C480 Chapter 7

verickle's version from 2016-10-19 21:07

WAN Properties

Question Answer
Dedicated leased lineA connection interconnecting two sites. This logical connection might physically connect through a service provider's facility or a telephone company's central office (CO).
Circuit-switched connectionA connection that is brought up on an as-needed basis.
Packet-switched connectionSimilar to a dedicated leased line because most are always on. However, unlike a dedicated leased line, allows multiple customers to share a service provider's bandwidth.
always onthe connection is always available without having to first set up the connection
on demandthe connection is not established until needed

OCx Specifications

OCx SpecificationDescription
OC11 OC channel with a data rate of 51.84 Mbps
OC33 OC channels with a data rate of 155.52 Mbps
OC99 OC channels with a data rate of 466.56 Mbps
OC1212 OC channels with a data rate of 622.08 Mbps
OC1818 OC channels with a data rate of 933.15 Mbps
OC2424 OC channels with a data rate of 1.24 Gbps
OC3636 OC channels with a data rate of 1.87 Gbps
OC192192 OC channels with a data rate of 9.95 Gbps

Typical WAN Data Rates

WAN TechnologyTypical Available Bandwidth
Frame Relay56 Kbps to 1.544 Mbps
T11.544 Mbps
T344.736 Mbps
E12.048 Mbps
E334.4 Mbps
ATM155 Mbps to 622 Mbps
SONET51.84 Mbps (OC-1) to 159.25 Gbps (OC-3072)

WAN Technologies

Question Answer
T1originally used in telephony networks
Super Frame (SF)Combines 12 standard 193-bit frames
Extended Super Frame (ESF)Combines 24 standard 193-bit frames
E1contains 32 channels, in contrast to the 24 channels on a T1 circuit
T3combines 672 DS0s into a single physical connection, commonly delivered to the customer over coaxial cable, which is called a Digital Signal 3 (DS3)
E3available bandwidth of 34.4 Mbps
channel service unit/data service unit (CSU/DSU)a digital-interface device used to connect a data terminal equipment (DTE), such as a router, to a digital circuit, such as a Digital Signal 1 (T1) line
Metro Etherneta general term used to describe an Ethernet technology network in a metropolitan area
Point-to-Point ProtocolA common Layer 2 protocol used on dedicated leased lines
Multilink interfaceallows multiple physical connections to be bonded together into a logical interface. This logical interface allows load balancing across multiple physical interfaces.
Looped link detectionA Layer 2 loop (of PPP links) can be detected and prevented.
Error detectionFrames containing errors can be detected and discarded by PPP.
Asymmetric DSL (ADSL)allows an existing analog telephone to share the same line used for data for simultaneous transmission of voice and data
Symmetric DSL (SDSL)does not allow simultaneous voice and data on the same phone line
Very High Bit-Rate DSL (VDSL)boasts a much higher bandwidth capacity than ADSL or SDSL
Synchronous Optical Network (SONET)a Layer 1 technology that uses fiber-optic cabling as its media
Integrated Services Digital Network (ISDN)a digital telephony technology that supports multiple 64-Kbps channels (known as bearer channels [B channels]) on a single connection
basic rate interface (BRI) circuitcontains two 64-Kbps B channels and one 16-Kbps D channel
primary rate interface (PRI) circuitan ISDN circuit built on a T1 or E1 circuit
Frame Relaya standardized wide area network technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology
data-link connection identifiers (DLCIs)A number of a private or switched virtual circuit in a Frame Relay network that tells the Frame Relay how to route the data.
permanent virtual circuit (PVC)a connection that is permanently established between two or more nodes in frame relay and asynchronous transfer mode (ATM) based networks
switched virtual circuits (SVCs)a temporary virtual circuit that is established and maintained only for the duration of a data transfer session
Asynchronous Transfer Modeuses fixed-length cells as its protocol data unit (PDU), as opposed to the variable frames used by Frame Relay
Multiprotocol Label Switching (MPLS)a type of data-carrying technique for high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table
shim headerMPLS inserts a 32-bit header between Layer 2 and Layer 3 headers.

ISDN Network Reference Points and Elements

Question Answer
R reference pointresides between a non-ISDN device and a terminal adapter (TA).
S/T reference pointresides between a network termination 1 (NT1) and a terminal endpoint 1 (TE1).
U reference pointresides between a network termination 1 (NT1) and the wall jack connecting back to an ISDN service provider.
Terminal adapter (TA)performs protocol conversion between a non-ISDN device and a terminal endpoint 1 (TE1) device.
Terminal endpoint 1 (TE1)a device (such as an ISDN phone) that natively supports ISDN.
Terminal endpoint 2 (TE2)a device (such as a PC) that does not natively support ISDN.
Network termination 1 (NT1)a device that interconnects a four–wire ISDN circuit and a two–wire ISDN circuit.

MPLS Network Elements

Question Answer
customer premise equipment (CPE)device resides at a customer site (i.e. router)
customer edge (CE) routeruse static or dynamic routing protocols but do not run MPLS. The MPLS function is done in the service provider network.
edge label switch router (ELSR)resides at the edge of an MPLS service provider's cloud and interconnects a service provider to one or more customers.
provider edge (PE) routerthe MPLS service provider's router that connects to the customer router (another name for ESLR)
label switch router (LSR)resides as part of a service provider's MPLS cloud and makes frame–forwarding decisions based on labels applied to frames
provider (P) routera service provider internal router that doesn't directly interface with the customer routers