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 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,...

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...

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...

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...

Chapter

1 How many IP routing tables are there when more than one routing protocol is configured on a Cisco router A There is only one IP routing table, which can include routing information dynamically discovered using OSPF or RIP. For example, the following indicates all the possible routing methods on a Cisco router Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external...

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...

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...

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...

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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 323 Full Configuration on R6

Interface Loopback0 ip address 141.108.9.1 255.255.255.128 ip ospf network point-to-point interface Loopback1 ip address 141.108.9.129 255.255.255.128 ip ospf network point-to-point interface Loopback2 ip address 141.108.12.1 255.255.255.0 ip ospf network point-to-point interface Ethernet0 ip address 131.108.26.1 255.255.255.0 media-type 10BaseT interface Serial0 ip address 141.108.10.6 255.255.255.252 clockrate 125000 ip address 141.108.10.2 255.255.255.252 clockrate 125000 router ospf 6 area...

Example 324 show ip ospf Output

Routing Process ospf 3 with ID 141.108.2.1 Supports only single TOS(TOSO) routes SPF schedule delay 5 secs, Hold time between two SPFs 10 secs Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs Number of external LSA 0. Checksum Sum 0x0 Number of DCbitless external LSA 0 Number of DoNotAge external LSA 0 Number of areas in this router is 1. 1 normal 0 stub 0 nssa Area BACKB0NE(0) Number of interfaces in this area is 4 Area has no authentication SPF algorithm executed 3 times Area ranges...

Example 327 show ip ospf neighbor detail from R6

Neighbor 141.108.2.1, interface address 141.108.10.5 In the area 0 via interface Serial0 Neighbor priority is 1, State is FULL, 6 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 2 Dead timer due in 00 00 35 Neighbor 131.108.6.2, interface address 141.108.10.1 In the area 2 via interface Serial1 Neighbor priority is 1, State is FULL, 6 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 2 Router R6 has no adjacency across any broadcast media, such as Ethernet. Therefore, the neighbors are all...

Example 332 R2s OSPF Routing Table

141.108.0.0 16 is variably subnetted, 7 subnets, 3 masks O 141.108.1.128 25 110 846 via 141.108.10.2, 3d03h, Serial1 0 O 141.108.9.128 25 110 782 via 141.108.10.2, 3d03h, Serial1 0 O 141.108.1.0 25 110 846 via 141.108.10.2, 3d03h, Serial1 0 O 141.108.9.0 25 110 782 via 141.108.10.2, 3d03h, Serial1 0 O 141.108.12.0 24 110 782 via 141.108.10.2, 3d03h, Serial1 0 O 141.108.10.4 30 110 845 via 141.108.10.2, 3d03h, Serial1 0 131.108.0.0 16 is variably subnetted, 9 subnets, 3 masks O 131.108.4.129 32...

Example 34 R1s IP Routing Table

131.108.0.0 16 is variably subnetted, 7 subnets, 4 masks 128 25 is directly connected, Loopbackl 33 32 110 11 via 131.108.1.2, 00 02 22, 1 32 110 11 via 131.108.1.2, 00 02 22, 0 27 is directly connected, Loopback2 2 32 110 11 via 131.108.1.2, 00 02 22, 0 25 is directly connected, Loopback0 0 24 is directly connected, Ethernet0 0 The remote network is displayed as a 32 route when a 27 mask is used because, by default, OSPF advertises loopbacks as host addresses, or as 32 routes. Change this...

Example 341 show ip ospf neighbor Command on R3

As you can see from the lack of output in Example 3-41, Router R3 has no adjacencies. The IOS on R3 in Example 3-41 tells you there are no OSPF relationships to R4 and R5. That lack of relationships is because OSPF Hello packets (using multicast address, of course) are not sent over a nonbroadcast OSPF network type. Figure 3-4 shows a classic example of OSPF over NBMA. In an NBMA environment, broadcasts or multicasts do not propagate over the Frame Relay. Example 3-42 displays the OSPF network...

Example 344 Ip Ospf Priority Set to 0 on R4 and R5

R4(config) interface serial 0 R4(config-if) ip ospf priority 0 R5(config) interface serial 0 R5(config-if) ip ospf priority 0 Examples 3-45 displays the OSPF neighbors on R3. Examples 3-45 displays the OSPF neighbors on R3. Example 3-45 show ip ospf neighbor Command on R3 The state shown in Example 3-45 displays a FULL adjacency and a state known as DROTHER, which indicates that the neighbor was not chosen as the DR or BDR and cannot be because the priority has been set to zero. Example 3-46...

Example 354 show ip ospf interface Command on Chicago

Ethernet0 0 is up, line protocol is up Internet Address 131.108.1.2 24, Area 0.0.0.0 Process ID 2, Router ID 131.108.7.1, Network Type BROADCAST, Cost 10 Transmit Delay is 1 sec, State WAITING, Priority 1 Internet Address 131.108.1.2 24, Area 0.0.0.0 Process ID 2, Router ID 131.108.7.1, Network Type BROADCAST, Cost 10 Transmit Delay is 1 sec, State WAITING, Priority 1 Timer intervals configured, Hello 10, Dead 40, Wait 120, Retransmit 5 Wait time before Designated router selection 00 01 46...

Example 356 debug ip ospf adj and Sample IOS Display

OSPF adjacency events debugging is on SanFran OSPF adjacency events debugging is on SanFran The error message displayed by the IOS in Example 3-56 clearly states you have a mismatch in the hello interval. In other words, the hello interval the Router SanFran uses (local router where the display is taken from) is different from the router sending out a Hello packet with the router ID 131.108.7.1, through the IP address 131.108.1.2. Remember that hello and dead intervals must match before...

Example 358 San Fran IP Routing Table

131.108.0.0 16 is variably subnetted, 5 subnets, 2 masks C 131.108.5.0 24 is directly connected, Loopbackl C 131.108.4.0 24 is directly connected, LoopbackO C 131.108.1.0 24 is directly connected, Ethernet0 0 The Router SanFran now discovers the remote networks 131.108.7.1 32 and 131.108.6.0 32 through OSPF. This scenario has introduced you to some powerful OSPF commands that you can use to discover why OSPF is not functioning correctly. Cisco IOS is updated almost daily, so you need to...

Example 41 R1s OSPF Routing Table

131.109.0.0 24 is subnetted, 14 subnets 131.109.0.0 24 is subnetted, 14 subnets The remote networks are indicated by O IA, which indicates interarea routes. Intra-area routes are indicated by O. Two more types of OSPF routes exist external type 1 routes, indicated by Cisco IOS as O E1, and external type 2 routes, indicated by Cisco IOS as O E2. External OSPF routes are routing entries in OSPF route tables injected by an external routing protocol, such as BGP or IGRP. When calculating the cost...

Example 413 R4s Full Configuration

Ip address 131.108.36.4 255.255.255.0 interface SerialO ip address 131.108.255.6 255.255.255.252 interface Seriall ip address 131.108.255.17 255.255.255.252 interface Serial2 ip address 131.108.255.21 255.255.255.252 clockrate 128000 Example 4-14 displays R5's full working configuration. R5 is an internal OSPF area.

Example 418 R5s Current IP Routing Table

Codes C - connected, 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 131.108.0.0 16 is variably subnetted, 41 subnets, 2 masks E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP 131.108.0.0 16 is variably subnetted, 41 subnets, 2 masks 255.16 30 110 983 via 131.108.255. 255.20 30 110 983 via 131.108.255. 255.0 30 110 128 via 131.108.255.9 255.4 30 110 919 via 131.108.255.9...

Example 425 Stub Configuration on R5

R5(config-router) area 10 stub R5 sh ip ospf neighbor Neighbor ID Pri State Dead Time Address 131.108.255.13 1 FULL - 00 00 38 131.108.255.9 Now, view the IP routing table on R5. Example 4-26 displays the new IP routing table after the stub configuration is completed on both Routers R3 and R5. Gateway of last resort is 131.108.255.9 to network 0.0.0.0 131.108.0.0 16 is variably subnetted, 10 subnets, 3 masks Gateway of last resort is 131.108.255.9 to network 0.0.0.0 131.108.0.0 16 is variably...

Example 429 R5s IP Routing Table

Gateway of last resort is 131.10 .255.9 to network 0.0.0.0 131.10 .0.0 16 is variably subnetted, 9 subnets, 2 masks O 131.108.255.16 30 110 138 via 131.10 8.255.9, 00 01 04, O 131.108.255.20 30 110 138 via 131.10 8.255.9, 00 01 04, C 131.108.255.8 30 is directly connected, Serial0 O 131.108.255.12 30 110 128 via 131.10 8.255.9, 00 01 04, O 131.108.131.0 24 110 148 via 131.10 8.255.9, 00 01 04, Serial0 O 131.108.130.0 24 110 138 via 131.10 8.255.9, 00 01 04, Serial0 O 131.108.129.0 24 110 148...

Example 44 R1 Routing Table

Codes C - connected, 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, 131.108.0.0 16 is variably subnetted, 39 subnets, 2 masks O IA 131.108.255.16 30 110 855 via 131.108.1.2, 00 08 21, Ethernet0 0 O IA 131.108.255.20 30 110 855 via 131.108.1.2, 00 05 29, Ethernet0 0 C 131.108.255.0 30 is directly connected, Serial0 0 O 131.108.255.4 30 110 791 via 131.108.1.2, 00 12 44, O IA 131.108.255.8 30 110...

Example 440 Sample Output of show clns isisneighbor Command from R4

System Id Interface State Type Priority Circuit Id System Id Interface State Type Priority Circuit Id R4 has two CLNS neighbors, namely Routers R8 and R9. This means all routers share the same IS-IS link-state database. To view the link-state database on an IS-IS router, use the command show isis database, which is displayed in Example 4-41.

Example 442 R4s Full Configuration

Enable password cisco ip subnet-zero no ip domain-lookup interface Ethernet0 ip address 141.108.2.1 255.255.255.0 ip router isis interface Serial1 ip address 131.108.255.17 255.255.255.252 interface Serial2 ip address 141.108.255.6 255.255.255.252 ip router isis clockrate 128000 interface Serial3 ip address 141.108.255.1 255.255.255.252 ip router isis clockrate 128000 router isis net 00.0001.0050.5460.98e8.00 Example 4-43 displays R8's full working configuration.

Example 445 Sample Ping Requests from R4

Sending 5, 100-byte ICMP Echos to 141.108.3.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 28 36 60 ms R4 ping 141.108.4.1 Sending 5, 100-byte ICMP Echos to 141.108.4.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 17 20 ms R4 ping 141.108.255.9 Sending 5, 100-byte ICMP Echos to 141.108.255.9, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 16 20 ms R4 ping 141.108.255.10 Sending 5,...

Example 446 Routing OSPF to ISIS on R4

R4(config) router isis R4(config-router) redistribute metric Metric for redistributed routes metric-type OSPF IS-IS exterior metric type for redistributed routes ospf Open Shortest Path First (OSPF) rip Routing Information Protocol (RIP) R4(config-router) redistribute ospf < 1-65535> Process ID R4(config-router) redistribute ospf 1 level-1 IS-IS level-1 routes only level-1-2 IS-IS level-1 and level-2 routes level-2 IS-IS level-2 routes only Redistribution of OSPF routes Metric for...

Example 447 R8s IP Routing Table

Codes C - connected, i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area 141.108.0.0 16 is variably subnetted, 6 subnets, 2 masks C 141.108.255.8 30 is directly connected, Seriall C 141.108.255.4 30 is directly connected, SerialO i L1 141.108.255.0 30 115 20 via 141.10 8.255.9, Serial1 C 141.108.3.0 24 is directly connected, Ethernet0 i L1 141.108.2.0 24 115 30 via 141.10 8.255.9, Serial1 i L1 141.108.4.0 24 115 20 via 141.10 8.255.9, Serial1 Example 4-47 displays the...

Example 449 IP Routing Table on R9

Codes C - connected, i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level- 141.108.0.0 16 is variably subnetted, 6 subnets, 2 masks C 141.108.255.8 30 is directly connected, Serial1 i L1 141.108.255.4 30 115 50 via 141.10 8.255.1, Serial0 115 50 via 141.108.255.10, Serial1 Example 4-49 displays the next hop address of 141.108.255.1 (R4). Now, R4 can ping the remote address as confirmed by Example 4-50.

Example 452 Configuring ISIS to OSPF Redistribution

R4(config-router) redistribute isis level-1 IS-IS level-1 routes only level-2 metric metric-type route-map IS-IS level-2 routes only Metric for redistributed routes OSPF IS-IS exterior metric type for redistributed routes Route map reference Consider subnets for redistribution into OSPF tag Set tag for routes redistributed into OSPF R4(config-router) redistribute isis level-1-2 OSPF IS-IS exterior metric type for redistributed routes Route map reference Consider subnets for redistribution into...

Example 465 Simons IP Routing Table

Gateway of last resort is 141.108.255.2 to network 0.0.0.0 Gateway of last resort is 141.108.255.2 to network 0.0.0.0 i.255.4 30 is directly connected, Serial2 J.255.0 24 is a summary, 00 12 23, Null0 .255.0 30 is directly connected, Serial3 O 141.108.2.0 24 is a summary, 00 12 23, Null0 O 141.108.2.0 24 is a summary, 00 12 23, Null0 6 How many OSPF neighbor adjacencies do you expect to see on the router named Simon A There should be two OSPF neighbors one to SanFran and one to Mel. Configure...

Example 48 show ip router ospf Command on R1

131.108.0.0 16 is variably subnetted, 41 subnets, 2 masks O IA 131.108.255.16 30 110 855 via 131.108.1.2, 00 00 47, Ethernet0 0 O IA 131.108.255.20 30 110 855 via 131.108.1.2, 00 00 47, Ethernet0 0 O 131.108.255.4 30 110 791 via 131.108.1.2, 00 00 47, O IA 131.108.255.8 30 110 128 via 131.108.255.2, 00 00 47, Serial0 0 O IA 131.108.255.12 30 110 128 via 131.108.255.2, 00 00 47, Serial0 0 O IA 131.108.131.0 24 110 865 via 131.108.1.2, 00 00 47, thernet0 0 O IA 131.108.130.0 24 110 138 via...

Example 51 R1 Eigrp Configuration

R1(config) router eigrp 1 R1(config-router) network 131.108.1.0 Notice that 131.108.1.0 is, by default, a Class B network. Next, view the configuration after you enter the network 131.108.1.0 command. Example 5-2 displays the running configuration of R1, truncated for clarity. IOS version 12.0.4(T) supports the use of the wildcard mask, which works as the OSPF wildcard mask does. For example, the network 131.108.1.1 0.0.0.0 command places the Ethernet interface of R1 in EIGRP 1. Consult the...

Example 512 R1s Eigrp Routing Table

131.108.0.0 16 is variably subnetted, 8 subnets, 2 masks To support large IP networks, you can use several Cisco IOS enhancements, such as network summarization, load balancing, and reducing the load on WAN links with the bandwidth command, to fine-tune EIGRP. Several factors can contribute to a poorly designed network, such as the amount of routing information exchanged between routers, the number of routers in your network, the network diameter of your network (hop count in EIGRP is still...

Example 514 Sample Output of show ip eigrp interfaces on R1

Xmit Queue Mean Pacing Time Multicast Interface Peers Un Reliable SRTT Un Reliable Flow Timer Interface Peers Un Reliable SRTT Un Reliable Flow Timer Example 5-14 displays a number of physical (E0 0 and Se0 0) interfaces running EIGRP and a number of loopbacks numbered from 0 to 13. Also, note that you have EIGRP neighbors through E0 0 and S0 0. In other words, R1 has established a neighbor relationship to R2 through Ethernet 0 0 and R3 through S0 0. Next, display the neighbors on R1 by using...

Example 516 show ip route eigrp on R1

131.108.0.0 16 is variably subnetted, 41 subnets, 2 masks D 131.108.255.16 30 90 21529600 via 131.108.255.2, 00 00 15, 90 21529600 via 131.108.1.2, 00 00 15, .255.20 30 90 21529600 via 131.108.1.2, 00 04 14, 90 21529600 via 131.108.255.2, 00 04 14, .255.4 30 90 20537600 via 131.108.1.2, 00 04 16, .255.8 30 90 21504000 via 131.108.255.2, 00 04 15, .255.12 30 90 21504000 via 131.108.255.2, 00 04 16, .130.0 24 90 21529600 via 131.108.255.2, 00 04 14, D 131.108.129.0 24 9 0 215552 0 0 via...

Example 519 show ip eigrp neighbors on R4

Router R4 resides in two different autonomous systems 1 and 2. Hence, R4 has established EIGRP neighbors with routers in AS 1 and AS 2. Display the IP routing table on R8, and ensure connectivity to the rest of the network. Example 5-20 displays the IP routing table on R8.

Example 520 show ip route neighbors on R8

168.131.0.0 16 is variably subnetted, 2 subnets, 2 masks C 168.131.2.0 30 is directly connected, SerialO C 168.131.1.0 24 is directly connected, Ethernet0 R8 has no remote EIGRP entries because R4 is not redistributing IP networks from EIGRP AS 1 into 2. R4 must be configured for redistribution because EIGRP does not automatically redistribute among different autonomous systems. (EIGRP and IGRP automatic redistribution occurs only if the AS is the same.) If the routers in AS 1 want to send data...

Example 522 show ip route Command on R8

Codes C - connected, D - EIGRP, EX - EIGRP external 168.131.0.0 16 is variably subnetted, 2 subnets, 2 masks C 168.131.2.0 30 is directly connected, SerialO C 168.131.1.0 24 is directly connected, Ethernet0 131.108.0.0 16 is variably subnetted, 41 subnets, 3 masks D EX 131.108.255.16 30 17 0 26112000 via 168.131.2.1, 00 02 57, D EX 131.108.14.0 24 17 0 26112000 via 168.131.2.1, 00 02 58, Serial0 D EX 131.108.13.0 24 17 0 26112000 via 168.131.2.1, 00 02 58, Serial0 D EX 131.108.12.0 24 17 0...

Example 531 R3s IP Routing Table

168.131.0.0 16 is variably subnetted, 3 subnets, 3 masks D EX 168.131.2.0 30 17 0 25625600 via 131.108.36.4, 10 54 34, EthernetO D EX 168.131.1.0 24 17 0 25625600 via 131.108.36.4, 10 54 34, Ethernet0 D EX 168.131.0.0 16 17 0 25625600 via 131.108.36.4, 10 54 34, Ethernet0 131.108.0.0 16 is variably subnetted, 40 subnets, 2 masks D 131.108.255.16 30 90 21017600 via 131.108.36.4, 11 13 47, C 131.108.255.0 30 is directly connected, Serial0 D 131.108.255.4 30 90 21017600 via 131.108.36.4, 11 17 45,...

Example 533 R3s IP Routing Table

D 131.108.15.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.14.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.13.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.12.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.11.0 24 90 21171200 via 131.10 8.36.4, 00 02 51, D 131.108.10.0 24 90 21171200 via 131.10 8.36.4, 00 02 51, D 131.108.9.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.8.0 24 90 21171200 via 131.108.36.4, 00 02 51, D 131.108.7.0 24 90 21171200 via...

Example 536 show ip route eigrp on R3

168.131.0.0 16 is variably subnetted, 3 subnets, 3 masks D EX 168.131.2.0 30 17 0 25625600 via 131.108.36.4, 00 02 17, Ethernet0 D EX 168.131.1.0 24 17 0 25625600 via 131.108.36.4, 00 02 17, Ethernet0 D EX 168.131.0.0 16 17 0 25625600 via 131.108.36.4, 00 02 17, Ethernet0 131.108.0.0 16 is variably subnetted, 12 subnets, 3 masks D 131.108.255.16 30 90 21017600 via 131.108.36.4, 00 02 17, D 131.108.255.4 30 90 21017600 via 131.108.36.4, 00 02 22, D 131.108.130.0 24 90 21017600 via...

Example 539 Summary Eigrp Configuration on R2

Interface Ethernet0 0 ip address 131.108.1.2 255.255.255.0 ip summary-address eigrp 1 131.108.16.0 255.255.240.0 ip address 131.108.255.5 255.255.255.252 ip summary-address eigrp 1 131.108.16.0 255.255.240.0 clockrate 128000 This scenario demonstrates the capability of EIGRP to handle VLSM with a simple four-router topology. Figure 5-4 displays the four-router topology along with the IP addressing scheme. Four routers in Figure 5-4 reside in the same AS, so you do not need to configure any...

Example 55 R1s Eigrp Topology Table

Interfaces IP-EIGRP interfaces neighbors IP-EIGRP neighbors topology IP-EIGRP Topology Table traffic IP-EIGRP Traffic Statistics IP-EIGRP Topology Table for process 1 Codes P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - Reply status P 131.108.15.0 24, 1 successors, FD is 409600 via 131.108.1.2 (409600 128256), Ethernet0 0 P 131.108.14.0 24, 1 successors, FD is 409600 via 131.108.1.2 (409600 128256), Ethernet0 0 P 131.108.13.0 24, 1 successors, FD is 409600 via 131.108.1.2...

Example 555 Redistribution on R3

R3(config-router) redistribute eigrp 1 metric Metric for redistributed routes route-map Route map reference < cr> R3(config-router) redistribute eigrp 1 metric route-map Route map reference < cr> R3(config-router) redistribute eigrp 1 metric R3(config-router) redistribute eigrp 1 metric 128 20000 255 R3(config-router) redistribute eigrp 1 metric 128 20000 255 < 1-255> IGRP Effective bandwidth metric (Loading) where 255 is 100 R3(config-router) redistribute eigrp 1 metric 128 20000...

Example 56 R1s IP Routing Table

Codes D - EIGRP, EX - EIGRP external 131.108.0.0 24 is subnetted, 15 subnets D 131.108.15.0 90 409600 via 131.108.1.2, 00 31 02, Ethernet0 0 D 131.108.14.0 90 409600 via 131.108.1.2, 00 31 02, Ethernet0 0 If you simulate a network failure by shutting down the network 131.108.15.0 on R2, Example 5-7 displays R1's new topology table.

Example 560 Redistribution on R4 from OSPF to EIGRP

R4(config) router eigrp 1 R4(config-router) passive-interface s2 R4(config-router) redistribute ospf 1 metric R4(config) router eigrp 1 R4(config-router) passive-interface s2 R4(config-router) redistribute ospf 1 metric < 1-4294967295> Bandwidth metric in Kbits per second (config-router) redistribute ospf 1 metric 128 < 0-4294967295> IGRP delay metric, in 10 microsecond (config-router) redistribute ospf 1 metric 128 20000 < 0-255> IGRP reliability metric where 255 is 100 reliable...

Example 563 Sample Ping Request from R1

Sending 5, 100-byte ICMP Echos to 141.108.128.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 28 31 32 ms R1> ping 10.1.1.1 Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 32 33 36 ms R1> ping 131.108.255.1 Sending 5, 100-byte ICMP Echos to 131.108.255.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 28 30 32 ms R1> ping 131.108.255.9 Sending 5,...

Example 57 R1s Topology Table

Example 5-7 does not display the remote entry 131.108.15.0 24, and, therefore, it is not present in the IP routing table. EIGRP maintains IP routes by using DUAL and maintaining an EIGRP topology table. For remote entries with multiple routes, EIGRP uses the feasible condition (FC) to determine the best path. The EIGRP routing algorithm always chooses the path to a remote destination with the lowest metric. The topology table maintains all paths to remote networks, so by simply viewing the...

Example 610 R2s Routing Table

131.108.0.0 24 is subnetted, 5 subnets C 131.108.255.0 is directly connected, Serial1 0 131.108.0.0 24 is subnetted, 5 subnets C 131.108.255.0 is directly connected, Serial1 0 C 131.108.1.0 is directly connected, Ethernet0 0 The three remote networks are inserted into the IP routing tables as BGP-learned networks. Example 6-11 displays R3's BGP and IP routing table.

Example 611 R3s BGP and IP Tables

BGP table version is 10, local router ID is 131.108.255.2 Status codes s suppressed, d damped, h history, * valid, > best, i - Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path Network Next Hop Metric LocPrf Weight Path 131.108.0.0 24 is subnetted, 5 subnets C 131.108.255.0 is directly connected, Serial0 131.108.0.0 24 is subnetted, 5 subnets C 131.108.255.0 is directly connected, Serial0 C 131.108.1.0 is directly connected, EthernetO C 131.108.1.0 is...

Example 619 R1s BGP Table

BGP table version is 4, local router ID is 131.108.4.1 Status codes s suppressed, d damped, h history, * valid, > best, i -internal Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path Network Next Hop Metric LocPrf Weight Path R1 has three local interfaces in BGP and three remote networks advertised by R2 (next hop address is 131.108.1.2). Also, notice that the default weight on R1 is set to 32768 (for local networks), and the local preference is 100 for the...

Example 622 show ip bgp neighbors on R1

BGP neighbor is 131.108.1.2, remote AS 1, internal link Established, table version 5, up for 00 04 30 Last read 00 00 30, hold time is 180, keepalive interval is 60 seconds Minimum time between advertisement runs is 5 seconds Received 1297 messages, 0 notifications, 0 in queue Sent 1290 messages, 0 notifications, 0 in queue Prefix advertised 14, suppressed 0, withdrawn 0 Connections established 7 dropped 6 Last reset 00 04 39, due to User reset 4 accepted prefixes consume 128 bytes 0 history...

Example 624 show ip bgp neighbors on R1 Truncated

BGP neighbor is 131.108.1.2, remote AS 1, internal link Index 1, Offset 0, Mask 0x2 BGP version 4, remote router ID 131.108.255.1 BGP state Established, table version 8, up for 00 58 56 Last read 00 00 56, hold time is 180, keepalive interval is 60 seconds Minimum time between advertisement runs is 5 seconds Received 1351 messages, 0 notifications, 0 in queue Sent 1347 messages, 0 notifications, 0 in queue Prefix advertised 16, suppressed 0, withdrawn 1 Connections established 7 dropped 6 Last...

Example 626 show ip bgp summary on R4

A.B.C.D IP prefix < network> < length> , e.g., 35.0.0.0 8 neighbors connections paths peer-group quote-regexp expression Network in the BGP routing table to display Display only routes with non-natural netmasks Display routes matching the communities Display routes matching the community-list Display paths suppressed due to dampening Display routes conforming to the filter-list Display flap statistics of routes Display only routes with inconsistent origin ASs Address family Detailed...

Example 628 R3s BGP Table

BGP table version is 16, local router ID is 141.108.1.1 Status codes s suppressed, d damped, h history, * valid, > best Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path A lot of information is stored here. Start by analyzing why the remote network 131.108.1.0 has a dual path and why the next hop address 13.108.255.5, or the link to R1, is preferred as the path through R4. BGP does not load balance and always chooses one path. (Static routes can be used to...

Example 630 show ip bgp on R3

BGP table version is 16, local router ID is 141.108.1.1 Status codes s suppressed, d damped, h history, * valid, > best, i - Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path Network Next Hop Metric LocPrf Weight Path *> 131.108.7.0 24 *> 141.108.1.0 24 *> 151.108.1.0 24 The change is not implemented because you must first clear the BGP peer session. Clear the BGP TCP peer session on R3 to R4 with the clear ip bgp 131.108.255.10 command. Example 6-31...

Example 631 show ip bgp on R3

BGP table version is 32, local router ID is 141.108.1.1 Status codes s suppressed, d damped, h history, * valid, > best, i - Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path BGP table version is 16, local router ID is 141.108.1.1 Status codes s suppressed, d damped, h history, * valid, > best, i - Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path Network Next Hop Metric LocPrf Weight Path Even though the path to the...

Example 632 R1s Full Working Configuration

Interface LoopbackO ip address 131.108.2.1 255.255.255.0 interface Loopback1 ip address 131.108.3.1 255.255.255.0 interface Loopback2 ip address 131.108.4.1 255.255.255.0 interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 interface Serial0 0 ip address 131.108.255.5 255.255.255.252 clockrate 125000 router ospf 1 network 131.108.1.0 0.0.0.255 area 0 network 131.108.2.0 0.0.0.255 area 0 network 131.108.3.0 0.0.0.255 area 0 network 131.108.4.0 0.0.0.255 area 0 line con 0 line aux 0 line...

Example 633 R2 s Full Working Configuration

No ip domain-lookup interface Loopback0 ip address 131.108.5.1 255.255.255.0 interface Loopback1 ip address 131.108.6.1 255.255.255.0 interface Loopback2 ip address 131.108.7.1 255.255.255.0 interface Ethernet0 0 ip address 131.108.1.2 255.255.255.0 interface Serial1 0 ip address 131.108.255.1 255.255.255.0 clockrate 128000 neighbor 131.108.255.2 remote-as 2 no auto-summary neighbor 131.108.255.2 remote-as 2 no auto-summary line con 0 line aux 0 line vty 0 4 end Example 6-34 display R3's full...

Example 638 show ip bgp neighbors on R1

BGP neighbor is 161.108.1.1, remote AS 2, Index 1, Offset 0, Mask 0x2 BGP version 4, remote router ID 0.0.0, Last read 00 03 37, hold time is 180, keepalive interval is 60 seconds Minimum time between advertisement runs is 30 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Prefix advertised 0, suppressed 0, withdrawn 0 Connections established 0 dropped 0 Last reset never 0 accepted prefixes consume 0 bytes 0 history paths consume 0 bytes...

Example 642 show ip bgp neighbors on R1

BGP neighbor is 161.108.1.1, remote AS 2, external link Index 1, Offset 0, Mask 0x2 BGP version 4, remote router ID 161.108.1.1 BGP state Established, table version 3, up for 00 03 51 Last read 00 00 51, hold time is 180, keepalive interval is 60 seconds Minimum time between advertisement runs is 30 seconds Received 7 messages, 0 notifications, 0 in queue Sent 7 messages, 0 notifications, 0 in queue Prefix advertised 1, suppressed 0, withdrawn 0 Connections established 1 dropped 0 Last reset 00...

Example 644 R1s Full Working Configuration

Interface Ethernet0 0 ip address 131.108.1.1 255.255.255.0 no ip directed-broadcast interface Serial0 0 ip address 131.108.255.1 255.255.255.252 clockrate 125000 interface Serial0 1 ip address 131.108.255.5 255.255.255.252 clockrate 125000 router bgp 1 network 131.108.1.0 mask 255.255.255.0 neighbor 161.108.1.1 remote-as 2 neighbor 161.108.1.1 ebgp-multihop 255 neighbor 161.108.1.1 update-source Ethernet0 0 line con 0 line aux 0 line vty 0 4 end Example 6-45 displays R2's full working...

Example 655 Extended Ping on R1

Policy routing debugging is on R1 ping Target IP address 161.108.1.1 Repeat count 5 Datagram size 100 Timeout in seconds 2 Extended commands n y Source address or interface 131.108.1.1 Loose, Strict, Record, Timestamp, Verbose none Sweep range of sizes n Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 161.108.1.1, timeout is 2 seconds Success rate is 100 percent (5 5), round-trip min avg max 16 18 20 ms 00 26 57 IP s 131.108.1.1 (local), d 161.108.1.1, len 100, policy 00 26 57...

Example 66 show ip bgp on R1

BGP table version is 4, local router ID is 131.108.1.1 Status codes s suppressed, d damped, h history, * valid, > best, i internal Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path Status codes s suppressed, d damped, h history, * valid, > best, i internal Origin codes i - IGP, e - EGP, - incomplete Network Next Hop Metric LocPrf Weight Path The BGP table on R1 displays three local networks (next hop is 0.0.0.0 or local interfaces). Example 6-6 also...