CCNA Practice Questions (Exam 640-802), 3rd Edition

CCNA Practice Questions (Exam 640-802), 3rd Edition

* By Jeremy Cioara
* Published Apr 3, 2008 by Exam Cram. Part of the Exam Cram series.
* Less Info
o Copyright 2008
o Dimensions 6x9
o Pages: 288
o Edition: 3rd.
o ISBN-10: 0-7897-3714-0
o ISBN-13: 978-0-7897-3714-4
o Request an Instructor or Media review copy
o Corporate, Academic, and Employee Purchases
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More Info CCNA Practice Questions (Exam 640-802), 3rd Edition

Table of Contents
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Part I: ICND1
Chapter 1: Operation of Data Networks. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 3
Quick Answer Key............................................... .....................................16
Answers and Explanations .................................................. ......................17
Chapter 2: Switching Foundations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23
Quick Answer Key............................................... .....................................39
Answers and Explanations .................................................. ......................40
Chapter 3: Basic IP Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Quick Answer Key............................................... .....................................59
Answers and Explanations .................................................. ......................60
Chapter 4: IOS and Routing Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Quick Answer Key............................................... .....................................87
Answers and Explanations .................................................. ......................88
Chapter 5: Wireless and Network Security Concepts. . . . . . . . . . . . . . . 93
Quick Answer Key............................................... ...................................105
Answers and Explanations .................................................. ....................106
Chapter 6: Basic WAN Connectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Quick Answer Key............................................... ...................................122
Answers and Explanations .................................................. ....................123
Part II: ICND2
Chapter 7: Advanced Switching Concepts. . . . . . . . . . . . . . . . . . . . . . . . 129
Quick Answer Key............................................... ...................................150
Answers and Explanations .................................................. ....................151
Chapter 8: Subnetting, VLSM, and IPv6 . . . . . . . . . . . . . . .. . . . . . . . . . . 159
Quick Answer Key............................................... ...................................175
Answers and Explanations .................................................. ....................176
Chapter 9: Advanced Routing Configuration. . . . . . . . . . . . . . . . . . . . . . 183
Quick Answer Key............................................... ...................................202
Answers and Explanations .................................................. ....................203
Chapter 10: Access Lists and Network Address Translation . . . . . . . . . 209
Quick Answer Key............................................... ...................................230
Answers and Explanations .................................................. ....................231
Chapter 11: Frame Relay, PPP, and VPN Connectivity . . .. . . . . . . . . 237
Quick Answer Key............................................... ...................................251
Answers and Explanations .................................................. ....................252
Appendix: What’s on the CD-ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Multiple Test Modes............................................. ..................................257
Attention to Exam Objectives .................................................. ..............258
Installing the CD .................................................. ..................................258
Creating a Shortcut to the MeasureUp Practice Tests .........................259
Technical Support........................................... ........................................260


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CCNA4 Exploration FINAL Exam (Score 87.5)

CCNA4 Exploration FINAL Exam (Score 87.5)
1. A technician has been asked to run Cisco SDM one-step lockdown on the router of a customer. What will be the result of this process?

Traffic is only forwarded from SDM-trusted Cisco routers.
Security testing is performed and the results are saved as a text file stored in NVRAM.
**The router is tested for potential security problems and any necessary changes are made.
All traffic entering the router is quarantined and checked for viruses before being forwarded.



2. Refer to the exhibit. A network administrator is trying to configure a router to use SDM but it is not functioning correctly. What could be the problem?

The username and password are not configured correctly.
The authentication method is not configured correctly.
The HTTP timeout policy is not configured correctly.
**The vtys are not configured correctly.



3. Refer to the exhibit. How is the TCP/IP configuration information specified by the default-router and dns-server commands made available?

The TCP/IP information is forwarded to a 10.0.1.3 to be supplied to DHCP clients.
**The TCP/IP information is used by DHCP clients that are configured to request a configuration from R1.
The TCP/IP information is supplied to any DHCP client on the network connected to the FastEthernet 0/0 interface of R1.
The TCP/IP information is applied to each packet that enters R1 through the FastEthernet 0/0 interface that are hosts on the 10.0.1.0 /24 network except packets from addresses 10.0.1.2, 10.0.1.16, and 10.0.1.254.

4. What is a major characteristic of a worm?

malicious software that copies itself into other executable programs
tricks users into running the infected software
a set of computer instructions that lies dormant until triggered by a specific event
**exploits vulnerabilities with the intent of propagating itself across a network


5. Refer to the exhibit. What can be concluded from the exhibited output of the debug ip nat command?

The 10.1.1.225 host is exchanging packets with the 192.168.0.10 host.

The native 10.1.200.254 address is being translated to 192.168.0.10.

**The 192.168.0.0/24 network is the inside network.

Port address translation is in effect.

6. A technician is talking to a colleague at a rival company and comparing DSL transfer rates between the two companies. Both companies are in the same city, use the same service provider, and have the same rate/service plan. What is the explanation for why Company A reports higher download speeds than Company B?

Company B has a higher volume of POTS voice traffic than Company A.

Company B shares the conection to the DSLAM with more clients than Company A.

Company A only uses microfilters on branch locations.

**Company A is closer to the service provider.




7. Refer to the exhibit. Which statement correctly describes how Router1 processes an FTP request entering interface s0/0/0, destined for an FTP server at IP address 192.168.1.5?

It matches the incoming packet to the access-list 201 permit any any statement and allows the packet into the router.
**It reaches the end of ACL 101 without matching a condition and drops the packet because there is no access-list 101 permit any any statement.

It matches the incoming packet to the access-list 101 permit ip any 192.168.1.0 0.0.0.255 statement, ignores the remaining statements in ACL 101, and allows the packet into the router.

It matches the incoming packet to the access-list 201 deny icmp 192.168.1.0 0.0.0.255 any statement, continues comparing the packet to the remaining statements in ACL 201 to ensure that no subsequent statements allow FTP, and then drops the packet.


8. Refer to the exhibit. Which two conclusions can be drawn from the output shown? (Choose two.)

This network is experiencing congestion.

**The Frame Relay connection is in the process of negotiation.
Data is not flowing in this network.

**The network is discarding eligible packets.

The DLCI is globally significant.



9. A system administrator must provide Internet connectivity for ten hosts in a small remote office. The ISP has assigned two public IP addresses to this remote office. How can the system administrator configure the router to provide Internet access to all ten users at the same time?

Configure DHCP and static NAT.

Configure dynamic NAT for ten users.

Configure static NAT for all ten users.

**Configure dynamic NAT with overload.



10. Refer to the exhibit. Company ABC expanded its business and recently opened a new branch office in another country. IPv6 addresses have been used for the company network. The data servers Server1 and Server2 run applications which require end-to-end functionality, with unmodified packets that are forwarded from the source to the destination. The edge routers R1 and R2 support dual stack configuration. What solution should be deployed at the edge of the company network in order to successfully interconnect both offices?

a new WAN service supporting only IPv6

NAT overload to map inside IPv6 addresses to outside IPv4 address

**a manually configured IPv6 tunnel between the edge routers R1 and R2

static NAT to map inside IPv6 addresses of the servers to an outside IPv4 address and dynamic NAT for the rest of the inside IPv6 addresses

11. Refer to the exhibit. You are a network administrator who has been tasked with completing the Frame Relay topology that interconnects two remote sites. How should the point-to-point subinterfaces be configured on HQ to complete the topology?

HQ(config-subif)#frame-relay interface-dlci 103 on Serial 0/0/0.1
HQ(config-subif)#frame-relay interface-dlci 203 on Serial 0/0/0.2
**HQ(config-subif)#frame-relay interface-dlci 301 on Serial 0/0/0.1
HQ(config-subif)# frame-relay interface-dlci 302 on Serial 0/0/0.2

HQ(config-subif)#frame-relay map ip 172.16.1.1 103 broadcast on Serial 0/0/0.1
HQ(config-subif)#frame-relay map ip 172.16.2.2 203 broadcast on Serial 0/0/0.2
HQ(config-subif)#frame-relay map ip 172.16.1.1 301 broadcast on Serial 0/0/0.1
HQ(config-subif)#frame-relay map ip 172.16.2.2 302 broadcast on Serial 0/0/0.2



12. An established company has recently transitioned from outsourced LAN support to a completely in-house staff. The outsourcing company is no longer in business, so no records are available. There are many user complaints about application speed and availability. What two considerations apply to this situation? (Choose two.)

A network utilization baseline should quickly reveal application availability.

A period of 24 to 48 hours should provide a sufficient baseline to track normal network activity.

It is easier to start with monitoring all available data inputs on application servers, and then fine-tune to fewer variables along the way.

The initial baseline results have little relevance to current values after the network has been modified or grown in usage.

**When it is practical, network administrators should attempt to automate the collection of performance data and stay away from manual collection.

**Creating a network baseline data helps determine device thresholds for alerting.


13. Which combination of Layer 2 protocol and authentication should be used to establish a link without sending authentication information in plain text between a Cisco and a non-Cisco router?

PPP with PAP

**PPP with CHAP

HDLC with PAP

HDLC with CHAP



14. An administrator is unable to receive e-mail. While troubleshooting the problem, the administrator is able to ping the local mail server IP address successfully from a remote network and can successfully resolve the mail server name to an IP address via the use of the nslookup command. At what OSI layer is the problem most likely to be found?

physical layer

data link layer

network layer

**application layer



15. When configuring a Frame Relay connection, what are two instances when a static Frame Relay map should be used? (Choose two.)

when the remote router is a non-Cisco router

**when the remote router does not support Inverse ARP

when the local router is using IOS Release 11.1 or earlier

**when broadcast traffic and multicast traffic over the PVC must be controlled

when globally significant rather than locally significant DLCIs are being used

16. Which three statements are true about creating and applying access lists? (Choose three.)

Access list entries should filter in the order from general to specific.

**One access list per port per protocol per direction is permitted.

Standard ACLs should be applied closest to the source while extended ACLs should be applied closest to the destination.

**There is an implicit deny at the end of all access lists.

**Statements are processed sequentially from top to bottom until a match is found.

The inbound keyword refers to traffic entering the network from the router interface where the ACL is applied.


17. Which technology would provide the highest bandwidth connections between company sites at the lowest cost?

**broadband Internet site-to-site VPN connections

satellite based network connections

dedicated point-to-point circuits

Frame Relay PVCs



18. Refer to the exhibit. This serial interface is not functioning correctly. Based on the output shown, what is the most likely cause?

improper LMI type

interface reset

**PPP negotiation failure

unplugged cable



19. What three statements describe the roles of devices in a WAN? (Choose three.)

**A CSU/DSU terminates a digital local loop.

A modem terminates a digital local loop.

A CSU/DSU terminates an analog local loop.

**A modem terminates an analog local loop.

**A router is commonly considered a DTE device.

A router is commonly considered a DCE device.



20. A network administrator is instructing a technician on best practices for applying ACLs. Which suggestion should the administrator provide?

Named ACLs are less efficient than numbered ACLs.

Standard ACLs should be applied closest to the core layer.

ACLs applied to outbound interfaces are the most efficient.

**Extended ACLs should be applied closest to the source that is specified by the ACL.

CCNA3 FINAL EXAM NEW EXPLORATION #5

41. Refer to the exhibit. How is port Gi1/1 on SwT-A functioning in the spanning-tree topology?

It is sending and receiving data frames
It is receiving BPDUs, but not sending data frames
It is participating in the election process by forwarding the BPDUs it receives
It is receiving BPDUs and populating the MAC address table, but not sending data

42. Refer to the exhibit. Sw-T has been configured with a single trunking interface. Which VLANs will be allowed across the trunk?

Only VLAN 1 will be allowed across the trunk
All configured VLANs will be allowed across the trunk
Only the native VLAN wil be allowed across the trunk
Only the the management and native VLANs will be allowed across the trunk
Only VLANs that are configured on the VTP server in the domain will be allowed across the trunk

43. Refer to the exhibit.Router RA receives a packet with a source address of 192.168.1.65 and destination address of 192.168.1.161. What will the router do with this packet?

The router will drop the packet
The router will forward the packet out interface FastEthernet 0/1.1
The router will forward the packet out interface FastEthernet 0/1.2
The router will forward the packet out interface FastEthernet 0/1.3
The router will forward the packet out interface FastEthernet 0/1.2 and interface FastEthernet 0/1.3

44. Refer to the exhibit. How will switch S2 manage traffic coming from host PC1?

S2 will drop the traffic, unless it is management traffic
S2 will tag the frame with VLAN ID 99 when it forwards it over the trunk link
S2 will leave the traffic untagged when it forwards it over a trunk link
S2 will tag the traffic with the highest VLAN ID value when it forwards it over the trunk link

45. What is the purpose of VLAN trunking?

It improves network performance by reducing broadcast traffic
It select the best path to transmit data in a switched network
It carries the traffic of multiple VLANs through a single link
It avoids spanning tree loops in a switched network

46. Refer to the exhibit. The network administrator needs to remove the east-hosts VLAN and use the switch port from that VLAN in one of the existing VLANs. Which two sets of commands should be used when completely removing VLAN 2 from S1-Central ehile leaving the switch and all its interfaces operational?(Choose two)

S1-Central>enable
S1-Central#reload

S1-Central>enable
S1-Central#erase flash:

S1-Central>enable
S1-Central#delete flash:vlan.dat

S1-Central>enable
S1-Central#configure terminal
S1-Central(config)#no vlan 2

S1-Central>enable
S1-Central#configure terminal
S1-Central(config-if)#interface fastethernet 0/1
S1-Central(config-if)#switchport access vlan 3

47. Refer to the exhibit. What three statements describe why Host1 and Host2 are unable to communicate?(Choose three)

The switch ports are o different VLANs
The switch IP address is on the wrong subnet
The hosts are configured on different logical networks
A router is required to forward traffic between Host1 and Host2
The VLAN port assignments must be contiguous for each VLAN
The host default gateway addresses must be on the same logical network

48. Refer to the exhibit. Router R-West and switch S-West1 are connected via a single ethernet cable between the router interface fa0/0 and the switch interface fa0/1. The router and switch have been configured with the commands that are displayed in the exhibit. The network administrator enters the show interfaces trunk command and receives the output as shown. What is the cause of the "not-trunking" status for switch port Fa0/1?

The trunk is established, but no VLANs have been configured to
use it
The router is missing the dynamic trunking protocol statements
necessary to form a trunk
Because the router does not support Dynamic Trunking Protocol, the trunk has not been established
The router, the switch, or both must be configured with the dynamic desirable option for Dynamic Trunking Protocol to establish a trunk

49. Refer to the exhibit. Which two facts about STP can be determined from the displayed output?(Choose two)

Switch S1 has the lowest configured STP priority in the network

Switch S1 is configured as the root bridge for VLAN1
Fa0/21 is the root port of switch S1
Fa0/22 is the redundant link
Fa0/24 is considered the best path to the root bridge

50. Refer to the exhibit. In what two ways will the router handle VLAN traffic that is received on the trunk?(Choose two)

Traffic to VLAN 1 received by the router interface Fa0/0 will be dropped by the router Because interface Fa0/0 requires an iP address, the router will not be able to route between the VLANs Packets that are received from network 192.168.20.0/24 will be handled by subinterface Fa0/0.20 The router will use subinterface MAC addersses to identify the VLAN traffic that is received on the physical interface The router will continue to process traffic from the attached VLANs even if the physical interface goes down

DHCP Group of Four Questions

(Updated from real CCNA exam on 09-Jan-2009)

Refer to the exhibit. Using the information shown, answer the question

Question 1:

All hosts in the networks have been operational for several hours when the DHCP server goes down. What happens to the hosts that have obtained service from the DHCP server?

A - The hosts will not be able to communicate with any other hosts.
B - The hosts will continue to communicate normally for a period of time.
C - The hosts will be able to communicate with hosts outsides their own network
D - The hosts will only be able to communicate with other hosts by IP address not by hostname

Answer: B

Explanation:

DHCP often uses dynamic allocation mechanism to save IP addresses, which assigns an IP address to a client for a limited period of time. So when the DHCP server goes down, that client can still use the allocated IP address for a period of time

Question 2:

What is the purpose of the DHCP server?

A - to provide storage for email
B - to translate URLs to IP addresses
C - to translate IPv4 addresses to MAC addresses
D - to provide an IP configuration information to hosts

Answer: D

Explanation:

The main purpose of the DHCP server is to provide IP configuration parameters to hosts such as the default gateway, domain name, Domain Name System (DNS) server...

CCNA-4.BLOGSPOT.COM

Question 3:

How is the message sent from a PC2 when is first powers on and attempts to contact the DHCP Server?

A - Layer 3 unicast
B - Layer 3 broadcast
C - Layer 3 multicast
D - Without any Layer 3 encapsulation

Answer: B

Explanation:

When a client boots up for the first time, it transmits a DHCPDISCOVER message on its local physical subnet. Because the client has no way of knowing the subnet to which it belongs, the DHCPDISCOVER is an all-subnets broadcast (destination IP address of 255.255.255.255, which is a layer 3 broadcast address). The client does not have a configured IP address, so the source IP address of 0.0.0.0 is used.

Question 4: What is the default behavior of R1 when PC1 requests service from DHCP server?

A - Drop the request
B - Broadcast the request to P4S2 and P4S3
C - Forward the request to P4S2
D - Broadcast the request to P452, P4S3 and ISP

Answer: A

Explanation:

When PC1 requests service from DHCP server (for example, it requests an IP address), it sends a broadcast packet. But R1 router, by default, will not forward broadcast packet and drop it.

For your information, if you want to use the DHCP server from another network (like in this case) you can use the ip helper-address command which will make the router forward UDP broadcasts.

In the real exam you will be taken to a LAB simulation environment but it is, in fact, just a group of 4 multi-choice questions!

Exam : 640-821 Introduction to Cisco Networking Technologies (INTRO) #1

Topic 1, Design and Support (26 questions)
Section 1: Use a subset of Cisco IOS commands to analyze and report network
problems. (11 questions)
QUESTION 1
Exhibit



The result of the show interfaces serial 0/0 command is displayed in the exhibit.
What command should be executed to make this interface operational?
A. Certkiller C(config-if)# enable
B. Certkiller C(config-if)# no keepalive
C. Certkiller C(config-if)# encapsulation ppp
D. Certkiller C(config-if)# no shutdown
E. Certkiller C(config-if)# clockrate 56000
F. Certkiller C(config-if)# line protocol up
Answer: D
Explanation:

no shutdown

Enable the interface and the configuration changes you have just made on the interface.

Serial0 is administratively down, line protocol is up.
The possible causes for this state are

• The serial interface has been disabled with the shutdown interface configuration command.
• Different interfaces on the router are using the same IP address.

The following are some steps you can take to isolate the problem:

• Use the show configuration privileged EXEC command to display the serial port configuration. If "shutdown" is displayed after "interface Serial0," use the no shutdown interface configuration command to enable the interface.
• Use the show interface privileged EXEC command to display the IP addresses for all router interfaces. Use the ip address interface configuration command to assign unique IP addresses to the router interfaces.

QUESTION 2
Which command will reinitialize the router and totally replace the running configuration with the
current startup configuration?
A. Certkiller B# reload
B. Certkiller B# copy tftp startup-config
C. Certkiller B# copy startup.-config running-config
D. Certkiller B# copy running-config flash
E. Certkiller B# setup
Answer: A
Explanation:
Enter the copy system:running-config nvram:startup-config command to save your configuration changes to
your startup configuration
so that they will not be lost if there is a system reload or power outage. For example:
Router# copy system:running-config nvram:startup-config
Building configuration...
It might take a minute or two to save the configuration. After the configuration has been saved, the following
output appears:
[OK]
Router#
On most platforms, this task saves the configuration to NVRAM. On the Class A Flash file system platforms,
this task saves the
configuration to the location specified by the CONFIG_FILE environment variable. The CONFIG_FILE
variable defaults to NVRAM.
QUESTION 3
Which is the correct fallback sequence for loading the Cisco IOS?
A. ROM, Flash, NVRAM
B. ROM, TFTP server, Flash
C. Flash, TFTP server ROM
D. Flash NVRAM, RAM
Answer: C
QUESTION 4
Study the Exhibit below carefully:

z
A new router has been installed in the branch office in Lisbon. However, the network administrator
cannot make a backup of the IOS image of the new route to the TFTP server located in the Gibraltar
office. Following the network diagram, can you identify the cause of the problem?
A. IP address if the TFTP server not correct.
B. Incorrect subnet mask of the TFTP server.
C. Default gateway of the TFTP server not properly set.
D. Subnet mask on the Lisbon router not correct
E. Incorrect IP address configured on E0 of the Gibraltar router
Answer: B
Explanation:
An incorrect subnet mask on the TFTP server is the cause of this problem. If you look at the subnet masks of all
the other devices you'll notice that they are /28. If you rewrite the subnet mask of the TFTP server, of
255.255.255.192 you'll notice that it translates to a subnet mask of /26. A subnet mask of 255.255.255.240,
which is a /28, applied to the TFTP server will fix this problem.
QUESTION 5
You are the network administrator at Certkiller . Certkiller users report that they cannot access resources
on the LAN attached to interface e0 of router CK1 . You want to view the current IP addressing and the
Layer 1 and Layer 2 status of this interface.
Which of the following commands could you use? (Choose three.)
A. CK1 # show version
B. CK1 # show protocols
C. CK1 # show interfaces
D. CK1 # show controllers
E. CK1 # show ip interface
F. CK1 # show startup-config
Answer: C, D, E
Explanation:
show interfaces is used to see the IP addresses and layer 2 information configured on the interfaces.
show controllers is used to see the layer 1 statistics. It tells about the V.35 cables whether they are physically
attached or not.
show ip interfaces is used to see the IP addresses configured on the interfaces.
QUESTION 6
You are a network technician at Certkiller . You are troubleshooting a LAN connectivity problem.
Which of the following router IOS commands could you use? (Select three options.)
A. show ip route
B. winipcfg
C. tracert
D. show interfaces
E. traceroute
F. ping
Answer: A D F
Explanation
A: The show ip route command displays the IP route table.
D: The show interfaces EXEC command to display statistics for all interfaces configured on the router or
access server.
F: The ping command tests connectivity to a remote node.
QUESTION 7
You are a technician at Certkiller . Your newly appointed Certkiller trainee wants to know what command
she can use to verify the active configuration on a Cisco router.
What would your reply be?
A. Router# show memory
B. Router# show startup-config
C. Router# show running-config
D. Router# show flash
Answer: C
Explanation:
The two commands that list the currently used configuration in a router is reloaded are show running-config
and write terminal.
Reference:
CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) page 494
QUESTION 8
You are a technician at Certkiller . Your newly appointed Certkiller trainee is troubleshooting a
connectivity problem on the Certkiller network. She asks you what command she should use to test
application layer connectivity the between source and destination.
What would your reply be?
A. ping
B. telnet
C. traceroute
D. verify
E. trace
Answer: B
Explanation:
Telnet - The standard terminal emulation protocol in the TCP/IP protocol stack. Telnet is used for remote
terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a
local system.
I was going to choose answer A (ping), but the keyword in the question is "application layer". Ping only needs
to hit the NIC and that would mean layer 1 (Physical layer).
Reference:
CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) page 589
QUESTION 9
You are the network administrator at Certkiller . Your assistant made a number of errors when utilizing
the router setup mode facility. You want to exit setup mode without applying the changes that your
assistant made.
What should you do? (Select two.)
A. Type exit at the setup dialog.
B. Type close at the setup dialog.
C. Press the Ctrl-C key combination.
D. Press the Ctrl-X key combination.
E. Issue the copy startup-config command.
F. Issue the 'write e" command.
G. Issue the "write mem" command
Answer: A, C
Explanation:
The command 'exit' will set you back from wherever you were without saving any changes. Pressing Ctrl-C
will do the same thing.
Incorrect Answers:
B. This is an invalid command
E. This command is used to save the configuration stored on NVRAM to a location.
F. This will have the effect of erasing the running configuration, and setting the router configuration back to the
factory default settings.
G. This is an old command that is still supported on the latest Cisco IOS. It is short for "write memory" and
has the same effect as the "copy running-config startup-config" command
QUESTION 10
With regard to bandwidth, which of the following statements are true? (Choose all that apply.)
A. Bandwidth availability is decreasing.
B. Bandwidth availability is infinite.
C. Bandwidth is used when analyzing network performance.
D. Bandwidth availability is finite.
E. Bandwidth availability is fixed.
Answer: C, D
Explanation: C is correct because performance analyzing software is notorious for consuming bandwidth.
Most network management devices use SNMP, which consumes bandwidth. D is correct because although new
technologies are providing for more bandwidth and a network can be engineered to give more priority to
different devices, there is a finite amount of bandwidth available at any given time.
Incorrect Answers:
A. This is incorrect because new technologies are actually increasing the amount of potential bandwidth.
B. For any given network, the amount of bandwidth available to end users is usually fixed, and based on the
speed of the connection to access connection. For example, any given PC with a 10/100 NIC will be limited to
100Mbps of throughput at any given time.
E. This is incorrect because it's always possible to upgrade a scalable technology or allocate resources
differently.
QUESTION 11
You are the network administrator at Certkiller . From your workstation you telnet to a router VTY line.
You perform a number of configurations on the router. You now want to terminate the telnet connection.
What command must you issue to terminate the Telnet connection?
A. close
B. disable
C. disconnect
D. suspend
E. exit
Answer: C
Explanation:
Terminating a Telnet session
Use the disconnect from the router you Telnetted from.
Reference:
CCNA Self-Study CCNA INTRO exam certification Guide (Cisco Press, ISBN 1-58720-094-5) Page 398

Building Straight-Through and Crossover UTP Cables

Background / Preparation
In this lab you will build and terminate Ethernet straight-through patch cables and crossover cables. With a straight-through cable, the color of wire used by pin 1 on one end is the same color used by pin 1 on the other cable end, and similarly for the remaining seven pins. The cable will be constructed using either TIA/EIA T568A or T568B standards for Ethernet, which determine which color wire is used on each pin. Straightthrough patch cables are normally used to connect a host directly to a hub or switch or to a wall plate in and office area.
With a crossover cable the second and third pairs on the RJ-45 connector at one end of the cable are reversed at the other end. The pinouts for the cable are the T568A standard on one end and the T568B standard on the other end. Crossover cables are normally used to connect hubs and switches or can be used to directly connect two hosts to create a simple network. This is a two-part lab that can be done individually, in pairs, or in groups.
The following resources will be required:
• Two 0.6 to 0.9m (2 to 3 ft.) lengths of cable, Category 5 or 5e
• A minimum of four RJ-45 connectors (more may be needed if mis-wiring occurs)
• An RJ-45 crimping tool
• An Ethernet cable tester
• Wire cutters

Build and test an Ethernet straight-through patch cable

Step 1: Obtain and prepare the cable
a. Determine the length of cable required. This could be from a device such as a computer to the device
to which it connects (like a hub or switch) or between a device and an RJ-45 outlet jack. Add at least
30.48 cm (12 in.) to the distance. The TIA/EIA standard states the maximum length is 5 m (16.4 ft.).
Standard Ethernet cable lengths are usually .6 m (2 ft.), 1.83 m (6 ft.), or 3.05 m (10 ft.).
b. Which length of cable did you choose and why did you choose this length?
____________________________________________________________________________
Answers will vary
c. Cut a piece of cable to the desired length. Stranded UTP cable is commonly used for patch cables
(the cables between an end network device such as a PC and an RJ-45 connector) because it is
more durable when bent repeatedly. It is called stranded because each of the wires within the cable is
made up of many strands of fine copper wire, rather than a single solid wire. Solid wire is used for
cable runs that are between the RJ-45 jack and a punch-down block.
d. Using wire strippers, remove 5.08 cm (2 in.) of the cable jacket from both ends of the cable.
Step 2: Prepare and insert the wires
a. Determine which wiring standard will be used. Circle the standard.
[T568A | T568B]
b. Locate the correct table based on the wiring standard used.
c. Spread the cable pairs and arrange them roughly in the desired order based on the standard chosen.
d. Untwist a short length of the pairs and arrange them in the exact order needed by the standard. It is
very important to untwist as little as possible. The twists are important because they provide
noise cancellation.
e. Straighten and flatten the wires between your thumb and forefinger.
f. Ensure the cable wires are still in the correct order as the standard.
g. Cut the cable in a straight line to within 1.25 to 1.9 cm (1/2 to 3/4 in.) from the edge of the cable
jacket. If it is longer than this, the cable will be susceptible to crosstalk (the interference of bits from
one wire with an adjacent wire).
h. The tang (the prong that sticks out from the RJ-45 connector) should be on the underside pointing
downward when inserting the wires. Insert the wires firmly into the RJ-45 connector until all wires are
pushed as far as possible into the connector.
Step 3: Inspect, crimp, and re-inspect
a. Visually inspect the cable and ensure the right color codes are connected to the correct pin numbers.
b. Visually inspect the end of the connector. The eight wires should be pressed firmly against the end of
the RJ-45 connector. Some of the cable jacket should be inside the first portion of the connector.
This provides strain relief for the cable. If the cable jacket is not far enough inside the connector, it
may eventually cause the cable to fail.
c. If everything is correctly aligned and inserted properly, place the RJ-45 connector and cable into the
crimper. The crimper will push two plungers down on the RJ-45 connector.


d. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.
Step 4: Terminate the other cable end
a. Use the previously described steps to attach an RJ-45 connector to the other end of the cable.
b. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.
c. Which standard [T568A | T568B] is used for patch cables in your school? __________________
School dependent
Step 5: Test the cable
a. Using a cable tester, test the straight-through cable for functionality. If it fails, repeat the lab.
b. (Optional) Use the cable to connect a PC to a network.
c. (Optional) Click the Start button and select the Run option.
d. (Optional) Type cmd and press Enter.
e. (Optional) From the command prompt, type ipconfig.
f. (Optional) Write down the default gateway IP address. _________________________________
Machine dependent
g. (Optional) From the command prompt, type ping followed by the default gateway IP address. If the
cable is functional, the ping should be successful (provided that no other network problem exists and
the default gateway router is connected and functional).

Build and test an Ethernet crossover cable

Step 1: Obtain and prepare the cable
a. Determine the length of cable required. This could be from a hub to a hub, hub to switch, switch to
switch, computer to router, or from one computer to another computer. Add at least 30.48 cm (12 in.)
to the distance. Which length of cable did you choose and why did you choose this length?
____________________________________________________________________________
Answers will vary
b. Cut a piece of cable to the desired length and, using wire strippers, remove 5.08 cm (2 in.) of the
cable jacket from both ends of the cable.
Step 2: Prepare and insert the T568A wires
a. Locate the T568A table at the beginning of the lab.
b. Spread the cable pairs and arrange them roughly in the desired order based on the T568A standard.
c. Untwist a short length of the pairs and arrange them in the exact order needed by the standard. It is
very important to untwist as little as possible. Twists are important because they provide noise
cancellation.
d. Straighten and flatten the wires between your thumb and forefinger.
e. Ensure the cable wires are in the correct order based on the standard.
f. Cut the cable in a straight line to within 1.25 to 1.9 cm (1/2 to 3/4 in.) from the edge of the cable
jacket. If it is longer than this, the cable will be susceptible to crosstalk (the interference of bits from
one wire with an adjacent wire).
g. The tang (the prong that sticks out from the RJ-45 connector) should be on the underside pointing
downward when inserting the wires. Insert the wires firmly into the RJ-45 connector until all wires are
pushed as far as possible into the connector.
Step 3: Inspect, crimp, and re-inspect
a. Visually inspect the cable and ensure the right color codes are connected to the correct pin numbers.
b. Visually inspect the end of the connector. The eight wires should be pressed firmly against the RJ-45
connector. Some of the cable jacket should be inside the first portion of the connector. This provides
for cable strain relief which can eventually cause the cable to fail.
c. If everything is correctly aligned and inserted properly, place the RJ-45 connector and cable into the
crimper. The crimper will push two plungers down on the RJ-45 connector.


d. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.

Step 4: Terminate the T568B cable end
a. On the other end, use the previously described steps (but use the T568B table and standard) to
attach an RJ-45 connector to the cable.
b. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.
c. Which standard [T568A | T568B] would you rather use at home if you have or would like to have a
home network? Student dependent
Step 5: Test the cable
a. Using a cable tester, test the crossover cable for functionality. If it fails, repeat the lab.
b. Use the cable to connect two PCs.
c. On both computers, click the Start button and select Run.
NOTE: If the Run command is unavailable on your PC, visually check the LED status lights on the
NIC card. If they are on (usually green or amber) the cable is functional.
d. On both computers, type cmd and press Enter.
e. On both computers from the command prompt, type ipconfig.
f. Write the IP address of both computers.
Computer 1: _________________________ Machine dependent
Computer 2: _________________________ Machine dependent
g. From the command prompt of one computer, type ping followed by the IP address of the other
computer. If the cable is functional, the ping should be successful. Do the ping on the other computer
as well.
NOTE: The Windows Firewall on the target computer must be temporarily disabled for the ping to be
successful. Refer to Lab 3.1.5 if you need help with this. If you disable the firewall, be sure to reenable
it.
Step 6: Reflection
a. Which part of making these cables did you find the most difficult? Compare your views with a
classmate.
Student’s opinion
b. Are all four pairs of cables twisted the same amount? Discuss the reasons why or why not.
The twisting of the pairs is done to cancel electromagnet interference. The twisting ratio is different for
each cable pair so that they do not fit closely together. If they did fit snugly together it would not help
the EMI cancellation feature as much.
c. Ask a local business or check a site such as http://www.workopolis.com/ to see how much a
beginning cable installer earns and which criteria they look for in a cable installer. Write the
information you discover in the space provided.
____________________________________________________________________________
____________________________________________________________________________
d. Many technicians keep a crossover cable in their toolkit. When do you think that you would use a
crossover cable and when do you think a network technician would use this cable?
____________________________________________________________________________
____________________________________________________________________________
Student’s opinion

Build and test an Ethernet straight-through patch cable

Step 1: Obtain and prepare the cable
a. Determine the length of cable required. This could be from a device such as a computer to the device
to which it connects (like a hub or switch) or between a device and an RJ-45 outlet jack. Add at least
30.48 cm (12 in.) to the distance. The TIA/EIA standard states the maximum length is 5 m (16.4 ft.).
Standard Ethernet cable lengths are usually .6 m (2 ft.), 1.83 m (6 ft.), or 3.05 m (10 ft.).
b. Which length of cable did you choose and why did you choose this length?
____________________________________________________________________________
Answers will vary
c. Cut a piece of cable to the desired length. Stranded UTP cable is commonly used for patch cables
(the cables between an end network device such as a PC and an RJ-45 connector) because it is
more durable when bent repeatedly. It is called stranded because each of the wires within the cable is
made up of many strands of fine copper wire, rather than a single solid wire. Solid wire is used for
cable runs that are between the RJ-45 jack and a punch-down block.
d. Using wire strippers, remove 5.08 cm (2 in.) of the cable jacket from both ends of the cable.
Step 2: Prepare and insert the wires
a. Determine which wiring standard will be used. Circle the standard.
[T568A | T568B]
b. Locate the correct table based on the wiring standard used.
c. Spread the cable pairs and arrange them roughly in the desired order based on the standard chosen.
d. Untwist a short length of the pairs and arrange them in the exact order needed by the standard. It is
very important to untwist as little as possible. The twists are important because they provide
noise cancellation.
e. Straighten and flatten the wires between your thumb and forefinger.
f. Ensure the cable wires are still in the correct order as the standard.
g. Cut the cable in a straight line to within 1.25 to 1.9 cm (1/2 to 3/4 in.) from the edge of the cable
jacket. If it is longer than this, the cable will be susceptible to crosstalk (the interference of bits from
one wire with an adjacent wire).
h. The tang (the prong that sticks out from the RJ-45 connector) should be on the underside pointing
downward when inserting the wires. Insert the wires firmly into the RJ-45 connector until all wires are
pushed as far as possible into the connector.
Step 3: Inspect, crimp, and re-inspect
a. Visually inspect the cable and ensure the right color codes are connected to the correct pin numbers.
b. Visually inspect the end of the connector. The eight wires should be pressed firmly against the end of
the RJ-45 connector. Some of the cable jacket should be inside the first portion of the connector.
This provides strain relief for the cable. If the cable jacket is not far enough inside the connector, it
may eventually cause the cable to fail.
c. If everything is correctly aligned and inserted properly, place the RJ-45 connector and cable into the
crimper. The crimper will push two plungers down on the RJ-45 connector.


d. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.
Step 4: Terminate the other cable end
a. Use the previously described steps to attach an RJ-45 connector to the other end of the cable.
b. Visually re-inspect the connector. If improperly installed, cut the end off and repeat the process.
c. Which standard [T568A | T568B] is used for patch cables in your school? __________________
School dependent
Step 5: Test the cable
a. Using a cable tester, test the straight-through cable for functionality. If it fails, repeat the lab.
b. (Optional) Use the cable to connect a PC to a network.
c. (Optional) Click the Start button and select the Run option.
d. (Optional) Type cmd and press Enter.
e. (Optional) From the command prompt, type ipconfig.
f. (Optional) Write down the default gateway IP address. _________________________________
Machine dependent
g. (Optional) From the command prompt, type ping followed by the default gateway IP address. If the
cable is functional, the ping should be successful (provided that no other network problem exists and
the default gateway router is connected and functional).

Building Straight-Through and Crossover UTP Cables

Background / Preparation
In this lab you will build and terminate Ethernet straight-through patch cables and crossover cables. With a straight-through cable, the color of wire used by pin 1 on one end is the same color used by pin 1 on the other cable end, and similarly for the remaining seven pins. The cable will be constructed using either TIA/EIA T568A or T568B standards for Ethernet, which determine which color wire is used on each pin. Straightthrough patch cables are normally used to connect a host directly to a hub or switch or to a wall plate in and office area.
With a crossover cable the second and third pairs on the RJ-45 connector at one end of the cable are reversed at the other end. The pinouts for the cable are the T568A standard on one end and the T568B standard on the other end. Crossover cables are normally used to connect hubs and switches or can be used to directly connect two hosts to create a simple network. This is a two-part lab that can be done individually, in pairs, or in groups.
The following resources will be required:
• Two 0.6 to 0.9m (2 to 3 ft.) lengths of cable, Category 5 or 5e
• A minimum of four RJ-45 connectors (more may be needed if mis-wiring occurs)
• An RJ-45 crimping tool
• An Ethernet cable tester
• Wire cutters

Boson Cisco CCIE Exam Lab Preparation Kit - Cisco Training

These products are based on Cisco's published objectives for the CCIE certification. Full objectives for all of CCIE's certification requirements can be found at Cisco's web site.

About the CCIE Certification

The Cisco Certified Internetworking Expert (CCIE) is one of the most respected high-level certifications. The exam certifies that the successful candidate has the skills and experience necessary to handle the most difficult networking tasks. Candidates choose from one of the following tracks:

• Routing and Switching
• Security
• Service Provider
• Storage Networking
• Voice

Certification is a two-step process. The first step is to pass a rigorous written pre-qualification exam. Step two is a hands-on lab.

http://www.mediafire.com/?fxonmzztg4t

CHAP over Frame Relay

Consider two routers connected back-to-back like this

Router1 ---- [Frame Relay Cloud] ---- Router2

Here is the relevant config for the routers

Router1

interface Serial2/0
ip address 150.150.12.1 255.255.255.0
encapsulation frame-relay
no keepalive
no fair-queue
frame-relay interface-dlci 102

Router2

interface Serial2/0
ip address 150.150.12.2 255.255.255.0
encapsulation frame-relay
no keepalive
no fair-queue
frame-relay interface-dlci 201

The two routers can successfully ping over the frame relay interfaces.

Now, we wish to run CHAP between the two routers over the frame relay link for security reasons. How will the config need to be modified to make that happen? Assume that the usernames to be used for CHAP are the router hostnames itself and the password for both routers is "cisco".

BGP quick tips

There are three most important keywords which we should have in mind while setting up BGP neighbor relationship. Even sometimes when we have successful BGP relationship, we are not able to see routes in the routing table. Following are the three important keywords.

1)ebgp-multihop :- In EBGP, neighbor relationships are only formed if we have directly connected networks. We would require to use ebgp-multihop keyword with neighbor statement so that neighbors which are not directly connected can form relationship with each other. We need to specify a number with ebgp-multihop keyword, number can be between 1-255. This number represents how many hop counts is the router away.

2)update-source. We need to specify the interface which will be used to update neighbor table incase routers are not directly connected. Without update-source we will not be able to form BGP neighbor relationships. update-source keyword will update the interface which will be used to form neighbor relationship. see configuration example below for better understanding.

3) next-hop-self:- When ebgp relation replicates , next hop always changes.IBGP routers only connected with other ibgp routers in same AS will not be able to talk with routers outside the AS, if they are not directly connected with each other. We would require a next-hop-self keyword in the ibgp router which is directly connected with ebgp neighbor so that other router in same AS (IBGP) can talk with ebgp routers. Refer to configuration examples below:-

Lets assume that we have three routers and we have to setup a ebgp relationship in between them. Router A ( AS :- 34 Serial0 192.168.1.1 , loopback0 1.1.1.1) , RouterB ( AS 34, loopback0 2.2.2.2 , Serial0 192.168.1.2 , Serial1 172.16.1.1), RouterC ( AS 400 , loopback0 3.3.3.3, Serial0 172.16.1.2)

Lets start configuring Router A

router BGP 34 –> As soon as we type 34 BGP process will start in the background
neighbor 192.168.1.2 remote-as 34 –> Bgp will know that this is IBGP looking at AS

Router B

router BGP 34
neighbor 192.168.1.1 remote-as 34
neighbor 172.16.1.2 remote-as 400 –> neighbor relationship with ebgp peer.
neighbor 3.3.3.3 remote-as 400
neighbor 3.3.3.3 ebgp-multihop 255 –> 255 is number of hops that neighbor is away. we can use any number from 1-255, it can be more specific by using 1 or 2 but my personal fav is 255 as it avoids confusion.
neighbor 3.3.3.3 update-source loopback 0 –> Here is the idea, when its sourcing the packets its sourcing it from serial interface, we need to inform the otherside that source interface is not serial interface, it is looback interface so that it cann match ip ip’s with the right interface and form neighbor relationship.

we would require to do similar configuration on router c

router bgp 400
neighbor 172.16.1.1 remote-as 34
neighbor 2.2.2.2 remote-as 34
neighbor 2.2.2.2 ebgp-multihop 255
neighbor 2.2.2.2 update-source loopback 0

Now after forming the neighbro relationships we’ll use network commands to add neighbors in routing table. Network command in BGP is bit different then Network command in other routing protocols. we ‘ll need to define mask keywork with network command in order to advertise clasless network where as if it is using a default mask we can ignore the same.

Example

Router C

router bgp 400
neighbor 172.16.1.0 mask 255.255.255.0
note:- i cannot use network 172.16.0.0 command without mask keyword as it will treat this as class B network. For any customised subnetting scheme we ‘ll need to specify subnet mask with mask keyword in network command.

Even after configuring above, Router A will not be able to talk with Router C. If we will use show ip bgp command on Router A. we’ll see that it has a valid route for Router C but it will not be able to ping router c. This is because next hop will be 3.3.3.3 which is not directly connected with Router A. . First thing which will come in our mind is that rule of synchronisation has taken in to effect but even after disabling synchronisation between router a and router B, Router C will not be reachable. we would need a special command on Router B so that all IBGP peers of AS 34 can talk with AS 400

To troubleshoot this we can use “debug ip bgp updates” but before using this debug we should use ” clear ip bgp *” command. We’ll see that it will show us that there is no valid path for networks in Router C. Next hop should be Router B but in the updates it will show next hp as router c. to avoid the we will use next-hop self keyword in Router B.

Router B

router bgp 34

neighbor 192.168.1.1 next-hop-self

When Router B is sending an update to Router A it is sending the update without changging its next hop so router A will receive next hop as Router C which is not directly connected. To avoid this we will use next-hop-self command in Router B so that router A should receve valid route.

Cable Access Technologies - Introduction

Introduction

Historically, CATV has been a unidirectional medium designed to carry broadcast analog video channels to the maximum number of customers at the lowest possible cost. Since the introduction of CATV more than 50 years ago, little has changed beyond increasing the number of channels supported. The technology to provide high-margin, two-way services remained elusive to the operator.

During the 1990s, with the introduction of direct broadcast satellite (DBS) and digital subscriber line (DSL), the cable operators experienced a serious challenge to their existence by competing technologies threatening to erode market share of their single product.

DBS operators marketed more choice and better quality entertainment product through digital technology, whereas the incumbent local exchange carriers (LEC) proposed to offer a combination of voice, video, and data by means of DSL.

Fearing loss of market share and the need to offer advanced services to remain economically viable, key multiple system operators (MSOs) formed the Multimedia Cable Network System Partners, Ltd. (MCNS), with the purpose of defining a product and system standard capable of providing data and future services over CATV plants. MCNS proposed a packet-based (IP) solution in contention with a cell-based (ATM) solution promoted by IEEE 802.14. MCNS partners included Comcast Cable Communications, Cox Communications, Tele-Communications Inc., Time Warner Cable, MediaOne, Rogers CableSystems, and Cable Television Laboratories (CableLabs).

The Data Over Cable Service Interface Specification (DOCSIS) 1.0 standard that resulted from the MCNS effort was unanimously accepted as the North American standard, and vendors aggressively introduced products in compliance with this standard. MSOs defined upgrade and construction programs to increase the supporting bandwidth of their plants and to provide two-way functionality.

The DOCSIS 1.0 standard prescribes multivendor interoperability and promotes a retail model for the consumer's direct purchase of a cable modem (CM) of choice. To ensure multivendor interoperability, CableLabs subjects all products offered to rigorous testing. Equipment successfully passing all tests will be CableLabs Qualified for head-end Cable Modem Terminating System (CMTS), and CableLabs Certified for CM devices.

To date, the DOCSIS 1.0 standard is proving to be a universal success, with deployments now in operation worldwide.

CableLabs, in conjunction with the vendor and user communities, is now in the process of defining DOCSIS 1.1 for the purpose of supporting Voice Over Internet Protocol (VoIP) and advanced security, and is also paving the way for advanced future multimedia services.

Cable Access Technologies - Evolution from One-Way Broadcast to Two-Way Hybrid Fiber Coax

Evolution from One-Way Broadcast to Two-Way Hybrid Fiber Coax

A CATV network consists of a head-end location where all incoming signals are received and, regardless of their source, frequency-division multiplexing (FDM) is applied, amplified, and transmitted downstream for distribution to the complete cable plant.

Original CATV networks, as shown in Figure 22-1, were exclusively one-way, comprised of diverse amplifiers in cascade to compensate for the intrinsic signal loss of the coaxial cable in series with taps to couple video signal from the main trunks to subscriber homes via drop cables.

Figure 22-1 A Simple, One-Way Video Broadcast Topology Using Coaxial Cabling Exclusively

Besides being unidirectional, the long amplifier cascades resulted in a system with high noise that was inherently unreliable and failure-prone, in addition to being susceptible to lightning strikes and ingress noise from foreign radio frequency (RF) signals.

The first significant improvement to the CATV plant was the introduction of fiber-optic technology and the advent of the HFC plant (see Figure 22-2).

Figure 22-2 Simple HFC Distribution Network

Portions of the coaxial cable and supporting amplification elements are replaced with multifiber optic cable from a head end or hub location. The aggregated video signal is used to modulate a downstream laser, which transmits the optical signal to an optical node, which in turn converts the signal from an optical to an electrical signal that can then be propagated downstream to the entire customer serving area.

It can be readily seen that the introduction of the fiber can significantly reduce the number of cascaded amplifiers consequently improving system reliability, the signal-to-noise ratio (SNR) of the downstream video signal, and potential system bandwidth. In addition, this makes the system ready for the next step to two-way operation. As an added benefit, HFC reduces operational and maintenance costs, and improves the immunity of the system to ingress noises.

Two-way operation is achieved by the addition of requisite upstream amplifiers in the amplifier housings, the addition of a narrow-band upstream laser in the optical node, a dedicated upstream fiber to the head end, and a compatible optical receiver to convert any upstream information to an electrical signal. When all components are in place, proper return path alignment is required.

By means of adding an optical RING topography, the cable network affords greater reliability, supports greater bandwidth with the capability to transport more information, and is ready to support two-way operation by the simple addition of requisite components, as illustrated in Figure 22-3.

Figure 22-3 Advanced HFC Network with Ring Topography

Network robustness, scalability, and flexibility is further improved by the introduction of the intermediate hub from which advanced services can ultimately be launched.

The HFC network and topography as outlined become the basic building blocks for developing access transport capabilities needed by the MSOs to compete in the dynamic communication environment.

Cable Access Technologies - Limitations and Specifications of the HFC Plant

Limitations and Specifications of the HFC Plant

The HFC network has the potential to offer tremendous bandwidth in the downstream or forward direction from the head end or hub to the customer. Depending upon the extent of the plant upgrade, the available bandwidth could be as much as from 54 to 860 MHz. Downstream channel bandwidths are determined by the individual country's video broadcast standards.

The historical broadcast video channel assignments limit the upstream or reverse direction from the customer to the spectrum between 5 to 42 MHz. This upstream spectrum is frequently hostile to return path connectivity due to the ingress of foreign interfering signals such as ham radio citizen band (CB), among other legitimate RF emissions.

Table 22-1 summarizes the specifications for the downstream direction, and Table 22-2 summarizes the specifications for the upstream direction.

A DOCSIS system must provide greater than 99 percent availability when forwarding 1500-byte packets at the rate of at least 100 packets per second. To achieve these criteria, certain CATV performance specifications are mandated on both the upstream and downstream spectrum.

Table 22-1 Downstream Cable Specifications

Downstream Parameter	Assumes nominal analog video carrier level (peak envelope power) in a 6-MHz channel with all conditions present concurrently and referenced to frequencies greater than 88 MHz
RF channel spacing (BW)	6 MHz
Transit delay, CMTS to most distant customer	Less than or equal to 0.800 ms
CNR in a 6-MHz band	Not less than 35 dB (analog video level)
C/I ratio for total power (discrete and broadband ingress signals)	Not less than 35 dB within the design BW
Composite triple-beat distortion for analog-modulated carriers	Not greater than -50 dBc within the design BW
Composite second-order distortion for analog-modulated carriers	Not greater than -50 dBc within the design BW
Cross-modulation level	Not greater than -40 dBc within the design BW
Amplitude ripple	0.5 dB within the design BW
Group delay ripple in the spectrum occupied by the CMTS	75 ns within the design BW
Microreflections bound for dominant echo	-10 dBc at less than or equal to 0.5 ms -15 dBc at less than or equal to 1.0 ms -20 dBc at less than or equal to 1.5 ms -30 dBc at less than or equal to 1.5 ms
Carrier hum modulation	Not greater than -26 dBc (5 percent)
Burst noise	Less than 25 ms at a 10 Hz average rate
Seasonal and diurnal signal level variation	8 dB
Signal level slope (50 to 750 MHz)	16 dB
Maximum analog video carrier level at the CM input, inclusive of above signal level variations	17 dBmV
Lowest analog video carrier level at the CM input, inclusive of above signal level variation	-5 dBmV

Good engineering, design, and maintenance practices for CATV plants ensure that these traditional video parameters can easily be met and maintained for operational systems. Parameters of primary concern, however, relate to signal level and noise.

Table 22-2 Upstream Cable Specifications

Upstream	Assumes all conditions present concurrently
Frequency range	5 to 42 MHz, edge to edge
Transit delay, most distant CM to nearest CM or CMTS	Less than or equal to 0.800 ms
Carrier-to-noise ratio	Not less than 25 dB
Carrier-to-ingress power (the sum of discrete and broadband ingress signals) ratio	Not less than 25 dB
Carrier-to-interference (the sum of noise, distortion, common path distortion, and cross-modulation) ratio	Not less than 25 dB
Carrier hum modulation	Not greater than -23 dBc (7 percent)
Burst noise	Not longer than 10 ms at a 1 kHz average rate for most cases
Amplitude ripple	0.5 dB/MHz (5 - 42 MHz)
Group delay ripple	200 ns/MHz (5 - 42 MHz)
Microreflections: single echo	-10 dBc at less than or equal to 0.5 ms -20 dBc at less than or equal to 1.0 ms -20 dBc at less than or equal to 1.0 ms
Seasonal and diurnal signal level variation	Not greater than 8 dB min to max

The greater challenge for the operator is to realize sufficient usable upstream bandwidth to achieve the systems throughput requirements for data or other services. The limited upstream bandwidth must often be shared with other services, ranging from impulse pay-per-view (IPPV), telemetry, and alarm gathering information from the active elements in the cable plant, as well as having to compete with interfering signals that radiate into the lower frequency range.

Because of the limited and often-hostile upstream bandwidth, the hardware design must implement diverse countermeasures to mitigate the effects of both fixed and transient harmful noise. In addition, the network designer must choose from the available remaining spectrum and often must implement bandwidth compromises for a DOCSIS deployment.

A combination of upstream signal quality measured by carrier-to-noise ratio (CNR), anticipated market penetration, services offered, and available upstream spectrum will ultimately dictate the physical configuration of the return-path physical layer.

Cable Access Technologies - DOCSIS Standards, Signaling Protocols, and Applications

The DOCSIS interface specifications enabled the development and deployment of data-over-cable systems on a nonproprietary, multivendor, interoperable basis for transparent bidirectional transfer of Internet Protocol (IP) traffic between the cable system head end and customer locations over an all-coaxial or hybrid-fiber/coax (HFC) cable network.

The system consists of a CMTS located at the head end, a coaxial or HFC medium, and a CM located at the premises of the customer, in conjunction with DOCSIS-defined layers that support interoperability and evolutionary feature capabilities to permit future value-added services.

DOCSIS layer definitions are as follows:

•IP network layer

•Data link layer comprised of:

–Logical Link Control (LLC) sublayer conforming to Ethernet standards

–Link security sublayer for basic privacy, authorization, and authentication

–Media Access Control (MAC) sublayer for operation supporting variable-length protocol data units (PDU) and featuring:

CMTS control of contention and reservation transmission opportunities

A stream of minislots in the upstream

Bandwidth efficiency through variable-length packets

Extensions for the future support of Asynchronous Transfer Mode (ATM) or other types of PDU

Support for multiple grade of service and wide range of data rates

•Physical (PHY) layer comprised of:

–Downstream convergence layer conforming to MPEG-2 (Rec. H.222.0)

–Physical Media Dependent (PMD) sublayer for:

Downstream based on ITU-T Rec J.83 Annex B with either 64 or 256 quadrature amplitude modulation (QAM), concatenation of Reed-Solomon and Trellis forward error correction (FEC), in addition to variable-depth interleaving

Upstream, employing:

Quadrature phase shift keying (QPSK) or 16 QAM

Support for multiple symbol rates

CM controlled and programmable from the CMTS

Frequency agility

Support for fixed-frame and variable-length PDU formats

Time-division multiple access (TDMA)

Programmable Reed-Solomon FEC and preambles

Capability to support future physical layer technologies

In addition, the specification defines means by which a CM can self-discover the appropriate upstream and downstream frequencies, bit rates, modulation format, error correction, and power levels. To maintain equitable service levels, individual CMs are not allowed to transmit except under defined and controlled conditions.

The DOCSIS layers are represented by Figure 22-4 and are compared with the classic OSI layer.

Figure 22-4 DOCSIS and OSI Protocol Layers

The DOCSIS physical layer permits considerable flexibility to ensure quality transmission can be achieved over cable plants of varying quality. Of significance are the optional upstream channel bandwidths and modulation choices available for both the upstream and downstream signal flows.

Based upon bandwidth and modulation options, in addition to DOCSIS-specified symbol rates, the total and effective data rates of DOCSIS facilities are summarized in Tables 22-3 through 22-5. The overhead generated by FEC inefficiency represents the difference between the respective rates.

Table 22-3 Nominal DOCSIS Downstream Data Rates in 6-MHz Channel

Modulation type	64 QAM	256 QAM
Symbol rate	5.057 MSs	5.360 MSs
Total data rate	30.34 Mbps	42.9 Mbps
Effective data rate	27 Mbps	38 Mbps

Table 22-4 Nominal DOCSIS Upstream Data Rates for QPSK

Bandwidth	200 kHz	400 kHz	800 kHz	1600 kHz	3200 kHz
Symbol rate	0.16 MSs	0.32 MSs	0.64 MSs	1.28 MSs	2.56 MSs
Total data rate	0.32 Mbps	0.64 Mbps	1.28 Mbps	2.56 Mbps	5.12 Mbps
Effective data rate	0.3 Mbps	0.6 Mbps	1.2 Mbps	2.3 Mbps	4.6 Mbps

Table 22-5 Nominal DOCSIS Upstream Data Rates for 16 QAM

Bandwidth	200 kHz	400 kHz	800 kHz	1600 kHz	3200 kHz
Symbol rate	0.16 MSs	0.32 MSs	0.64 MSs	1.28 MSs	2.56 MSs
Total data rate	0.64 Mbps	1.28 Mbps	2.56 Mbps	5.12 Mbps	10.24 Mbps
Effective Data Rate	0.6 Mbps	1.2 Mbps	2.3 Mbps	4.5 Mbps	9 Mbps

DOCSIS further specifies that for a system to become functional and operational, mandatory servers must interface the CMTS and CM deployments. These servers include the following:

•Dynamic Host Configuration Protocol (DHCP) server, as defined by RFC 2181. This server provides needed IP addresses for both the CM and subsequent PC devices that follow.

•Time of Day (TOD) server, as defined by RFC 868 for the purpose of time-stamping operational system events.

•Trivial File Transfer Protocol (TFTP) server, as defined by RFC 1350 for the purpose of registering and downloading CM configuration files for individual customer service. These configurations could include quality of service (QoS) parameters, baseline privacy (BPI) implementation, operating frequency assignments, the number of host devices, and so on.

For large-scale deployments, it is recommended that these servers be supported by dedicated hardware platforms to ensure rapid system response and scalability.

The DOCSIS specifications dictate a CM registration process as represented by Figure 22-5. In an environment equipped with a CMTS and supported with the required servers, a CM scans the downstream spectrum when it is initially powered on for a compatible RF channel carrying data adhering to DOCSIS physical layer characteristics. The CMTS periodically broadcasts upstream channel descriptors (UCD) over the DS channel, from which a CM will learn its assigned upstream operational frequency. The CM has now established both a US and a DS frequency.

Figure 22-5 Cable Modem Registration Sequence

The CMTS periodically transmits upstream bandwidth allocation maps (henceforth referred to as MAP) in shared time slots in the DS direction.

The CMTS assigns a temporary service identifier (SID) (typically SID = 0) to the CM, which begins a coarse power ranging (R1 using 3 dB increments) and time synchronization process between itself and the CMTS on a contention basis using shared time slots.

The CMTS periodically sends keepalive messages to verify link continuity between itself and all CM units in the same domain. When a CM receives its first keepalive message, it reverts to a fine power ranging (R2 using 0.25 dB increments).

Following the R2 process, a CM is considered to have established a link between itself and the CMTS, but the link will be broken if 16 consecutive keepalive messages are lost.

On a contention basis in shared time slots, using a temporary SID, a CM forwards a bandwidth request to the CMTS, which in turn forwards a grant to the CM, permitting
it to forward upstream information in allocated time slots. The CM subsequently
makes a DHCP discovery followed by a DHCP request. The CMTS forwards a DHCP acknowledgment from the DHCP server containing an IP address, a default gateway, the addresses of a TFTP and TOD server, and a TFTP configuration file name.

The CM subsequently initiates the TOD and TFTP process. From the TFTP server, the CM receives a configuration file containing QoS, security, applicable frequency assignments, and any new software images.

The CM forwards this configuration file to the CMTS and initiates a registration request. If the configuration file is valid, the CMTS assigns the CM a permanent SID and registers the CM to online status.

Following registration, the CM optionally initiates the activation of the 56-bit DES encryption algorithm to provide security between the CMTS and itself over the cable plant.

As CMs register, their individual status can be monitored remotely via access commands to the CMTS. Table 22-6 defines status messages from a Cisco universal broadband router.

Table 22-6 List and Definition of Show Cable Modem State Commands from a Cisco CMTS

Message	Message Definition
Offline	Modem is considered offline
init(r1)	Modem is sent initial ranging
init(r2)	Modem is ranging
init(rc)	Ranging is complete
init(d)	DHCP request was received
init(i)	DHCP reply was received; IP address was assigned
init(t)	TOD request was received
init(o)	TFTP request was received
online	Modem is registered and enabled for data
online(d)	Modem is registered, but network access for the CM is disabled
online(pk)	Modem is registered, BPI is enabled, and KEK was assigned
online(pt)	Modem is registered, BPI is enabled, and TEK was assigned
reject(m)	Modem did attempt to register; registration was refused due to bad MIC
reject(c)	Modem did attempt to register; registration was refused due to bad COS
reject(pk)	KEK modem key assignment was rejected
reject(pt)	TEK modem key assignment was rejected

DOCSIS prescribes that data forwarding through the CMTS may be transparent bridging or, as an alternate, may employ network layer routing or IP switching. It also specifies that data forwarding through the CM is link layer transparent bridging with modifications allowing the support of multiple network layers.

In addition, DOCSIS defines generic CMTS and CM hardware specifications to ensure multivendor interoperability in field deployments. These are summarized in Table 22-7.

Table 22-7 A Generic CMTS Hardware Specification

Parameter	Characteristic
Frequency range	Upstream Downstream	5 to 42 MHz (5 to 65 MHz offshore) 88 to 860 MHz
Bandwidth	Upstream Downstream	200, 400, 800, 1600, 3200 kHz 6 MHz (8 MHz offshore)
Modulation modes	Upstream Downstream	QPSK or 16 QAM 64 or 256 QAM
Symbol rates	Upstream Downstream	160, 320, 640, 1280, 2560 Ksymbols/sec 5.056941 or 5.360537 Msymbols/sec
CMTS power level range upstream downstream

For the DOCSIS availability criteria to be realized or exceeded, the hardware must support noise-mitigating countermeasures or properties to operate in the hostile upstream. For the upstream, the operator has a choice of either QPSK or 16 QAM enabling operation within a degraded CNR, but with reduced spectral efficiency.

Additionally, forward error correction (FEC) can be optionally configured to reduce the amount of data corrupted by noise. Furthermore, an optimal upstream BW can be selected by the operator to fit data channels between either noisy spectrum or spectrum assigned to other services.

The last countermeasure available is a concept of spectrum management, in which the selected upstream frequency, modulation, and channel bandwidth can be altered to ensure reliable access transmission between the CMTS and CM in case of transitory noise periods.

The physical characteristics of the generic DOCSIS 1.0 hardware, noise-mitigating countermeasures, and the associated cable plant parameters have been defined and specified in Table 22-8. Based on this information, and knowing the actual cable plants characteristics, the operator can now consider deploying hardware to develop a network.

Table 22-8 Generic CM Hardware Specification

Parameter	Characteristic
CM power level range: Output Input	QPSK: 8 to 58 dBmV 16 QAM: 8 to 55 dBmV -15 to 15 dBmV
Transmission level	-6 to -10 dBc