ORACLE Access to SYBASE Data
Posted on | February 7, 2010 | No Comments
TRANSPARENT GATEWAY FOR Sybase configuration steps
1.Oracle installed on the server where the Sybase client (or on the same server to install Oracle, Sybase Server) to ensure that access to Sybase databases;
2. TRANSPARENT GATEWAY FOR Sybase installation option, to use a custom installation. Correct choice of Sybase installation directory;
3. Select a sid string ready to assign the Sybase database. Such as: tg4sybs set the dll path to the Sybase environment variable PATH (This step is very important);
4. Modify the initialization file, the default is:
Oracle_HOME \ tg4sybs \ admin \ inittg4sybs.ora
Setting Parameters
HS_FDS_CONNECT_INFO
Format:
HS_FDS_CONNECT_INFO = server_name. Database_name [, INTERFACE = interface_file]
server_name. database_name is case sensitive.
INTERFACE Optional
Example: the following
# This is a sample agent init file that contains the HS parameters that are # needed for the Transparent Gateway for Sybase # # HS init parameters # HS_FDS_CONNECT_INFO = migration_serv.taxHS_FDS_TRACE_LEVEL = OFFHS_FDS_RECOVERY_ACCOUNT = RECOVERHS_FDS_RECOVERY_PWD = RECOVER # # Environment variables required for Sybase # set SYBASE = d: \ sybase above example
server_name is the migration_serv
database_name is the tax
5. Configure the oracle network services listener, the configuration file is: listener.ora
Default Path: ORACLE_HOME \ network \ admin
Add the following:
SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = gateway_sid) (ORACLE_HOME = oracle_home_directory) (PROGRAM = tg4sybs))) gateway_sid are three options sid string
oracle_home_directory is the ORACLE_HOME
If the SYBASE is tg4sybs specific. If the other databases, will be different. Source: big-Microsoft certification exams test
Examples are as follows:
(SID_DESC = (SID_NAME = tg4sybs) (ORACLE_HOME = D: \ oracle \ ora92) (PROGRAM = tg4sybs)) 6. Stop listening
lsnrctl stop
Restart the listener
lsnrctl start
7. Configure oracle server’s tnsnames.ora to be able to access sybase
connect_descriptor = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = host_name) (PORT = port_number)) (CONNECT_DATA = (SID = gateway_sid)) (HS = OK)) connect_descriptor the connection string, he was taken, usually sybs
host_name: oracle server’s name
port_number: oracle listen port
gateway_sid are three options sid string
Examples are as follows:
sybs = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = dw-server1) (PORT = 1521))) (CONNECT_DATA = (SID = tg4sybs)) (HS = OK)) 8. to establish database link
Such as:
CREATE DATABASE LINK sybs CONNECT TO sa IDENTIFIED BY prient USING ‘SBYS’;
Can access sybase database.
Note that, sybase database table name, field names, if it is lowercase, then the time of the visit in the oracle where to add double quotation marks “”
Such as:
SQL> select “a” from “b” @ sybs;
CiscoIOS of 16 Kinds of Permission Levels
Posted on | February 5, 2010 | No Comments
A lot of work on top of the Cisco IOS network administrators have never bothered to considered that they are using permission levels or those levels of meaning. However, Cisco IOS actually 16 kinds of different permission levels. David Davis discusses these different levels and to introduce you to configure these permissions need to use the main command.
Do you know why Cisco IOS commands with different permission levels provide a 16? A lot of work environment in the Cisco IOS network administrators have never bothered to considered that they are using permission levels or those levels of meaning.
When the Cisco IOS enter a different permission levels, your competence level higher in your router operation can be carried out by the more. But the majority of users of Cisco routers are familiar with only two privilege levels:
User EXEC mode – privilege level 1
Privileged EXEC mode – privilege level 15
In the default configuration when you log on to the Cisco router, you are in user EXEC mode (level 1), the. In this mode, you can view the router’s some information, such as interface status, and you can view the routing table in routing. However, you can not make any changes or view the running configuration file.
Because of these limitations, Cisco routers, the majority of users immediately type enable to exit the user EXEC mode. By default, the input enable will enter grade 15, that is, privileged EXEC mode. In the Cisco IOS, this level is equivalent to have root privileges in UNIX or Windows, has administrator privileges. In other words, you can take full control of the router.
Because the Internet is only by a small number of people to maintain, each of them usually has access to privileged mode password. However, in some cases, those small or medium-sized companies will continue to grow, while the rights issue will become more complex.
Many times, when there is a support group or do not need too much access to the router on the lack of experienced administrators when problems emerged. Maybe they just need to connect to the router to view the running configuration or reset interfaces.
In this case, these people will need between Level 1 to a level between grades 15 to operate. Please keep in mind the principle of least privilege: only give access to the necessary minimum.
There are many possible configurations of the method of IOS users and permissions, I can not described in detail in an article for each method. Therefore, we will pay attention to permissions when you configure the basic commands used.
Show privilege: This command displays the current permissions. Here’s an example:
router # show privilege
Current privilege level is 3
Enable: Administrators typically use this command to enter privileged EXEC mode. However, it can also bring you access to any privileged mode. Here’s an example:
router # show privilege
Current privilege level is 3
router # enable 1
router> show privilege
Current privilege level is 1
router>
User: This command can not only set the user, it can tell the IOS, when the user login will have what permission levels. Here’s an example:
router (config) # u-sername test password test privilege 3
Privilege: This command set some commands can be used only in a certain level. Here’s an example:
router (config) # enable secret level 5 level5pass
Enable secret: By default, this command creates a password to enter privileged mode 15. However, you can also use it to create access to other areas that you can create a privileged mode password.
Let us examine an example. Suppose you want to create a maintenance user, he can log on to the router and view the boot information (and any other level 1 information). You will enter the command might be:
router (config) # u-ser support privilege 3 password support
router (config) # privilege exec level 3 show startup-config
Note that does not need to enable secret command, unless you want to level a user logged in. In order to be raised to Level 3 to use a password. In our example, the new user (maintenance) has been at Level 3, and no additional enable secret password to login.
In addition, important to note that this configuration assumes you already have a configured user name and password of the router, the example also assumes that you have to define the enable secret level 15 command, you have a have a level 15 super-user , and you have super-user privileges to save the startup configuration file.
CCIE Certified Cisco training expert analysis of 20 Q
Posted on | February 4, 2010 | No Comments
Question 1: CCIE symbol of what?
Answer: CCIE is Cisco-certified experts in interconnection networks. At the same time, is currently the most advanced technological capabilities Cisco certification.
Question 2: CCIE certification what is the procedure?
A: CCIE certification program is recognized Cisco introduced the industry’s best experts in the interconnection network of an advanced certification program.
Question 3: CCIE certification program provides a what?
Answer: CCIE Certification Program offers:
“Expert” the definition of technical knowledge and competence
Assessment of the authority of such knowledge and ability of the method
The quality of services as those “best-level” engineer of target demand.
Question 4: complete this certification process will Certified Engineer What are the benefits?
A: The CCIE certification process to complete the unique advantages:
Industry-recognized-CCIE is the industry’s recognition of the interconnection network of industry in the high-quality technical experts.
-CCIE special technical support from Cisco can be automatically second-class experts. This will allow them to experience all the known problems experienced direct access to Cisco technical experts.
CCO access and other CCIE via E-mail in the form of direct participation in CCIE Forum.
CCIE upgrades can be only a conversation topic to get CCIE training invitation.
Question 5: In order to reap Carpenter eligible to participate in CCIE certification exams, I have to attend a series of required training courses?
A: Not really. Cisco has identified and recommended routing and switching on a series of training courses, they are not mandatory. However, interconnection network industry experience is very useful.
Question 6: There are lab exam training?
A: Cisco has opened at the Wichita State University lab exam training courses (ie Pre-lab course).
Question 7: CCIE certification form from the What?
A: The certification examination by the laboratory accreditation (from Sylvan Prometric’s test centers to conduct examinations), as well as a long two days of laboratory time, together constitute the certification exams.
Question 8: I am able to Cisco Training Partner (Cisco Training Partner) seat of the CCIE certification do?
Answer: You can not. CCIE Certified Cisco designated locations only by the implementation. Written by Sylvan Prometric test centers implemented; laboratory examinations, conducted by Cisco to implement.
Question 9: Sylvan Prometric written how?
A: Sylvan Prometric is a three-hour written multiple-choice exam. Remember, for the CCIE Routing and Switching classes, the examination subjects number is 350-001; for Internet service provider (ISP) dial-up class CCIE, the examination subjects number is 350-004; for wide area network (WAN) type CCIE, the examination subjects number is 350-007.
Question 10: Preparing CCIE written and lab exam What is the best way?
A: In addition to reading the contents listed in the table, Cisco recommends a series of router / switch as well as the configuration IP (BGP, OSPF, RIP, IGRP, EIGRP), LAN / WAN, ISDN, RSRB, and DLSW experimental content routing protocols access to skilled master experience.
Cisco 642-825 Free Demo – 7
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Section 4: Verify Basic Teleworker Configuration (7 Questions)
Q31
The Cisco VPN client is being installed on a new Exambible teleworker’s laptop.
When configuring the Cisco software VPN client on a PC, which values need to be entered to complete the
setup when pre-shared key authentication is used?
A. IP address of server, groupname and password, and default gateway
B. IP address of server, groupname and password, default gateway, and DNS servers
C. IP address of server, groupname, and password
D. IP address of server, groupname and password, default gateway, DNS servers, and local IP address
Answer: C
Q32
The Cisco VPN client is being installed on a teleworkers laptop. When configuring the Cisco VPN Client,
what action is required prior to installing Mutual Group Authentication?
A. The option to “Allow Local LAN Access” must be selected.
B. A group pre-shared secret must be properly configured.
C. A valid root certificate must be installed.
D. Transparent tunneling must be enabled.
Answer: C
Q33
The Cisco VPN client was installed on a Exambible laptop as shown below:
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Based on the diagram shown above, what does the “Allow Local LAN Access” option enable a Cisco software
VPN client to do?
A. It allows local traffic from trusted resources to pass through the VPN connection
B. It allows a user to access the resources on the local LAN when connected through a secure gateway to a
central-site VPN device
C. It allows secured remote clients to access local LAN resources through the VPN connection
D. It allows remote connections from trusted clients to access local resources
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Answer: B
Q34
The following VPN Client Statistics exhibit was seen on a Exambible laptop:
A new VPN Connection Entry was made on this laptop as shown below:
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Which two statements are true about the information that is shown above from theCisco VPN client screens
on this Exambible laptop? (Select two)
A. The 10.10.32.32 network entry in the Route Details screen represents the IP address of the server end
of the encrypted tunnel.
B. The 10.10.32.32 network entry in the Route Details screen represents an IP address that will be
accessed without traversing the VPN.
C. Selecting IPSec over TCP on the connection entry on the right allows Local LAN Routes to be available
on the Route Details on the left screen.
D. Selecting Enable Transparent Tunneling on the connection entry on the right allows Local LAN Routes to
be available on the Route Details on the left screen.
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E. Selecting Allow Local LAN Access on the connection entry on the right allows Local LAN Routes to be
available on the Route Details on the left screen.
Answer: B, E
Q35
You need to set up the Cisco VPN client software on a new Exambible laptop. When configuring the Cisco
VPN Client with transparent tunneling, what is true about the IPSec over TCP option?
A. The port number is negotiated automatically.
B. Clients will have access to the secured tunnel and local resources.
C. Packets are encapsulated using Protocol 50 (Encapsulating Security Payload, or ESP).
D. The port number must match the configuration on the secure gateway.
Answer: D
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Cisco 642-825 Free Demo – 6
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Q26
ADSL broadband connections using the PPPoE access method typically uses which type of user authentication method?
A. AAA authentication
B. DNIS authentication
C. Caller-ID authentication
D. PPP CHAP authentication
E. IPSec authentication
F. L2TP authentication
Answer: D
Explanation:
Once the DSL device is installed and configured for PPPoE the encapsulation of all traffic with PPPoE/PPP headers is performed. The default authentication mechanism for PPPoE is Password Authentication Protocol (PAP). The user has the option to configure Challenge Handshake Authentication Protocol (CHAP) or MS-CHAP manually.
Generally, the CHAP method is preferred and is normally used to overcome the security limitations of PAP.
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Q27
When comparing the differences between PPPoA and PPPoE, which of the following statements are true?
A. PPPoE does not support session authentication with an aggregation router.
B. PPPaE provides simple bridged connections for a limited number of hosts.
C. PPPoA relies on client software to provide connectivity and authentication.
D. PPPoA is routed end-to-end over ATM from the user’s PC to the aggregation router.
E. None of the above
Answer: D
Explanation:
Some key advantages of PPPoE and how they differ from PPPoA include:
* Per session authentication based on Password Authentication Protocol (PAP) or Challenge Handshake Authentication Protocol (CHAP). This is the greatest advantage of PPPoE as authentication overcomes the security hole in a bridging architecture.
* Per session accounting is possible, which allows the service provider to charge the subscriber based on session time for various services offered. The service provider may also require a minimal access charge.
* PPPoE can be used on existing CPE installations that cannot be upgraded to PPP or that do not have the ability to run PPPoA, extending the PPP session over the bridged Ethernet LAN to the PC.
* PPPoE preserves the point-to-point session used by Internet Service Providers (ISPs) in the current dialup model. PPPoE is the only protocol capable of running point-to-point over Ethernet without requiring an intermediate IP stack.
* The Network Access Provider (NAP) or Network Service Provider (NSP) can provide secure access to a corporate gateway without managing end-to-end permanent virtual circuits (PVCs) and making use of Layer 3 routing and/or Layer 2 Tunneling Protocol (L2TP) tunnels. This makes the business model of selling wholesale services and virtual private networks (VPNs) scalable.
* PPPoE can provide a host (PC) access to multiple destinations at a given time. There can be multiple PPPoE sessions per PVC.
* The NSP can oversubscribe by deploying idle and session time-outs using an industry standard Remote Authentication Dial-In User Service (RADIUS) server for each subscriber.
* PPP can be used with the service selection gateway (SSG) feature.
Some key disadvantages of PPPoE and how they differ from PPPoA include:
* PPPoE client software must be installed on all hosts (PCs) connected to the Ethernet segment. This means that the access provider must maintain the CPE and the client software on the PC.
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* Because PPPoE implementation uses RFC1483 bridging, it is susceptible to broadcast storms and possible denial-of-service attacks.
Reference:
http://www.cisco.com/warp/public/794/pppoe_arch.html
Q28
DSL connections commonly use PPP over Ethernet (PPoE). What process does a Exambible host have to perform to establish a PPoE SESSION_ID?
A. A DHCP request process to request and IP address and session ID.
B. A Discovery process to identify a PPPoE server and request a session ID.
C. A RARP request process to request a MAC address and session ID.
D. A BOOTP process to request a configuration and session ID.
E. None of the above
Answer: B
Explanation:
When a router wants to initiate a PPPoE session, it must first perform Discovery to identify the Ethernet MAC address of the peering device and establish a PPPoE SESSION_ID. Discovery is inherently a client/server relationship. During Discovery, a router discovers the provider DSLAM. Discovery allows the CPE router to discover all available DSLAMs, and then select one. When Discovery completes successfully, both the CPE router and the selected DSLAM have the information they will use to build their point-to-point connection over Ethernet.
Reference:
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Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page 253
Q29
Many Exambible remote offices use DSL for their connectivity. Which four features are usually required for an 827 ADSL router to support a home ADSL broadband Internet connection with multiple end-user PCs? (Choose four)
A. IPSec
B. Bridging (IRB or RBE)
C. PPPoE client
D. PAT
E. DHCP server
F. Static default route
Answer: C, D, E, F
Explanation:
In Cisco IOS?Software Release 12.1(3)XG, a PPP over Ethernet (PPPoE) client feature was introduced for the Cisco 827 router. This feature allows the PPPoE functionality to be moved to the router. Multiple PCs can be installed behind the Cisco 827. Before their traffic is sent to the PPPoE session, it can be encrypted, filtered, and so forth. Also, Network Address Translation (NAT) can run.
PAT is needede to be able to translate multiple internal IP addresses into one single IP address. Since the majority of DSL connections provide only IP address, this is necessary.
A DHCP server is normally required, so that IP addresses can be dynamically assigned to the PC’s sharing the DSL connection.
Finally, a static default route needs to be configured on the 827 DSL router pointing out the DSL interface, so that all traffic destined for the Internet will be forwarded out to the DSL network.
Q30
The following was issued on a Exambible DSL router:
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Observe the output from the show dsl int atm 0 command shown above. What does the display of the upstream and downstream speed indicate?
A. Layer 1 connectivity has been established
B. Layer 2 connectivity has been established
C. Layer 1 and 2 connectivity has been established
D. Layer 3 connectivity has been established
E. Layer 2 and 3 connectivity has been established
Answer: C
Explanation:
The output in this example shown above displays the normal operation of a DSL router that is fully functioning. If the modem state changes from “0×8″ to “SHOWTIME,” it means that the Cisco 827 has successfully trained with the DSLAM. This verifies connectivity at layer 1. Layer 2 connectivity can be verified via the speed of the conections both upstream and downstream. For a complete overview of the ourput from the “show dsl interface atm” command, see the link provided below:
Reference:
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Cisco 642-825 Free Demo – 5
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Q21
Part of the configuration of a Exambible router is shown below:
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Based on the information above, what is needed to complete the PPPoA configuration on this Exambible router?
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A. The ATM PVC needs to be configured.
B. The VPDN group needs to be created.
C. PPPoE encapsulation needs to be configured on the ATM interface.
D. PAP authentication needs to be configured.
E. A static route to the ISP needs to be configured.
F. None of the above
Answer: A
Q22
A small Exambible office needs to connect their Cisco router to the DSL service provider. Which three configuration steps must be taken to connect a DSL ATM interface to a service provider? (Select three)
A. Configure the ATM PVC.
B. Assign a VPDN group name.
C. Configure PPPoE on the VPDN group.
D. Enable VPDN.
E. Configure the correct PPP encapsulation on the ATM virtual circuit.
F. Configure a dialer interface.
Answer: A, E, F
Q23
Router TK1 is configured as shown below:
interface ATM0/0 no ip address pvc 8/35 encapsulation aaa15mux ppp dialer dialer pool-member 1 !
interface dialer 0 ip address negotiated encapsulation ppp
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dialer pool 1 no cdp enable ppp chap hostname Exambible ppp chap password Exambible
Given the above configuration, which statement is true?
A. This device is configured as a PPPoE client.
B. This device is configured as a PPPoA client.
C. This device is configured as RFC 1483/2684 bridge.
D. This device is configured an an aggregation router.
Answer: B
Explanation:
This following is an example of configuring a Cisco router as a PPPoA client. The command “encapsulation aal5muxppp dialer” placed under the ATM interface is the indication that it is using PPPoA.
Cisco ADSL WIC !version 12.1service timestamps debug datetime msecservice timestamps datetime msec!hostname R1!ip subnet-zero!ip dhcp excluded-address 10.0.0.1!— the DHCP pool does not lease this address;!— it is used by interface FastEthernet0!ip dhcp pool poolnamenetwork 10.0.0.0 255.0.0.0 default-router 10.0.0.1!— default gateway is assigned to local devices!interface FastEthernet0 ip address 10.0.0.1 255.0.0.0 no ip directed-broadcast no ip mroute-cache!interface ATM0no ip addressno ip directed-broadcastno ip mroute-cacheno atm ilmi-keepalive pvc
1/150encapsulation aal5mux ppp dialerdialer pool-member 1
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! hold-queue 224 in!interface Dialer0ip address 172.18.0.1 255.255.0.0ip nat outsideno ip directed-broadcastencapsulation pppdialer pool 1dialer-group 2ppp pap sent-username username password password!ip nat inside source list 1 interface Dialer0 overloadip classlessip route 0.0.0.0 0.0.0.0 Dialer0no ip http server!access-list 1 permit 10.0.0.0 0.255.255.255dialer-list 2 protocol ip permit!end Reference:
http://www.cisco.com/en/US/tech/tk175/tk15/technologies_configuration_example09186a0080093e60.shtml
Q24
The configuration of the 827 ADSL router depends on tbe encapsulation method used for the ADSL connection. What are the three common encapsulation methods? (Choose three)
A. PPPoE
B. PPPoA
C. HDLC over ATM
D. DOCSIS
E. RFC 1483 Bridged
F. IP over ATM
Answer: A, B, E
Explanation:
Before you can successfully configure your Cisco DSL Router with Asymmetric Digital Subscriber Line (ADSL) service, you need specific information from your Internet Service Provider (ISP). If your ISP is unsure, unable, or unwilling to provide answers to the questions outlined below, you may not be able to correctly configure your Cisco DSL Router.
The most fundamental piece of information you will need is the type of DSL service. The following lists the type of DSL services that are available and can be configured on the Cisco 827 ADSL router:
1. Point-to-Point Protocol over Ethernet (PPPoE) 2. Point-to-Point Protocol over ATM (PPPoA) 3. RFC1483 Bridging 4. RFC1483 Routing
Q25
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Which two encapsulation methods require that an 827 ADSL router be configured with a PPP username and CHAP password? (Choose two)
A. PPPoE with the 827 configured as a bridge.
B. PPPoE with the 827 configured as the PPPoE client.
C. PPPoA
D. RFC 1483 Bridged with the 827 configured as the PPPoE client.
E. RFC 1482 Bridged with the 827 configured as a bridge.
Answer: B, C
Explanation:
When using the Point to Point Protocol over Ethernet (PPPoE) or the Point to Point Protocol over ATM (PPPoA), you must configure a PPP username and password to match the settings configured from the Internet Service Provider. This is required for both PPPoE and PPPoA in order to overcome some of the security concerns of these two Internet access methods.
Refecener: cisco CCNP CCNA CCIE
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Q17
When designing an ADSL network; if you want minimal local loop impairments, what should be the maximum distance of your lines?
A. 1000 feet (0.3 km)
B. 4000 feet (1,5 km)
C. 12,000 feet (3.65 km)
D. 18,000 feet (5,5 km)
E. 28,000 feet (8.52 km)
Answer: D
Explanation:
DSL is a highly distance-sensitive technology. As the distance from the CO increases, the signal quality and connection speeds decrease. ADSL service is limited to a maximum distance of 18,000 feet (5460 m) between the DSL CPE and the DSLAM, although many ADSL providers place an even lower limit on the distance to ensure quality. The 18,000-foot distance limitation for DSL is not a limitation for voice telephone calls, but for data transmission. The telco uses small amplifiers, called loading coils, to boost voice signals. Loading coils have a nasty tendency to disrupt DSL data signals. This means that if there are loading coils in the loop between the CPE and CO, you probably are not within an area that can receive DSL service.
Reference:
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page 247
Q18
A new ADSL line is being installed in the home office of the Exambible administrator.
What best describes ADSL?
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A. Equal upload and downloads speeds.
B. Slow upload, fast download speeds.
C. An ISDN line with no D channel.
D. Used as a T-1 replacement.
Answer: B
Explanation:
The variation called ADSL (Asymmetric Digital Subscriber Line) is the form of DSL that will become most familiar to home and small business users. ADSL is called “asymmetric” because most of its two-way or duplex bandwidth is devoted to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream or user-interaction messages. However, most Internet and especially graphics- or multi-media intensive Web data need lots of downstream bandwidth, but user requests and responses are small and require little upstream bandwidth. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream. The high downstream bandwidth means that your telephone line will be able to bring motion video, audio, and 3-D images to your computer or hooked-in TV set. In addition, a small portion of the downstream bandwidth can be devoted to voice rather data, and you can hold phone conversations without requiring a separate line.
Reference:
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci213915,00.html
Q19
Which two statements are true about DSL? (Choose two)
A. SDSL and POTS can work together.
B. It uses the unused bandwidth of your existing phone line.
C. Bandwidth is shared among users in the same geographical area.
D. It has a maximum distance limitation of 18,000 feet from the CO.
Answer: B, D
Explanation:
DSL is a very high-speed connection that uses the same wires as a regular telephone line.
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Precisely how much benefit you see will greatly depend on how far you are from the central office of the company providing the ADSL service. ADSL is a distance-sensitive technology: As the connection’s length increases, the signal quality decreases and the connection speed goes down. The limit for ADSL service is 18,000 feet (5,460 meters) from the central office, though for speed and quality of service reasons many ADSL providers place a lower limit on the distances for the service. At the extremes of the distance limits, ADSL customers may see speeds far below the promised maximums, while customers nearer the central office have faster connections and may see extremely high speeds in the future. ADSL technology can provide maximum downstream (Internet to customer) speeds of up to 8 megabits per second (Mbps) at a distance of about 6,000 feet (1,820 meters), and upstream speeds of up to 640 kilobits per second (Kbps). In practice, the best speeds widely offered today are 1.5 Mbps downstream, with upstream speeds varying between 64 and 640 Kbps.
Section 3: Configure ADSL (i.e., PPPoE or PPPoA) (11
Questions)
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Q20
Two Exambible routers are connected as shown below:
Exambible 1 is configured as shown below:
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Refer to the exhibit and the partial configuration on the Exambible router.
The Exambible DSL Router is connected to a service provider using a PPPoE session over a DSL line. The FTP traffic, generated from inside the network 10.92.1.0/24, fails to reach the PPPoE Server. What should be configured on the DSL Router to fix the problem?
A. The ip mtu command with a bytes argument set greater than 1500 needs to be configured for the Dialer1 interface.
B. The ip mtu command with a bytes argument set lower than 1500 needs to be configured for the ATM0 interface.
C. The ip mtu command with a bytes argument set greater than 1500 needs to be configured for the ATM0 interface.
D. The ip mtu command with a bytes argument set lower than 1500 needs to be configured for the Dialer1 interface.
E. None of the above
Answer: D
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Q13
Which ADSL modulation type:
1. is prominent in residential applications has 120 subchannels 2.
doesn’t need a splitter 3.
has a 1.5 Mbps maximum downstream speed? 4.
A. CAP
B. DMT
C. G.Lite
D. PPPoA
E. PPPoE
Answer: C
Explanation:
ITU GLITE (ITU G.992.2) describes splitterless Asymmetric Digital Subscriber Line (ADSL) Transceivers on
a metallic twisted pair that allows high-speed data transmission between the Central Office (ATU-C) and
the customer end remote terminal (ATU-R).
G.LITE can provide ADSL transmission simultaneously on the same pair with voice (band) service, ADSL
transmission simultaneously on the same pair with ISDN services (G.961 Appendix I or II); or ADSL
transmission on the same pair with voice band transmission and with TCM-ISDN (G.961 Appendix III) in an
adjacent pair.G.992.2 supports a maximum 1.536 Mbps downstream and 512 kbps upstream net data rate.
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G.LITE uses discrete Multitone (DMT) line code. DMT is based in the use of the IFFT to generate a set of
sub-channels, and transmit information in each sub-channel independently. Figure 1 shows the G.LITE
spectrum with indication of the POTS, upstream pilot tone, downstream pilot tone, subcarrier spacing, and
number of subcarriers for the upstream and downstream direction. Dividing the available bandwidth into a
set of independent, orthogonal subchannels are the key to DMT performance. By measuring the SNR of each
subchannel and then assigning a number of bits based on its quality, DMT transmits data on subcarriers
with good SNRs and avoids regions of the frequency spectrum that are too noisy or severely attenuated.
The underlying modulation technique is based on quadrature amplitude modulation (QAM). Each subchannel is
4.3125 kHz wide and is capable of carrying up to 15 bits. The downstream is up to 552 kHz, offering 122
subchannels, and the upstream from 26 to 138 kHz, offering 25 upstream subchannels.
Reference: http://www.vocal.com/data_sheets/full/glite.pdf
Q14
Certain physical factors are capable of severely limiting the maximum speed available on a DSL
connection. Which of the following describe the factors that are capable of it? (Choose all that apply)
A. Number of telephones attached to the local loop.
B. Gauge of wire used on the local loop.
C. Distance between the CPE and the DSLAM.
D. Bridge taps in the local loop.
E. Loading coils in the subscriber’s line.
Answer: B, C
Explanation:
DSL is a highly distance-sensitive technology. As the distance from the CO increases, the signal quality
and connection speeds decrease. ADSL service is limited to a maximum distance of 18,000 feet (5460 m)
between the DSL CPE and the DSLAM, although many ADSL providers place an even lower limit on the distance
to ensure quality. The 18,000-foot distance limitation for DSL is not a limitation for voice telephone
calls, but for data transmission. The telco uses small amplifiers, called loading coils, to boost voice
signals. Loading coils have a nasty tendency to disrupt DSL data signals. This means that if there are
loading coils in the loop between the CPE and CO, you probably are not within an area that can receive
DSL service.
Reference:
Leading the way in IT testing and certification tools, www.exambible.com
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page 247
Q15
A local Internet Service Provider is going to start offering ADSL with 640 kbps upload speed and 4Mbps
download speeds. They have retained you to help in their advertisement campaign to help them find their
target market. What groups of users should you target your marketing efforts to? (Choose two)
A. Central data processing facilities receiving simultaneous uploads of data from remote offices.
B. Support organizations providing ftp services for software distribution and documentation.
C. Small home offices requiring 24 hour connection to the Internet for email and web communication.
D. Web services companies providing dynamic web content serving, including video-on-demand.
Answer: A, C
Explanation:
Based on the expanding number of options currently and coming soon for the broadband market, competition
for home and remote user dollars has reached a frenzied state. The deployment of broadband and similar
technologies has involved quite a large amount of trial and error. The competition has seen the emergence
of two primary services for widespread deployment. These are Cable and DSL.
Loosely defined, DSL is a technology that exploits unused frequencies on copper telephone lines to
transmit traffic, typically at multimegabit speeds. DSL uses existing telephone wiring, without requiring
any additional cabling resources. It has the capability to allow voice and high-speed data to be sent
simultaneously over the same copper pair.
The service is always available, so the user does not have to dial in or wait for call setup.
DSL technologies can be broken down into two fundamental classifications: asymmetric (ADSL) and symmetric
(SDSL). As the name implies, ADSL uses higher downstream rates and lower upstream rates. In contrast,
SDSL uses the same downstream and upstream rates. ADSL is the most commonly deployed DSL technology, and
is the primary focus of the DSL portion of the CCNP Remote Access Exam.
Incorrect Answers:
B: In order to maximize the use of an FTP server, you would want a greater upload speed, since the
majority of users will be downloading files from the FTP server.
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D: Again, we would want to ensure that the upload speed was as large as possible, due to the fact that
the majority of the bandwidth will be consumed as uploads to the end users.
Reference:
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page 245 to 247
Q16
What’s true about the G.Lite (G.922) ADSL ITU standard?
A. It offers equal bandwidth for upstream and downstream data traffic.
B. It has limited operating range of less than 4,500 feet.
C. It was developed specifically for the consumer market segment requiring higher
download speeds.
D. Signals cannot be carried on the same wire as POTS signals.
E. All of the above
Answer: C
Explanation:
G.Lite is the informal name for what is now a standard way to install Asymmetric Digital Subscriber Line
(ADSL) service. Also known as Universal ADSL, G.Lite makes it possible to have Internet connections to
home and business computers at up to 1.5 Mbps (millions of bits per second) over regular phone lines.
Even at the lowest downstream rate generally offered of 384 Kbps (thousands of bits per second), G.Lite
is about seven times faster than regular phone service with a V.90 modem and three times faster than an
Integrated Services Digital Network (ISDN) connection. Upstream speeds from the computer are at up to 128
Kbps. (Theoretical speeds for ADSL are much higher, but the data rates given here are what is
realistically expected.) With G.Lite, your computer’s analog-to-digital modem is replaced with an “ADSL
modem.” and the transmission from the phone company is digital rather than the analog tranmission of
“plain old telephone service.” G.Lite is also known as “splitterless DSL” because, unlike other DSL
technologies, it does not require that a technician come to install a splitter, a device that separates
voice from data signals, at the home or business (sometimes referred to as “the truck roll”).
The G.Lite standard is officially known as G.992.2.
DSL technologies can be broken down into two fundamental classifications: asymmetric (ADSL) and symmetric
(SDSL). As the name implies, ADSL uses higher downstream rates and lower upstream rates. In contrast,
SDSL uses the same downstream and upstream rates. ADSL is the most commonly deployed DSL technology, and
is the primary focus of the DSL portion of the CCNP Remote Access Exam.
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DSL is a highly distance-sensitive technology. As the distance from the CO increases, the signal quality
and connection speeds decrease. ADSL service is limited to a maximum distance of 18,000 feet (5460 m)
between the DSL CPE and the DSLAM, although many ADSL providers place an even lower limit on the distance
to ensure quality.
References:
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page 245 to 247
http://whatis.techtarget.com/definition/0,,sid9_gci212198,00.html
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Section 2: Describe xDSL Technologies (11 Questions)
Q9
Exambible operates a DSL network. What does the “dsl operating-mode auto”
command configure on a Cisco router?
A. It configures a Cisco router to automatically detect the proper modulation
method to use when connecting an ATM interface.
B. It configures a Cisco router to automatically detect the proper DSL type
(ADSL, IDSL, HDSL, VDSL) to use when connecting an ATM interface.
C. It configures a Cisco router to automatically detect the proper
encapsulation method to use when connecting an ATM interface.
D. It configures a Cisco router to automatically detect the proper
authentication method to use when connecting an ATM interface.
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E. None of the above
Answer: A
Q10
Exambible is a DSL service provider using providing xDSL to its customers.
Which statement about xDSL implementations is true?
A. All xDSL standards operate in lower frequencies than the POTS system and
can therefore coexist on the same media.
B. Other than providing higher data rates, HDSL is identical to ADSL.
C. The ADSL standard operates in higher frequencies than the POTS system and
can therefore coexist on the same media.
D. The HDSL standard operates in higher frequencies than the POTS system and
can therefore coexist on the same media.
E. All xDSL standards operate in higher frequencies than the POTS system and
therefore can coexist on the same media.
F. None of the above.
Answer: C
Q11
Which proprietary DSL encapsulation type has the potential of dividing
telephone lines into three widely separated, distinct channels for the sake of
minimizing interference between voice, upstream and downstream data flows?
A. G.Lite
B. CAP
C. DMT
D. Half-rate DMT
Answer: B
Explanation:
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CAP operates by dividing the signals on the telephone line into three distinct
bands:
Voice conversations are carried in the 0 to 4 KHz (kilohertz) band, as they
are in all POTS circuits. The upstream channel (from the user back to the
server) is carried in a band between 25 and 160 KHz. The downstream channel
(from the server to the user) begins at 240 KHz and goes up to a point that
varies depending on a number of conditions (line length, line noise, number of
users in a particular telephone company switch) but has a maximum of about 1.5
MHz (megahertz). This system, with the three channels widely separated,
minimizes the possibility of interference between the channels on one line, or
between the signals on different lines.
References:
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page
248 & 249 http://www.esi-websolutions.com/technology_ADSL.htm
Q12
Over which of the following DSL services is the foundation that Cisco’s Long
Reach Ethernet (LRE) is based on?
A. ADSL
B. HDSL
C. IDSL
D. VDSL
E. E. None of the above
Answer: D
Explanation:
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Cisco Long Range Ethernet (LRE) solution leverages Very High Data Rate Digital
Subscriber Line (VDSL) technology to dramatically extend Ethernet services
over existing Category 1/2/3 twisted pair wiring at speeds from 5 to 15 Mbps
(full duplex) and distances up to 5,000 feet. The Cisco LRE technology
delivers broadband service on the same lines as Plain Old Telephone Service
(POTS), digital telephone, and ISDN traffic.
In addition, Cisco LRE supports modes compatible with Asymmetric Digital
Subscriber Line (ADSL) technologies, allowing service providers to provision
LRE to buildings where broadband services already exist Reference:
Cisco Press – BCRAN 821 – Exam Certification Guide 2004 (ISBN 1-587208) Page
251
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Q5
A new cable modem was shipped to the home of a Exambible user, where it is being installed for the first time. When a DOCSIS 1.1 compliant cable modem first initializes, (boots up) what does it do?
A. Establishes IP connectivity (DHCP).
B. Determines the time of day.
C. Requests a DOCSIS configuration file from a TFTP server.
D. Scan for a downstream channel and the establishment of timing synchronization with the CMTS.
E. None of the above.
Answer: D
Explanation:
According to the DOCSIS (Data-over-Cable Service Interface Specifications) when you first power up a cable modem it starts scanning (starting at a low frequency) for a cable signal. When it ‘hears’ a cable modem stream it listens for a broadcast (from the service provider) which contains information (ie. frequency) needed to talk back with the head end. It then ‘talks back’ and if it communicates the right authentication information, it is allowed to proceed.
References: Page 225 of the CCNP Self-Study BCRAN (642-821) ISBN: 1-587208
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http://www.cisco.com/en/US/products/hw/cable/ps2217/products_feature_guide_chapter09186a008019b57f.html
Q6
You are building a small network at your home and you intend on connecting your cable modem to a Cisco router. Which router interface would you connect the modem to?
A. Synchronous serial
B. Asynchronous serial
C. Ethernet
D. auxiliary
E. BRI
Answer: C
Explanation:
In certain environments where a non Cisco Cable Modem (CM) is used, and the CM is only capable of bridging, a Cisco router such as the Cisco 806 can be connected to the Cable Modem via the Ethernet interface. The routing can then be performed by the Cisco router behind the Cable Modem and the Client PC or Customer Premises Equipment (CPE) will be connected to the Cisco router. Network Address Translation (NAT) can then be configured on the Cisco router.
When the Cisco router is connected behind the Cable Modem the first problem that might be encountered is not obtaining an IP address dynamically on the Cisco router’s Ethernet interface. Most Internet Service Providers (ISPs) allow only one host or PC behind the Cable Modem. Some ISPs assign an IP address to the PC based on the host name.
Therefore, if you have a Cisco router behind the Cable Modem, then the host name for the router configured using the hostname command should be the same host name given by the ISP.
Example:
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Q7
When a cable modem is being provisioned to operate with a host system for Internet services, which two options must occur before Layer 1 and 2 connectivity can occur? (Choose two)
A. The cable modem must request an IP address and core configuration information from a Dynamic Host Configuration Protocol (DHCP) server.
B. The cable modem powering up must scan and lock on the RF data channel in the downstream path.
C. The modem must request a DOCSIS configuration file from a TFTP server.
D. The cable modem must register with the CMTS.
E. The modem must read specific maintenance messages in the downstream path.
Answer: B, E
Explanation:
According to the DOCSIS (Data-over-Cable Service Interface Specifications) when you first power up a cable modem it starts scanning (starting at a low frequency) for a cable signal. When it ‘hears’ a cable modem stream it listens for a broadcast (from the service provider) which contains information (ie. frequency) needed to talk back with the head end. It then ‘talks back’ and if it communicates the right authentication information, it is allowed to proceed. Once these steps are completed, layers 1 and 2 will be operational.
Q8
How is cable broadband technology able to transmit downstream and upstream data while at the same time delivering television content?
A. The cable operator uses the VHF hyperband to transmit and receive data signals.
B. The cable operator assigns any available spectrum to data, depending on how its own
television spectrum is being used.
C. The cable operator uses specific bandwidths for data signals specified by DOCSIS.
D. The cable operator places its data signals into clean areas where there is no
interference from noise or other signals.
Answer: C
Explanation:
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Developed by CableLabs and approved by the ITU in March 1998, Data Over Cable Service Interface Specification (DOCSIS) defines interface standards for cable modems and supporting equipment.
In a cable TV system, signals from the various channels are each given a 6-MHz slice of the cable’s available bandwidth and then sent down the cable to your house. In some systems, coaxial cable is the only medium used for distributing signals.
When a cable company offers Internet access over the cable, Internet information can use the same cables because the cable modem system puts downstream data — data sent from the Internet to an individual computer — into a 6-MHz channel. On the cable, the data looks just like a TV channel. So Internet downstream data takes up the same amount of cable space as any single channel of programming. Upstream data — information sent from an individual back to the Internet — requires even less of the cable’s bandwidth, just 2 MHz, since the assumption is that most people download far more information than they upload.