Advanced OSPF

OSPF is an industry-standard routing protocol developed by the Internet Engineering Taskforce (IETF) as a replacement for legacy routing protocols that did not scale well in large environments. OSPF supports the following features Variable-length subnet masks (VLSM). The use of areas to minimize Central Processing Unit (CPU) and memory requirements. A simple cost metric that you can manipulate to support up to six equal cost paths. The number of paths is limited only by the Internet Operating...

Basic Border Gateway Protocol BGP4 Defined

The different versions of BGP range from 1-4 the industry standard is Version 4. You can, however, configure BGP Versions 2, 3, and 4 on a Cisco IOS router. The default standard is BGP Version 4 and is referred to as BGP4. BGP4 is defined in industry standard RFC 1771. BGP enables you to create an IP network free of routing loops among different autonomous systems. An AS is a set of routers under the same administrative control. BGP is called a path-vector protocol because BGP carries a...

Basic IBGP Configuration 05 Hours

Configure IBGP on all routers in your network Do not use any WAN IP interfaces for IBGP sessions, as your network is prone to failures across the Frame Relay cloud. Configure R5 and R8 as route reflectors, and ensure that all traffic uses a preferred path through router R5. Minimize IBGP configurations as much as possible. Do not disable BGP synchronization. Use AS 2002 on all IBGP routers. As long as there is IP connectivity in your network, ensure BGP is active in all routers. Using the...

Basic Internet Protocol

IP is a term widely used in today's networking world to describe a Network layer protocol that logically defines a distinct host or end systems such as a PC or router with an IP address. An IP address is configured on end systems to allow communication between hosts that are geographically dispersed. An IP address is 32 bits in length with the network mask or subnet mask (also 32 bits in length) defining the host and subnet portion. A subnet is a network that you, as network administrator,...

Basic ISDN Configuration 05 Hours

ISDN switch type basic-5ess Configure the ISDN interfaces on R1 and R4 as follows Only when S0 of R1 goes down, R1 should place an outgoing call to R4. R4 cannot call R1 under any circumstances. Use PPP encapsulation and the strongest authentication available. Ensure that you never bring up more than one B channel to keep costs to a minimum. When the Frame Relay link is restored, bring down the ISDN link after 25 minutes. When the ISDN is active, all routers must be able to ping and telnet the...

BGP Attributes

BGP has a number of complex attributes used to determine a path to a remote network. These attributes allow greater flexibility and enable a complex routing decision to ensure that the path to a remote network is the best possible path. The network designer can also manipulate these attributes. BGP, when supplied with multiple paths to a remote network, always chooses a single path to a specific destination. (Load balancing is possible with static routes.) BGP always propagates the best path to...

BGP Routing Configuration 5 Hours

The aim of this exercise is to configure IBGP among the routers in your IGP network (Routers R1-R6) and minimize the number of IBGP peer sessions for easy configuration. R1 is the focal point for all IBGP peering sessions and has two EBGP connections to the same ISP provided for redundancy purposes. You will also be asked to configure BGP attributes to influence routing decisions made in your IBGP network and also influence which path the Internet ISP routers, ISP1 and ISP2, choose to use for...

Catalyst Ethernet Switch Setup I 025 Hours

Configure the Ethernet switch for five VLANs VLAN 2, named VLAN_A, is connected to R1 and R2. VLAN 3, named VLAN_B, is connected to R3. VLAN 4, named VLAN_C, is connected to R4. VLAN 6, named VLAN_D, is connected to R6 and R9. VLAN 7, named VLAN_E, is connected to R7. Using VLAN_A, configure the management interface SC0 with the address 131.108.0.2 25. Ensure that all devices in your network can telnet to the switch even if R1 or R2 is down. Ensure that the switch is configured in the VTP...

Catalyst Ethernet Switch Setup II 025 Hours

Configure the following spanning-tree parameters on the Catalyst 6509 Ensure that the switch never becomes the root bridge on VLAN_D. Ensure that the switch has the best possible chance of becoming the root bridge in VLAN_E. Set all Ethernet ports to forward data immediately after a device is plugged in or activated. Set the hello time on VLAN_B to 10 seconds. Configure the following miscellaneous parameters Disable Cisco Discovery Protocol on ports 3 1-8. Ensure that any IP phones installed or...

Catalyst Switch Setup 6SG9 G2S Hours

Configure the Ethernet switch for seven VLANs and cable a catalyst switch for the following VLAN number assignments VLAN 100 is connected to R1 E0 0. VLAN 200 is connected to R2 E0 0. VLAN 300 is connected to R3 E0. VLAN 400 is connected to R4 E0. VLAN 500 is connected to R5 E0. VLAN 550 is connected to R5 E1. VLAN 600 is connected to R6 E0. Configure the management interface (or sc0) on the switch with the IP address 133.33.1.2 29, and ensure that all routers can Telnet to the switch after you...

Chapter

1 Given the following host address and subnet mask combinations, determine the subnet address and broadcast addresses 151.108.100.67 255.255.255.128 171.199.100.10 255.255.255.224 161.88.40.54 255.255.255.192 A Performing a logical AND reveals the following Subnet 131.18.1.0 and broadcast address 131.108.1.255 Subnet 151.108.100.0 and broadcast address 151.108.1.127 Subnet 171.199.100.0 and broadcast address 171.199.100.31 Subnet 161.88.40.0 and broadcast address 161.88.40.63 2 Given the...

Routing Principles

This chapter describes how to configure a Cisco Internet Operating System (IOS) router for IP routing and explains common troubleshooting techniques by covering the following Internet Protocol (IP) routing tables Classful and classless routing Using show, debug, ping, and trace commands This chapter focuses on a number of objectives relating to the CCNP routing principles. Understanding basic routing principles not only applies to the CCNP certification but to all Cisco-based certification. A...

Basic Open Shortest Path First

Chapter 3 covers basic OSPF routing principles and how OSPF routing is fundamental for any small or large network. Basic OSPF terminology is described and configured. The chapter briefly explains why OSPF is considered an improved routing protocol over RIP by explaining how OSPF discovers, chooses, and maintains routing tables. Nonbroadcast multiaccess (NBMA) is demonstrated using a common network topology. The issues and challenges facing network designers when configuring OSPF in larger...

Advanced OSPF and Integrated Intermediate Systemto Intermediate System

This chapter focuses on a number of objectives falling under the CCNP routing principles. Understanding advanced OSPF routing principles not only applies to the CCNP Routing certification but to all Cisco-based certifications, and it lays the foundations for future certifications in any field of networking. Chapter 3, Basic Open Shortest Path First, started by covering some of the basic Open Shortest Path First (OSPF) concepts. This chapter covers some of the ways OSPF deals with large Internet...

Enhanced Interior Gateway Routing Protocol

Now that you have learned about and practiced with some basic and advanced routing protocols, this chapter covers a protocol developed by Cisco Systems used on Cisco IOS routers only. The chapter starts by covering the basic Enhanced Interior Gateway Routing Protocol (EIGRP) concepts. It then explains of how EIGRP can be configured and monitored. You discover how EIGRP learns about new neighbors and how EIGRP operates in NBMA networks. The five scenarios in this chapter help to complete your...

Basic Border Gateway Protocol

This chapter focuses on Border Gateway Protocol Version 4 (BGP4). BGP4 is covered only slightly in the CCNP routing examination. However, this chapter covers BGP4 in a little more detail to ensure that you have a good appreciation of the way networks connect to the Internet or in large organizations. This chapter covers the basics of Border Gateway Protocol (BGP). Chapter 7, Advanced BGP, covers more advanced BGP topics and scenarios. This chapter contains five practical scenarios to complete...

Advanced BGP

This chapter focuses on the advanced features of Border Gateway Protocol Version 4 (BGP4) and builds on the material presented in Chapter 6, Basic Border Gateway Protocol. This chapter covers BGP4 in even greater detail than the CCNP Routing Exam does in order to ensure that you have a good appreciation for how networks are connected to the Internet. BGP is a routing protocol designed for use in large IP networks. The five practical scenarios in this chapter complete your understanding and...

Route Redistribution and Optimization

This chapter covers the issues and challenges facing networks when information from one routing algorithm is redistributed into another. In such a situation, information can be controlled to ensure that the network is routing Internet Protocol (IP) as correctly and efficiently as possible. Routing with one particular algorithm is difficult enough, and managing and controlling many different routing algorithms that might be used in a network is a considerable challenge. The CCNP Routing exam...

CCNP Routing Self Study

This chapter is designed to assist you in your final preparation for the Routing exam by providing you an extensive lab scenario that incorporates many of the technologies and concepts covered in this book. The lab presented here requires a broad perspective and knowledge base. This means that any knowledge you have acquired through the practical examples presented in this guide and real-life network implementations will help you achieve the end goal a routable network according to the set...

Chapter Organization

Each chapter (except Chapter 9) contains brief background information, five scenarios with detailed explanations and full Cisco IOS configurations, a Practical Exercise with solutions, and review questions. This book also contains four appendixes. In each chapter, following the scenarios, one practical lab requires you to configure the network on your own. The solution contains the full configuration, so readers without network equipment can still follow the...

Cisco IOS Command Syntax for Redistribution

To configure redistribution among routing protocols, the following command is used under the routing process configuration redistribute protocol process-id level-1 level-1-2 level-2 as-number metric metric-value metric-type type-value match internal external 1 external 2 tag tag-value route-map map-tag weight number-value subnets The redistribution command syntax is further explained in Table 8-2. The redistribution command syntax is further explained in Table 8-2. Table 8-2. Command Syntax for...

Classful and Classless Routing Protocols

Routing protocols can also be described as classful and classless. Classful addressing is the use of Class A, Class B, and Class C addresses. (Class D is reserved for multicasts, and Class E is reserved for future use.) Class A, B, and C addresses define a set number of binary bits for the subnet portion. For example, a Class A network ranges from 1-127 and uses a subnet mask of 255.0.0.0. A Class B network uses the mask 255.255.0.0, and Class C uses 255.255.255.0. Classful routing protocols...

Command Syntax Conventions

The conventions used to present command syntax in this book are the same conventions used in the Cisco IOS Command Reference, as follows Boldface indicates commands and keywords that are entered literally as shown. In examples (not syntax), boldface indicates user input (for example, a show command). Italics indicates arguments for which you supply values. Square brackets and indicate optional elements. Braces and contain a choice of required keywords. Vertical bars ( ) separate alternative,...

Configuring OSPF in a Single Area

When configuring any OSPF router, you must establish which area assignment to enable the interface for. OSPF has some basic rules when it comes to area assignment. OSPF must be configured with areas. The backbone area 0, or 0.0.0.0, must be configured if you use more than one area assignment. You can configure OSPF in one area you can choose any area, although good OSPF design dictates that you configure area 0. To enable OSPF on a Cisco router and advertise interfaces, the following tasks are...

Configuring Route Reflectors

Configuring route reflectors is a relatively straightforward exercise. On the route reflector, apply the following IOS command to all IBGP peers neighbor ip-address route-reflector-client Next, configure the four routers in Figure 7-2 for route reflectors with R1 configured as the route reflector. Example 7-1 displays the configuration on R1, which is configured as the route reflector, to R2 (peer address 131.108.2.2), R3 (peer address (131.108.3.2), and R4 (peer address 131.108.4.2).

Controlling Routing Updates

By now, you have discovered that minimizing routing table sze and simplifying how routers choose the next hop destination path are critical for a well-tuned IP network. When routing information from one routing protocol, such as Open shortest Path First (OSPF), is redistributed into Internet Gateway Routing Protocol (IGRP), for example, you must always be mindful of possible routing loops. A routing loop is a path to a remote network that alternates between two routers, each of which assumes...

DLSw Configuration 075 Hours

Configure DLSw+ on R1, R3, R5, and R8 Rings 100, 500, and 800 should have connectivity to VLAN 2 and 3. SNA hosts reside on Rings 100 and 500. Hosts on Ring 500 are used only when Ring 100 is not reachable. Ensure that all routers peer to R1 and only in a network failure do DLSw+ circuits terminate on R5. DLSw+ peers should be active only when user-based traffic (SNA NetBIOS) is sent or received. If IP connectivity exists, ensure that DLSw+ remains established. Use a different virtual ring...

EBGP Configuration 025 Hours

Configure EBGP on R5 and R8 as follows R5's remote peer is 171.108.1.2 24 and remote AS is 1024. R8's remote peer is 191.200.1.2 30 and remote AS is 4345. ISP1 and ISP2 are advertising the full Internet routing table. Ensure that the only route accepted is a default route and routes of the form 110.100.0.0 to 121.110.255.255. Set all routes in the range 110.100.0.0 to 121.110.255.255 with the following attributes Ensure that BGP origin is set to IGP. Prepend with paths with the AS paths 1000...

EIGRP Configuration 05 Hours

Configure EIGRP on Routers R3, R7, and R8 only Configure EIGRP in domain 333 between the serial link on R7 to R8, R3 to R8, and Ring 800. Summarize as much as possible to reduce the redistributed routes into OSPF, but ensure that all routes appear in the IGRP and RIP domains. Ensure that EIGRP is authenticated across the Frame Relay connections. Redistribute the EIGRP routes into OSPF domains with a cost metric of 1000 seen on all OSPF routers. Ensure that R3 never sends any updates across the...

EIGRP Configuration 15 Hours

Configure EIGRP on Routers R1, R4, and R6 Configure the link between R4 and R6 in EIGRP domain 1. Configure VLAN 600 to reside in domain 2. Redistribute between EIGRP 1 and 2 and ensure network connectivity. Ensure that the IGRP domain and OSPF domain have these networks present in their respective IP routing tables. Ensure that VLAN 600 (133.33.6.0 24) and the loopback subnet on R6 (133.33.206.0 24) OSPF cost metric are set to 1000. (Metric type 2 by default is configured when redistributing...

EIGRP in NBMA Environments

You can successfully configure EIGRP over NBMA networks if you apply the following rules EIGRP traffic should not exceed the committed information rate (CIR). EIGRP aggregated traffic over all virtual circuits should not exceed the access line speed. The allocated bandwidth for EIGRP must be the same on each virtual circuit between two remote routers. The use of the bandwidth command should reflect the true speed of any interface. The bandwidth command is used in EIGRP metric calculation and...

EIGRP Route Summarization and Large IP Network Support

EIGRP supports the use of summarization to conserve IP routing table size. Summarization in EIGRP can be configured on any router in the same AS. By default, EIGRP automatically summarizes at the major network boundaries. To perform static summarization, you must disable this feature with the no auto-summary IOS command, under the routing process. To manually summarize networks, you must advertise the supernet, for example, on an interface level with the ip summary address eigrp autonomous...

Example 1 1 Summary with EIGRP

Interface serial 0 ip summary-address eigrp 1 131.108.1.0 255.255.248.0 Example 1-1 applies a summary on the serial interface. Also note that the EIGRP autonomous system number is 1, matching the configuration on the router because you can have more than one EIGRP process running. The actual summary is 131.108.1.0 255.255.248.0, which replaces the seven individual routers numbered 131.108.1-7.0 24 with one simple route. OSPF allows summarization manually under the OSPF process ID. Now look at...

Example 1 3 IP Configuration on R1

R1(config-if) ip address 161.108.1.1 255.255.255.0 4w1d LINK-3-UPDOWN Interface Ethernet0 0, changed state to up 4w1d LINEPROTO-5-UPDOWN Line protocol on Interface EthernetO Figure 1-3. IP Routing on Cisco Routers Figure 1-3. IP Routing on Cisco Routers When you enable the Ethernet interface with the command no shutdown, the IOS message tells you the Ethernet interface and the line protocol are up. To see these messages remotely, enable terminal monitor on any VTY lines. Also, by default, all...

Example 1 9 Eigrp Summary

R1(config-router) no auto-summary R1(config) interface serial 0 0 R1(config-if) ip summary-address eigrp 1 151.100.1.0 255.255.255.240 R1(config-if) ip summary-address eigrp 1 151.100.16.0 255.255.255.0 In Example 1-9, the router R1 sends only two updates one for the networks ranging from 151.100.1.0 to 151.100.15.0 and another for 151.100.16.0. These two are instead of 16 separate IP route entries. Even in a small scenario like this, you saved 14 IP route entries. Reducing IP routing tables...

Example 112 Sample Configuration

R1(config) interface ethernet 0 0 R1(config-if) ip summary-address eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) R1(config-if) ip summary-address eigrp 1 171.100.1.0 255.255.255.248 R1(config-if) ip summary-address eigrp Enhanced Interior Gateway Routing Protocol (EIGRP) R1(config-if) ip summary-address eigrp < 1-65535> Autonomous system number R1(config-if) ip summary-address eigrp 1 R1(config-if) ip summary-address eigrp 1 171.100.1.0 255.255.255.248 Example 1-12 displays the...

Example 14 show interface ethernet e00 on R1

Ethernet0 0 is up, line protocol is up Interface is up and active Hardware is AmdP2, address is 0001.9645.ff40 (bia 0001.9645.ff40) Internet address is 161.108.1.1 24 configure IP address MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usee, rely 255 255, load 1 255 Encapsulation ARPA, loopbaek not set, keepalive set (10 see) ARP type ARPA, ARP Timeout 04 00 00 Last input 00 00 21, output 00 00 02, output hang never Last clearing of show interface counters never Queueing strategy fifo Output queue 0...

Example 16 show interfaces ethernet

Ethernet0 0 is up, line protocol is up Hardware is AmdP2, address is 0001.9645.ff40 (bia 0001.9645.ff40) MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usee, rely 255 255, load 1 255 Encapsulation ARPA, loopbaek not set, keepalive set (10 see) truneated Example 1-6 does not show the secondary addressing on R1. Unfortunately, the Cisco IOS does not display IP secondary addressing, and the only way to view any secondary addressing is to view the configuration. Example 1-7 displays the full working...

Example 18 IP Configuration on R1 with Four Subnets

R1(config-if) ip address 131.108.1.1 255.255.255.192 R1(config) interface ethernet 0 1 R1(config-if) ip address 131.108.1.65 255.255.255.192 R1(config) interface ethernet 0 2 R1(config-if) ip address 131.108.1.129 255.255.255.192 R1(config) interface ethernet 0 3 R1(config-if) ip address 131.108.1.193 255.255.255.192 The mask is 255.255.255.192 in Example 1-8. The mask or subnet mask is derived from the six bits you borrowed to extend the Class B address 131.108.1.0. Binary 1100000 is 192. To...

Example 21 show ip route Command on R1

C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate 172.108.0.0 24 is subnetted, 2 subnets C 172.108.1.0 is directly connected, EthernetO C 172.108.2.0 is directly connected, Ethernet1 In Example 2-1, the C on the left side of the IP...

Example 210 show ip route on R2

- static, I - IGRP, R - RIP, M - mobile, B - EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate U - per-user static route, o - ODR Gateway of last resort is not set 131.108.0.0 16 is variably subnetted, 9 subnets, 3 masks U - per-user static route, o - ODR Gateway of last resort is not set 131.108.0.0 16 is...

Example 213 debug ip rip Output on R1

RIP protocol debugging is on R1 debug ip rip events 2w1d 2w1d (131 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d (131 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d 2w1d Update sent via Serial0 1 Update contains 5 routes sending v1 update to 255.255.255.255 via Loopback1 sending v1 update to 255.255.255.255 via Loopback2 .1) subnet 131.108.5.0, metric 1 subnet 131.108.4.0, metric 1 subnet 131.108.3.0, metric 1 subnet 131.108.2.0, metric 2 subnet 131.108.1.0, metric 1 Example 2-13 displays routing...

Example 215 R1s RIP Entries Only

131.108.0.0 24 is subnetted, 9 subnets R 131.108.9.0 120 1 via 131.108.3.2, 00 00 20, Serial0 1 As you can see in Example 2-15, R2 is advertising the Class B subnetted networks 131.108.2.0 24, 131.108.7.0 24, 131.108.8.0 24, and 131.108.108.9.0 24 through the next hop address 131.108.3.2. The outgoing interface is serial 0 1. RIP works in this environment because all the networks are Class C. Another important field described in the IP routing table is the administrative distance and the...

Example 217 show ip route on R1

131.108.0.0 16 is variably subnetted, 5 subnets, 2 masks C 131.108.6.0 24 is directly connected, Loopback2 C 131.108.5.0 24 is directly connected, Loopback1 C 131.108.4.0 24 is directly connected, Loopback0 131.108.3.0 30 is directly connected, Serial0 1 131.108.1.0 24 is directly connected, Ethernet0 0 Notice what happens to the IP RIP routes. Also notice that the serial link to R2 through Serial 0 1 is a 30 subnet, whereas all the other directly connected interfaces are 24. Because you use a...

Example 219 R1s IP Route Table with RIPv2 Enabled

131.108.0.0 16 is variably subnetted, 9 subnets, 2 masks R 131.108.9.0 24 120 1 via 131.108.3.2, 00 00 00, Serial0 1 R 131.108.8.0 24 120 1 via 131.108.3.2, 00 00 00, Serial0 1 R 131.108.7.0 24 120 1 via 131.108.3.2, 00 00 00, Serial0 1 C 131.108.6.0 24 is directly connected, Loopback2 C 131.108.5.0 24 is directly connected, Loopback1 C 131.108.4.0 24 is directly connected, Loopback0 C 131.108.3.0 30 is directly connected, Serial0 1 R 131.108.2.0 24 120 1 via 131.108.3.2, 00 00 00, Serial0 1 C...

Example 22 Routing Protocols You Can Enable on a Cisco Router

Traffic-engineering Traffic engineered routes traffic-engineering Traffic engineered routes Border Gateway Protocol (BGP), EIGRP, IGRP, Intermediate System-to-Intermediate System (IS-IS) Protocol, OSPF, and RIP are dynamic routing protocols and are all covered in this book. You can use static routing to minimize large routing tables and can manually configure it to override dynamic information. When you configure multiple routing algorithms on a Cisco router, deciding which path to take is...

Example 220 R1 Full Configuration

Interface LoopbackO ip address 131.108.4.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 131.108.5.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 131.108.6.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 no ip directed-broadcast interface Serial0 1 ip address 131.108.3.1 255.255.255.252 no ip directed-broadcast clockrate 128000 transport input none line aux 0 line vty 0 4 end

Example 221 R2 Full Configuration

Interface Loopback0 ip address 131.108.7.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 131.108.8.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 131.108.9.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.2.1 255.255.255.0 interface Serial1 1 ip address 131.108.3.2 255.255.255.252 ip directed-broadcast line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 i In both cases, the command no ip...

Example 223 IP Address Change and Disabling Ip Rip on R2

R2(config-if) ip address 131.108.4.4 255.255.255.255 R2(config-if) ip address 131.108.4.5 255.255.255.255 R2(config-if) ip address 131.108.4.6 255.255.255.255 R2(config-if) exit it is not required to exit interface mode to remove RIP Now that RIP is removed and the IP addressing is redone, configure R1 for OSPF by using the process number 1 and for R2 using process number 2. Example 2-24 and Example 2-25 display the new OSPF configurations on R1 and R2.

Example 225 OSPF Configuration on R2

R2(config-router) network 131.108.2.1 0.0.0.255 area 2 R2(config-router) network 131.108.4.4 0.0.0.0 area 2 R2(config-router) network 131.108.4.5 0.0.0.0 area 2 R2(config-router) network 131.108.4.6 0.0.0.0 area 2 R2(config-router) network 131.108.3.2 0.0.0.0 area 0 The wildcard mask 0.0.0.0 indicates an exact match. The wildcard mask 0.0.0.255 means the first three octets must match and the last octet does not matter. For example, the command network 131.108.1.0 0.0.0.255 means 131.108.1.1 to...

Example 226 IP Routing Table on R1

131.108.0.0 16 is variably subnetted, 9 subnets, 3 masks 131.108.0.0 16 is variably subnetted, 9 subnets, 3 masks You can see from Example 2-26 that R1 discovers four remote networks (R2's Ethernet and three loopback interfaces) through OSPF. In addition, there are also the directly attached links. R1 dynamically learns the remote networks on R2 through the next hop address of 131.108.3.2 and the outbound interface Serial 0 1. Notice once again the administrative distance and metric pairing. In...

Example 228 28 R1 Full Configuration

Ip subnet-zero no ip domain-lookup interface LoopbackO ip address 131.108.4.1 255.255.255.255 no ip directed-broadcast interface Loopback1 ip address 131.108.4.2 255.255.255.255 no ip directed-broadcast interface Loopback2 ip address 131.108.4.3 255.255.255.255 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 no ip directed-broadcast interface Serial0 1 ip address 131.108.3.1 255.255.255.252 clockrate 128000 router ospf 1 network 131.108. network 131.108....

Example 229 R2 Full Configuration

Interface Loopback0 ip address 131.108.4.4 255.255.255.255 interface Loopbackl ip address 131.108.4.5 255.255.255.255 interface Loopback2 ip address 131.108.4.6 255.255.255.255 interface Ethernet0 0 ip address 131.108.2.1 255.255.255.0 interface Serial1 1 ip address 131.108, line con 0 exec-timeout 0 0 transport input none line aux 0 line vty 0 4 no login

Example 230 IP Addressing on R1

R1(config-if) ip address 199.100.1.1 255.255.255.0 R1(config-if) ip address 199.100.4.1 255.255.255.0 R1(config-if) ip address 199.100.5.1 255.255.255.0 R1(config-if) ip address 199.100.6.1 255.255.255.0 R1(config-if) ip address 199.100.3.1 255.255.255.0 Example 2-31 displays the IP address changes made to router R2.

Example 231 IP Addressing on R2

R2(config-if) ip address 199.100.2.1 255.255.255.0 R2(config-if) ip address 199.100.7.1 255.255.255.0 R2(config-if) ip address 199.100.8.1 255.255.255.0 R2(config-if) ip address 199.100.9.1 255.255.255.0 R2(config-if) ip address 199.100.3.2 255.255.255.0 Example 2-32 displays the IOS commands required to enable IGRP in AS 1. When using a class C network with the default class C mask, you must specify each network in IGRP.

Example 234 R1 IP Routing Table

C 199.100.4.0 24 is directly connected, Loopback0 On R1, you can see four remote IGRP networks learned through the next hop address 199.100.3.2 (R1's link to R2) and through the outbound interface Serial 0 1. R1 dynamically learns the remote networks on R2 through the next hop address of 131.108.3.2 and the outbound interface Serial 0 1. Notice the administrative distance and metric pairing. In the case of IGRP, the administrative distance is 100 (more trusted than RIP at 120 and OSPF at 110)...

Example 235 Full Configuration for R1

Interface LoopbackO ip address 199.100.4.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 199.100.5.1 255.255.255.0 interface Loopback2 ip address 199.100.6.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 199.100.1.1 255.255.255.0 no ip directed-broadcast interface Serial0 1 ip address 199.100.3.1 255.255.255.0 clockrate 128000 router igrp 1 network 199.100.1.0 network 199.100.3.0 network 199.100.4.0 network 199.100.5.0 network 199.100.6.0...

Example 236 Full Configuration for R2

Interface Loopback0 ip address 199.100.7.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 199.100.8.1 255.255.255.0 interface Loopback2 ip address 199.100.9.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 199.100.2.1 255.255.255.0 no ip directed-broadcast no cdp enable interface TokenRing0 0 no ip address no ip directed-broadcast shutdown ring-speed 16 no cdp enable interface Serial1 1 ip address 199.100.3.2 255.255.255.0 ip directed-broadcast...

Example 237 Configuring EIGRP on R1

Iremove igrp 1 R1(config) router eigrp 1 R1(config-router) network 131.108.1.0 Idefine network in eigrp R1(config-router) network 199.100.4.0 R1(config-router) network 199.100.5.0 R1(config-router) network 199.100.6.0 R2(config-router) network 131.108.1.0 R1(config-router) network 199.9.3.0 R1(config-router) int e 0 0 I change IP address on R1 e0 0 R1(config-if) ip address 131.108.1.1 255.255.255.128 Example 2-38 displays the removal of IGRP and the enabling of EIGRP in AS 1 on Router R2.

Example 238 Configuring EIGRP on R2

R2(config) no router igrp 1 R2(config) router eigrp 1 R2(config-router) exit R2(config) int e 0 0 R2(config-if) ip address 131.108.1.129 255.255.255.128 R2(config-if) router eigrp 1 R2(config-router) network 199.100.7.0 R2(config-router) network 199.100.8.0 R2(config-router) network 199.100.9.0 R2(config-router) network 131.108.1.0 R2(config-router) network 199.9.3.0 Notice IGRP is removed first and the AS number is the same in R1 and R2 so that both routers can share information. You have not...

Example 239 R1s IP Routing Table

D 199.100.9.0 24 90 2297856 via 199.100.3.2, 00 00 55, Serial0 1 D 199.100.8.0 24 90 2297856 via 199.100.3.2, 00 00 55, Serial0 1 131.108.0.0 16 is variably subnetted, 2 subnets, 2 masks D 131.108.0.0 16 is a summary, 00 00 55, Null0 D 199.100.7.0 24 90 2297856 via 199.100.3.2, 00 00 55, Serial0 1 R1 On R1, you can see four remote EIGRP networks learned through the next hop address 199.100.3.2 (R1's link to R2) and through the outbound interface Serial 0 1. One of these routes is to nullO. R1...

Example 24 show controllers s01 on R2

CD2430 Slot 1, Port 0, Controller 0, Channel 0, Revision 15 Channel mode is synchronous serial idb 0x61209474, buffer size 1524, V.35 DTE cable output omitted The output in Example 2-4 is different from that of Example 2-3 because this scenario uses different model routers for R1 (2600) and R2 (3600), and the cable types used on the routers are V.35. Router R2 has the data terminal equipment (DTE), so R2 requires a clocking source. In this case, R1, the DCE, supplies the clock. To configure the...

Example 240 Ping Request from R1

Sending 5, 100-byte ICMP Echos to 131.108.1.130, timeout is 2 seconds The response from the router in Example 2-40 is no reply ( ) or, in this case, the packets are sent to null0. Packets sent to null0 are discarded. To solve the problem of packets being discarded, you need to disable automatic summarization. Configure R1 and R2 to disable automatic summarization as in Example 2-41.

Example 242 show ip route eigrp on R1

D 199.100.9.0 24 90 2297856 via 199.100.3.2, 00 00 01, Serial0 1 D 199.100.8.0 24 90 2297856 via 199.100.3.2, 00 00 01, Serial0 1 131.108.0.0 25 is subnetted, 2 subnets D 131.108.1.128 90 2195456 via 199.100.3.2, 00 00 01, Serial0 1 D 199.100.7.0 24 90 2297856 via 199.100.3.2, 00 00 01, Serial0 1 R1 ping 131.108.1.129 Sending 5, 100-byte ICMP Echos to 131.108.1.129, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 16 ms R1 Notice that the 131.108.1.128 25 is...

Example 243 R1 Full Configuration

Interface Loopback0 ip address 199.100.4.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 199.100.5.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 199.100.6.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.1 255.255.255.128 interface Serial0 1 ip address 199.100.3.1 255.255.255.0 no ip directed-broadcast clockrate 128000 router eigrp 1 network 131.108.0.0 network 199.100.3.0 network 199.100.4.0 network...

Example 244 R2 Full Configuration

No ip domain-lookup interface Loopback0 ip address 199.100.7.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 199.100.8.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 199.100.9.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.129 255.255.255.128 no ip directed-broadcast no cdp enable interface Serial1 1 ip address 199.100.3.2 255.255.255.0 ip directed-broadcast

Example 246 R2 IP Address Changes

R2(config-if) ip address 131.108.7.1 255.255.255.255 R2(config-if) ip address 131.108.8.1 255.255.255.128 R2(config-if) ip address 131.108.9.1 255.255.255.224 R2(config-if) ip address 131.108.8.129 255.255.255.128 R2(config-if) ip address 131.108.3.2 255.255.255.0 On R1, configure IGRP again IGRP is classful, so you need to enable IGRP only in AS 1. R2 runs both IGRP and OSPF hence redistribution is required. Example 2-47 enables IGRP in AS 1 on R1.

Example 248 Enabling IGRP on R1

R2(config) router igrp 1 R2(config-router) network 131.108.0.0 R2(config) router ospf 1 R2(config-router) network 131.108.8.0 0.0.0.255 area 0 R2(config-router) network 131.108.7.1 0.0.0.0 area 0 R2(config-router) network 131.108.9.1 0.0.0.0 area 0 R2(config-router) no network 131.108.8.0 0.0.0.255 area 0 R2(config-router) network 131.108.8.1 0.0.0.0 area 0 R2(config-router) network 131.108.8.129 0.0.0.0 area 0 You also need to configure redistribution on R2 so that R1 discovers the OSPF...

Example 249 Enabling Redistribution on R2

R2(config-router) redistribute ospf 1 metric < 1-4294967295> Bandwidth metric in Kbits per second R2(config-router) redistribute ospf 1 metric 128 < 0-4294967295> IGRP delay metric, in 10 microsecond units R2(config-router) redistribute ospf 1 metric 128 20000 < 0-255> IGRP reliability metric where 255 is 100 reliable R2(config-router) redistribute ospf 1 metric 128 20000 255 < 1-255> IGRP Effective bandwidth metric (Loading) where 255 is 100 loaded R2(config-router)...

Example 25 IP Address Configuration on R1

2w1d LINK-3-UPDOWN Interface LoopbackO, changed state to up 2w1d LINEPROTO-5-UPDOWN Line protocol on Interface LoopbackO, changed state to up R1(config-if) ip address 131.108.4.1 255.255.255.0 R1(config-if) interface loopback 1 2w1d LINK-3-UPDOWN Interface Loopback1, changed state to up 2w1d LINEPROTO-5-UPDOWN Line protocol on Interface Loopbackl, changed state to up R1(config-if) ip address 131.108.5.1 255.255.255.0 R1(config-if) interface loopback 2 2w1d LINK-3-UPDOWN Interface Loopback2,...

Example 251 IP Routing Table on R2

C 199.100.8.0 24 is directly connected, Loopback1 131.108.0.0 16 is variably subnetted, 8 subnets, 4 masks C 131.108.8.128 25 is directly connected, Ethernet0 0 C 131.108.8.0 27 is directly connected, Loopback2 via 131.108.3.1, 00 00 52, Serial1 1 C 131.108.7.1 32 is directly connected, Loopback0 via 131.108.3.1, 00 00 52, Serial1 1 via 131.108.3.1, 00 00 52, Serial1 1 C 131.108.3.0 24 is directly connected, Serial1 1 via 131.108.3.1, 00 00 53, Serial1 1 On R1 in Example 2-50, you only see the...

Example 253 R1s IP Routing Table

131.108.0.0 24 is subnetted, 5 subnets connected, Loopback2 connected, Loopbackl connected, Loopback0 connected, Serial0 1 connected, Ethernet0 0 Still there are no routing entries. Can you think why IGRP on R1 is still not aware of the remote networks on R2 The problem is that OSPF assumes that only a nonsubnetted network will be sent. For example, in this case, you are using the Class B network 131.108.0.0. You also need to use the command redistributed connected subnets to advise OSPF to...

Example 256 R1 Full Configuration

Service timestamps log uptime no service password-encryption interface Loopback0 ip address 131.108.4.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 131.108.5.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 131.108.6.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 interface Serial0 1 ip address 131.108.3.1 255.255.255.0 no ip directed-broadcast clockrate 128000 transport input none line aux 0...

Example 257 R2 Full Configuration

No ip domain-lookup interface Loopback0 ip address 131.108.7.1 255.255.255.255 ip address 131.108.8.1 255.255.255.128 interface Loopback2 ip address 131.108.9.1 255.255.255.224 interface Ethernet0 0 ip address 131.108.8.129 255.255.255.128 interface Serial1 1 ip address 131.108.3.2 255.255.255.0 ip directed-broadcast redistribute connected subnets summary-address 131.108.8.0 255.255.255.0 summary-address 131.108.7.0 255.255.255.0 summary-address 131.108.9.0 255.255.255.0 redistribute igrp 1...

Example 258 show ip route on R2

131.108.0.0 16 is variably subnetted, 12 subnets, 4 masks C 131.108.8.128 25 is directly connected, Ethernet0 0 O 131.108.9.0 24 is a summary, 00 04 59, Null0 C 131.108.9.0 27 is directly connected, Loopback2 O 131.108.8.0 24 is a summary, 00 04 59, Null0 C 131.108.8.0 25 is directly connected, Loopback1 0 131.108.7.0 24 is a summary, 00 04 59, Null0 1 131.108.6.0 24 100 80625 via 131.108.3.1, 00 00 38, Serial1 1 C 131.108.7.1 32 is directly connected, Loopback0 via 131.108.3.1, 00 00 38,...

Example 259 R1s IGRP Routes

131.108.0.0 24 is subnetted, 8 subnets I 131.108.9.0 100 100125 via 131.108.3.2, 00 01 01, Serial0 1 I 131.108.8.0 100 100125 via 131.108.3.2, 00 01 01, Serial0 1 I 131.108.7.0 100 100125 via 131.108.3.2, 00 01 01, Serial0 1 Almost all troubleshooting techniques involve the ping command. Ping is a simple tool that sends an ICMP-request packet to the remote network and back. A successful ping receives an ICMP-reply. Example 2-60 displays a sample ping from R1 to R2 and the three remote networks...

Example 26 IP Address Configuration on R1

R1(config-if) ip address 131.108.1.1 255.255.255.0 R1(config-if) ip address 131.108.3.1 255.255.255.0 R1(config-if) clock rate 128000 This time you did not get any messages to indicate the link is active. The lack of such a message is because that all physical interfaces are shut down by default when you first configure a router from the default state. You need to enable the interfaces. You can assume that the Ethernet on R1 is connected to a Catalyst switch. Example 2-7 displays the Ethernet...

Example 260 Ping Tests from R1 to R2

Sending 5, 100-byte ICMP Echos to 131.108.7.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 16 ms R1 ping 131.108.8.1 Sending 5, 100-byte ICMP Echos to 131.108.8.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 16 ms R1 ping 131.108.1.1 Sending 5, 100-byte ICMP Echos to 131.108.1.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 1 1 4 ms R1 This is an example of the standard ping...

Example 262 R1s IP Routing Table

131.108.0.0 24 is subnetted, 9 subnets I 131.108.10.0 24 is possibly down, I 131.108.9.0 100 100125 via I 131.108.8.0 100 100125 via I 131.108.7.0 100 100125 via You can see from Example 2-62 that the remote network 131.108.10.0 24 is possibly down. Use the command debug ip routing to see whether you can see the problem. This debug displays routing entries added or deleted into the IP routing table. Use the command on R1. Example 2-63 displays a command used to debug the IP routing table and...

Example 263 debug ip routing and clear ip route Commands

IP routing debugging is on R1 clear ip route * 02 03 45 RT add 131.108.8.0 24 via 131.108.3.2, igrp metric 100 100125 02 03 45 RT add 131.108.7.0 24 via 131.108.3.2, igrp metric 100 100125 02 03 45 RT add 131.108.8.0 24 via 131.108.3.2, igrp metric 100 100125 02 03 45 RT add 131.108.7.0 24 via 131.108.3.2, igrp metric 100 100125 Example 2-64 displays another clear ip route * after the network 131.108.10.0 24 is restored.

Example 264 clear ip route on R1

02 07 25 RT add 131.108.9.0 24 via 131.108.3.2, igrp metric 100 100125 02 07 25 RT add 131.108.8.0 24 via 131.108.3.2, igrp metric 100 100125 02 07 25 RT add 131.108.7.0 24 via 131.108.3.2, igrp metric 100 100125 02 08 03 RT delete route to 131.108.10.0 via 131.108.3.2, igrp metric 100 85 02 08 03 RT no routes to 131.108.10.0, entering holddown This time, you see the route added, but it enters the holddown state, which means the remote network 131.108.10.0 is not accepted and inserted into the...

Example 265 R1 IP Route IGRPOnly Table

131.108.0.0 24 is subnetted, 9 subnets I 131.108.10.0 24 is possibly down, I 131.108.9.0 100 100125 via I 131.108.8.0 100 100125 via I 131.108.7.0 100 100125 via When the IP network 131.108.10.0 goes into holddown mode, the entry in the IP routing table is displayed as possibly down during holddown. After a set interval, known as the flush timer, the entry is completely removed. Example 2-66 displays the IP routing table on R1 after this happens.

Example 266 R1s IGRP Routing Table

131.108.0.0 24 is subnetted, 8 subnets I 131.108.9.0 100 100125 via 131.108.3.2, 00 00 29, Serial0 1 I 131.108.8.0 100 100125 via 131.108.3.2, 00 00 29, Serial0 1 I 131.108.7.0 100 100125 via 131.108.3.2, 00 00 29, Serial0 1 If the remote entry is re-advertised as a valid route after the holddown interval, the network 131.108.1.0 24 is re-inserted into the IP routing table. The command show ip protocol is a useful command that displays the characteristic of the protocols in use on a Cisco...

Example 267 show ip protocol Command

Routing Protocol is igrp 1 Sending updates every 90 seconds, next due in 32 seconds Invalid after 270 seconds, hold down 280, flushed after 630 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Default networks flagged in outgoing updates Default networks accepted from incoming updates IGRP metric weight K1 1, K2 0, K3 1, K4 0, K5 0 IGRP maximum hopcount 100 IGRP maximum metric variance 1 Redistributing igrp 1 Routing for Networks 131.108.0.0...

Example 269 R1s Full Configuration

Interface LoopbackO ip address 131.108.4.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 131.108.5.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 131.108.6.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 interface Serial0 1 ip address 131.108.3.1 255.255.255.252 clockrate 128000

Example 27 no shutdown Command on R1

R1(config-if) interface e0 0 R1(config-if) no shutdown R1(config-if) 2w1d LINK-3-UPDOWN Interface Ethernet0 0, changed state to up 2w1d LINEPROTO-5-UPDOWN Line protocol on Interface Ethernet0 0, changed state to up R1(config-if) int s 0 1 R1(config-if) no shutdown The Ethernet interfaces is running, but you still have no active connection on R1 serial link because R1 S0 1 connects to R2, and you have yet to enable R2 serial interface to R1. Example 2-8 displays IP address configuration and the...

Example 270 R2 s Full Configuration

Interface Loopback0 ip address 131.108.7.1 255.255.255.0 no ip directed-broadcast interface Loopback1 ip address 131.108.8.1 255.255.255.0 no ip directed-broadcast interface Loopback2 ip address 131.108.9.1 255.255.255.0 no ip directed-broadcast interface Ethernet0 0 ip address 131.108.2.1 255.255.255.0 interface Serial1 1 ip address 131.108.3.2 255.255.255.252 ip directed-broadcast line con 0 exec-timeout 0 0 transport input none line aux 0

Example 271 show ip route on R1

Sending 5, 100-byte ICMP Echos to 131.108.7.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 16 ms R1 ping 131.108.8.1 Sending 5, 100-byte ICMP Echos to 131.108.8.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 16 ms R1 ping 131.108.9.1 Sending 5, 100-byte ICMP Echos to 131.108.9.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 12 15 16 ms 131.108.0.0 16 is variably subnetted, 9...

Example 28 Enabling E00 and S11 on R2

R2(config-if) ip address 131.108.2.1 255.255.255.0 R2(config-if) no shutdown R2(config-if) 2w1d LINK-3-UPDOWN Interface Ethernet0 0, changed state to up 2w1d LINEPROTO-5-UPDOWN Line protocol on Interface Ethernet0 0, changed state to up R2(config-if) ip address 131.108.3.2 255.255.255.0 R2(config-if) no shut R2(config-if) 2w1d LINK-3-UPDOWN Interface Serial1 1, changed state to up 2w1d LINEPROTO-5-UPDOWN Line protocol on Interface Serial1 1, changed state to up On this occasion, notice both the...

Example 29 show ip route Command on R1

- static, I - IGRP, R - RIP, M - mobile, B - D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate U - per-user static route, o - ODR Gateway of last resort is not set 131.108.0.0 24 is subnetted, 5 subnets connected, Loopback2 connected, Loopback1 connected, Loopback0 connected, Serial0 1...

Example 31 Configuring OSPF in a Single Area

Network 0.0.0.0 255.255.255.255 area 0 The following is a list of reasons OSPF is considered a better routing protocol than RIP OSPF has no hop count limitations. (RIP has 15 hops only.) OSPF understands variable-length subnet masks (VLSMs) and allows for summarization. OSPF uses multicasts (not broadcasts) to send updates. OSPF converges much faster than RIP, because OSPF propagates changes immediately. OSPF allows for load balancing with up to six equal-cost paths. OSPF has authentication...

Example 310 Configuration of R2 as ABR

R2(config-router) network 141.108.10.0 0.0.0.3 area 2 Now, enable OSPF on R3 and R6. Notice the IP addressing in Figure 3-2 has a mixture of the Class B networks 131.108.0.0 and 141.108.0.0 with different subnets. Hence, this scenario uses VLSM extensively to illustrate the capability of OSPF to handle VLSM. To enable OSPF on R6, start the OSPF process with the process ID 6 and enable the interfaces to advertise the networks as displayed by Example 3-11.

Example 312 Enable OSPF on R3

R3(config-router) network 141.108.10.4 0.0.0.3 area 0 R3(config-router) network 141.108.1.0 0.0.0.127 area 0 R3(config-router) network 141.108.1.128 0.0.0.127 area 0 R3(config-router) network 141.108.2.0 0.0.0.31 area 0 R3(config-router) network 131.108.33.0 0.0.0.255 area 0 Now that OSPF is configured on all four routers, examine the routing table on the backbone network to ensure that all networks are routable. Example 3-13 displays the IP routing table on R6.

Example 313 IP Routing Table on R6

141.108.0.0 16 is variably subnetted, 7 subnets, 3 masks 141.108.0.0 16 is variably subnetted, 7 subnets, 3 masks C 141.108.9.0 25 is directly connected, LoopbackO C 141.108.10.0 30 is directly connected, Serial1 C 141.108.12.0 24 is directly connected, Loopback2 C 141.108.10.4 30 is directly connected, Serial0 C 141.108.9.0 25 is directly connected, LoopbackO C 141.108.10.0 30 is directly connected, Serial1 C 141.108.12.0 24 is directly connected, Loopback2 C 141.108.10.4 30 is directly...

Example 314 R3s IP Routing Table

6 is variably subnetted, 8 subnets, 4 128 25 is directly connected, Loopbac 128 25 110 65 via 141.108.10.6, 00 0 25 is directly connected, Loopback0 0 27 is directly connected, Loopback2 0 25 110 65 via 141.108.10.6, 00 23 .0 30 110 128 via 141.108.10.6, 00 .0 24 110 65 via 141.108.10.6, 00 2 .4 30 is directly connected, Serial1 Once more, Example 3-14 doesn't display the networks in area 1 on Routers R1 and R2. Example 3-15 displays R2's IP routing table.

Example 315 R2s IP Routing Table

141.108.0.0 16 is variably subnetted, 7 subnets, 3 masks O IA 141.108.1.128 25 110 846 via 141.108.10.2, 00 08 05, Serial1 0 O IA 141.108.9.128 25 110 782 via 141.108.10.2, 00 26 20, Serial1 0 141.108.1.0 25 110 846 via 141.108.10.2, 00 08 15, Serial1 0 141.108.9.0 25 110 782 via 141.108.10.2, 00 26 20, Serial1 0 141.108.10.0 30 is directly connected, Serial1 0 141.108.12.0 24 110 782 via 141.108.10.2, 00 26 2 141.108.10.4 30 110 845 via 141.108.10.2, 00 26 2 131.108.0.0 16 is variably...

Example 319 show ip ospf virtuallinks

Virtual Link OSPF_VL0 to router 141.108.12.1 is up Run as demand circuit DoNotAge LSA allowed. Transit area 2, via interface Serial1 0, Cost of using 781 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00 00 07 Adjacency State FULL (Hello suppressed) Example 3-19 displays an active link to the remote OSPF router with the ID 141.108.12.1. Now, view the routing tables on R3 to determine whether the area 1 networks...

Example 320 show ip route on R3

141.108.0.0 16 is variably subnetted, 8 subnets, 4 masks C 141.108.1.128 25 is directly connected, Loopback1 O 141.108.9.128 25 110 65 via 141.108.10.6, 00 01 43, Serial1 C 141.108.1.0 25 is directly connected, Loopback0 C 141.108.2.0 27 is directly connected, Loopback2 O 141.108.9.0 25 110 65 via 141.108.10.6, 00 01 43, Serial1 O IA 141.108.10.0 30 110 128 via 141.108.10.6, 00 01 43, Serial1 O 141.108.12.0 24 110 65 via 141.108.10.6, 00 01 43, Serial1 C 141.108.10.4 30 is directly connected,...

Example 321 Full Configuration on

Ip ospf network point-to-point ip ospf cost 1000 interface Loopback1 ip address 131.108.6.1 255.255.255.255 interface Loopback2 ip address 131.108.6.2 255.255.255.255 interface Ethernet0 0 ip address 131.108.1.2 255.255.255.0 interface Serial1 0 ip address 141.108.10.1 255.255.255.252 router ospf 2 area 2 virtual-link 141.108.12.1 network 131.108.1.0 0.0.0.255 area 1 network 131.108.5.32 0.0.0.31 area 1 network 131.108.6.1 0.0.0.0 area 1 network 131.108.6.2 0.0.0.0 area 1 network 141.108.10.0...

Example 322 Full Configuration on R3

Ip address 141.108.1.1 255.255.255.128 ip address 141.108.1.129 255.255.255.128 ip address 141.108.2.1 255.255.255.224 ip address 131.108.33.1 255.255.255.0 ip address 141.108.10.5 255.255.255.252 network 131.108.33.0 0.0.0.255 area 0 network 141.108.1.0 0.0.0.127 area 0 network 141.108.1.128 0.0.0.127 area 0 network 141.108.2.0 0.0.0.31 area 0 network 141.108.10.4 0.0.0.3 area 0 line con 0 line aux 0 Example 3-23 displays R6's full configuration.