represent many downstream networks 9 The following are true about BGP: 13 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... routers in other autonomous systems 19 There are three basic elements that are required for a router to be able to forward a packet: 1 2 3 The best route Destination address Summarized routes entry 14 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... which is used to indicate the best route to reach a destination network 32 The show controller command will allow you to determine whether a serial interface is connected to a DTE or DCE cable 15 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml... efficient manner, and summarization can be performed with different prefix lengths throughout the network 46 The default router priority is 1 for purpose of participating in an OSPF DR/BDR election 16 www .testkiller. com GFI - Security & Communication tools for NT/2000: FAXmaker fax server software, Mail essentials email content checking & anti-virus software and LANguard network security software http://www.gfi.com/tt.shtml . Building Scalable Cisco Networks (BSCN) Exam 640-503 Edition 2 www .testkiller. com Congratulations!! You have purchased a Testkiller, Ltd Study Guide. This study. the maximum extent possible under law.  Copyright 2001 Testkiller, Ltd. All Rights Reserved. www .testkiller. com Table of Contents Routing Principles .