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Describe how the Cisco Enterprise Composite Model (ECNM) provides integrated services over an Enterprise network.
Describe the key WAN technology concepts.
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WAN
A WAN is a data communications network that operates beyond the geographic scope of a LAN.
WAN allows the transmission of data across greater geographic distances
WANs use facilities provided by a service provider, or carrier.
WANs use serial connections.
LAN connects computers, peripherals, and other devices in a single building or other small geographic area
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Describe How ECNM Provides Integrated Services over an Enterprise Network
Explain the purpose of Cisco Enterprise Architectures
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WAN functions in terms of the OSI Reference Model
The physical layer (OSI Layer 1) protocols describe how to provide electrical, mechanical, operational, and functional connections to the services of a communications service provider.
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ATM – asynchronous transfer mode
HDLC – high level data link control – used instead of clock in RT to RT comm before
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Graphic 1.2.2.1
If space permits add graphics 1.2.2.2 & 1.2.2.3 (if forced to make a choice between the 2 graphic pick 1.2.2.2)
PSTN devices – multiplexer (time division and frequency division multiplexing) used in switches
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WAN physical-layer protocols describe how to provide electrical, mechanical, operational, and functional connections for WAN services.
The WAN physical layer also describes the interface between the DTE and the DCE.
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Key WAN Technology Concepts
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Switching technologies used for WANs in an Enterprise setting
A circuit-switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate.
PSTN and ISDN are two types of circuit-switching technology that may be used to implement a WAN in an enterprise setting.
Packet switching splits traffic data into packets that are routed over a shared network. Packet-switching networks do not require a circuit to be established, and they allow many pairs of nodes to communicate over the same channel. Packets are divided and sent through available connections.
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Packet-switching for computers (SMS and email)
We can’t use packet-switching for telephone calls because it divides packets
We can use circuit-switching for transmitting packets
Alternative graphic can be found at the following URL (not necessary to use – just a thought): http://www.cisco.com/image/jpg/en/us/guest/products/ps6438/c1244/cdccont_0900aecd802c2010_0900aecd802c2010-08.jpg
graphic 1.2.4.2
Delays (latency) and variability of delay (jitter) are greater in packet-switched than in circuit-switched networks. This is because the links are shared, and packets must be entirely received at one switch before moving to the next.
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Enterprises use leased line services to provide a WAN connection
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Leased line uses dedicated line
Telephone lines use analog communication
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The objective stated above does not make sense to me. Reword the above objective as follows: List factors to consider when selecting a WAN connection
Graphic 1.3.5.4
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A WAN is defined as
A data communications network that operates beyond the geographic scope of a LAN
WAN primarily operate on layer 1 & 2 of the OSI model
WAN technologies include
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Cisco Enterprise Architecture
This is an expansion of the hierarchical model that further divides the enterprise network into
Physical areas
Logical areas
Functional areas
Selecting the appropriate WAN technology requires considering some of the following:
WAN’s purpose
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