Network+

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OC-3

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155.52Mbps

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OC-12

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622.08Mbps

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SONET

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Synchronous Optical Network.

A fiber - optic WAN tech. That delivers voice, data and video at speeds starting at 51.84 Mbps

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ISDN

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Integrated Services Digital Network

Enables transmission of voice and data over the same physical connection

Faster than regular modem connections

Two defined interface standards: BRI and PRI

Integrated Services for Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book.[1] Prior to ISDN, the telephone system was viewed as a way to transport voice, with some special services available for data. The key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system. The ISDN standards define several kinds of access interfaces, such as Basic Rate Interface (BRI), Primary Rate Interface (PRI), Narrowband ISDN (N-ISDN), and Broadband ISDN (B-ISDN).ISDN is a circuit-switched telephone network system, which also provides access to packet switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in potentially better voice quality than an analog phone can provide. It offers circuit-switched connections (for either voice or data), and packet-switched connections (for data), in increments of 64 kilobit/s. In some countries, ISDN found major market application for Internet access, in which ISDN typically provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions. Channel bonding can achieve a greater data rate; typically the ISDN B-channels of three or four BRIs (six to eight 64 kbit/s channels) are bonded.ISDN is employed as the network, data-link and physical layers in the context of the OSI model, or could be considered a suite of digital services existing on layers 1, 2, and 3 of the OSI model. In common use, ISDN is often limited to usage to Q.931 and related protocols, which are a set of signaling protocols establishing and breaking circuit-switched connections, and for advanced calling features for the user. They were introduced in 1986.[2]In a videoconference, ISDN provides simultaneous voice, video, and text transmission between individual desktop videoconferencing systems and group (room) videoconferencing systems.

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BRI

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128Kbps speed

2 B channels and 8 D channels (4 to each B)

Transmission carrier: ISDN

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PRI

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Primary rate interface

1.544Mbps speed

23 B channels

1 D channel

T1 transmission carrier

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Coaxial cables

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Constructed to add resistance to attenuation (loss of signal strength as signal travels over distance), crosstalk, and EMI.

Thin coax=thin net or 10 BASE 2

Thick coax=thick net

Thin coax categories:

RG-59: Used to generate low-power video connections. Cannot be used over long distances because of its high frequency power loses

RG-6" Often used for cable TV and cable modems.

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Fiber - optic Cable

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Video, data, voice

Most secure

Light transmission

Fiber is incompatible with most electronic nwtwork equipment

Two types of fiber - optic cable:

>Multimode fiber: Many beams of light travel through the cable, bouncing off the cable walls. This strategy actually weakens the signal, reducing the length and speed at which the data signal can travel.

>Single-mode fiber: Uses a single direct beam of light, thus allowing for greater distances and increased speeds.

Common types:

◇62.5-micron core/125-micron cladding Multimode

◇50-micron core/125-micron cladding Multimode

◇8.3-micron core/125-micron cladding single mode

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Frame relay

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Frame relay is a packet-switching telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between endpoints in wide area networks (WANs). The service, once widely available and implemented, is in the process of being discontinued by major Internet service providers. Sprint ended its frame relay service in 2007, while Verizon said it plans to phase out the service in 2015. AT&T stopped offering frame relay in 2012 but said it would support existing customers until 2016.

Frame relay puts data in a variable-size unit called a frame and leaves any necessary error correction (retransmission of data) up to the endpoints, which speeds up overall data transmission. For most services, the network provides a permanent virtual circuit (PVC), which means that the customer sees a continuous, dedicated connection without having to pay for a full-time leased line, while the service provider figures out the route each frame travels to its destination and can charge based on usage. Switched virtual circuits (SVC), by contrast, are temporary connections that are destroyed after a specific data transfer is completed.An enterprise can select a level of service quality, prioritizing some frames and making others less important. A number of service providers, including AT&T, offer frame relay, and it's available on fractional T-1 or full T-carrier system carriers. Frame relay complements and provides a mid-range service between ISDN, which offers bandwidth at 128 Kbps, and Asynchronous Transfer Mode (ATM), which operates in somewhat similar fashion to frame relay but at speeds of 155.520 Mbps or 622.080 Mbps.

DevicesIn order for a frame relay WAN to transmit data, data terminal equipment (DTE) and data circuit-terminating equipment (DCE) are required. DTEs are typically located on the customer's premises and can encompass terminals, routers, bridges and personal computers. DCEs are managed by the carriers and provide switching and associated services.Frame relay is based on the older X.25 packet-switching technology that was designed for transmitting analog data such as voice conversations. Unlike X.25, which was designed for analog signals, frame relay is a fast packet technology, which means that the protocol does not attempt to correct errors. When an error is detected in a frame, it is simply dropped (that is, thrown away). The end points are responsible for detecting and retransmitting dropped frames (though the incidence of error in digital networks is extraordinarily small relative to analog networks).Frame relay is often used to connect LANs with major backbones as well as on public wide area networks and also in private network environments with leased T-1 lines. It requires a dedicated connection during the transmission period and is not ideal for voice or video, which require a steady flow of transmissions. Frame relay transmits packets at the data link layer of the Open Systems Interconnection (OSI) model rather than at the network layer. A frame can incorporate packets from different protocols such as Ethernet and X.25. It is variable in size and can be as large as a thousand bytes or more.

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802.11 Wireless Standards

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FHSS

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Frequency - hopping Spread - spectrum Technology

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DSSS

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Direct-Sequence Spread - spectrum Technology

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OFDM

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Orthogonal Frequency Division Multiplexing

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SSID

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Service set identifier

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BSS

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Basic service set

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ESS

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Extended service set

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ESSID

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Extended service set identifier

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BSSID

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Basic service set identifier

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BSA

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Basic service area

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Spread Spectrum and Standards

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MIMO

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IEEE 802.11n. Transmits 2.4GHz and 5GHz at the same time, the streams are directed to a single address (MIMO).

MIMO (multiple input, multiple output)

MIMO uses multiplexing to increase the range and speed of wireless networking. Combines multiple signals for transmission of multiple data streams traveling on different antennas in the same channel at the same time.

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MUMIMO

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802.11ac

Allows for Multiuser MIMO (Mumimo) to let an AP send multiple frames to multiple clients at the exact same time (thus allowing the AP to act like a switch instead of just a hub).

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What standard is used for port authentication?

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802.1x

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Your organization has contracted with a cloud-based company to provide access to an application via the cloud. However, application performance is extremely slow. Which of the following tools would you use to identify outages?

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(A)Protocol analyzer(B)Sniffer(C)Environmental monitor(D)Network analyzer

D is correct.

A network analyzer can measure the performance of a network including identifying outages and top talkers (users generating the most traffic) and protocols using the most bandwidth.A and B are incorrect. A protocol analyzer (also called a sniffer) can capture and analyze traffic, but isn't as well suited for identifying outages as a protocol analyzer is for measuring the application performance.C is incorrect. An environmental monitor records environmental conditions such as temperature and humidity. It does not measure network application performance.Objective: 2.1 Given a scenario, use appropriate monitoring tools.

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NAT

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http://www.openbsd.org/faq/pf/nat.html

Network Address Translation (NAT) is a way to map an entire network (or networks) to a single IP address. NAT is necessary when the number of IP addresses assigned to you by your Internet Service Provider is less than the total number of computers that you wish to provide Internet access for. NAT is described in RFC 1631, "The IP Network Address Translator (NAT)."NAT allows you to take advantage of the reserved address blocks described in RFC 1918, "Address Allocation for Private Internets." Typically, your internal network will be setup to use one or more of these network blocks. They are: 10.0.0.0/8 (10.0.0.0 - 10.255.255.255) 172.16.0.0/12 (172.16.0.0 - 172.31.255.255) 192.168.0.0/16 (192.168.0.0 - 192.168.255.255)An OpenBSD system doing NAT will have at least two network interfaces, one to the Internet, the other to your internal network. NAT will be translating requests from the internal network so they appear to all be coming from your OpenBSD NAT system.How NAT WorksWhen a client on the internal network contacts a machine on the Internet, it sends out IP packets destined for that machine. These packets contain all the addressing information necessary to get them to their destination. NAT is concerned with these pieces of information:Source IP address (for example, 192.168.1.35)Source TCP or UDP port (for example, 2132)When the packets pass through the NAT gateway they will be modified so that they appear to be coming from the NAT gateway itself. The NAT gateway will record the changes it makes in its state table so that it can a) reverse the changes on return packets and b) ensure that return packets are passed through the firewall and are not blocked. For example, the following changes might be made:Source IP: replaced with the external address of the gateway (for example, 198.51.100.1)Source port: replaced with a randomly chosen, unused port on the gateway (for example, 53136)Neither the internal machine nor the Internet host is aware of these translation steps. To the internal machine, the NAT system is simply an Internet gateway. To the Internet host, the packets appear to come directly from the NAT system; it is completely unaware that the internal workstation even exists.When the Internet host replies to the internal machine's packets, they will be addressed to the NAT gateway's external IP (198.51.100.1) at the translation port (53136). The NAT gateway will then search the state table to determine if the reply packets match an already established connection. A unique match will be found based on the IP/port combination which tells PF the packets belong to a connection initiated by the internal machine 192.168.1.35. PF will then make the opposite changes it made to the outgoing packets and forward the reply packets on to the internal machine.Translation of ICMP packets happens in a similar fashion but without the source port modification.IP ForwardingSince NAT is almost always used on routers and network gateways, it will probably be necessary to enable IP forwarding so that packets can travel between network interfaces on the OpenBSD machine. IP forwarding is enabled using the sysctl(3) mechanism:# sysctl net.inet.ip.forwarding=1# echo 'net.inet.ip.forwarding=1' >> /etc/sysctl.confOr, for IPv6:# sysctl net.inet6.ip6.forwarding=1# echo 'net.inet6.ip6.forwarding=1' >> /etc/sysctl.confConfiguring NAT

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169.254.34.67

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APIPA

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Tunneling

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technology that enables one network to send its data via another network's connections. Tunneling works by encapsulating a network protocol within packets carried by the second network. For example, Microsoft's PPTP technology enables organizations to use the Internet to transmit data across a VPN. It does this by embedding its own network protocol within the TCP/IP packets carried by the Internet.Tunneling is also called encapsulation.

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Split horizon and Convergence

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All routers in your network have learned the same routing information. What is the best name for this state?(A)Split-horizon(B)ConvergenceCorrectB is correct. Convergence is the state of routers when they have learned the same routing information. At convergence, they have learned all there is to learn within the network using a routing protocolA is incorrect. Split horizon route advertisements is a method used to prevent routing loops with Routing Information Protocol version 2 (RIPv2). It prevents the router from advertising a route on the same interface where the router learned the route.