Building a WAN TDJ3M7 Northview Heights Mr. Zaheer Bhyat

2 Introduction The following slides offer a presentation identifying the steps necessary for designing a simple Wide Area Network, including: A schematic diagram of the network An IP addressing structure Media connections Router configuration Establishing connectivity, and Troubleshooting

3 Premise A small company with three locations in different cities requires Wide Area Network connectivity The company requires: 7 Subnetworks a minimum of 20 Hosts per subnet The company has been given a Class B IP Address:

4 Procedure The following slides will identify the sequence of steps necessary to meet the requirements of the client. Network configuration/schematic IP Addressing structure Subnet addressing Subnet masks Interface addressing Usable host addressing Physical device connections Router configuration Configuration modes Configure Hostnames Setting Passwords Configure routing protocols Configure Interfaces Configure Routing Tables Configure Console Terminal Save configuration Test Connectivity Telnet Ping Troubleshooting Physical Logical

5 Network Schematic

6 Calculating Subnets In order to get 7 subnet addresses… Borrow 4 bits for networks from the 3 rd octet… The four bits will produce a number of subnets and a corresponding subnet mask… S S S S H H H H. HHHHHHHH You are given a Class B IP address = The default Subnet Mask = You require 7 subnets, with at least 20 hosts on each subnet = 240 Subnet Mask # of subnets = 2 4 = 16

7 Calculate subnet address range Note: 8 bit octet: value = (0-255) 4 bits borrowed: value = Subnet range limit = 16 Network ID – – –

8 How to Determine Hosts In order to get a minimum of 20 addresses per subnet … A total of 4 bits for hosts remain in the 3 rd octet and 8 in the 4 th octet … The 12 bits will produce a number of hosts … ____NETWORK_____ _______HOSTS__________ SSSS H H H H. HHHHHHHH You are given a Class B IP address = The default Subnet Mask = You require 7 subnets, with at least 20 hosts on each subnet. # of Hosts per subnet = 2 12 =4096 (Minus 2) =4094 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x2

9 Calculate usable host address range Subnet # # Subnet IP ID # of Hosts per subnet = 2 12 =4096 (Minus 2) =4094 Host addresses per subnet Range

10 Identify Subnets and Interfaces

11 IP Configuration Table Network IP Configuration and Addressing Map Subnet IPTorontoNew YorkLondon IP Address Subnet Mask Subnet Subnet Subnet Subnet Subnet Subnet Subnet Interface S Int S0 Clockrate Subnet Mask Interface S Subnet Mask Interface E Subnet Mask Interface E Subnet Mask Note: Reserved Addresses Addresses with:Network Address - Binary numbering equal to all zero - E.g. 0 – – Network Broadcast – Binary numbering with all ones - E.g. 224 – –

12 Assign Network IP Configuration

13 Physical Components

14 Router Configuration Access Hyperterminal from the Console Terminal Configure Com Port settings as indicated

15 Entering Router Modes 1. Enter User Exec Mode 2. Enter Privileged Exec Mode 3. Enter Global Config Mode 4. Enter Int Config Mode

16 Router Configuration Commands … Enable Global Config Mode Configure Terminal Configure Hostname Set Secret password Routing Protocol – (Hop Count Metric limit 15 – good for small WANs) Configure Serial Interface Set DCE connection Configure Serial Interface Configure Ethernet Interface Enable Configure terminal Hostname Toronto Enable secret class Router rip Network Network Network Int S0 Ip address Clockrate No shut Int S1 Ip address No shut Int E0 Ip address No shut

17 Router Configuration Commands Line con 0 Password cisco Login Line vty 0 4 Password cisco Login Exit Ip host Toronto Ip host New York Ip host London Exit Copy run start Configure Line console for remote/telnet access and set login passwords Configure Routing Table Exit Save configuration

18 Testing Connectivity Basic Network Testing include the following commands: telnet Ping Trace Show ip route Show interfaces, and debug

19 Telnet – virtual terminal protocol Part of the TCP/IP protocol suite: Allows connections to hosts Allows connection between router and connecting device Allows verification of application layer between source and destination – thereby including all lower layers It is the most complete test mechanism available. Three different commands to initiate a telnet session from London to Toronto London> connect toronto or London> toronto or London> Toronto>

20 Ping – Packet Internet groper An ICMP (Internet Control Message Protocol) echo message and its reply: Echo protocols are used to test whether protocols are being routed The ping command sends a packet to the destination host and then waits for a reply packet from that host Tests end-to-end connectivity Echo results help to: Evaluate path-to-host reliability Identify delays over the path Determine whether the host can be reached or is functioning Router> ping Type escape sequence to abort Sending 5, 100 byte ICMP Echos to , timeout is 2 seconds: ! ! ! ! ! Success rate is 100 percent, round-trip min/avg/max – 1/3/4 ms Router>

21 Show interfaces serial Show interfaces serial shows a serial connection between two router interfaces Interface has hardware and software pieces Hardware includes cables, connectors, and interfaces Software is responsible for messages such as keepalive, control and user information Testing physical and data link layers include checking for: Carrier detect signal Physical connection status Keepalive messages being received Data packet transmission across physical link Router# show int s1 Serial is up, line protocol is up Hardware is cxBus Serial Description. 56Kb San Jose - MP Carrier detect (line status) Keepalives Serial 1 is up, line protocol is up Operational Serial 1 is up, line protocol is downConnection problems Serial 1 is down, line protocol is downInterface problem Serial 1 is administratively down, line protocol is downDisabled

22 Trace - traceroute A program that traces the path a packet takes to a destination Used to debug routing problems between hosts. Trace tests each step along the way Traces takes advantage of error messages generated by routers when a packet exceeds its Time To Live (TTL) or hop count value. Trace sends incrementing ping echos and displays round-trip for each. Each successive gets closer to the destination Trace identifies which router was the last reached – allowing for fault isolation York# trace Rome Type escape to abort Tracing the route to Rome ( ) 1 London ( ) 8 msec 8 msec 8 msec 2 Paris ( ) 8 msec 8 msec 8 msec 3 Rome ( ) 8 msec 8 msec 4 msec

23 Show ip route Show ip route displays the routing table Table contains directions that the router uses to determine how it will direct traffic across the network It is used to determine whether a routing table entry exists for the target network Paris# show ip route Code: I – IGRP derived, R – derived, O – OSPF derived C – Connected, S – static, E – EGP derived, B – BGP derived I – IS – IS derived, D – EIGRP derived * - candidate default route, IA – OSPF inter area route E1 – OSPF external type 1 route, E2 – OSPF external type 2 route L1 - IS – IS level 1 route, L2 - IS – IS level 2 route EI – EIGRP external route Gateway of last resort is not set I [100/1300] via :00:22 Ethernet is subnetted (mask is ), 3 subnets I [100/180771] via , 0:01:29, Ethernet C is directly connected, Ethernet1 C is directly connected, Ethernet0 I [100/1200] via :00:22 Ethernet Below Rome ( ) is reachable by Paris ( ) via the Ethernet1 interface

24 General model for troubleshooting Step 1.Define the problem. What are the symptoms and the possible causes? Step 2. Gather the facts. Isolate the possible causes. Step 3. Consider the possibilities. Based on the gathered facts, narrow the focus relevant to the specific problem. Step 4. Create an action plan. Devise a plan in which you manipulate only one variable at a time Step 5. Implement the action plan. Perform each step carefully while testing to see if the symptom disappears Step 6.Observe the results. Determine if the you resolved the problem, if yes stop the process, if no… Step 7. Repeat the process. Return to Step 4.

25 Network Troubleshooting Effective Troubleshooting is facilitated by keeping excellent documentation: Hardware or physical problems may be addressed visually and by using appropriate tools Software problems may addressed by using software detection (IOS) tools including ping, trace ip route, telnet, and show arp Throughout this 2nd semester you use the same basic configuration for your labs and simulations. For these troubleshooting labs, you can refer to this configuration and imagine what could go wrong with it, in terms of the OSI layers. - Examples of problems in each layer might include Layer 1 - incorrect cable used Layer 2 - interface not configured for Ethernet Layer 3 - subnet mask is incorrect

26 Layer 1 Errors Layer 1 errors include: broken cables disconnected cables cables connected to the wrong ports intermittent cable connection wrong cables used for the task at hand (must use rollovers, cross-connects, and straight-through cables correctly) transceiver problems DCE cable problems DTE cable problems devices turned off

27 Layer 2 errors Layer 2 errors include: improperly configured serial interfaces improperly configured Ethernet interfaces improper encapsulation set (HDLC is default for serial interfaces) improper clockrate settings on serial interfaces

28 Layer 3 errors Layer 3 errors include: routing protocol not enabled wrong routing protocol enabled incorrect IP addresses incorrect Subnet Masks incorrect DNS to IP bindings

29 Possible induced network problems… # Category Symptom Possible Problems Solution 1 Router Can't get from user to exec mode Unknown enable password Perform password recovery procedure 2 Router Ping consistently fails on 1 interface Wrong IP address or mask entered on 1 end of the ping While in interface mode properly configure ip address 3 Router Ping test consistently fails on 1 interface Interface is shut down Use no shutdown on that interface 4 Router Can't ping across a serial line Clock rate not set on DCE end Set clock rate on DCE end 5 Router Can't ping across serial line Clock rate is set on both DCE and DTE ends Clock rate should only be set on DCE end 6 Router Typing router's name doesn't substitute for it's IP address; connection timed out Bad DNS entry Use ip host command to fix IP address 7 Router Router won't boot into user mode Config register has been changed Change config register to 0x2102

30 Possible induced network problem… 8 Router Router has blank configuration file even when you show start No configuration in NVRAM Either in setup mode or line by line create a router config 9 Router Wrong or empty routing table Wrong routing protocol enabled Change routing protocol with router rip command 10 Router Wrong or empty routing table Wrong or missing networks when routing protocol was enabled Issue a proper router rip and network command 11 Router Router won't even begin boot process Router power unplugged or power supply has a problem Plug in the router 12 Router Router is running a limited IOS No IOS image in flash or on tftp server Find a source for the IOS image and copy into flash 13 Router Can telnet to a router but can't get past its password You have an incorrect vty password Go to the router in question and look up the vty password in its configuration file 14 Workstation Can't console into router Wrong settings on terminal emulation program Enter correct settings for terminal emulation program

31 Possible induced network problem 15 Workstations Workstation cannot link to routers and routers and workstations seem properly configured No power to hubs or cable may be plugged into hub's uplink port Supply power to the hubs or move cable 16 Workstation Can't ping or telnet to the desired workstation Incorrect TCP/IP settings on one of the workstations Correct the TCP/IP settings on the workstation with the problem 17 Transceiver No link light on Ethernet AUI connections Transceiver is improperly seated in the sliding latch connector or wrong cable type Properly seat the transceiver or replace cable with a straight- through 18 Cabling Can't ping even though everything else seems OK Cable unplugged broken or discontinuous somewhere Isolate the bad cable and replace it 19 Cabling Can't ping even though everything seems OK with devices Wrong cable used somewhere. This lab setup requires straight- through cross-connect and rollover cables and they are sometimes confused for each other Make sure the right cable is used for every connection

32 Conclusion This presentation offered a step-by-step process necessary for creating a simple Wide Area Network, including: –A schematic diagram of the network –An IP addressing structure –Media connections –Router configuration –Establishing connectivity, and –Troubleshooting It is vital to note the importance of: –Careful planning –Good documentation –Systematic approach –Logical thinking.