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CCNA4 (Chapter2)

Terms in this set (14)

Fill in the blank.
The default encapsulation for WAN interfaces is ________ on Cisco routers.
HDLC

Refer to curriculum topic: 2.1.2
Which PPP option enables load balancing on PPP-enabled interfaces that connect to a single destination?
Multilink

Refer to curriculum topic: 2.3.1
Multilink spreads traffic across multiple WAN links. Authentication and PPP Callback are used for security reasons. Error detection is used to identify faulty connections. Compression is used to maximize the throughput on PPP connections.
Which additional functionality is available on an interface when the encapsulation is changed from HDLC to PPP?
authentication

Refer to curriculum topic: 2.2.1
PPP supports two types of authentication, PAP and CHAP. CHAP is the more secure option.
Match the PPP frame field to the description. (Not all options are used.)
1. Flag: a single byte that designates the beginning or end of a PPP frame
2. Address: a byte filled with all 1s
3. Control: a field with 00000011 so that data link establishment is not required
4. Protocol: one (if compression allowed) or two bytes
5. Data: 0 to 1500 bytes of information
6. Frame Check Sequence: up to 4 bytes for error detection

Refer to curriculum topic: 2.2.2
A network engineer is troubleshooting an unsuccessful PPP multilink connection between two routers. The multilink interface has been created and assigned a number, the interface has been enabled for multilink PPP, and the interface has been assigned a multilink group number that matches the group assigned to the member physical serial interfaces. The physical serial interfaces have also been enabled for PPP multilink. Which additional command should to be issued on the multilink interface?
p address 192.168.10.1 255.255.255.252

Refer to curriculum topic: 2.3.1
An IP address needs to be assigned to the multilink interface. The physical serial interfaces are configured with the no ip address, encapsulation ppp, and clock rate commands.
Which protocol is used by PPP to provide authentication and protection from playback attacks?
CHAP

Refer to curriculum topic: 2.3.2
CHAP, or Challenge Handshake Authentication Protocol, can be configured on PPP interfaces to provide authentication and protection from playback attacks. PAP does not provide this level of protection. Authentication occurs within the LCP process but the LCP and NCP protocols are not directly responsible for authentication.
During a PPP session establishment phase, which two messages are sent by the requested party if the options are not acceptable? (Choose two.)
1. Configure-Nak
2. Configure-Reject

Refer to curriculum topic: 2.2.3
Configure-Nak and Configure-Reject are messages used while establishing a link. Protocol-Reject, Code-Reject, and Discard-Request are frames that are sent as maintenance messages.
Fill in the blank.
When a Cisco router is being connected to a non-Cisco router across a point-to-point serial link, the ________ encapsulation should be configured.
PPP

Refer to curriculum topic: 2.2.1
The default encapsulation on Cisco point-to-point serial interfaces is HDLC, which is an industry standard, but on a Cisco router, Cisco uses a non-ISO compliant extension. For connecting to a non-Cisco router, the default encapsulation will need to be changed to PPP, which is an open standard protocol.
What function does NCP perform in the establishment of a PPP session?
1. It completes the specific configuration of the network layer protocol that is being used.


Refer to curriculum topic: 2.2.3
The PPP Network Control Protocol (NCP) negotiates and configures for specific network layer protocols. This allows PPP to carry packets from these network layer protocols such as IPv4 or IPv6.
PPP authentication is performed at which OSI layer?
Refer to curriculum topic: 2.3.2
Because PPP is a Layer 2 technology, it provides Layer 2 authentication through the use of either PAP or CHAP.
With which layers of the OSI model do the PPP control protocols interface?
NCP interfaces with Layer 3; LCP interfaces with Layer 1

Refer to curriculum topic: 2.2.2
PPP is a data-link protocol that contains two control protocols. LCP sets up and terminates the PPP connection, so it works at L2 and interfaces with L1. NCP works at L2 and interfaces with the higher layer protocol configurations at L3.
Which two options are negotiated via NCP during the establishment of a PPP connection that will use the IPv4 network layer protocol? (Choose two.)
1. the algorithm to compress TCP and IP headers
2. an IPv4 address to use for routing IP over the PPP link

Refer to curriculum topic: 2.2.3
The options determining which algorithm to compress TCP and IP headers and an IPv4 address to use for routing IP over the PPP link can be negotiated during the NCP negotiation phase. The other three options are negotiated via LCP.
Which PPP protocol allows a device to specify an IP address for routing over the PPP link?
IPCP

Refer to curriculum topic: 2.2.3
At the NCP layer, IPCP is responsible for configuring IP at both ends of the link. This allows the initiating node to specify an IPv4 address to use for routing over the PPP link. PAP and CHAP are both PPP protocols used for authentication and LCP is the PPP protocol responsible for establishing a data-link connection.
Match the transmission rate standards with their designated bandwidth. (Not all options are used.)
T1: 1.544 Mb/s
DS0: 64 Kb/s
OC-1: 51.84 Mb/s
E1: 2.048 Mb/s
T3: 44.736 Mb/s

Refer to curriculum topic: 2.1.1
T-carrier refers to the bundling of DS0s used in serial WAN connections. The hierarchy specifies the different levels of bundling that carriers offer for bandwidth. The E-carrier system is used in Europe and the OC rates define the transmission rate of digital signals on fiber-optic networks.
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