Physical Layout and Prestaging

Connect the hubs and serial cables to the routers, as shown in Figure 17-8. Use HDLC as the WAN protocol. Connect the three Ethernet hubs to the routers to form three LAN segments, as shown in Figure 17-8. Configure EIGRP across the network, use 2001 as the Autonomous System ID. Add and configure the NTP server on the Ethernet segment of the ticket_central router. Enable NTP broadcast, and set the stratum level to 3 on the software. The IP address of the server is 206.191.241.45. Lab 35...

About the Authors

Karl Solie, CCIE 4599, is a principal network engineer for Comdisco Inc. Karl has more than 13 years of experience in the field designing and implementing LAN WAN-based networks internally and externally for McDonnell Douglas, Unisys, and Comdisco. Over the past 13 years, Karl has worked on a vast array of internetworks, including some of the largest commercial and government-based IP and SNA networks in the United States. He has performed LAN WAN design and implementation on networks ranging...

Additional Commands for Configuring Frame Relay

Some additional commands are available to control or modify your Frame Relay network. The following list includes some of the more commonly tuned features of Frame Relay. For a complete list, see the IOS WAN Configuration Guide. Router(config-if)no frame-relay inverse-arp Disables the sending of Inverse ARP requests. Use this command in conjunction with no arp frame-relay to prevent the dynamic mapping of PVCs. Router(config-if)no arp frame-relay Disables ARP responses. Use this in conjunction...

Appendix B The Abridged OSI Reference Model

Almost every book on networking has some reference to the OSI reference model this one will be no exception. However, instead of repeating the same text that you've probably already read 50 times, I would like to offer a new twist on the model in Table B-1. This information is presented here in less then 10 words per level, as an abridged OSI reference model. To read unabridged versions, refer to Interconnections, Second Edition Bridges, Routers, Switches, and Internetworking Protocols by Radia...

Appendix C Rfc List

Table C-1 provides a list of some of the more common RFCs found throughout the text. The complete text version of these RFCs can be found at www.isi.edu. The PPP Bandwidth Allocation Protocol (BAP) The PPP Bandwidth Allocation Control Protocol (BACP) Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI TCP Selective Acknowledgment Options PPP Challenge Handshake Authentication Protocol (CHAP) Address Allocation for Private Internets Management Information Base for version 2 of...

Appendix D Common Cable Types and Pinouts

This appendix provides the following pinout information Console Port Pinouts (RJ-45) Auxiliary Port Pinouts (RJ-45) EIA-530 DTE Cable Pinout (DB-60 to DB-25) EIA TIA-232 DTE Cable Pinout (DB-60 to DB-25) EIA TIA-232 DCE Cable Pinout (DB-60 to DB-25) EIA TIA-449 DTE Cable Pinout (DB-60 to DB-37) EIA TIA-449 DCE Cable Pinout (DB-60 to DB-37) V.35 DTE Cable Pinout (DB-60 to 34-Pin) V.35 DCE Cable Pinout (DB-60 to 34-Pin) X.21 DTE Cable Pinout (DB-60 to DB-15) X.21 DCE Cable Pinout (DB-60 to DB-15)...

BaseLX Gigabit Ethernet

LX GBICs use a laser-based wavelength of 1300 nms. Depending on the cable type, LX GBIC operate at distances of 550 m to 5000 m, as listed in Table 2-4. Cisco also supports an LH and LX GBIC, which extends the IEEE 1000Base-LX maximum distance of 5 km. Table 2-4. 1000Base-LX Cable Limitations Table 2-4. 1000Base-LX Cable Limitations

Link State Protocols Open Shortest Path First OSPF

Since its conception in 1987, OSPF has continued to evolve with the modern internetwork. Today, OSPF is clearly the dominant Open Systems interior routing protocol. Because of the constant RFC enhancements to OSPF, it has proven itself to be a scalable protocol with networks in the tens of thousands of nodes. OSPF officially was documented in 1989 by the Internet Engineering Task Force (IETF) to address many of the limitations of distance vector protocols, such as RIP and IGRP. Since 1989, OSPF...

Configuring Bridging and Data Link Switching Plus

Most of the early protocols were designed without explicit network addresses. For that reason, the protocol does not have the same concept of traditional Layer 3 that we have grown to love. Protocols without explicit network layer addresses, by definition, are called nonroutable or bridged protocols. Some examples of common bridged protocols are IBM Systems Network Architecture (SNA), NetBEUI, NetBIOS, and DEC LAT. The most commonly used bridged protocols today are SNA and NetBEUI. IBM's SNA is...

LAN Protocols Configuring Catalyst Ethernet and Token Ring Switches

In the realm of networking, no technology is outpacing that of local-area networks (LANs). In less than a decade, LANs have become common in many homes and are a must for any small business. Many, if not all, new commercial buildings are wired with some type of copper or fiber cable plant for local-area networking. Even when you travel, many hotels offer the use of a LAN to access the Internet. Many new residential communities are incorporating what you might call community-area networks, or...

WAN Protocols and Technologies Asynchronous Transfer Mode ATM

Authoring contribution by Galina Diker Pildush Asynchronous Transfer Mode (ATM) has been looked upon as the technology that can do it all carry voice, data, and video information, implying that both voice and data payloads, batch and real-time, can be transferred from one part of the world to another. This is implemented with guarantees in quality, such as integrity of the information and its throughput, toward different classes of services. In my book Cisco ATM Solutions, I elaborate on the...

Cisco [OS PlannerWW

Ov Cd< -i IOS ilinKi ttti m .ir fktbufV h WK I Y--m -r icl-ncd J Jj 1. i c ar u I iit-Jlj j-.nl r.r m . i rtkut ri 1 lmrr > r J 1 - mkr c vu J d t c SfUn --r Jzr f j Ini.itt tt-if A rr-ijcm i rr I. A. p jHaor-j. mi * EfeBW r. J t,.jH- L-fi-jUrr I. Ti 11- Lrt- -n. a - r ltw. '-r F-fhi-j.- friftrr J-i iri ri 4 efcr ccrv < h vci tur-J n jvm K-k rlv'-r urti v v wrv-, ' y.-w r rrlrr 1 t--.y F -J tjtf.Kr uf tvirc 1 riftwi f i .TiTii- ri'. rrr.cn so iyjil I , n-t i* Hkt+cv fcilr* II f i 'nvr...

Classful Routing RIP1 Only

RIP-1 is a classful routing protocol, so it does not advertise a subnet mask along with advertised routes. For RIP to determine what the subnet mask is of the destination network, RIP uses the subnet mask of the interface in which the route was received. This is true only if the route received is a member of a directly connected major network. If the route received is not of the same major network, the router tries to match only the major bit boundary of the route either Class A, B, or C. For...

Clearing and Changing NAT Translations

NAT TCP translations will time out after a default of 24 hours. You can change the timeout values on a per-protocol basis with the following commands ip nat translation timeout seconds Specifies the timeout value that applies to dynamic translation, except for ones with overload translations. The default is 86,400 seconds, or 24 hours. ip nat translation udp-timeout seconds Specifies the timeout value of UDP translations. The default is 300 seconds, or 5 minutes. ip nat translation dns-timeout...

Common Protocols

Network layer protocols, such as IP, IPX, and AppleTalk Other RFCs significant to PPP are listed here RFC 1144 TCP IP header compression. RFC 1220 Point-to-Point Protocol extensions for bridging. This RFC replaces RFC 1220. RFC 1334 PPP authentication protocols. RFC 1378 PPP AppleTalk Control Protocol (ATCP). RFC 1552 PPP Internetworking Packet Exchange Control Protocol (IPXCP). RFC 1570 PPP LCP extensions. RFC 1661 Point-to-Point Protocol (PPP). RFC 1662 PPP in HDLC-like framing. RFC 1990 PPP...

Configuring Analog Remote Access

Remote access to a network can be considerably useful during your studies and in the field. The Cisco TAC often asks if an analog modem is attached, to help in troubleshooting your problem. Problem solving can be significantly easier when another person can get a firsthand view of the problem. Being able to troubleshoot from a remote location with this type of an out-of-band connection alone can be invaluable. The sections presented here are intended to arm you with enough knowledge to...

Configuring and Using the Access Server

The access server provides out-of-band configuration to several devices at a single time. At a large site where several key routers and switches are located, an access server provides the best method for configuration access. You use the access server to configure the routers and switches in the upcoming lab. The configuration of the access server requires a logical tie between an IP address and a TTY session. To configure what Cisco refers to as reverse Telnet, you need to configure three...

Configuring Catalyst Ethernet Switches

The colorful history of Ethernet switching is present in the Catalyst line. Each family of Catalyst switches has a slightly different command-line interface. The Catalyst switches such as the 1900 and 2800 come from Grand Junction and have one type of configuration interface and method. The Catalyst 3000 originated with Kalpana and has another method of configuration. The Catalyst 5500 family started with Cisco's acquisition of Crescendo. The Catalyst 5500 and 6500 families have a unique...

Configuring Dialon Demand Routing DDR

For ISDN to work properly, dial-on-demand routing (DDR) options must be created on the interface. Often, ISDN links are used to back up point-to-point or Frame Relay circuits. If not configured correctly, the ISDN link can stay up constantly or can continuously connect, hang up, and then connect again. Because ISDN carrier's normally charge usage by the minute, a small configuration error can result in a customer getting ISDN bills of more than 1000 per month. Unless you enjoy long discussions...

Configuring Microsoft Windows 9598 Networking

The goal of all internetworking is to reliably transfer data from one network to another. Therefore, no model could be called reliable if it were not properly tested with real data and real applications. Therefore, the last components needed to completely model the internetwork are test data and test applications. As previously mentioned, the entire Microsoft Windows OS line, Windows 95 98 2000 and NT, provides all the network protocols needed to test many network models. The two protocols that...

Configuring NAT Dynamic Translation

Using the four-step process listed, now you will walk through the NAT configuration that you did earlier in this chapter. Figure 15-2 illustrates a private IP network of 172.16.1.0 24. This network needs reachability to the Internet specifically, the host 128.100.1.10 on the UW Ethernet segment. The router nat_router has a T1 connection to the Internet through the isp_router. The ISP has assigned the network 128.100.100.0 24 to nat_router for access to the Internet. The engineers who support...

Configuring OSPF Stub Areas

Three types of OSPF stub areas must be configured To configure stub areas, use the area command followed by what type of stub area you want to configure. All routers on the same IP network must be in the same area, and area parameters also must match for neighbors and adjacencies to form. To configure Area X as a stub area, enter the following To configure Area X as a not-so-stubby area, enter the following Router(config-route)area X nssa default-information originate . Use the keyword...

Configuring PPP on Asynchronous Ports for Analog Dial Links

Configuring PPP on asynchronous interfaces for analog dial connections can be more involved than configuring PPP on serial links. This section briefly lists the steps needed to configure PPP and then goes into greater detail on the more complex steps. The steps to configure PPP for use on an asynchronous dialup connection are as follows Step 1. Configure the modem and asynchronous port. Step 1 involves attaching and configuring the modem, and configuring the asynchronous port of the router....

Configuring PPP on Synchronous Serial Links

To configure PPP on a serial interface, you must first enable PPP encapsulation on the interface with the encapsulation ppp command. If you are configuring both ends of the PPP link, you need to configure PPP encapsulation on each side. If you are configuring a PPP link with two routers, using DTE-to-DCE cable connections, you also need to use the clock rate bps command on the DCE side of the connection. Essentially, setting the encapsulation coupled with a network layer address is all that is...

Configuring RFC 2225 Classical IP

Classical IP, specified in RFC 2225, is a dynamic method of IP interconnectivity through the ATM network. Classical IP uses RFC 2684 encapsulation. It provides a dynamic method for IP interconnectivity through the ATM network, freeing you from the necessity of configuring manually intensive mapping statements. Here is my definition of Classical IP It internetworks IP only. It allows native behavior of IP through the ATM cloud. This implies that the IP ARP function of mapping IP addresses to the...

Configuring Source Route Bridging

Source-route bridging can be configured in three primary ways Remote source-route bridging (RSRB) Configuring Basic Local Source-Route Bridging Local SRB in its simplest form exists between two rings on a router. Figure 13-16 illustrates this type of configuration. Figure 13-16. Basic Local SRB Configuration Figure 13-16. Basic Local SRB Configuration To configure this type of SRB, follow this two-step process Step 1. Enable the use of the RIF, if required, with the router interface command...

Configuring the Simple Network Time Protocol SNTP

On smaller routers that do not > support NTP, such as the Cisco 100x series, the 80x series, and other lower-end routers, you can deploy SNTP. However, SNTP lacks some of the enhanced features of NTP It cannot be an NTP server, and it provides no authentication and statistics mechanisms. SNTP can be configured in two ways, much like NTP Configure the router to passively listen for SNTP broadcasts on a wire. Statically map SNTP to a specific server. If both methods are configured, the router...

Configuring Transparent Bridging

Configuring transparent bridging is a simple three-step process Step 1. Assign a bridge group number and define the Spanning-Tree Protocol. This is accomplished with this global command Router(config) bridge-group 1-255 protocol ieee ibm dec Step 2. Assign each network interface that is to be bridged to a bridge group by using the following interface command Router(config-if) bridge-group 1-255 If the interface is a Frame Relay multipoint interface, a frame-relay map statement will be needed to...

Control Examples

You must verify two things within the routing domains to allow IP end-to-end connectivity Notice that the IGRP domain is on a 24-bit boundary. This means that when the IGRP domain receives a route, it must exist on a major bit boundary or a 24-bit boundary for the interface to accept that route. Mutual redistribution must occur between EIGRP and IGRP, and EIGRP and OSPF. Beginning with the configuration for the canada_1 router, you can follow the three-step process for configuring EIGRP as...

Debug ip ospf adj and debug ip ospf events Commands

Two debug commands provide the Big D for OSPF debug ip ospf adj and debug ip ospf events. For the most part, the commands are identical. The output can be fairly heavy, so turn on logging if using this command in a production environment. This debug command is so comprehensive that it will alert you to a majority of common OSPF issues, such as the following Mismatched hello dead interval Mismatched authentication key Mismatched area IDs and area types

Default Administrative Distance

Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol (BGP) Intermediate System-to-Intermediate System (IS-IS) A static route becomes floating when it is assigned a higher AD than that of the routing protocols. It is called floating because when a route known through some other means goes away, the floating static route floats to the top and is used by the router. For example, if you use the command ip route 10.1.1.0 255.255.255.0 BRI 0 200, you have...

Digital Voice Technology

Digital loop carrier technology was developed in the early 1970s with the idea of increasing transmission performance through digital technology. In addition to performance enhancements, digital technology is more reliable and easier to maintain than analog signaling. One of the key reasons for converting analog to digital is that digital signals are regenerated and do not accumulate noise in the same manner that analog signals do. Whereas analog signaling is represented as a continuous...

DLSw Advanced Configuration

DLSw provides many features that allow for easier peer configuration, explorer control, and backup and filtering capabilities. This section covers configuration of some of the more advanced features of DLSw+. These features include the following DLSw+ promiscuous peers configurations DLSw+ backup configurations DLSw+ border peers, peer groups, and demand peers Controlling DLSw explorers with ring lists, bridge group lists, and port lists Configuring DLSw+ reachability with the icanreach command...

DLSw Backup over DDR

The other method of DLSw+ backup involves keeping the peer connection established during a link failure. For example, if you are using an ISDN link for backup, you might want to keep the peer active while the ISDN line dials and makes a connection. The time for link such as this to converge can exceed the DLSw+ keepalive timers and force the peer down. The DLSw+ keepalives operate on TCP port 2065, which also makes it hard to control significant traffic with ACLs because data and keepalives use...

DLSw Backup Peers

Backup peers are created by simply adding the backup-peer argument to the new remote peer. Before creating a backup peer, you must define the primary peer. The backup peer must point at a different DLSw router than the primary peer. The linger keyword tells the router not to disconnect the backup peer until the primary has been up for X amount of seconds. Without the linger keyword, the primary peer immediately becomes active when connectivity is restored. LLC2 sessions automatically are...

DLSw Border Peers Peer Groups and Demand Peers

Border peers and peer groups provide an effective way to scale DLSw networks that require any-to-any reachability and to control explorers. A DLSw router that requires any-to-any reachability would need a remote-peer statement to every router that it has a connection to. For example, Figure 13-37 illustrates a common network. Figure 13-37. DLSw Full Reachability Figure 13-37. DLSw Full Reachability Only two workstations are illustrated in the figure, but they represent workstations that would...

DLSw Capabilities Exchange

A key process that occurs during DLSw circuit establishment is the capabilities exchange. The capabilities exchange the process that differentiates DLSw from other bridging technologies. The exchange is a special DLSw SSP control message that describes the capabilities of the sending DLSw router. The initial capabilities exchange is always the first SSP message sent when a new connection between two DLSw devices occur. It is used to identify the DLSw version and other options that the DLSw...

DLSw Circuit Establishment

Circuit establishment occurs between two end systems. SNA circuit establishment occurs when a SNA TEST or XID explorer frame with a specific MAC address is generated from an end station. The DLSw router sends a CANUREACH frame to each active peer. The correct peer responds with an ICANREACH frame. After a series of XIDs and other information is exchanged, a circuit is established. Each circuit has a unique ID that allows a TCP peer connection to support multiple circuits. The ID is composed of...

DLSw Technical Overview

IEEE 802.2 LLC Type 2 was designed under the assumption that network transit delay would be small and predictable. After all, Token Ring and Ethernet are LAN protocols. When remote bridging is used over vast geographical distances, the network delay can vary drastically with the load on the link. When the delay becomes too large, LLC2 timeouts occur and retransmissions start happening. Because the frame is only delayed, LLC2 can become confused when it starts to see duplicate frames, and it...

Dynamic Access Lists

A dynamic access list is an access list that allows temporary access after a user has authenticated with the router. For example, in the field, you might want a Cisco engineer from the TAC to help you troubleshoot your network by logging into the routers. A dynamic access list could be created giving Cisco complete privileges for a predetermined amount of time. After a configured time limit expires, the session is closed and traffic is again denied. This form of access list is also referred to...

EIGRP Autosummarization

By default, EIGRP performs autosummarization in two situations Autosummarization will occur at the major class boundary during redistribution from EIGRP into a classful routing protocol, such as IGRP or RIP. This type of summarization cannot be disabled. Autosummarization will occur at the major class boundary when the route is advertised out an interface that is on a different major class boundary. This summarization can be disabled with the command no auto-summary from the...

EIGRP Equal and Unequal Cost Load Balancing

By default, EIGRP load-shares over four equal-cost paths. For load sharing to happen, the routes to load-share over must show up in the IP forwarding table or with the show ip route command. Only when a route shows up in the forwarding table with multiple paths to it will load sharing occur. Use the bandwidth interface command on serial links to ensure that EIGRP has a consistent perspective of the metrics of the network. This also might aid in making the route show up in the IP forwarding...

EIGRP Redistribution and Route Control

To filter routing updates in EIGRP, use a distribute list. A distribute list calls a standard or extended access list and filters routing updates accordingly. When redistributing one protocol into another, use the redistribute command along with a default metric. A route map should be used in place of a distribute list when controlling specific routes during the redistribution process. Redistribution happens automatically between IGRP and EIGRP when they are in the same autonomous systems....

EIGRP Stub Routing

In Cisco IOS Software Release 12.0(7)T, Cisco introduced EIGRP stub routing to further control stability and reduce resource utilization. This feature was fully integrated into Release 12.0(15)S. EIGRP stub routing functions very much like that of an OSPF stub area. The stub router has one exit path from the routing domain and forwards all traffic to a central or distribution router. Another way to say this is that the stub network cannot be a transit router for EIGRP, and it can have only one...

EIGRP Summarization

Understanding EIGRP summarization and knowing how to effectively use it are absolutely vital to the design of large EIGRP networks. EIGRP scales very well, but when the number of routes starts to climb into the hundreds, extra care should be taken to control route propagation and the query range. As much as EIGRP is plug-and-play on small networks, it is not on large networks. The larger the network is, the more care should be taken to control how routes propagation. Summarization provides two...

Equipment List

One Frame Relay switch four serial ports One access server backbone router eight asynchronous interfaces, one Ethernet port Two lab routers one Ethernet, two serial interfaces Three lab routers one Token Ring, two serial interfaces One lab router two Ethernet ports, one Token Ring port Three Ethernet hubs, four Token Ring hubs MAUs The hubs and MAUs may be substituted for a Catalyst 5000 with the appropriate number of ports. This lab is designed to be performed without any Catalyst switches....

Ethernet A Brief History of an Evolutionary Protocol

Its conception occurred at the Xerox Palo Alto Research Center (PARC), developed by Bob Metcalfe in 1972. In 1979, Digital Equipment Corp., Intel, and Xerox standardized the DIX V1.0 frame two years later, they refined it with the Version 2.0 frame. In 1981, the Institute of Electrical and Electronic Engineers (IEEE) project 802 decided to form the 802.3 subcommittee, which is almost synonymous with the Ethernet that we know today. Table 2-1 provides a great...

Ethernet CSMACD

Ethernet technology commonly is referred to as carrier-sense multiple access collision detect (CSMA CD). Ethernet transmits frames in the following manner 1. Carrier sense This also is known as listen before talking. An Ethernet station wanting to transmit a frame listens to the medium before it transmits to ensure that the medium is available. 2. Talk if quiet If the channel is quiet for a specific amount of time, the interframe gap (IFG) before the station might begin a transmission. If the...

Ethernet Operation

Ethernet operates at the OSI Layer 2, the data link layer. The data link layer actually is divided into two sublayers the MAC layer and the Logical Link Control (LLC) layer. The LLC layer 802.2, in this case is a standardized interface between a hardware-specific MAC and a Layer 3 protocol. The MAC layer has the following responsibilities Generating the physical source and destination address for a frame. These are 48-bit industry-wide unique addresses the first 3 bytes are assigned by the...

Example 102 Output of the show ip protocols Command

Routing Protocol is igrp 2001' Sending updates every 90 seconds, next due in 19 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 2001 Routing for Networks...

Example 104 debug ip igrp transactions Command Output

Received update from 206.191.241.42 on Ethernet0 network 172.16.0.0, metric 1121211 (neighbor 1121111) sending update to 255.255.255.255 via Ethernet0 ( sending update to 255.255.255.255 via Ethernet1 ( sending update to 255.255.255.255 via Ethernet3 ( sending update to 255.255.255.255 via Ethernet5 (

Example 1145 Eigrp Configuration of All Routers to This Point

Router eigrp 2001 network 172.16.0.0 At this time, you can verify routing by performing source pings and examining the route table. When basic routing is working, you can proceed to the next portion of the lab, which requires that barneys not propagate the subnet 172.16.3.0 throughout the EIGRP domain. There are many ways to accomplish this, but for this lab, you will use a distribution list. The list will be applied to EIGRP updates leaving the s0.1 and s0.2 interfaces on the barneys router....

Example 1146 Configuration of a Distribution List

Barneys(config) access-list 10 deny 172.16.3.0 0.0.0.255 barneys(config) access-list 10 permit any 10 out serial 0.1 barneys(config-router) distribute-list 10 out serial 0.2 By observing the forwarding table on g_and_s in Example 11-47, you can see that the route 172.16.3.0 24 is now missing. You still can ping the 172.16.20.0 24 subnet, so you know that the filter was a success.

Example 1148 Configuring a Default Route for EIGRP

Solar_bucks(config) ip route 0.0.0.0 0.0.0.0 172.16.50.1 solar_bucks(config) router eigrp 2001 solar_bucks(config-router) redistribute static 1544 100 254 1 1500 solar_bucks(config-router) Az solar_bucks By viewing the route or forwarding table on g_and_s or barneys, you can see that the default route is being propagated and is marked as an external, default candidate route, as shown in Example 11-49. Example 11-49 Viewing the Default Route on Barneys Codes C - connected, S - static, I - IGRP,...

Example 115 Identifying Line Entries of a Router the show line Command

Table 1-12 explains the line numbers and the numbering schemes found in Example 1-15. Table 1-12. Line Types and Number Schemes Table 1-12. Line Types and Number Schemes RS-232 DTE port used as a backup async port (TTY). asynchronous interface. Used typically for remote-node dial-in sessions that use protocols such as SLIP, PPP, and Xremote. Used for incoming Telnet, LAT, X.25 PAD, and protocol translation connections onto synchronous ports. Last TTY line number plus 2, through the maximum...

Example 1151 Final Router Configurations for the Internet Coffee Shop Network

< < < text omitted> > > interface EthernetO ip address 172.16.50.5 255.255.255.0 no ip directed-broadcast interface SerialO no ip address no ip directed-broadcast encapsulation frame-relay no ip mroute-cache frame-relay lmi-type cisco interface Serial0.1 point-to-point bandwidth 64 ip address 172.16.128.1 255.255.255.252 no ip directed-broadcast interface Serial0.2 point-to-point ip address 172.16.128.5 255.255.255.252 no ip directed-broadcast frame-relay interface-dlci 111 < <...

Example 116 Configuration of a Reverse Telnet Session

Enter configuration commands, one per line. End with CNTL Z. Router(config) ip host r1 2001 201.201.1.1 Router(config-line) transport input all Router(config-line) no exec Router(config-line) Az Router Example 1-16 also makes use of the no exec command entered under the line. This is optional in a reverse Telnet configuration. Adding this command lessens the likelihood of contention over the asynchronous port. An executive process, or exec, exists on all lines. These two process buffer data to...

Example 117 Clearing a Line

Trying r1 (201.201.1.1, 2001) Connection refused by remote host Trying r1 (201.201.1.1, 2001) Open R1> Upon successful completion of a reverse Telnet or any Telnet session, you might want to get back to the original starting point or the origination point. Cisco refers to this as suspending a session. To accomplish this, use the escape character. To enter the default escape character, press Ctrl-Shift-6 at the same time, and then let up and press the X key by itself. This will take you back...

Example 118 show sessions Command

Address 201.201.1.1 201.201.1.1 201.201.1.1 The number that appears on the far left is called the relative line number. For example, to return to the session on host r3, key in 3 to resume the session on r2, key in 1 and press the Enter key. The * character in front of host r1 indicates the last session that was active. To return to this session, simply press Return or Enter. The following process makes jumping past the origination point possible 1. Origination point (the first Cisco router...

Example 119 Configuring a Basic Frame Relay Switch

Enter frame frame frame frame frame frame frame frame frame frame frame frame frame frame frame frame switch switch switch switch switch switch switch switch switch switch switch switch switch switch switch switch commands, one per line. End with CNTL Z. (config) frame-relay switching (config) interface serial 0 (config-if) encapsulation frame-relay (config-if) frame-relay intf-type dce (config-if) frame-relay lmi-type ansi (config-if) clock rate 56000 (config-if) frame-relay route 101...

Example 1216 show ip ospf Command Output on Router john

Routing Process ospf 7 with ID 192.168.250.250 Supports only single T0S(T0S0) routes Supports opaque LSA It is an area border router SPF schedule delay 5 sees, Hold time between two SPFs 10 sees Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs Number of external LSA 0. Checksum Sum 0x0 Number of opaque AS LSA 0. Checksum Sum 0x0 Number of DCbitless external and opaque AS LSA 0 Number of DoNotAge external and opaque AS LSA 0 Number of areas in this router is 3. 2 normal 1 stub 0 nssa...

Example 1217 show log Command Output Documents a Down Neighbor

Syslog logging enabled (0 messages dropped, 0 flushes, 0 overruns) Console logging level debugging, 1228 messages logged Monitor logging level debugging, 0 messages logged Buffer logging level debugging, 2 messages logged Trap logging level informational, 68 message lines logged 1d00h SYS-5-CONFIG_I Configured from console by console 1d00h OSPF-5-ADJCHG Process 7, Nbr 172.16.250.1 on Serial0.1 from FULL to DOW

Example 1224 Route Table of the mark Router

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is not set The final summary that you want to...

Example 1226 Route Table of paul

< < < text omitted> > > 128.100.0.0 24 is subnetted, 2 subnets C 128.100.1.0 is directly connected, Loopback20 C 128.100.2.0 is directly connected, Loopback21 O E2 192.168.0.0 16 110 10 via 172.16.9.5, 00 01 17, Ethernet0 0 paul 128.100.0.0 24 is subnetted, 2 subnets C 128.100.1.0 is directly connected, Loopback20 C 128.100.2.0 is directly connected, Loopback21 O E2 192.168.0.0 16 110 10 via 172.16.9.5, 00 01 17, Ethernet0 0 paul

Example 1232 Frame Relay Switch Configuration

< < < text omitted> > > interface SerialO no ip address encapsulation frame-relay no fair-queue clockrate 148000 frame-relay intf-type dce frame-relay route 111 interface Serial1 110 frame-relay route 121 interface Serial3 102 frame-relay route 150 interface Serial5 151 interface Serial1 no ip address encapsulation frame-relay clockrate 148000 frame-relay intf-type dce frame-relay route 110 interface Serial0 111 interface Serial2 no ip address shutdown interface Serial3 no ip...

Example 1238 Ospf Nssa Configuration on fillings

Router ospf 2002 router-id 192.168.200.3 area 10 nssa network 172.16.2.6 0.0.0.0 area 10 network 172.16.3.3 0.0.0.0 area 10 At this point, OSPF is fully operational, and you have IP connectivity to every router in the network. To verify this, we can examine the neighbors and the route table, and you can perform standard ping tests. To verify the NSSA area, use the show ip ospf command. Example 12-39 lists the output of the show ip ospf neighbor and show ip ospf commands on the dental_ho router.

Example 1239 Verify OSPF Operation and NSSA Configuration

Neighbor ID Pri State Dead Time Address Interface 192.168.200.1 0 FULL DROTHER 00 01 42 172.16.1.1 Serial0.1 192.168.200.6 0 FULL DROTHER 00 01 44 172.16.1.6 Serial0.1 192.168.200.3 1 FULL - 00 00 38 172.16.2.6 Serial0.2 Routing Process ospf 2002 with ID 192.168.200.200 Supports only single TOS(TOS0) routes < < < text omitted> > > Area 10 Number of interfaces in this area is 1 It is a NSSA area Perform type-7 type-5 LSA translation generates NSSA default route with cost 1 Area has...

Example 124 Configuring OSPF on the Router john

John(config-router) network 172.16.9.0 0.0.0.255 area 0 john(config-router) network 172.16.1.0 0.0.0.255 area 10 john(config-router) network 172.16.2.4 0.0.0.3 area 100 You can configure the network statements on the remaining routers in many ways. We personally prefer limiting the network statement with a specific wildcard mask to one network per statement, or to a single interface with the 0.0.0.0 as the wildcard mask. In large networks, this type of configuration might be less desirable, and...

Example 124 Output from the debug framerelay lmi Command

06 01 52 Serial5(in) StEnq, myseq 122 06 01 52 RT IE 1, length 1, type 1 06 01 52 KA IE 3, length 2, yourseq 123, myseq 122 06 01 52 Serial5(out) Status, myseq 123, yourseen 123, DCE up 06 01 53 SerialO Invalid LMI type 1 06 01 58 Serial0(down) DCE LMI timeout This log further confirms an LMI problem with Serial 0. An invalid LMI type of 1 indicates that the switch is receiving Cisco LMI from the DTE end, thereby causing the timeout and the down condition. If there were an invalid LMI type 2 or...

Example 1241 Route Table of fillings

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route Gateway of last resort is 172.16.2.5 to network 0.0.0.0 172.16.0.0 16...

Example 1244 Route Table of paincenter Router

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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 default U - per-user static route, o - ODR Gateway of last resort is 172.16.10.1 to network 0.0.0.0 128.10.0.0 24 is subnetted, 1 subnets O IA 128.10.1.0 110 35 via...

Example 1245 Conditional Default Route Configuration

Router ospf 2002 router-id 192.168.200.200 area 10 nssa default-information-originate network 128.10.1.5 0.0.0.0 area 0 network 172.16.1.5 0.0.0.0 area 0 network 172.16.2.5 0.0.0.0 area 10 neighbor 172.16.1.6 neighbor 172.16.1.1 ip prefix-list cond seq 5 permit 128.10.1.0 24 'match route 128.10.1.0 24 call prefix-list called cond When the Ethernet interface is shut down, the dental_ho router no longer advertises the default route. Because the NSSA default route is controlled differently, you...

Example 1247 Frame Relay Switch Configuration

< < < text omitted> > > no ip address encapsulation frame-relay no fair-queue clockrate 148000 frame-relay intf-type dce frame-relay route 111 interface Serial1 110 frame-relay route 121 interface Serial3 102 frame-relay route 150 interface Serial5 151 interface Serial1 no ip address encapsulation frame-relay clockrate 148000 frame-relay intf-type dce frame-relay route 110 interface Serial0 111 interface Serial2 no ip address shutdown interface Serial3 no ip address encapsulation...

Example 1248 Frame Relay Configurations

< < < text omitted> > > interface Serial0.1 point-to-point ip address 10.1.128.1 255.255.255.0 frame-relay interface-dlci 121 interface Serial0.2 point-to-point ip address 10.1.129.1 255.255.255.0 frame-relay interface-dlci 111 interface Serial0.3 point-to-point ip address 10.1.130.1 255.255.255.0 frame-relay interface-dlci 150 < < < text omitted> > > no ip directed-broadcast encapsulation frame-relay no ip mroute-cache frame-relay lmi-type cisco interface Serial0.1...

Example 1249 Serial Configuration of the Router boa

Interface Serial1 ip address 10.1.80.2 255.255.255.0 clockrate 56000 After the LAN and WAN interfaces have been configured and basic IP connectivity has been established, begin to configure OSPF and IGRP. First, you will configure OSPF, and then you will integrate it with IGRP. Recalling the detailed process to configure OSPF, you have the following Step 1. Perform area design, DR BDR designation. Step 2. Assign RIDs with the use of loopback on routers prior to Cisco IOS Software 12.0. Step 3....

Example 125 show ip ospf neighbor Performed on the Router john

Neighbor ID Pri State Dead Time Address Interface 192.168.250.9 1 FULL BDR 00 00 34 172.16.9.9 Ethernet0 192.168.250.3 1 FULL - 00 00 38 172.16.2.6 Serial0.2 Notice how clearly the router IDs show up in the previous command. This can significantly help troubleshooting OSPF on any size network. Step 5 calls for the configuration of additional neighbor support to remedy the adjacency situation between john, mark, and mathew. Because you took the extra time to hard-code RIDs on all the routers,...

Example 1250 Preliminary OSPF Configuration of hinhq

Router ospf 2001 router-id 192.168.200.5 redistribute igrp 2001 subnets tag 5 network 10.1.5.1 0.0.0.0 area 0 network 10.1.128.1 0.0.0.0 area 0 network 10.1.129.1 0.0.0.0 area 0 default-metric 64 The network statements in the previous example could be simplified with one command-network 10.1.0.0 0.0.255.255 area 0. In production networks, it pays to be specific on the mask. As changes occur in the network, new interfaces in different areas might be added. If the wildcard mask is too general,...

Example 1252 Preliminary OSPF Configuration of the python and boa Routers

Router ospf 2001 network 10.1.80.1 0.0.0.0 area 75 network 10.1.1.2 0.0.0.0 area 20 router ospf 2001 network 10.1.0.0 0.0.255.255 area 75 Step 5 requires you to configure the additional neighbor support. In this model, adjacencies automatically form over the Frame Relay point-to-point networks. No additional neighbor configuration support is needed. At this point, OSPF is operational, except for Area 75, and you have IP connectivity to every router in the network. To verify this, you can...

Example 1254 Verifying the Virtual Link

Tree_frog show ip ospf virtual-links Virtual Link OSPF_VL0 to router 192.168.200.8 is up Run as demand circuit DoNotAge LSA allowed. Transit area 20, via interface Ethernet2, Cost of using 10 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 00 Adjacency State FULL (Hello suppressed) tree_frog The OSPF domain is now fully functional. By viewing the route table on the boa router, you can see that you have routes...

Example 1255 Verifying the OSPF Domain

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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 default U - per-user static route, o - ODR 10.0.0.0 8 is variably subnetted, 8 subnets, 4 masks O IA 10.1.1.0 27 110 74 via 10.1.80.1, 00 28 02, Serial1 O IA 10.1.6.0 28 110...

Example 1256 Configuring IGRP on hinhq

Router igrp 2001 passive-interface Ethernet0 passive-interface Serial0.1 passive-interface Serial0.2 network 10.0.0.0 Next, you need to configure redistribution between IGRP and OSPF. There is only one redistribution point in the network, so you do not have to worry about route feedback or redistribution loops. Example 12-57 lists the configuration of the hin_hq router, highlighting the redistribution commands. In this example, you use an OSPF default metric of 64 because it is the cost of a T1...

Example 1258 Route Table of the chameleon Router

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route 10.0.0.0 24 is subnetted, 10 subnets C 10.1.3.0 is directly connected,...

Example 126 Configuring a Route Generator

Enter configuration commands, one per line. End with CNTL Z. r1(config) interface loopback 20 02 41 51 LINK-3-UPDOWN Interface 02 41 52 LINEPROTO-5-UPDOWN Line ate to up r1(config-if) ip address 172.16.1.1 r1(config-if) interface loopback 21 r1(config-if) ip address 172.16.2.1 r1(config-if) interface loopback 22 r1(config-if) ip address 172.16.3.1 r1(config-if) interface loopback 23 r1(config-if) ip address 172.16.4.1 r1(config-if) interface loopback 24 r1(config-if) ip address 172.16.5.1...

Example 126 OSPF Configuration of john mark and mathew Routers

Interface Serial0.1 multipoint ip address 172.16.1.5 255.255.255.0 no ip directed-broadcast ip ospf priority 255 Set this routers priority to 255, forcing the DR frame-relay map ip 172.16.1.6 121 broadcast frame-relay map ip 172.16.1.1 111 broadcast interface Serial0.2 point-to-point ip address 172.16.2.5 255.255.255.252 no ip directed-broadcast frame-relay interface-dlci 150 router ospf 7 router-id 192.168.250.250 network 172.16.1.0 0.0.0.255 area 10 network 172.16.2.4 0.0.0.3 area 100 network...

Example 1260 OSPF Configuration of hinhq

Router ospf 2001 router-id 192.168.200.5 summary-address 10.1.16.0 255.255.252.0 redistribute igrp 2001 subnets tag 5 network 10.1.5.1 0.0.0.0 area 0 network 10.1.128.1 0.0.0.0 area 0 network 10.1.129.1 0.0.0.0 area 0 default-metric 64 router igrp 2001 redistribute ospf 2001 passive-interface Ethernet0 passive-interface Serial0.1 passive-interface Serial0.2 network 10.0.0.0 To view the summary route, list the route table on the boa router, as in Example 12-61.

Example 1261 Route Table of the boa Router Highlighting the Summary Route

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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 default U - per-user static route, o - ODR 10.0.0.0 8 is variably subnetted, 12 subnets, 4 masks O E2 10.1.3.0 24 110 64 via 10.1.80.1, 00 37 49, Serial1 O IA 10.1.1.0 27 110...

Example 1263 Route Table on gecko

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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, ia - IS-IS inter area * - candidate default, U - per-user static route, o - ODR P - periodic downloaded static route 10.0.0.0 8 is variably subnetted, 11 subnets, 5 masks 10.0.0.0 8 is...

Example 1266 Final Configurations of the HIN

< < < text omitted> > > interface EthernetO ip address 10.1.5.1 255.255.255.0 interface SerialO no ip address encapsulation frame-relay interface SerialO.1 point-to-point ip address 10.1.128.1 255.255.255.0 frame-relay interface-dlci 121 interface Serial0.2 point-to-point ip address 10.1.129.1 255.255.255.0 frame-relay interface-dlci 111 interface Serial0.3 point-to-point ip address 10.1.130.1 255.255.255.0 frame-relay interface-dlci 150 router ospf 2001 router-id 192.168.200.5...

Example 127 Route Generator Advertising Networks to a Downstream Router

Codes C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP 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 default U - per-user static route, o - ODR T - traffic engineered route 172.16.0.0 16 is variably subnetted, 6 subnets, 2 masks C 172.16.128.0 30 is directly connected,...

Example 128 Output for the show line Command

If you perform the same show line command on your access server, the output is a little more complicated. In Example 1-29, the absolute line number for the AUX port is 17. Therefore, if you want to add a modem to this AUX port, you need to begin your configuration with the statement Line 17 from configuration mode.

Example 128 show ip ospf neighbor Command Output for Router mathew

Neighbor ID Pri State Dead Time Address Interface 192.168.250.250 255 FULL DR 00 01 48 172.16.1.5 Serial0 You could accomplish this in other ways without using neighbor commands. Another way is to change the OSPF network type to either broadcast or point-to-multipoint. Technically, a point-to-multipoint would be a more accurate network type to use. Configuring the same network model, you will now use the network type of point-to-multipoint to create adjacencies between mathew, mark, and john....

Example 129 The show line Command Performed on the Access Server

When you identify the appropriate line entry to modify, you can configure the line to support a modem. The characteristics that you want to configure at this point apply to Layer 1. That is the speed at which the router communicates with the modem, how the modem handles flow control, and how it handles the carrier. Addressing speed first, it is important to note that the port speed of the router is not the same as the modem transmission rate. Comparing the two in Table 1-15, you find the...

Example 130 The Output from the show modemcap Command

Hardware Flowcontrol (HFL) not set Software Flowcontrol (SFL) not set This listing also shows the predefined AT strings for the modem type called default. Over the years, Cisco has made great strides in improving the robustness and ease of configuration for analog support. In the past, and still supported, are what Cisco refers to as chat scripts. The chat script is entered from the configuration mode in the format chat-script EXPECT SEND EXPECT SEND. You then call the chat script from the line...

Example 131 Transparent Bridge Configuration on the enterprise Router

< < < text omitted> > > interface Ethernet2 ip address 172.16.10.1 255.255.255.0 no ip directed-broadcast media-type 10BaseT < < < text omitted> > > interface Serial0 no ip address no ip directed-broadcast encapsulation frame-relay no ip mroute-cache logging event subif-link-status logging event dlci-status-change frame-relay lmi-type cisco interface Serial0.1 multipoint ip address 172.16.1.1 255.255.255.0 no ip directed-broadcast frame-relay map ip 172.16.1.6 130...

Example 131 Walkthrough of Configuring Analog Dial Access on an AUX Port

Tty Typ Tx Rx A Modem Roty AccO AccI * 0 1 AUX 9600 9600 - - - - - Enter configuration commands, one per line. End with CNTL Z. Router(config) line 1 Router(config-line) transport input all Router(config-line) modem inout Router(config-line) modem autoconfigure discovery After the line commands have been entered, verify modem connectivity by opening a reverse Telnet session to it. In Example 1-32, you add a loopback interface with the IP address of 201.201.201.1, to support the reverse Telnet...

Example 1311 Local SRB Configuration

No ip directed-broadcast ring-speed 16 interface TokenRing1 no ip address no ip directed-broadcast ring-speed 16 RIF enabled From ring 1 thru bridge 1 to ring 2 RIF enabled From ring 2 thru bridge 1 to ring 1 Configuring Multiport Local Source-Route Bridging The other type of SRB is needed when there are more than two Token Ring interfaces to bridge between. This type of configuration requires a virtual ring to be defined on the router. A virtual ring is just as the name describes, a virtual...

Example 1313 Status of the SRB

Local Interfaces receive transmit srn bn trn r p s n max hops cnt cnt drops To0 1 1 100 * b 7 7 7 7297 2 154 Global RSRB Parameters TCP Queue Length maximum 100 Ring Group 100 virtual ring Number No TCP peername set, TCP transport disabled Maximum output TCP queue length, per peer 100 Rings bn 1 rn 1 local ma 4007.781a.e789 TokenRing0 fwd 0 Explorer fastswitching enabled Local switched 6300 flushed 0 The show source-bridge interface command displays a quick overview of the SRB on the network....

Example 1315 SRB Configuration of shuttle15 and shuttle3 Routers

< < < text omitted> > > interface TokenRingO ip address 172.16.1.1 255.255.255.0 no ip directed-broadcast no ip route-cache no ip mroute-cache ring-speed 16 SRB from ring 15 through bridge 10 to V-Ring 100 Enable support for NETBios and NetBEUI interface TokenRingO ip address 172.16.3.3 255.255.255.0 ring-speed 16 source-bridge 3 3 100 * SRB from ring 3 through bridge 3 to V-Ring 100 source-bridge spanning Enable support for NETBios and NetBEUI

Example 1316 RSRB Configuration of the enterprise Router

Interface Loopback20 ip address 172.16.128.10 255.255.255.252 no ip directed-broadcast interface SerialO no ip address no ip directed-broadcast encapsulation frame-relay no ip mroute-cache logging event subif-link-status logging event dlci-status-change frame-relay lmi-type cisco interface Serial0.1 multipoint ip address 172.16.2.5 255.255.255.252 no ip directed-broadcast frame-relay map ip 172.16.2.6 170 broadcast interface Serial0.2 point-to-point ip address 172.16.2.1 255.255.255.252 no ip...

Example 1317 RSRB Configuration of the shuttle15 Router

Source-bridge remote-peer 100 tcp 172.16.128.1 Peer for the local router source-bridge remote-peer 100 tcp 172.16.128.1 Peer for the local router interface Loopback20 ip address 172.16.128.1 255.255.255.252 no ip directed-broadcast interface Serial0 ip address 172.16.2.6 255.255.255.252 no ip directed-broadcast encapsulation frame-relay no ip route-cache no ip mroute-cache logging event subif-link-status logging event dlci-status-change frame-relay map ip 172.16.2.5 171 broadcast < < <...