ccna


A P P E N D I X
F
Additional Scenarios
Each chapter of this book focuses on a small set of related topics so that you can more easily
digest the material. However, the CCNA exams require that you be able to apply a relatively
wide set of topics to answer an individual question. Oftentimes, the skills for applying the
wide-ranging topics to solve a single problem can be best learned through experience. Even
so, many CCNA candidates may not get on-the-job experience with all technologies on the
CCNA exams, and some may not get any experience. The scenarios included in this book
attempt to provide some of the same exam-preparation benefits as would on-the-job
experience.
You can think of each scenario as a slice of what you might do in a real networking job,
with an experienced mentor walking through the solutions with you after you have tried to
solve a particular problem. Each scenario presents a variety of internetwork topologies,
concepts, commands, and protocols, with a variety of tasks. By reading over the scenarios,
and doing the exercises and answering the open-ended questions listed with the scenarios,
you can practice applying different knowledge areas to the same scenario. By reading the
answers, you can see at least one possible solution to the problems listed in the scenario,
along with the reasons why that solution makes sense.
The two scenarios in this chapter are

IP Address Planning, Configuration, and Analysis

CDP Analysis
Scenario 1: IP Address Planning, Configuration,
and Analysis
This scenario presents a typical progression of the tasks required to deploy a new network,
particularly the tasks related to IP addressing and subnetting. This scenario has three parts,
listed as Parts A, B, and C. Part A begins with some planning guidelines that mainly consist
of planning an IP addressing scheme for a network. After you complete Part A, Part B of
the scenario asks you to configure the three routers and one switch to implement the
planned design. Finally, Part C asks you to examine router command output and answer
4 Appendix F: Additional Scenarios
questions about the details of current operation of the network. Part C also lists some
questions related to the user interface and protocol specifications.
Scenario 1, Part A: Planning
Your job is to deploy a new network with three sites, as shown in Figure F-1. The decision
to use point-to-point serial links has already been made, and the products have been chosen.
For Part A of this scenario, perform the following tasks:
Step 1
Plan the IP addressing and subnets used in this network. Use Class B network
163.1.0.0. Use the same mask throughout the Class B network, and choose a mask
that supports subnets that have up to 100 hosts.
Step 2
Assign IP addresses to the PCs as well.
Step 3
Assign addresses for the switches near R1 for management purposes.
Figure F-1
Scenario 1 Network Diagram
PC11
Server 1
PC12
Server 2
Server 3
PC13
S0
S0 S0
S1
S1
S1
Fa0/1
Fa0/1 Fa0/1
Fa0/2
Fa0/2 Fa0/2
R2
e0 e0
e0
R1
R3
PC21 PC31 PC32
SW3
SW1 SW2
Scenario 1: IP Address Planning, Configuration, and Analysis 5
Assume that a single VLAN is used on the switches near Router 1 (R1).
Tables F-1 and F-2 are provided as a convenient place to record your IP subnets and IP
addresses when performing the planning tasks for this scenario.
Table F-1
Scenario 1, Part A: IP Subnet and IP Address Planning Chart
Location of Subnet/Network Geographically Subnet Mask Subnet Number
R1 Ethernet
R2 Ethernet
R3 Ethernet
Serial between R1 and R2
Serial between R1 and R3
Serial between R2 and R3
Table F-2
Scenario 1, Part A: IP Address Planning Chart
Host Address
PC11
PC12
PC13
PC21
PC31
PC32
SW1
SW2
SW3
R1–E0
R1–S0
R1–S1
continues
6 Appendix F: Additional Scenarios
Scenario 1, Part A: Solution
It is a good idea to keep the design as simple as possible, without making it so simple that
it will not be useful as the network evolves. In this case, any subnet mask with at least
7 host bits would work, including the easy mask of 255.255.255.0. Any choice of mask
between 255.255.224.0 and 255.255.255.128 would have allowed for 6 subnets and
100 hosts per subnet.
Table F-3 shows one solution for the subnet numbers chosen, using mask 255.255.255.128,
with Table F-4 showing some sample IP address assignments.
R2–E0
R2–S0
R2–S1
R3–E0
R3–S0
R3–S1
Server 1
Server 2
Server 3
Table F-3
Scenario 1, Part A: The Completed IP Subnet Planning Chart
Location of Subnet/Network Geographically Subnet Mask Subnet Number
R1 Ethernet 255.255.255.128 163.1.1.128
R2 Ethernet 255.255.255.128 163.1.2.128
R3 Ethernet 255.255.255.128 163.1.3.128
Serial between R1 and R2 255.255.255.128 163.1.12.128
Serial between R1 and R3 255.255.255.128 163.1.13.128
Serial between R2 and R3 255.255.255.128 163.1.23.128
Table F-2
Scenario 1, Part A: IP Address Planning Chart (Continued)
Host Address
Scenario 1: IP Address Planning, Configuration, and Analysis 7
As long as the numbers are in the right subnet, the actual IP addresses that you chose for
your answer are fine. I just picked numbers between 200 and 209 for the last octet for router
addresses, and between 210 and 239 for the switches and PCs. In real networks, you might
reserve particular ranges of last octet values in each subnet for network overhead devices.
For instance, all of your routers’ LAN interface IP addresses might always be between
1 and 5.
Table F-4
Scenario 1, Part A: The Completed IP Address Planning Chart
Host Address
PC11 163.1.1.211
PC12 163.1.1.212
PC13 163.1.1.213
PC21 163.1.2.221
PC31 163.1.3.231
PC32 163.1.3.232
SW1 163.1.1.214
SW2 163.1.1.215
SW3 163.1.1.216
R1–E0 163.1.1.201
R1–S0 163.1.12.201
R1–S1 163.1.13.201
R2–E0 163.1.2.202
R2–S0 163.1.12.202
R2–S1 163.1.23.202
R3–E0 163.1.3.203
R3–S0 163.1.13.203
R3–S1 163.1.23.203
Server 1 163.1.1.241
Server 2 163.1.1.242
Server 3 163.1.2.243
8 Appendix F: Additional Scenarios
Scenario 1, Part B: Configuration
The next step in your job is to deploy the network designed in Part A. Perform the following
tasks:
Step 1
Configure IP addresses based on the design from Part A.
Step 2
Configure RIP Version 2 (RIP-2) on each router.
Step 3
Use PPP as the data-link protocol on the link between R2 and R3. Use
the default serial encapsulation elsewhere.
Step 4
Configure basic administrative settings for SW3, assuming that it is a
2960 series switch. Set the host name, IP address, default gateway, enable
password, Telnet password, and console password. Save the
configuration as well.
Scenario 1, Part B: Solution
Examples F-1, F-2, F-3, and F-4 show the configurations for Part B.
Example F-1
R1 Configuration
hostname R1
!
interface Serial0
ip address 163.1.12.201 255.255.255.128
!
interface Serial1
ip address 163.1.13.201 255.255.255.128
!
Ethernet0
ip address 163.1.1.201 255.255.255.128
!
router rip
network 163.1.0.0
version 2
Example F-2
R2 Configuration
hostname R2
!
interface Serial0
ip address 163.1.12.202 255.255.255.128
!
interface Serial1
encapsulation ppp
ip address 163.1.23.202 255.255.255.128
!
Scenario 1: IP Address Planning, Configuration, and Analysis 9
Ethernet0
ip address 163.1.2.202 255.255.255.128
!
! the following 2 commands configure RIP.
!
router rip
network 163.1.0.0
version 2
Example F-3
R3 Configuration
hostname R3
!
interface Serial0
ip address 163.1.13.203 255.255.255.128
!
interface Serial1
encapsulation ppp
ip address 163.1.23.203 255.255.255.128
!
Ethernet0
ip address 163.1.3.203 255.255.255.128
!
router rip
network 163.1.0.0
version 2
Example F-4
SW3 Configuration
Switch>
enable
Switch#
configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#
hostname SW3
SW3(config)#
enable secret cisco
SW3(config)#
line vty 0 15
SW3(config-line)#
password cisco
SW3(config-line)#
login
SW3(config-line)#
line con 0
SW3(config-line)#
login
SW3(config-line)#
password cisco
SW3(config-line)#
interface vlan 1
SW3(config-if)#
ip address 163.1.1.216 255.255.255.128
SW3(config-if)#
no shutdown
SW3(config-if)#
exit
SW3(config)#
ip default-gateway 163.1.1.201
continues
Example F-2
R2 Configuration (Continued)
10 Appendix F: Additional Scenarios
Scenario 1, Part C: Verification and Questions
The ICND1 exam tests you on your memory of the kinds of information you can find in the
output of various
show
commands. Using Examples F-5, F-6, and F-7 as references, answer
the questions following the examples.
SW3(config)#
interface fastEthernet 0/1
SW3(config-if)#
description connection to SW1
SW3(config-if)#
interface fastethernet 0/2
SW3(config-if)#
description connection to SW2
SW3(config-if)#
^Z
SW3#
SW3#
copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
SW3#
NOTE
In the network from which these commands were captured, several
administrative settings not mentioned in the scenario were configured. For example, the
enable password was configured. So, the configurations might contain additional items
not specifically mentioned in the instructions, but none of those impact the actual
behavior of the features discussed in the scenario.
Example F-5
Scenario 1, Part C: R1
show
and
debug
Output
R1#
show ip interface brief
Interface IP-Address OK? Method Status Protocol
Serial0 163.1.12.201 YES NVRAM up up
Serial1 163.1.13.201 YES NVRAM up up
Ethernet0 163.1.1.201 YES NVRAM up up
R1#
show access-lists
Standard IP access list 83
deny 163.1.3.0, wildcard bits 0.0.0.127
permit any
R1#
Example F-6
Scenario 1, Part C: R2
show
and
debug
Output
R2#
show interface
Serial0 is up, line protocol is up
Hardware is HD64570
Internet address is 163.1.12.202/25
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Example F-4
SW3 Configuration (Continued)
Scenario 1: IP Address Planning, Configuration, and Analysis 11
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
1242 packets input, 98477 bytes, 0 no buffer
Received 898 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
1249 packets output, 91395 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
12 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Serial1 is up, line protocol is up
Hardware is HD64570
Internet address is 163.1.23.202/25
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set
Keepalive set (10 sec)
LCP Open
Open: IPCP, CDPCP
Last input 00:00:03, output 00:00:03, output hang never
Last clearing of "show interface" counters 00:00:15
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
1654 packets input, 90385 bytes, 0 no buffer
Received 1644 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
1674 packets output, 96130 bytes, 0 underruns
0 output errors, 0 collisions, 8 interface resets
0 output buffer failures, 0 output buffers swapped out
13 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
continues
Example F-6
Scenario 1, Part C: R2
show
and
debug Output (Continued)
12 Appendix F: Additional Scenarios
Ethernet0 is up, line protocol is up
Hardware is MCI Ethernet, address is 0000.0c89.b170 (bia 0000.0c89.b170)
Internet address is 163.1.2.202, subnet mask is 255.255.255.128
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 4:00:00
Last input 00:00:00, output 00:00:04, output hang never
Last clearing of "show interface" counters never
Queuing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
2274 packets input, 112381 bytes, 0 no buffer
Received 1913 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
863 packets output, 110146 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 output buffer failures, 0 output buffers swapped out
6 transitions
R2#show ip protocol
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 6 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Key-chain
Serial0 2 2
Serial1 2 2
Ethernet0 2 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
163.1.0.0
Routing Information Sources:
Gateway Distance Last Update
163.1.12.201 120 00:00:02
163.1.23.203 120 00:00:09
Distance: (default is 120)
Example F-6 Scenario 1, Part C: R2 show and debug Output (Continued)
Scenario 1: IP Address Planning, Configuration, and Analysis 13
Example F-7 Scenario 1, Part C: R3 show and debug Output
R3#show running-config
Building configuration...
Current configuration : 888 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname R3
!
enable secret 5 $1$J3Fz$QaEYNIiI2aMu.3Ar.q0Xm.
!
ip subnet-zero
no ip domain-lookup
!
interface Serial0
ip address 163.1.13.203 255.255.255.128
no fair-queue
!
interface Serial1
ip address 163.1.23.203 255.255.255.128
encapsulation ppp
!
interface Ethernet0
ip address 163.1.3.203 255. 255.255.128
!
router rip
network 163.1.0.0
version 2
!
ip classless
no ip http server
!
!
!
!
line con 0
password cisco
login
line aux 0
line vty 0 4
continues
14 Appendix F: Additional Scenarios
password cisco
login
!
end
R3#show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 163.1.3.203 - 0000.0c89.b1b0 SNAP Ethernet0
R3#show ip 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, 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
163.1.0.0/16 is variably subnetted, 7 subnets, 2 masks
R 163.1.2.128/25 [120/1] via 163.1.23.202, 00:00:22, Serial1
C 163.1.3.128/25 is directly connected, Ethernet0
R 163.1.1.128/25 [120/1] via 163.1.13.201, 00:00:28, Serial0
R 163.1.12.128/25 [120/1] via 163.1.13.201, 00:00:28, Serial0
[120/1] via 163.1.23.202, 00:00:22, Serial1
C 163.1.13.128/25 is directly connected, Serial0
C 163.1.23.128/25 is directly connected, Serial1
C 163.1.23.202/32 is directly connected, Serial1
R3#trace 163.1.1.211
Type escape sequence to abort.
Tracing the route to 163.1.1.211
1 163.1.13.201 16 msec 16 msec 16 msec
2 163.1.1.211 44 msec * 32 msec
R3#ping 163.1.1.211
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 163.1.1.211, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/66/68 ms
Example F-7 Scenario 1, Part C: R3 show and debug Output (Continued)
Scenario 1: IP Address Planning, Configuration, and Analysis 15
Answer the following questions using Examples F-5, F-6, and F-7 as references:
1. Which commands in the examples listed a router’s own IP addresses?
2. Which commands in the examples listed neighboring routers’ IP addresses?
3. Referring to Example F-7, which IP route does R3 use when the ping 163.1.1.211
command is used?
4. What command is used to find the path a packet would take from R3 to 163.1.1.1?
5. Imagine that R3’s E0 interface needs to use a new IP address and mask (10.1.1.1,
255.255.255.0). If the user is in user mode, what steps are necessary to change the IP
address?
6. Which command tells how much time has passed since R2 last received a RIP update
from R3? How much time has passed in this case?
7. Based on the IP addresses configured for Part A of this scenario, which IP subnets did
you expect to see in the R1, R2, and R3 routing tables? Did you see all those routes in
R3’s routing table (Example F-7)? Did you see any additional routes?
Scenario 1, Part C: Solution
The answers to the questions for Part C are as follows:
1. The show running-config, show ip interface brief, and show interfaces commands
each list a router’s own IP address. Also, the show ip arp command lists a router’s own
IP address on LAN interfaces.
2. The show ip protocol command lists a neighboring router’s IP address in cases in
which the neighboring router is sending routing updates. Also, the show ip route
command lists the next-hop router for routes learned from neighboring routers.
3. To answer this question, you need to analyze the IP subnets and masks (shown in prefix
format). In this case, subnet 163.1.1.128/25 contains IP addresses 163.1.1.129 through
163.1.1.254, with a subnet number of 163.1.1.128 and a subnet broadcast address of
163.1.1.255. So, R3 would match the route listed for subnet 163.1.1.128/25, and then
send the packet out R3’s Serial0 interface to R1 (163.1.13.201) next.
4. The trace 163.1.1.1 command.
5. The following steps should be used:
R3> enable
password: password
R3#configure terminal
R3(config)#interface ethernet 0
R3(config-if)#ip address 10.1.1.1 255.255.255.0
R3(config)#Ctrl-Z
R3#
16 Appendix F: Additional Scenarios
6. The show ip protocol command lists each neighboring router from which routes have
been learned, and the time since an update or hello has been heard from that neighbor.
In this case, Example F-6 shows that the last update from 163.1.23.203 (R3), received
on R2, was 7 seconds ago.
7. The subnets were listed in Table F-4 earlier in this scenario, each with a /25 prefix
length (listed in mask format of 255.255.255.128 in Table F-4). The show ip route
command on R3 (Example F-7) lists seven subnets—the six subnets listed in Table F-4,
plus subnet 163.1.23.202/32. By default, PPP adds a route for the neighboring router’s
IP address, with a /32 prefix length, to the routing table. The /32 prefix means that
the route matches packets to that single IP address only—163.1.23.202 in this case.
Scenario 2: CDP Analysis
This scenario focuses on Cisco Discovery Protocol (CDP). CDP provides a lot of useful
information in real internetworks, and it can be easily used for testing your knowledge of
basic network designs—two reasons why it can be a popular exam topic, particularly for
the ICND1 exam.
Scenario 2, Part A: CDP Command Output Memory Exercise
Part A makes you think about CDP command output before looking at any examples. For
this part, you need to list all variations of options on the show cdp command, for example
show cdp neighbor. Additionally, you should note which of the show cdp command
options supply the following pieces of information:
1. The name of one or more neighboring devices
2. The capabilities (functions supported by) a neighboring device (for example, router)
3. The IOS revision running on the neighboring device
4. The platform of the neighboring device
5. The interface/port used on the local device with which to connect to a particular CDP
neighbor
6. The interface/port used on the neighboring device
7. An IP address on a neighboring router
8. An IP address on a neighboring Layer 2 switch
9. The STP port status on a neighboring Layer 2 switch
10. Statistics about the number of CDP messages received from the neighboring device on
a point-to-point WAN link
Scenario 2: CDP Analysis 17
11. A list of CDP neighbors known by the neighboring device
12. The complete list of interfaces on which CDP is enabled on a local device
To perform this task, you can write the answers on any scrap of paper. However, the
upcoming answer lists the answers in a table, with the commands across the top, and the
numbers from the preceding list on the left side of the table.
Scenario 2, Part A: Solution
One of the keys to remembering all the CDP commands and their output is to remember
that only the neighbor and entry options on the show cdp command actually list
information about neighbors. The show cdp interfaces and show cdp commands simply
list the per-interface and global configuration settings, respectively. Finally, the show cdp
traffic command lists traffic statistics about sent and received CDP updates.
One additional perspective to remember is that the show cdp neighbors detail and show
cdp entry name commands each list the exact same information, with the same format. The
only difference is that the show cdp entry name command lists information only about the
neighbor whose name is listed in the command, whereas show cdp neighbors detail lists
information about every CDP neighbor.
Table F-5 lists the 12 items requested in the Scenario 2, Part A questions, along with the
commands that supply each piece of information. In particular, note that CDP does not
identify any STP information, so for item number 9, none of the cells in the table are
marked.
Table F-5 CDP Command Options and Information Listed
Reference
Number
show cdp
neighbor
show cdp neighbor
detail (and show cdp
entry name)
show cdp
interface
show cdp
traffic
show
cdp
1 ✓ ✓
2 ✓ ✓
3 ✓
4 ✓ ✓
5 ✓ ✓
6 ✓ ✓
7 ✓
8 ✓
continues
18 Appendix F: Additional Scenarios
Scenario 2, Part B: Draw an Internetwork Diagram Using CDP
Command Output
Your sole task for Part B is to create a diagram of an internetwork solely based on the output
of several show cdp commands on the various devices. Use the command output shown in
Example F-8 through Example F-12 to build the network diagram.
Please keep the following three important notes in mind when solving this puzzle. First, try
to avoid looking at Figure F-2, which shows the solution, until you have finished your own
work. Second, although you can draw the diagram with the devices located anywhere you
like, if you place the routers in the figure with the lower-numbered routers at the top of your
figure, and higher-numbered routers at the bottom, your figure will more closely match the
sample answer shown at the end of this scenario. For the switches, you might want to just
put them somewhat close to the routers to which they are connected. Lastly, to reduce
clutter, include only the following in the figure:
■ Routers and switches
■ Their connecting links
■ Interface numbers used to connect these devices
In addition to drawing the diagram, list the following information:
■ The names and device type (platform) of each device
■ Software version running on each device (feel free to list this information to the side
of the figure, to reduce clutter)
■ Interfaces in an up/up state but for which no CDP neighbors have been discovered
Note that you will not be able to find all of the information for all devices from the output
in the examples, but do try to find as much as you can.
Reference
Number
show cdp
neighbor
show cdp neighbor
detail (and show cdp
entry name)
show cdp
interface
show cdp
traffic
show
cdp
9
10 ✓ ✓
11 ✓ ✓
12 ✓
Table F-5 CDP Command Options and Information Listed (Continued)
Scenario 2: CDP Analysis 19
Example F-8 CDP Output for the Device Named “One”
One#show cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Sending CDPv2 advertisements is enabled
One#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
Seven Fas 0/0 126 S I WS-C3550- Fas 0/11
Two Ser 0/0/1 167 R S I 1841 Ser 0/0/1
One#show cdp entry Seven
-------------------------
Device ID: Seven
Entry address(es):
IP address: 10.10.5.2
Platform: Cisco WS-C3550-24, Capabilities: Switch IGMP
Interface: FastEthernet0/0, Port ID (outgoing port): FastEthernet0/11
Holdtime : 122 sec
Version :
Cisco IOS Software, C3550 Software (C3550-I5Q3L2-M), Version 12.2(25)SE, RELEASE SOFTWARE
(fc)
Copyright (c) 1986-2004 by Cisco Systems, Inc.
Compiled Wed 10-Nov-04 18:07 by yenanh
advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27,
value=00000000FFFFFFFF010221FF000000000000000AB7DCB780FF0000
VTP Management Domain: ''
Native VLAN: 1
Duplex: full
Example F-9 CDP Output for the Device Named “Two”
Two#show cdp neighbors detail
-------------------------
Device ID: Five
Entry address(es):
IP address: 10.10.2.2
Platform: Cisco 1841, Capabilities: Router Switch IGMP
Interface: Serial0/1/1, Port ID (outgoing port): Serial0/1/0
Holdtime : 164 sec
continues
20 Appendix F: Additional Scenarios
Version :
Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(9)T, RELEASE
SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2006 by Cisco Systems, Inc.
Compiled Fri 16-Jun-06 21:26 by prod_rel_team
advertisement version: 2
VTP Management Domain: ''
-------------------------
Device ID: One
Entry address(es):
IP address: 10.10.1.1
Platform: Cisco 1841, Capabilities: Router Switch IGMP
Interface: Serial0/0/1, Port ID (outgoing port): Serial0/0/1
Holdtime : 155 sec
Version :
Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(9)T, RELEASE
SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2006 by Cisco Systems, Inc.
Compiled Fri 16-Jun-06 21:26 by prod_rel_team
advertisement version: 2
VTP Management Domain: ''
-------------------------
Device ID: Three
Entry address(es):
IP address: 10.10.3.2
Platform: Cisco 1841, Capabilities: Router Switch IGMP
Interface: Serial0/1/0, Port ID (outgoing port): Serial0/1/0
Holdtime : 142 sec
Version :
Cisco IOS Software, 1841 Software (C1841-ADVIPSERVICESK9-M), Version 12.3(11)T3, RELEASE
SOFTWARE (fc4)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Tue 25-Jan-05 14:20 by pwade
advertisement version: 2
VTP Management Domain: ''
Two#show cdp interface
Example F-9 CDP Output for the Device Named “Two” (Continued)
Scenario 2: CDP Analysis 21
FastEthernet0/0 is up, line protocol is up
Encapsulation ARPA
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
FastEthernet0/1 is administratively down, line protocol is down
Encapsulation ARPA
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
Serial0/0/0 is administratively down, line protocol is down
Encapsulation HDLC
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
Serial0/0/1 is up, line protocol is up
Encapsulation HDLC
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
Serial0/1/0 is up, line protocol is up
Encapsulation HDLC
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
Serial0/1/1 is up, line protocol is up
Encapsulation HDLC
Sending CDP packets every 60 seconds
Holdtime is 180 seconds
Example F-10 CDP Output for the Device Named “Three”
Three#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
Four Fas 0/0 165 S I WS-C2950-2Fas 0/13
Two Ser 0/1/0 169 R S I 1841 Ser 0/1/0
Example F-11 CDP Output for the Device Named “Four”
Four#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone
Device ID Local Intrfce Holdtme Capability Platform Port ID
Six Fas 0/4 148 S I WS-C2950T-Fas 0/3
Three Fas 0/13 149 R S I Cisco 1841Fas 0/0
Example F-9 CDP Output for the Device Named “Two” (Continued)
22 Appendix F: Additional Scenarios
Scenario 2, Part B: Solution
To build the diagram, you need to look at the show cdp neighbors, show cdp neighbors
detail, and show cdp entry name commands in Example F-8 through Example F-12. Each
of these commands lists neighboring device names, the local device’s interface connecting
it to the neighbor, the neighbor’s interface on the other end of the link, and the neighbor's
device type (platform). With these four pieces of information in hand, you can decide
whether to draw a router or switch icon for the neighboring device, list its name, and put
interface numbers on each end of the link.
To help you see the specific information you need to focus on to draw the figure,
Example F-13 repeats a part of Example F-8, taken from device One, highlighting these
details.
Example F-12 CDP Output for the Device Named “Five”
Five#show cdp entry Six
-------------------------
Device ID: Six
Entry address(es):
IP address: 10.10.4.4
Platform: cisco WS-C2950T-24, Capabilities: Switch IGMP
Interface: FastEthernet0/0, Port ID (outgoing port): FastEthernet0/17
Holdtime : 179 sec
Version :
Cisco Internetwork Operating System Software
IOS (tm) C2950 Software (C2950-I6Q4L2-M), Version 12.1(22)EA1, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2004 by cisco Systems, Inc.
Compiled Mon 12-Jul-04 08:18 by madison
advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27,
value=00000000FFFFFFFF010221FF000000000000000F234387C0FF0000
VTP Management Domain: ''
Native VLAN: 1
Duplex: full
Example F-13 Highlighted CDP Output for the Device Named “One”
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! The highlighted portions below show that device "One" connects to device "Seven"
! using One's local Fa0/0 interface. Seven uses its Fa0/11 interface. Seven's
! platform is listed as WS-C3550-, which is a 3550 workgroup switch.
One#show cdp neighbors
Scenario 2: CDP Analysis 23
Figure F-2 shows the completed internetwork diagram that could be drawn based on the
information in the CDP output from Examples F-8 through F-12.
Figure F-2 Network Diagram Derived from show cdp Output
Table F-6 lists the rest of the information requested for Part B. Finding all the information
listed in the table requires a bit of detective work. First, Examples F-8 through F-12 did not
list the IOS version used by every device, so in those cases, the Cisco IOS Software Release
column simply says “not shown.” Next, only Example F-9 (from device Two) listed any
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
Seven Fas 0/0 126 S I WS-C3550- Fas 0/11
Two Ser 0/0/1 167 R S I 1841 Ser 0/0/1
Example F-13 Highlighted CDP Output for the Device Named “One” (Continued)
10.10.5.2 Fa0/11
10.10.5.1 Fa0/0
Fa0/0
S0/1/0
Fa0/0
10.10.2.2
10.10.4.1 Fa0/0 10.10.4.2
10.10.4.4 Fa0/17
Fa0/4 Fa0/3
10.10.4.3 Fa0/13
10.10.3.2 S0/1/0
10.10.1.1 S0/0/1
10.10.1.2
10.10.6.2
10.10.2.1
S01/1
10.10.3.1
S01/0
S0/0/1
One
Two
Three Five
Seven
Four Six
(No Device
Found)
24 Appendix F: Additional Scenarios
information about which interfaces were up/up; from that information, you could see the
four up/up interfaces on Two, and only three CDP neighbors, meaning that Two had not
discovered a neighbor on one up/up interface. Finally, the platform field in the show cdp
neighbors command happens to truncate the output in some cases, often truncating the
platform type field. However, the output of the show cdp neighbors detail and show cdp
entry name commands do not truncate the platform type. So, if your answers omitted the
last few characters of the platform type compared to Table F-6, you might want to go back
and look more closely at a few of the other CDP commands.
1. The show cdp neighbors command in Example F-10 lists “WS-C2950-2” as the platform; this command truncates
the output to fit. The real device type is WS-C2950-24 (referring to 24 10/100 ports).
Scenario 2, Part C: CDP Configuration
This final step requires you to configure CDP. Write down the CDP configuration
commands required to achieve the following:
■ On the device named Two, disable CDP on all interfaces out which no CDP
neighbor has yet been found (according to the show cdp commands in Examples F-8
through F-12).
■ On the device named Three, disable CDP so that this device does not send CDP
updates on any interface. Use as few commands as possible.
Table F-6 Additional Information Learned via CDP Beyond Figure F-2
Device Name
Cisco IOS Software
Release Platform
Up/up Interfaces on
Which No Neighbors
Were Found
One 12.4(9)T 1841 Not shown
Two Not shown 1841 Fa0/0
Three 12.3(11)T3 1841 Not shown
Four Not shown WS-C2950-21 Not shown
Five 12.4(9)T 1841 Not shown
Six 12.1(22)EA1 WS-C2950T-24 Not shown
Seven Not shown WS-C3550-24 Not shown
Scenario 2: CDP Analysis 25
Scenario 2, Part C: Solution
This last step is just a reminder of how to enable and disable CDP on a single interface (as
shown in Example F-14) and how to enable and disable CDP globally (as shown in
Example F-15). The cdp enable and no cdp enable interface subcommands enable and
disable CDP, respectively, on that interface. The cdp run and no cdp run commands enable
and disable, respectively, CDP on the entire device.
Example F-14 Disabling CDP on One Interface, Device “Two”
interface fastethernet 0/0
no cdp enable
Example F-15 Disabling CDP Globally on Device “Three”
no cdp run