About the Contributing Author

Roy Spencer is a Cisco Certified Network Associate for WAN switching and a Certified Cisco Systems Instructor with over fifteen years experience in the education segment of the networking industry. He has worked as a course developer for Cisco Systems, Inc., 3Com Corporation, and Nortel Networks Limited. Roy has written and taught classes on ATM switch configuration, network management, router configuration, LAN switch configuration, SONET multiplexers, Ethernet, and TCP IP. He is currently...

Administrative Distance Configuration

To change the administrative distance for routing protocols, use the distance number command. The number value ranges from 0 to 255. For OSPF, separate distances are configured for external, intra-area, and internal routes. The command examples in Table 10-2 change the administrative distances of routing protocols to a number between 40 and 50. (Don't do this on a real internetwork ) Table 10-2 Use of the distance Command for Routing Protocols Static routes have a default administrative...

AS Path Length Attribute

The AS Path is a well-known, mandatory attribute that contains a list of AS numbers in the path to the destination. Each AS prepends its own AS number to the AS Path. The AS Path describes all the autonomous systems that a packet must travel to reach the destination IP network it ensures that the path is loop free. When the AS Path attribute selects a path, the route with the least number of AS hops is preferred. In the case of a tie, other attributes, such as MED, decide. Example 9-9 shows the...

ATM Cell Switching

The header of each cell contains addressing information consisting of a VPI and a VCI. The VPI VCI address pair is locally significant. For each interface in a switch, the VPI VCI uniquely identifies the cell as belonging to a particular connection. When a VC connection is established across a network, each switch involved in the connection creates an entry in its switching table that identifies the incoming VPI VCI and interface number for the connection. The switching table entry also...

Atm Lane

Cisco removed ATM LANE as a CCIE Routing and Switching lab exam topic but has retained it in the CCIE written blueprint, but with less emphasis. Know the LANE components and the SSRP that are used for redundancy. This section only covers LANE. Other ATM topics are covered in Chapter 5, Wide-Area Networks. LANE provides connectivity between Ethernet or Token Ring stations and ATM connected stations. LANE also provides connectivity for Ethernet or Token Ring stations across an ATM network. LANE...

ATM Traffic Management

ATM connections support various service classes. The different service classes in turn support various network services. For example, video transmission uses a constant bit rate (CBR) class of service (CoS). Compressed voice service uses a real-time variable bit rate (RT-VBR). Data might use a non-real-time variable bit rate (NRT-VBR) type of traffic, or if the data device supports flow control, an available bit rate (ABR) traffic type. Low priority data might use an unspecified bit rate (UBR)...

BGP Decision Algorithm

The BGP decision algorithm can be summarized as follows 1 If no next hop, drop the path. 2 For internal path with synchronization, and the route is not in the IGP, drop the path. 7 Lowest origin type (IGP < EGP < Incomplete). 9 External path over Internal path. 10 Nearest eBGP neighbor (best IGP path to eBGP neighbor). IP address that reaches the destination Configured on the router to assign a preference of routes from different sources (not an RFC attribute) Number of autonomous systems...

BGP Neighbors

BGP is usually configured between two directly connected routers that belong to different autonomous systems. Each AS is under different technical administration Usually, one is the enterprise company and the other is the service provider, or between different service providers, as shown in Figure 9-1. Before routing updates can be exchanged between two BGP routers, the routers must become established neighbors. After BGP routers establish a TCP connection, exchange information, and accept the...

BGP Redistribution

Another method to advertise BGP routes is to import them into the BGP routing table through redistribution of an IGP (such as OSPF and EIGRP). Both the network command and redistribution from an IGP add routes that are already in the IP table into the BGP table. You commonly use this method in large enterprise internetworks with iBGP cores. Filtering selects the redistributed prefixes and properly sets their attributes (especially origin). In Example 9-4, a route map specifies attributes to...

Binary Numbers

The binary number system uses two digits 1 and 0. Binary numbers are primarily used by computer systems. IP addresses and MAC addresses are represented by binary numbers. The number of binary 1s or 0s is the number of bits. For example, 01101010 is a binary number with 8 bits. An IP address has 32 bits and a MAC address has 48 bits. Table 2-2 shows that IP addresses are usually represented in dotted decimal format therefore, it is helpful to know how to covert between binary and decimal...

Bridges and Layer2 Switches

Bridges operate in the data-link layer of the OSI model. Bridges learn the MAC layer addresses of each node of the segments and remember off which port the MAC addresses are located. The bridge builds a table of MAC addresses and ports. If the destination MAC address of an incoming frame is not in the table, bridges forward the frame to all ports (minus the port from which the frame came). If the destination MAC address is in the table, bridges forward the frame only if the destination MAC...

Bridges and STP

Ethernet bridging occurs in the data-link layer of the OSI model. Switches perform the same function as bridges. For the rest of the chapter, the term switches refers to bridges. Bridges (and switches) forward frames from one interface to another based on the destination MAC address. For any incoming frame, bridges forward the frame out a specific port, if the destination MAC address is known, or it is flooded out all ports if the MAC address is unknown. If the destination MAC is unknown, the...

Car

CAR provides the means to limit the input or output transmission rate on an interface or subinterface based on traffic sources and destinations, while specifying policies for handling traffic that exceeds bandwidth allocations. Rate policies can be set based on IP access lists, IP Precedence, Media Access Control (MAC) addresses, or a QoS group. The difference between CAR and traffic shaping is that CAR is a policing scheme. CAR sets maximum limits on traffic but does not shape traffic to a...

Central Processing Unit CPU

Most Cisco routers have the Motorola 68000 series or Orion RISC (R4700) microprocessors. The CPU is the brain of the system. It runs route algorithms, exec processes, route filtering, network management, and so on. Some processes, such as Open Shortest Path First(OSPF), task the CPU with large computations. The CPU type can be checked with the show version command. Example 3-1 shows a Cisco MC3810 using the Motorola MPC860 processor. Example 3-1 show version Command Used to Check Processor Type...

Answers to Q A Section

1 What is the administrative distance of EIGRP external routes The administrative distance for internal EIGRP routes is 90. The administrative distance for external EIGRP routes is 170. 2 Which protocol do hosts use to join a multicast group Hosts use Internet Group Management Protocol (IGMP) to join a multicast group. IGMP operates between the host and the local router. 3 When redistributing EIGRP routes into RIP, how do the bandwidth and delay metrics get converted a. RIP assigns the...

Answers to Scenario Section

Answer the following questions based on Figure 2-11. Each question tests your knowledge of how different metrics affect the chosen route to a destination. 1 A user performs a Telnet from PC 1 to PC 2. If the metric that the configured routing protocol uses is bandwidth, which route will the packets take 1 A user performs a Telnet from PC 1 to PC 2. If the metric that the configured routing protocol uses is bandwidth, which route will the packets take c. Neither, there is not sufficient...

Answers to Scenario Section Scenario

This scenario reviews your knowledge of RSRB. Knowledge of RSRB configurations and RIF constructs in RSRB environments is essential for the CCIE written test. Use Figure 4-34 to answer the following questions. 1 What is the RIF from Host A to Host C d. 0630.01b9.121d.0120 Answer b From Host A to Host C, a frame travels from Ring 0x01b, Bridge 0x9, Ring 21 (0x015), Bridge 13 (0xd), Ring 12 (0xc). 2 What is the RIF from Host A to Host B d. 0830.01b9.0155.00f0 Answer d From Host A to Host B, a...

Cisco OSPF Command and Configuration Handbook

Parkhurst, Ph.D., CCIE 2969 1-58705-071-4 Available Now Cisco OSPF Command and Configuration Handbook is the comprehensive OSPF protocol command and interior IP routing protocols command reference that is invaluable for network designers, engineers, and architects. This book contains numerous scenarios covering every possible command and presents clear and concise commentary on the purpose and context of each command.

Configuration File Manipulation

The router configuration can reside in several locations NVRAM, DRAM, terminal, or on a TFTP server. When the router is booted, the configuration stored in NVRAM is the startup configuration. After the router is booted, the configuration is placed in DRAM. When users attaches to the console or telnets to the router, they view the active configuration on the terminal. The configuration file can also be transferred to or from a TFTP server. Figure 3-2 shows the commands that manipulate the...

Configuration Mode

In enable mode, you can enter configuration mode with the configure terminal command. You use configuration mode for interface, router, and line configuration Enter configuration commands, one per line. End with CNTL Z. routerlab(config) If an interface is configured, the prompt changes as follows router1(config) interface ethernet 0 If a routing protocol is configured, the prompt changes as follows router1(config) router rip router1(config-router) exit router1(config) router eigrp 100...

Connection Flow Control

After a connection is established, the sending TCP sends segments no larger than the received window size. The sender waits for the acknowledgment of sent segments before sending additional data. Each acknowledgment also has the window size, which indicates the amount of data that the receiver is willing to accept. The window can change in size, therefore, the name sliding window. Remember, the window size is represented in bytes. A TCP sender, for example, might have 200 bytes to send to a...

Contents at a Glance

Chapter 1 CCIE Certification, Test Preparation, and Using This Book 3 Chapter 2 Networking Concepts Review 15 Chapter 3 Cisco Equipment Operations 61 Chapter 4 Local-Area Networks and LAN Switching 105 Chapter 7 Static Routing and Distance Vector Routing Protocols 319 Chapter 8 IP Link-State Routing Protocols 371 Chapter 9 Border Gateway Protocol 427 Chapter 10 Administrative Distance, Access Lists, Route Manipulation, and IP Multicast 473 Chapter 11 Traffic Management 513 Chapter 12...

Converting Binary to Decimal

To convert a binary number to decimal, multiply each instance of 1 by the power of 2. Table 2-4 shows that each bit in the binary number 11111111 has a decimal equivalent from 1 to 128, which is based on the location of the bit in the binary. This is similar to decimal numbers where the numbers are based on 1s, 10s, 100s, and so on. In decimal format, the number 111 is 100+10+1. In binary format, the number 11111111 is the sum of 128+64+32+16+8+4+2+1 255. For 10101010, this results in...

Converting Decimal to Hexadecimal

First things first, memorize Table 2-1. For larger numbers, there are two methods. The first method is to convert decimal to binary and then from binary to hex. The second method is to divide the decimal number by 16 the residual is the right-most bit. Then keep dividing until the number is not divisible. 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 16. The residual is the first...

Converting Hexadecimal to Decimal

To convert a hex number to decimal, take the right-most digit and convert it to decimal (i.e., 0xC 12). Then add this number to the second right-most digit x 16 and the third rightmost digit x 256. Don't expect to convert numbers larger than 255 on the CCIE written exam because the upper limit of IP addresses in dotted decimal format is 255, although Token Ring numbers do reach 4096. Some examples follow. Conversion Example 5 Convert 177h to Decimal 1 x 256 256 7 x 16 112 7 x 1 _7_ 375d...

Data Link Connection Identifier DLCI

Frame Relay uses the DLCI to identify VCs. Each DLCI has local significance. The DLCI number at Router A can be different than the DLCI number at Router B for the same PVC. As shown in Figure 5-6, each router uses the local DLCI number to reach another through the Frame Relay network. Router A uses DLCI 200 to reach Router B, DLCI 300 to reach Router C, and DLCI 400 to reach Router D. The DLCI is configured for each interface or subinterface to mark the appropriate PVC. For example, the...

Debug

The debug commands are available only in privileged exec (enable) mode. If you attempt to use debug in user exec mode, the command is not recognized. You must use debug commands with caution because the router's CPU use significantly increases when debugging is enabled. NOTE If you access the router through a virtual terminal, such as Telnet, you need to enter the terminal monitor command to have debug output show on your screen. This command is not necessary if you access the router from the...

Dial Backup Configuration

ISDN can back up a primary circuit if it fails or has exceeded a use threshold. If the primary fails, the ISDN circuit is enabled. While the connection is up, IP traffic is passed through the backup interface. Also, the backup BRI can be enabled if the primary circuit reaches a certain load. In Example 5-11, the BRI is enabled if serial 0 reaches 60 percent load or if serial 0 is down for 25 seconds. The BRI is disabled if serial 0 is back up for 60 seconds or if the bandwidth in the primary is...

Do I Know This Already Quiz

The purpose of this assessment quiz is to help you determine how to spend your limited study time. If you can answer most or all of these questions, you might want to skim the Foundation Topics section and return to it later as necessary. Review the Foundation Summary section and answer the questions at the end of the chapter to ensure that you have a strong grasp of the material covered. If you intend to read the entire chapter, you do not necessarily need to answer these questions now. If you...

Eigrp

EIGRP was released in the early 1990s by Cisco Systems as a evolution of IGRP toward a scalable routing protocol. EIGRP is a classless protocol that permits the use of VLSMs and support for CIDR for scalable allocation of IP addresses. Routing updates are not sent periodically, as in IGRP. EIGRP allows for authentication, with simple passwords or with MD5. EIGRP autosummarizes networks at network borders and can load balance over unequal-cost paths. Packets use IP protocol 88. You can use only...

EIGRP Configuration

The configuration commands for EIGRP are similar to IGRP. After configuring the interfaces, the router eigrp command enables the routing protocol. The networks are defined with the network command. Using the physical network described in Figure 7-6, the configurations for Router8, Router9, and RouterlO are presented in this section. Figure 7-6 EIGRP Configuration Example Example 7-26 shows the configuration of Router8. EIGRP is configured with the autonomous system number 100. EIGRP hellos are...

EIGRP Packet Types

EIGRP uses the following packet types Hello packets assist in the discovery of EIGRP neighbors. The packets are multicast to 224.0.0.10. By default, hello packets are sent every 5 seconds (60 seconds on WAN links with 1544 Mbps speeds or less). An acknowledgment packet acknowledges the reception of an update packet. An acknowledgment packet is a hello packet with no data. Acknowledgment packets are sent to the unicast address of the sender of the update packet. Update packets contain the...

Fast Ether Channel FEC

Cisco's FEC provides a method to increase the bandwidth between two systems by bundling FE links. FEC also provides load sharing and redundancy capabilities. If a link fails in the FEC bundle, the other links take on the rest of the traffic load. Although this discussion focuses on FE, EtherChannel works for 10 Mbps Ethernet links and for GE links. The requirements for EtherChannel are that all ports must be of the same speed, be in duplex mode, and belong to the same VLAN. Up to four ports are...

Feedback Information

At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the professional technical community. Readers' feedback is a natural continuation of this process. If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through e-mail at...

Figure 614 DNS Tree

UDP is the recommended transport protocol for DNS queries. TCP is the recommended protocol for zone transfers between DNS servers. A DNS query searches for the IP address of a Fully Qualified Domain Name (FQDN), such as www.cisco.com. SNMP is a network protocol for the management of network devices. SNMP allows network managers to inspect or change parameters on a device remotely. SNMP was first defined by RFC 1067 (SNMPvl), which was succeeded by RFCs 1155, 1157,...

Figure 619 IP Header

E Experimental reserved 1111xxxx 240.0.0.0 to 254.255.255.255 E Experimental reserved 1111xxxx 240.0.0.0 to 254.255.255.255 Class Class C 11111111 11111111 11111111 00000000 255.255.255.0 C 11111111 11111111 11111111 00000000 255.255.255.0 Table 6-24 Address Assignment and Summarization Table 6-24 Address Assignment and Summarization A single subnet mask for the entire IP network number. Permits the use of different subnet masks for a network number. Routing protocols can aggregate subnet...

Foundation Summary

The Foundation Summary is a condensed collection of material that provides a convenient review of key concepts in this chapter. If you are already comfortable with the topics in this chapter, this summary will help you recall a few details. If you just read the Foundation Topics section, this review should help solidify some key facts. If you are doing your final preparation before the exam, these materials are a convenient way to review the day before the exam. Provides the user or operating...

Foundation Topics Administrative Distance

On routers running several IP routing protocols, two different routing protocols might have a route to the same destination. Cisco routers assign each routing protocol an administrative distance. The default values are shown in Table 10-1. In the event that two or more routing protocols offer the same route for inclusion in the routing table, the Cisco IOS selects the route from the routing protocol with the lowest administrative distance. Table 10-1 Default Administrative Distances for IP...

Frame Relay

This section covers the Frame Relay topics that are listed in the blueprint of the CCIE written test. Frame Relay is a Layer-2 WAN service that sends information in frames. Each frame has an address that the network uses to determine the destination of the frame. Frame Relay was developed when lines became more reliable and the high-overhead link error checking that is found in X.25 was no longer required. This provided more available bandwidth for WAN connectivity. Similar to X.25, Frame Relay...

Frame Relay Frame Format

Frame Relay uses Link Access Procedure for Frame Relay (LAPF) for frame format. LAPF is yet another variation of the HDLC frame format it supports Frame Relay. There is no control frame, flow control, and error control, and no sequence numbers. Figure 5-7 shows the LAPF frame format. Figure 5-7 Frame Relay LAPF Frame Format Figure 5-7 Frame Relay LAPF Frame Format Address sub-fields Bits 8 7 6 5 4 3 2 The 10-bit DLCI provides the PVC identifier, which has local significance between the router...

Frame Relay LMI Frame Relay Format

The LMI frame format is shown in Figure 5-8. Table 5-2 describes the fields of the LMI frame. Table 5-2 LMI Fields Table 5-2 describes the fields of the LMI frame. Table 5-2 LMI Fields The LMI DLCI is 1023 if you use a cisco-type LMI. It is 0 if you use either Unnumbered Information Indicator sets the poll final bit to 0. Protocol Discriminator contains a value indicating that the frame is an LMI Call Reference. This field always contains 0s and is not currently used. Status-inquiry message...

Frame Relay map Command

Before Inverse ARP was available (prior to 11.2), the most common method to configure Frame Relay was by using map statements. Looking at Figure 5-9, the serial interface configuration for Router A is displayed in Example 5-3, and the configuration for Router B is displayed in Example 5-4. Example 5-3 Router A Frame Relay Map Configuration Example Figure 5-9 Frame Relay Map Configuration Figure 5-9 Frame Relay Map Configuration Example 5-4 Router B Frame Relay Map Configuration Example...

Frame Relay show Commands

The most common commands that observe Frame Relay status and configuration are the following This section shows and explains sample outputs from each of these commands. Example 5-5 shows output from the show frame-relay map command. Example 5-5 show frame-relay map Command The output from the show frame-relay map command shows the current status and relevant information about the mappings. Example 5-5 shows two VCs mapped on serial 0. One has local DLCI 103, IP is the network protocol in use,...

Hierarchical Model for Networks

The use of a hierarchical design for networks facilitates the operation and management of the internetwork. With a hierarchical design, the network is easier to understand, the network can scale up as size requirements grow, it is easier to implement service policies, and troubleshooting network problems are simplified. The IP addressing assignment is accomplished by following a hierarchy that maximizes route summarization. Routing protocols can aggregate addresses into summary routes, which...

IGRP Configuration

The configuration commands for IGRP are as simple as for RIPvl. After configuring interfaces, use the router igrp command. You use an autonomous system number with the command because multiple instances of IGRP can be configured in a Cisco router. The configuration for the routers in this section is shown in Figure 7-5. Example 7-18 shows the configuration for Router8. IGRP 100 is enabled with the router igrp 100 command. The network 172.16.0.0 specifies that all interfaces on this router with...

Initial Configuration Dialog

At bootup, the router prompts the user to enter into the system configuration dialog if the router has no configuration (because it is new or because the configuration file was erased by the write erase command ). In Example 3-8, the router output shows a sample of the configuration dialog. If you enter the dialog, a series of questions walk you through the configuration of the router. In Example 3-8, you enter the basic network management configuration. The first level of configuration is...

IP Address Subnets

Subnetting plays an important part in IP addressing. The subnet mask helps determine the network, subnetwork, and host part of an IP address. The network architect uses subnetting to manipulate the default mask to create subnetworks for LAN and WAN segments. As mentioned earlier, one router interface with 16 million hosts off that interface is not a good thing. Subnet masks are for Class A, B, and C addresses only. Multicast addresses do not use subnet masks. Subnet masks are a 32-bit number...

IP Addressing

This section covers the IP address classes, network subnets, and address assignments. The CCIE candidate must be an expert in handling IP addresses. IP addresses assign a unique logical number to a network device. The number is 32-bits long. To make the number easier to read, you use the dotted decimal format. The bits are combined into four 8-bit groups, each converted into decimal numbers that are separated with dots. The following example shows an IP address in binary and decimal formats...

ISIS Configuration

Configuration for IS-IS is relatively simple. An IS-IS process is created by using the router isis tag command. Only one IS-IS process performing L2 routing is allowed per IS, and that process can also perform L1 routing. However, multiple L1-only IS-IS routing processes can be configured (up to 29 additional L1-only processes). If the tag value is not specified, a null tag is assumed. If multiple L1 routing processes are configured, each is labeled with a tag to facilitate area identification....

ISIS does not run over IP

Router LSAs with interface state information produced by all routers b. ASBR summary LSAs produced by ABRs c. Summary LSAs produced by ABRs d. External LSAs produced by ABRs Type 3 LSAs are Summary LSAs and are produced by ABRs. They are flooded into areas to advertise destinations outside the area. 27 The following router output is produced by which command Neighbor ID Pri State Dead Time Address 112.20.150.6 1 FULL DR 00 00 33 112.20.150.111 112.20.150.7 1 FULL - 00 00 34 112.20.150.236 d....

Link State Versus Distance Vector Routing Protocols

The first routing protocols were distance vector routing protocols, which are occasionally referred to as Bellman-Ford algorithms. In distance vector routing protocols, routes are advertised as vectors of distance and direction. The distance metric is usually the router hop count. The direction is the next-hop router to which the packet is forwarded. For RIP, the maximum number of hops is 15, which is a serious limitation especially in nonhierarchical networks. Distance vector algorithms call...

Local Preference Attribute

The local preference attribute indicates which path to use to exit the AS. It is a well-known discretionary attribute used between iBGP peers and not passed on to external BGP peers. In the IOS, the default local preference is 100 the higher local preference is preferred. The default local preference is configured on the BGP router with an external path. It then advertises its local preference to iBGP peers. An example of the local preference attribute where Routers B and C are configured with...

Local Area Networks and LAN Switching

This chapter covers the CCIE Written blueprint objectives related to bridging, local-area networks, and LAN switching. Other blueprint topics covered in this chapter include ATM LANE and LAN security. The purpose of this assessment quiz is to help you determine how to spend your limited study time. If you can answer most or all of these questions, you might want to skim the Foundation Topics section and return to it later as necessary. Review the Foundation Summary section and answer the...

Multicast Review

With multicast, packets are sent to a multicast group, which is identified with an IP multicast address. Multicast supports the transmission of IP packets from one source to multiple hosts. Packets with unicast addresses are sent to one device and broadcast addresses are sent to all hosts packets with multicast addresses are sent to a group of hosts. You use class D addresses from the IPv4 protocol for multicast addressing. Routing protocols (RIPv2, IS-IS, EIGRP and OSPF) use multicast...

Multiprotocol Label Switching MPLS

MPLS provides ways to perform traffic engineering, to guarantee bandwidth or set paths, and to enable Virtual Private Networks (VPNs). It specifies ways that Layer-3 traffic can be mapped to connection-oriented Layer-2 transport protocols, such as ATM. It adds a label containing specific routing information to each IP packet that directs traffic through explicitly defined paths, and it allows managers to implement policies that assign labels to various CoS. This enables the managers to offer...

Network Layer OSI Layer

The network layer is concerned with the routing of information and methods to determine paths to a destination. Information at this layer is called packets. Specifications include routing protocols, logical network addressing, and packet fragmentation. Routers operate in this layer. The CCIE lives and dies in this layer. Examples of network layer specifications are the following Routing Information Protocol (RIP) Open Shortest Path First (OSPF) Enhanced Interior Gateway Routing Protocol (EIGRP)...

Next Hop Attribute

The next-hop attribute is simply the IP address of the next eBGP hop that you use to reach the destination. The next-hop attribute is a well-known, mandatory attribute. With eBGP, the next hop is set by the eBGP peer when it announces the route. The next-hop attribute is used on multiaccess networks where there is more than one BGP speaker. With iBGP, routers advertise the next hop as the external (eBGP) peer instead of itself. In fully meshed multiaccess networks, you might want to minimize...

Numeric Conversion

This section focuses on the techniques used to convert between decimal, binary, and hexadecimal numbers. Although there might not be a specific question on the exam that asks you to convert a binary number to decimal, you need to know how to convert these numbers to complete problems on the test. A diagram might show a Token Ring with a decimal number but the RIF might be shown as hexadecimal. An IP address might be shown as binary or in dotted decimal format. Some show commands have output...

OSPF Adjacencies and Hello Timers

OSPF uses Hello packets for neighbor discovery. The default Hello interval is 10 seconds (30 seconds for nonbroadcast multiaccess (NBMA) networks). Hellos are multicasted to 224.0.0.5 (ALLSPFROuters). OSPF neighboring routers become adjacent when the parameters in their Hello packets match, the routers see their own address listed in a Hello packet from their neighbor (indicating bidirectional communication), they exchange link-state advertisements (LSAs), and their databases are synchronized....

OSPF Configuration

This section covers the configuration of OSPF routers and the commands that you use to verify OSPF routes. Use Figure 8-6 as a reference, where four routers are configured to run OSPF using area 0 and three other areas. Area 10 is configured to do authentication and has a Frame Relay link. Area 30 is connected to area 0 through a virtual link. Area 20 is a transit area with a p2p link. Router 3 is configured with a higher priority so that it is elected as the DR for the Ethernet segment. The...

Password Recovery

Router password recovery is accomplished by rebooting the router and breaking into ROM monitor mode, setting the device to ignore the configuration file, rebooting, canceling the Initial Configuration Dialog, configuring memory, and then reading or resetting the password. You must be familiar with the password recovery steps for the test. The following procedure is from Cisco's web site. This is the procedure for routers using Reduced Instruction Set Computer (RISC)-based processors Step 1 Turn...

Pim

PIM comes in sparse mode (PIM-SM) and dense mode (PIM-DM). As the names imply, the first operates in sparse mode and the second in dense mode. PIM-DM uses a technique known as reverse path forwarding (RPF). When the router receives a packet, it forwards it out all other interfaces, which allows the data stream to reach all segments. If no hosts are members of a multicast group on any of the router's attached or downstream subnets, the router sends a prune message up the distribution tree to...

Proxy ARP

Proxy ARP, as described in RFC 1027, specifies a method for which routers can respond to ARP requests from hosts that do not have a configured gateway, by replying with its local MAC address for destinations on other subnetworks. Cisco routers can reply to ARP requests for destination hosts on different major networks. Also, if the IP prefix is in the routing table, Cisco routers can send the ARP reply even if multiple segments are between the destination host and the router. Figure 6-12 shows...

Q A

The Q & A questions are more difficult than what you can expect on the actual exam. The questions do not attempt to cover more breadth or depth than the exam however, they are designed to make sure that you retain the material. Rather than allowing you to derive the answer from clues hidden inside the question itself, these questions challenge your understanding and recall of the subject. Questions from the Do I Know This Already quiz are repeated here to ensure that you have mastered the...

Ring Resiliency

DPT uses Intelligent Protection Switching (IPS), which uses SRP control packets to proactively monitor ring performance to perform fault isolation and to provide self-healing rings by wrapping around outages within 50 ms. If multiple events occur concurrently, IPS uses event hierarchy rules to determine which events to handle and which events to handle first. IPS is multilayer aware. It monitors and handles events at Layers 1, 2, and 3 instead of just Layer 1. An event that occurs at Layer 3 is...

RIPv2 Message Format

The RIPv2 message format takes advantage of the unused fields in the RIPv1 message format by adding subnet masks and other information. Figure 7-3 shows the RIPv2 message format. 1 2 3 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) The following is a description of each field The following is a description of each field Command Indicates whether the packet is a request or a response message. The request message asks that a router send all or part of its...

RIPvl Configuration

The configuration for Router9 is shown in Example 7-3. Example 7-3 Configuration of Router9 interface Ethernet0 ip address 172.16.1.1 interface Serial0 ip address 172.16.4.1 The configuration for RouterlO is shown in Example 7-4. Example 7-4 Configuration of Router10 interface Ethernet0 ip address 172.16.2.1 interface Serial0 ip address 172.16.4.2 The configuration for Router8 is shown in Example 7-5. Example 7-5 Configuration of Router8 After the routers are configured, you can verify the RIP...

RIPvl Message Format

As described in RFC 1058, the RIPv1 message format is shown in Figure 7-1. The RIP message is appended to a User Datagram Protocol (UDP) header. 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 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 Address Family Identified Unused (must be zero) IP address (2nd route entry-up to 25) Unused Unused Metric Address Family Identified Unused (must be zero) IP address (2nd route entry-up to 25) Unused Unused Metric The...

Route Reflectors

Network administrators can use route reflectors to reduce the number of required mesh links between iBGP peers. Some routers are selected to become the route reflectors to serve several other routers that act as clients. Route reflectors allow a router to advertise or reflect routes to clients. The route reflector and its clients form a cluster. All client routers in the cluster peer with the route reflectors within the cluster. The route reflectors also peer with all other route reflectors in...

Router CLI

Example 3-12 Some Options of the show Command Accounting data for active sessions display information about flash file system Example 3-12 Some Options of the show Command (Continued) Frame-Relay information Interface status and configuration IP information Show the contents of logging buffers Current operating configuration Spanning tree topology Hot standby protocol information Contents of startup configuration The show ip keywords command is one of the most common options. Example 3-13...

Routers and Layer3 Switches

Routers operate in the network layer of the OSI model. They make forwarding decisions based on network layer addresses (e.g., an IP address). Figure 2-7 shows that routers define both collision (bandwidth) and broadcast domains. Each router interface is a separate broadcast domain that is defined by a separate sub-network. Routers are protocol aware, which means that they are capable of forwarding packets of routable protocols such as IP, IPX, DECnet, and AppleTalk. Figure 2-7 Routers Define...

Rsvp

For the written test, you must be familiar with RSVP, which is covered in this section. RSVP is one of the first significant protocols to set up end-to-end QoS over IP. RSVP is a signaling protocol that enables stations to obtain special qualities of service for their application data flows. RSVP reserves bandwidth for the network application. RSVP works in conjunction with routing protocols and installs the equivalent of dynamic access lists along the routes that routing protocols calculate....

Scenario

Answer the following questions based on Figure 2-11. Each question tests your knowledge of how different metrics affect the chosen route to a destination. Answers to these questions are in the Appendix, Answers to Quiz Questions. 1 A user performs a Telnet from PC 1 to PC 2. If the metric that the configured routing protocol uses is bandwidth, which route will the packets take 1 A user performs a Telnet from PC 1 to PC 2. If the metric that the configured routing protocol uses is bandwidth,...

Scenario 42

This scenario reviews your knowledge of DLSw. Knowledge of DLSw configuration and RIF construct in DLSw environment is essential for the CCIE written test. Use Figure 4-35 to answer the following questions. 1 What is the RIF from Host A to Host C With DLSw, the RIF terminates at the local virtual ring. Frame travels from ring 0x01b, bridge 0x9, and ring 21 (0x015). 2 What is the RIF from Host A to Host B With DLSw, the RIF terminates at the local virtual ring. Frame travels from ring 0x01b,...

Scenarios Scenario

This scenario reviews your knowledge of RSRB. Knowledge of RSRB configurations and RIF constructs in RSRB environments is essential for the CCIE written test. Use Figure 4-34 to answer the following questions. 1 What is the RIF from Host A to Host C 2 What is the RIF from Host A to Host B 3 What is the correct configuration for Router A source-bridge remote-peer 21 tcp 1.1.1.1 source-bridge remote-peer 21 tcp 2.2.2.2 source-bridge remote-peer 21 tcp 3.3.3.3 interface loopback 0 ip address...

Signaling System 7 SS7

SS7 is a global ITU standard for telecommunications that allows voice network calls to be routed and controlled by central call-control centers. SS7 implements call setup, routing, and control, which ensure that intermediate and far-end switches are available when a call is placed. With SS7, telephone companies can implement modern consumer telephone services, such as caller ID, toll-free numbers, call forwarding, and so on. SS7 provides mechanisms for exchanging control, status, and routing...

SONET Interface Speeds

OC-192 9.952 Gbps Table 5-10 Framing Standards OC-192 9.952 Gbps Table 5-10 Framing Standards Password Authentication Protocol (PAP) Challenge Authentication protocol (CHAP) Encrypts passwords and uses three-way handshake Responsible for the transfer of video, voice, and data applications. The user plane is associated with flow control and error recovery. Responsible for interaction between the user plane, control plane, and the Responsible for call setup and maintenance, and call removal for...

SRB Operation

IBM developed SRB in the mid-80s as a way to bridge between Token Ring LANs. The IEEE adopted most of IBM's proposal into the IEEE 802.5 standard. As shown in Figure 4-20, in SRB, the source determines the route to the destination node by sending an explorer frame to it. SRB bridges do not keep a MAC table of hosts and do not worry about bridge loops. This is different to Ethernet transparent bridging where the bridges have the smarts of MAC layer destinations and determine the path by creating...

Static Route Configuration

Static routes are configured with the ip route global command. The format is as follows ip route destination-network mask destination-IP or ip route destination-IP mask egress-interface The following shows some options for the destination Router(config) ip route 10.0.0.0 255.0.0.0 A.B.C.D Forwarding router's address Ethernet IEEE 802.3 Null Null interface The following example reaches network 10.100.0.0 16 through IP address 192.172.1.1 router(config) ip route 10.100.0.0 255.255.0.0 192.172.1.1...

Static Versus Dynamic Routing Protocols

Static routes are manually configured on a router therefore, they cannot react based on network outages. The one exception to this is when the static route points to the outbound interface If the interface goes down, the static route is removed from the routing table. The size of today's networks prohibits the manual configuration of every router. This is why there are dynamic protocols that use algorithms that can react to network changes. The main benefit of static routing is that the router...

TCPIP Protocols Services and Applications

This section covers the different TCP IP protocols, services, and applications that are required knowledge for the CCIE written exam. When an IP packet needs to be sent over an Ethernet network, the sender must find out what 48-bit Media Access Control (MAC) physical address to send the frame to. Given the destination IP, ARP obtains the destination MAC. The destination MAC can be a local host or the gateway router's MAC address if the destination IP is across the routed network. ARP is...

The local Router ID is indicated in the first line the BGP table version is 66 and the local router ID is 17216991

Use the following router output to answer the questions in this scenario router show ip bgp neighbors 100.10.10.2 BGP neighbor is 100.10.10.2, remote AS 500, external link BGP version 4, remote router ID 100.10.10.10 BGP state Established, up for 00 00 22 Last read 00 00 21, hold time is 180, keepalive interval is 60 seconds Neighbor capabilities Route refresh advertised and received(new) Address family IPv4 Unicast advertised and received Received 4 messages, 0 notifications, 0 in queue Sent 4...

The OSI Reference Model

The discussion of the Open Systems Interconnection (OSI) model is always a mandatory topic in any internetworking book. The CCIE candidate must understand the OSI model, and in which OSI layer different networking protocols reside. The OSI model was developed by the International Standards Organization (ISO) in 1984 to describe the flow of data on a network. The model describes seven layers that start with the physical connection and end with the application. As shown in Figure 2-1, the seven...

Token Ring

Token Ring was developed by IBM for the forwarding of data on a logical unidirectional ring. Token Ring is implemented in the data-link layer. Token Ring networks move a small frame, called a token, around the network. Possession of the token grants the right to transmit data. After a station has the token, it modifies it into a data frame, appends the data for transmission, and sends the frame to the next station. No token is on the ring until the data frame is received by the source station...

Totally Stubby Area Configuration

In this section, you see what happens when you configure area 10 as a totally stubby area. First, area 10 is configured as a stub area, and the link-state database and routing tables of a router in the stub area are displayed. Next, area 10 is made a totally stubby area, with the same tables displayed. The following commands are added to all routers in area 10 to make the area a stub area. The link-state database and routing table on Router 7 had six summary network addresses and one external...

Transparent Bridge Functions

Transparent bridges have three primary functions To learn the MAC addresses of all nodes and their associated port To filter incoming frames whose destination MAC addresses are located on the same incoming port To forward incoming frames to the destination MAC through their associated port Table 4-16 WLAN Modes Basic Service Set (BSS) Also known as Infrastructure mode there is one Access Point. Independent Basic Service Also known as Ad-hoc mode there is no Access Point. Set (IBSS) Extended...

V

VAD (Voice Activity Detection), 551 VCs protocol multiplexing, 243 X.25, 200 verifying BGP neighbor establishment, 431 CPU operation, 65 IS-IS connectivity, 407-411 Version field (IP header), 269 viewing CPU type, 64-65 virtual links, 383 VLANs configuring, 90-91 private, 163 trunking, 153 VLSMs, 277-278 CIDR, 279 voice technologies Erlangs, 550 H.323 standard, 553 RTP, 551 SIP, 554-555 SS7, 555 VAD, 551 VoIP, 548 bandwidth utilization, 556 CNG, 551 dial peers, 549 dial plans, 549 IP...

Virtual Links

OSPF requires that all areas be connected to a backbone router. Sometimes, wide-area network (WAN) link provisioning or sudden failures can prevent an OSPF area from being directly connected to a backbone router. Virtual links can temporarily connect (virtually) the area to the backbone. As shown in Figure 8-5, Area 4 is not directly connected to the backbone. A virtual link is configured between Router A and Router B. Area 2 becomes the transit area, through which the virtual link is...

VLAN Trunking

Cisco's ISL is a proprietary trunk encapsulation method for carrying VLANs over FE or GE interfaces. ISL tags each frame to identify the VLAN it belongs to. The tag is a 30-byte header and CRC that is added around the FE frame. This includes a 26-byte header and 4-byte CRC. The header includes a 15-bit VLAN ID that identifies each VLAN. Although ISL is a point-to-point protocol (over FE and GE) between two Cisco devices, it can carry FDDI, Token Ring, and ATM in its payload. As shown in Figure...

Warning and Disclaimer

This book is designed to provide information about the CCIE Routing and Switching written exam. Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information is provided on an as is basis. The author, Cisco Press, and Cisco Systems, Inc. shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the...

Windows NT

Although newer implementations of NT (2000) implement TCP IP protocols and move away from WINS and NetBIOS, the CCIE candidate must still have knowledge of the legacy protocols in NT. Windows NT organizes clients and servers into NT domains. Each domain has a Primary Domain Controller (PDC) and one or more Backup Domain Controllers (BDC). Resources are given names that clients use to reach them. The four methods for a device to resolve friendly device names to IP addresses follow Windows...

Test Preparation Test Taking Tips and Using This Book

This section contains recommendations that can increase your probability of passing the CCIE written exam. If you do not already have the CCNA certification, you should pursue that certification before you attempt the CCIE tests. Even though CCNA certification is not a CCIE prerequisite, achieving CCNA certification gives you a chance to become familiarized with Cisco's computer-based test taking procedures and with Cisco test questions. Preparing for the CCNA exam helps you identify...

CCIE Certifications

The three CCIE certifications are as follows CCIE Routing and Switching (CCIE R& S) CCIE Communications and Services (CCIE C& S) This book prepares you for the written portion of the CCIE R& S exam and the general networking topics of the written portion of the CCIE C& S exam. The CCIE R& S certification is the traditional CCIE certification that involves routing and LAN WAN switching. The CCIE candidate must pass a two-hour written qualification test and a hands-on one-day lab...

Packet Voice

With the converging data and voice networks, the introduction of packet-voice technology provides the ability for companies to save toll charges on voice telephone calls. Voice is digitized (coded) into packets, cells, or frames sent as data throughout the networks, and converted back to analog voice. Coding for this is covered in the Codecs section. An example of packetized voice is when calls are placed on phones that are attached to routers, as shown in Figure 12-1. The routers digitize the...

Classless Interdomain Routing CIDR and Address Aggregation

CIDR permits the address aggregation of classful networks. This is accomplished by using the common bits between networks. The networks need to be continuous and have a common bit boundary. BGP version 4 supports CIDR, which permits the reduction of the size of routing tables by creating aggregated routes that result in supernets. CIDR eliminates the concept of network classes within BGP and supports the advertising of IP prefixes. With CIDR, ISPs assign groups of Class C networks to enterprise...

Cost

OSPF and IS-IS use the cost metric, which is can be derived from the bandwidth of the interface. IS-IS assigns a default cost of 10 for all interfaces. It does not use the auto cost determination that OSPF uses. To calculate cost in OSPF, use the following formula 108 BW, where BW is the default or configured bandwidth of the interface. For Ethernet, calculate the cost as follows BW 10 Mbps 10 x 106 107 Cost (Ethernet) 108 107 10 The sum of all the costs to reach a destination is the metric for...

RIPv2 Configuration

Example 7-10 shows the configuration of Router8 by using RIPv2. You use the version 2 command to enable RIPv2. Use plain text passwords for route authentication by using the key-chain named ccie. The RIP authentication is configured on Ethernet 0 by using the ip rip authentication command. Example 7-10 Configuration of Router8 Example 7-11 shows the output of the show ip route command on Router8. A mask accompanies the learned networks 172.16.4.0 30 and 172.16.2.0 24. Example 7-11 show ip route...

IP Access List Configuration

Cisco IOS contains two types of access lists for IP. The first is the standard access list the second is the extended access list. Each access list is configured using an access list number. Standard access lists are configured with numbers from 1 to 99. Extended access lists are configured from 100 to 199. The access list is a sequential list of permit or deny conditions. The router tests the packets' IP addresses and port numbers against each condition in the list one by one. The first match...

Real Time Transport Protocol RTP operates in the transport layer of the OSI model

7 Which H.323 protocol is responsible for call setup and signaling The Q.931 standard defines the procedures responsible for call setup and signaling. 8 Which unit measures the number of voice calls in one hour Erlangs is the unit that describes the number of calls in one hour. 9 Which feature does not transmit packets when there is silence Voice Activity Detection reduces traffic by not transmitting packets when there is silence in voice conversations. b. The RTP, TCP, and IP headers c. The...

ISIS show Commands

After all ISs are configured, several show commands can verify connectivity when using IS-IS. These commands are as follows All the configurations in this section refer to Figure 8-10. The output of these commands is displayed throughout this section. IS-IS routes are marked with an i. L1 and L2 mark L1 and L2 routes. IS-IS routes use 115 as an administrative distance in Cisco routers. Example 8-22 displays the routing table on Router 8. Codes C - connected, S - static, I - IGRP, R - RIP, M -...