CCNA_R&S-Student_Lab_Manual
.pdf
c.Verify that the ARP cache has been cleared.
d.Send a ping to the default gateway, using the ping 192.168.1.1 command.
e.Stop the Wireshark capture after pinging to the default gateway is finished.
f.Examine the Wireshark captures for the ARP exchanges in the packet details pane. What was the first ARP packet? ___________________________
Fill in the following table with information about your first captured ARP packet.
Field |
Value |
|
|
Sender MAC address
Sender IP address
Target MAC address
Target IP address
What was the second ARP packet? ______________________________
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 101 of 257
Fill in the following table with information about your second captured ARP packet.
Field |
Value |
|
|
Sender MAC address
Sender IP address
Target MAC address
Target IP address
Step 3: Examine network latency caused by ARP.
a.Clear the ARP entries on PC-A.
b.Start a Wireshark capture.
c.Ping switch S2 (192.168.1.12). The ping should be successful after the first echo request.
Note: If all the pings were successful, S1 should be reloaded to observe network latency with ARP.
C:\Users\User1> ping 192.168.1.12
Request timed out.
Reply from 192.168.1.12: bytes=32 time=2ms TTL=255 Reply from 192.168.1.12: bytes=32 time=2ms TTL=255 Reply from 192.168.1.12: bytes=32 time=2ms TTL=255
Ping statistics for 192.168.1.12:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss), Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 3ms, Average = 2ms
d.Stop the Wireshark capture after the pinging is finished. Use the Wireshark filter to display only ARP and ICMP outputs. In Wireshark, type arp or icmp in the Filter: entry area.
©2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public.
Page 102 of 257
e.Examine the Wireshark capture. In this example, frame 10 is the first ICMP request sent by PC-A to S1. Because there is no ARP entry for S1, an ARP request was sent to the management IP address of S1 asking for the MAC address. During the ARP exchanges, the echo request did not receive a reply before the request was timed out. (frames 8 – 12)
After the ARP entry for S1 was added to the ARP cache, the last three ICMP exchanges were successful, as displayed in frames 26, 27 and 30 – 33.
As displayed in the Wireshark capture, ARP is an excellent example of performance tradeoff. With no cache, ARP must continually request address translations each time a frame is placed on the network. This adds latency to the communication and could congest the LAN.
Reflection
1.How and when are static ARP entries removed?
_____________________________________________________________________________
__________
2.Why do you want to add static ARP entries in the cache?
_____________________________________________________________________________
__________
3.If ARP requests can cause network latency, why is it a bad idea to have unlimited hold times for ARP entries?
_____________________________________________________________________________
__________
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 103 of 257
Router Interface Summary Table
Router Interface Summary
Router Model |
Ethernet Interface #1 |
Ethernet Interface #2 |
Serial Interface #1 |
Serial Interface #2 |
|
|
|
|
|
1800 |
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/0/0 (S0/0/0) |
Serial 0/0/1 (S0/0/1) |
|
(F0/0) |
(F0/1) |
|
|
|
|
|
|
|
1900 |
Gigabit Ethernet 0/0 |
Gigabit Ethernet 0/1 |
Serial 0/0/0 (S0/0/0) |
Serial 0/0/1 (S0/0/1) |
|
(G0/0) |
(G0/1) |
|
|
|
|
|
|
|
2801 |
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/1/0 (S0/1/0) |
Serial 0/1/1 (S0/1/1) |
|
(F0/0) |
(F0/1) |
|
|
|
|
|
|
|
2811 |
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/0/0 (S0/0/0) |
Serial 0/0/1 (S0/0/1) |
|
(F0/0) |
(F0/1) |
|
|
|
|
|
|
|
2900 |
Gigabit Ethernet 0/0 |
Gigabit Ethernet 0/1 |
Serial 0/0/0 (S0/0/0) |
Serial 0/0/1 (S0/0/1) |
|
(G0/0) |
(G0/1) |
|
|
|
|
|
|
|
Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.
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Lab 12 - Using IOS CLI with Switch MAC Address Tables
Topology
Addressing Table
Part 10: |
Part 11: Int |
Part 12: IP |
Part 13: Sub |
Part 14: Defa |
evice |
erface |
Address |
net Mask |
ult Gateway |
|
|
|
|
|
R1 |
G0/1 |
192.168.1.1 |
255.255.255.0 |
N/A |
|
|
|
|
|
S1 |
VLAN 1 |
192.168.1.11 |
255.255.255.0 |
192.168.1.1 |
|
|
|
|
|
S2 |
VLAN 1 |
192.168.1.12 |
255.255.255.0 |
192.168.1.1 |
|
|
|
|
|
PC-A |
NIC |
192.168.1.3 |
255.255.255.0 |
192.168.1.1 |
|
|
|
|
|
PC-B |
NIC |
192.168.1.2 |
255.255.255.0 |
192.168.1.1 |
|
|
|
|
|
Objectives
Part 1: Build and Configure the Network
Cable the network according to the topology diagram.
Configure the network devices according to the Addressing Table.
Part 2: Examine the Switch MAC Address Table
Use show commands to observe the process of building the switch MAC address table.
Background / Scenario
The purpose of a Layer 2 LAN switch is to deliver Ethernet frames to host devices on the local network. The switch records host MAC addresses that are visible on the network, and maps those MAC addresses to its own Ethernet switch ports. This process is called building the MAC address table. When a switch receives a frame from a PC, it examines the frame’s source and destination MAC addresses. The source MAC address is recorded and mapped to the switch port from which
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 105 of 257
it arrived. Then the destination MAC address is looked up in the MAC address table. If the destination MAC address is a known address, then the frame is forwarded out of the corresponding switch port of the MAC address. If the MAC address is unknown, then the frame is broadcast out of all switch ports, except the one from which it came. It is important to observe and understand the function of a switch and how it delivers data on the network. The way a switch operates has implications for network administrators whose job it is to ensure secure and consistent network communication.
Switches are used to interconnect and deliver information to computers on local area networks. Switches deliver Ethernet frames to host devices identified by network interface card MAC addresses.
In Part 1, you will build a multi-switch and router topology with a trunk linking the two switches. In Part 2, you will ping various devices and observe how the two switches build their MAC address tables.
Note: The routers used with CCNA hands-on labs are Cisco 1941 Integrated Services Routers (ISRs) with Cisco IOS Release 15.2(4)M3 (universalk9 image). The switches used are Cisco Catalyst 2960s with Cisco IOS Release 15.0(2) (lanbasek9 image). Other routers, switches and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of this lab for the correct interface identifiers.
Note: Make sure that the routers and switches have been erased and have no startup configurations. If you are unsure contact your instructor.
Required Resources
1 Router (Cisco 1941 with Cisco IOS Release 15.2(4)M3 universal image or comparable) 2 Switches (Cisco 2960 with Cisco IOS Release 15.0(2) lanbasek9 image or comparable) 2 PCs (Windows 7, Vista, or XP with terminal emulation program, such as Tera Term)
Console cables to configure the Cisco IOS devices via the console ports Ethernet cables as shown in the topology
Note: The Fast Ethernet interfaces on Cisco 2960 switches are autosensing and an Ethernet straight-through cable may be used between switches S1 and S2. If using another model Cisco switch, it may be necessary to use an Ethernet crossover cable.
Part 7: Build and Configure the Network
Step 1: Cable the network according to the topology.
Step 2: Configure PC hosts.
Step 3: Initialize and reload the routers and switches as necessary. Step 4: Configure basic settings for each switch.
Configure device name as shown in the topology.
Configure IP address and default gateway as listed in Addressing Table.
Assign cisco as the console and vty passwords.
Assign class as the privileged EXEC password.
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 106 of 257
Step 5: Configure basic settings for the router.
Disable DNS lookup.
Configure IP address for the router as listed in Addressing Table.
Configure device name as shown in the topology.
Assign cisco as the console and vty passwords.
Assign class as the privileged EXEC password.
Part 8: Examine the Switch MAC Address Table
A switch learns MAC addresses and builds the MAC address table, as network devices initiate communication on the network.
Step 6: Record network device MAC addresses.
Open a command prompt on PC-A and PC-B and type ipconfig /all. What are the Ethernet adapter physical addresses?
PC-A MAC Address:
___________________________________________________________________
PC-B MAC Address:
___________________________________________________________________
Console into router R1 and type the show interface G0/1 command. What is the hardware address?
R1 Gigabit Ethernet 0/1 MAC Address:
____________________________________________________
Console into switch S1 and S2 and type the show interface F0/1 command on each switch. On the second line of command output, what is the hardware addresses (or burned-in address [bia])?
S1 Fast Ethernet 0/1 MAC Address:
______________________________________________________
S2 Fast Ethernet 0/1 MAC Address:
______________________________________________________
Step 7: Display the switch MAC address table.
Console into switch S2 and view the MAC address table, both before and after running network communication tests with ping.
Establish a console connection to S2 and enter privileged EXEC mode.
In privileged EXEC mode, type the show mac address-table command and press Enter.
S2# show mac address-table
Even though there has been no network communication initiated across the network (i.e., no use of ping), it is possible that the switch has learned MAC addresses from its connection to the PC and the other switch.
Are there any MAC addresses recorded in the MAC address table?
__________________________________________________________________________
__________
What MAC addresses are recorded in the table? To which switch ports are they mapped and to which devices do they belong? Ignore MAC addresses that are mapped to the CPU.
__________________________________________________________________________
__________
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 107 of 257
__________________________________________________________________________
__________
__________________________________________________________________________
__________
If you had not previously recorded MAC addresses of network devices in Step 1, how could you tell which devices the MAC addresses belong to, using only the output from the show mac address-table command? Does it work in all scenarios?
__________________________________________________________________________
__________
__________________________________________________________________________
__________
__________________________________________________________________________
__________
__________________________________________________________________________
__________
Step 8: Clear the S2 MAC address table and display the MAC address table again.
In privileged EXEC mode, type the clear mac address-table dynamic command and press Enter.
S2# clear mac address-table dynamic
Quickly type the show mac address-table command again. Does the MAC address table have any addresses in it for VLAN 1? Are there other MAC addresses listed?
__________________________________________________________________________
_________
Wait 10 seconds, type the show mac address-table command, and press Enter. Are there new addresses in the MAC address table? __________________
Step 9: From PC-B, ping the devices on the network and observe the switch MAC address table.
From PC-B, open a command prompt and type arp -a. Not including multicast or broadcast addresses, how many device IP-to-MAC address pairs have been learned by ARP?
__________________________________________________________________________
__________
From the PC-B command prompt, ping the router/gateway R1, PC-A, S1, and S2. Did all devices have successful replies? If not, check your cabling and IP configurations.
__________________________________________________________________________
__________
__________________________________________________________________________
__________
From a console connection to S2, enter the added additional MAC addresses to the devices?
show mac address-table command. Has the switch MAC address table? If so, which addresses and
__________________________________________________________________________
__________
__________________________________________________________________________
__________
From PC-B, open a command prompt and retype arp -a. Does the PC-B ARP cache have additional entries for all network devices that were sent pings?
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 108 of 257
__________________________________________________________________________
__________
Reflection
On Ethernet networks, data is delivered to devices by their MAC addresses. For this to happen, switches and PCs dynamically build ARP caches and MAC address tables. With only a few computers on the network this process seems fairly easy. What might be some of the challenges on larger networks?
_____________________________________________________________________________
__________
Router Interface Summary Table
|
|
|
Part 15: |
Router Interface Summary |
|
|
|
||
|
|
|
|
|
|
|
|
|
|
Part 16: |
Router |
Part 17: |
Ethernet |
Part 18: |
Ethernet |
Part 19: |
Serial |
Part 20: |
Serial |
Model |
Interface #1 |
Interface #2 |
Interface #1 |
Interface #2 |
|||||
|
|
|
|
|
|
|
|
||
1800 |
|
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/0/0 |
|
Serial 0/0/1 |
|
||
|
|
(F0/0) |
|
(F0/1) |
|
(S0/0/0) |
|
(S0/0/1) |
|
|
|
|
|
|
|
|
|
||
1900 |
|
Gigabit Ethernet 0/0 |
Gigabit Ethernet 0/1 |
Serial 0/0/0 |
|
Serial 0/0/1 |
|
||
|
|
(G0/0) |
|
(G0/1) |
|
(S0/0/0) |
|
(S0/0/1) |
|
|
|
|
|
|
|
|
|
||
2801 |
|
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/1/0 |
|
Serial 0/1/1 |
|
||
|
|
(F0/0) |
|
(F0/1) |
|
(S0/1/0) |
|
(S0/1/1) |
|
|
|
|
|
|
|
|
|
||
2811 |
|
Fast Ethernet 0/0 |
Fast Ethernet 0/1 |
Serial 0/0/0 |
|
Serial 0/0/1 |
|
||
|
|
(F0/0) |
|
(F0/1) |
|
(S0/0/0) |
|
(S0/0/1) |
|
|
|
|
|
|
|
|
|
||
2900 |
|
Gigabit Ethernet 0/0 |
Gigabit Ethernet 0/1 |
Serial 0/0/0 |
|
Serial 0/0/1 |
|
||
|
|
(G0/0) |
|
(G0/1) |
|
(S0/0/0) |
|
(S0/0/1) |
|
|
|
|
|
|
|
|
|
|
|
Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.
© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 109 of 257
Lab 13 - Viewing Host Routing Tables
Topology
Objectives
Part 1: Access the Host Routing Table
Part 2: Examine IPv4 Host Routing Table Entries
Part 3: Examine IPv6 Host Routing Table Entries
Background / Scenario
To access a resource on a network, your host will determine the route to the destination host using its routing table. The host routing table is similar to that of a router, but is specific to the local host and much less complex. For a packet to reach a local destination, the local host routing table is required. To reach a remote destination, both the local host routing table and the router routing table are required. The netstat –r and route print commands provide insight into how your local host routes packets to the destination.
In this lab, you will display and examine the information in the host routing table of your PC using the netstat –r and route print commands. You will determine how packets will be routed by your PC depending on the destination address.
Note: This lab cannot be completed using Netlab. This lab assumes that you have Internet access.
Required Resources
1 PC (Windows 7, Vista, or XP with Internet and command prompt access)
Part 21: Access the Host Routing Table
Step 1: Record your PC information.
On your PC, open a command prompt window and type the ipconfig /all command to display the following information and record it:
IPv4 Address
MAC Address
Default Gateway
Step 2: Display the routing tables.
In a command prompt window type the netstat –r (or route print) command to display the host routing table.
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