Network+ 9 Flashcards
LCP : Multilink interface: PPP’s multilink interface feature allows multiple physical connections to be bonded together into a logical interface. This logical interface allows load balancing across multiple physical interfaces. This is referred to as Multilink PPP.
Looped link detection: A Layer 2 loop (of PPP links) can be detected and prevented. Error detection: Frames containing errors can be detected and discarded by PPP.
Authentication: A device at one end of a PPP link can authenticate the device at the other end of the link. Three approaches are used to perform PPP authentication:
(1) Password Authentication Protocol (PAP): PAP performs one-way authentication (a client authenticates with a server). A significant drawback to PAP, other than its unidirectional authentication, is the security vulnerability of its clear-text transmission of credentials, which could permit an eavesdropper to learn the authentication credentials being used.
(2) Challenge-Handshake Authentication Protocol (CHAP): Like PAP, CHAP performs a one-way authentication. However, authentication is performed through a three-way handshake (challenge, response, and acceptance messages) between a server and a client. The three-way handshake allows a client to be authenticated without sending credential information across a network.
(3) Microsoft Challenge-Handshake Authentication Protocol (MS-CHAP): MS-CHAP is a Microsoft-enhanced version of CHAP, offering a collection of additional features, including two-way authentication.
LCP
PPPoE encapsulates PPP frames within Ethernet frames. PPP is used to leverage its features, such as authentication. PPP is often the protocol used by Microsoft Routing and Remote Access Server (RRAS), which is a Microsoft Windows Server feature that allows Microsoft Windows clients to remotely access a Microsoft Windows network.
PPPoE
digital subscriber line (DSL) is a group of technologies that provide high-speed data transmission over existing telephone wiring. ADSL allows an existing analog telephone to share the same line used for data for simultaneous transmission of voice and data (downstream speed = 8 Mbps, upstream speed = 1.544 Mbps).
A DSLAM acts as an aggregation point for multiple connections, and it connects via an ATM network back to a service provider’s router.
SDSL has symmetric (equal) upstream and downstream speeds. Another distinction between ADSL and SDSL is that SDSL does not allow simultaneous voice and data on the same phone line (upstream/downstream speed = 1.168 Mbps).
VDSL boasts a much higher bandwidth capacity than ADSL or SDSL, with a common downstream limit of 52Mbps and a limit of 12Mbps for upstream traffic.
DSL etc …
(SONET) is a Layer 1 technology that uses fiber-optic cabling as its media. SONET is a Layer 1 technology, it can be used to transport various Layer 2 encapsulation types, such as Asynchronous Transfer Mode (ATM). Also, because SONET uses fiber-optic cabling, it offers high data rates, typically in the 155Mbps to 10Gbps range, and long-distance limitations, typically in the 20 km to 250 km range.
SONET
Integrated Services Digital Network (ISDN) is a digital telephony technology that supports multiple 64Kbps channels (known as bearer channels, or B channels) on a single connection,
BRI: A BRI circuit contains two 64Kbps B channels and one 16Kbps D channel. Although such a circuit can carry two simultaneous voice conversations, the B channels can be logically bonded into a single VC (using the multilink interface feature of PPP to offer 128 Kbps data path, PRI: A PRI circuit is an ISDN circuit built on a T1 or E1 circuit. Recall that a T1 circuit has 24 channels. Therefore, if a PRI circuit is built on a T1 circuit, the ISDN PRI circuit has 23 B channels and one 64Kbps D channel. The twenty-fourth channel in the T1 circuit is used as the ISDN D channel (the channel used to carry the Q.921 and Q.931 signaling protocols, which are used to set up, maintain, and tear down connections).
ISDN
Local loop: A connection between a customer’s premises and their local telephone central office (CO).
Tip and ring: The red and green wires found in an RJ-11 wall jack, which carry voice, ringing voltage, and signaling information between an analog device and a telephone’s wall jack.
Central office (CO): A building containing a telephone company’s telephone switching equipment.
Local Loop Etc …
Frame Relay sites are interconnected using virtual circuits (VCs). Frame Relay is a Layer 2 technology, and a router uses locally significant identifiers for each VC. These identifiers are called data-link connection identifiers (DLCIs).
If a VC is always connected, it is considered to be a permanent virtual circuit (PVC). However, some VCs can be brought up on an as-needed basis, and they are referred to as switched virtual circuits (SVCs).
Frame Relay shares a service provider’s bandwidth with other customers of its service provider. In SLA terms, a minimum bandwidth guarantee is called a committed information rate (CIR).
Frame Relay
A SIP Trunk allows Internet telephony service providers (ITSPs) to deliver telephone services and unified communications to customers equipped with SIP-based private branch exchange (IP-PBX) and unified communications facilities.
Most unified communications applications offer voice, video, and other streaming media applications such as desktop sharing, web conferencing, and shared whiteboard technologies.
SIP Trunk
Asynchronous Transfer Mode (ATM) is a Layer 2 WAN technology that operates using the concept of PVCs and SVCs. However, ATM uses fixed-length cells as its protocol data unit (PDU), as opposed to the variable frames used by Frame Relay. ATM uses VCs to send voice, data, and video, those VCs are not identified with DLCIs. Rather, ATM uses a pair of numbers to identify a VC.
interconnections between ATM switches and ATM endpoints are called user-network interfaces (UNIs), whereas interconnections between ATM switches are called network-node interfaces (NNIs).
ATM
MPLS’s capability to support multiple protocols on the same network, and MPLS’s capability to perform traffic engineering (which allows traffic to be dynamically routed within an MPLS cloud based on current load conditions of specific links and availability of alternate paths).
The process of routing MPLS frames through an MPLS cloud is referred to as label switching. An MPLS frame does not maintain the same label throughout the MPLS cloud. Rather, an LSR receives a frame, examines the label on the frame, makes a forwarding decision based on the label, places a new label on the frame, and forwards the frame to the next LSR.
MPLS
