Intro to Networking Chapter 9: Wide Area Networking
DSL (digital subscriber line
A WAN connection technology that operates over the PSTN (public switched telephone network) and can support multiple data and voice channels over a single line.
DIA (dedicated Internet access)
A WAN service where the network media or a portion of its available bandwidth is dedicated to a single customer and comes with an SLA-defined guarantee of minimum uptime percentages and maximum recovery times if the service goes down.
Broadband
A WAN technology where the network media and available bandwidth are shared between multiple customers.
default route
A backup route, usually to another router, used when a router cannot determine a path to a message's destination.
CDMA (Code Division Multiple Access)
A cellular standard that uses spread-spectrum technology, in which a signal is spread over a wide bandwidth so that multiple users can occupy the same channel.
asymmetrical
A characteristic of transmission technology that offers faster download speeds than upload speeds.
symmetrical
A characteristic of transmission technology that offers the same download speeds as upload speeds.
routing table
A database stored in a router's memory that maintains information about the location of hosts and networks and the best paths for forwarding packets between them.
MONs (metropolitan optical networks)
A dense, localized grid of junctions and fiber cables designed to make direct fiber connections available to as many customers as possible.
DSL modem
A device that modulates a DSL signal between the ISP's telephone line and the customer's Ethernet network.
cable modem
A device that modulates and demodulates signals for transmission and reception via cable wiring.
Giants
A frame that is too large and is dropped.
AS (autonomous system)
A group of networks, often on the same domain, that are operated by the same organization.
private-direct connection
A leased line from a customer's location or from their ISP to a PoP (point of presence), or colocation, which provides connection with other providers (such as cloud providers). Also called an interconnection.
IS-IS (Intermediate System to Intermediate System)
A link-state routing protocol that uses a best-path algorithm. IS-IS was originally codified by ISO, which referred to routers as "intermediate systems," thus the protocol's name.
long-haul connection
A long-distance connection, such as across hundreds of miles, that supports the Internet backbone.
Runts
A message that is so small it is dropped.
TDMA (time division multiple access)
A method of multiplexing in which signals from several sources on a channel are separated by timeslots.
SIM (Subscriber Identity Module) card
A microchip installed in a cellular device to hold data about the subscription a user has with the cellular carrier.
modem
A modulation/demodulation device that converts between digital and analog signals.
FTTC (fiber-to-the-curb)
A nearby pole or equipment cabinet that serves a few customers
FTTN (fiber-to-the-node or fiber-to-the-neighborhood)
A nearby service junction that serves a few hundred customers
AD (administrative distance)
A number indicating a protocol's reliability, with lower values being given higher priority. This assignment can be changed by a network administrator.
HFC (hybrid fiber coaxial)
A physical infrastructure where fiber-optic cabling connects the cable company's distribution center to distribution hubs and then to optical nodes near customers; either fiber-optic or coaxial cable then connects a node to each customer's business or residence.
Active-active redundancy
A redundancy strategy in which all redundant resources are kept active at all times and work is distributed among them. If one resource fails, the other active resources continue handling the workload.
Active-passive redundancy
A redundancy strategy in which only one or a few redundant resources are kept active at all times, with backup devices on standby ready to fill in if they're needed.
Dynamic routes
A route automatically calculated by the router to determine the best path between two networks. As dynamic routes are identified and calculated, this information is collected in a routing table.
Static routes
A route manually configured by a network administrator to direct messages along specific paths between networks.
passes packets from one network to another
A router joins two or more networks and
Edge routers (the router that connects a business with its ISP is an edge router.)
A router that connects an autonomous system with an outside network—for example, the router that connects a business to its ISP. Also called a border router.
Exterior router
A router that directs data between autonomous systems, for example, routers used on the Internet's backbone.
Core routers (Cengage might have several LANs that all fall under its domain with each LAN connected to the others by core routers)
A router that directs data between networks within the same autonomous system. Also called an interior router.
intelligence—that is, its ability to interact with transmissions and make decisions
A router's strength lies in its
each routing protocol requires of routers and how much information must be transferred between routers and how often.
A routing protocol is rated on its overhead, or the burden placed on the underlying network to support the protocol. The difference here is related to how much
Hybrid routing protocols
A routing protocol that exhibits characteristics of both distance-vector and link-state routing protocols.
routing protocols
A set of standards that determines how routers communicate with each other about network status and connections. Routing protocols determine the best path for data to take between networks
LTE (Long-Term Evolution)
A transitional cellular network technology between 3G and 4G that takes advantage of some improved 4G technologies to exceed 3G speeds but does not reach 4G throughput requirements.
Link-state routing protocols
A type of routing protocol that enables routers to share performance and status information about their connected links with routers throughout the network, after which each router can independently map the network and determine the best path between itself and a message's destination node.
EGPs (exterior gateway protocols)
A type of routing protocol used by edge routers and exterior routers to distribute data outside of autonomous systems.
IGPs (interior gateway protocols)
A type of routing protocol, such as OSPF and IS-IS, used by core routers and edge routers within autonomous systems.
MPLS (multiprotocol label switching)
A type of switching that enables multiple types of layer 3 protocols to travel over any one of several connection-oriented layer 2 protocols.
internal processor, an operating system, memory, input and output jacks for different types of network connectors (depending on the network type), and, usually, a management console interface.
A typical router consists of an
Routing cost
A value assigned to a particular route as judged by the network administrator—the more desirable the path, the lower its cost.
a maximum theoretical throughput of 24 Mbps downstream and a maximum of 3.3 Mbps upstream (depending on how close it is to its source).
ADSL2+ upstream and downstream maximum
SD-WAN (software-defined wide area network)
Abstracted, centralized control of networking devices that manage network functions across a diverse infrastructure.
performance during normal operation, as all your available resources are actively working. the load distributed evenly among all resources, or you might have one or more redundant resources running a reduced load.
Active-active redundancy arrangement can provide increased
GLBP (Gateway Load Balancing Protocol)
Also proprietary to Cisco devices. GLBP gateways are weighted according to priority, and traffic is load balanced among all gateways.
cell site
Although their access methods and features might differ, all cellular networks share a similar infrastructure in which coverage areas are divided into cells. Each cell is served by an antenna array and its base station, together called a
OSPF (Open Shortest Path First)
An IGP (interior gateway protocol) and link-state routing protocol that improves on some of the limitations of RIP (Routing Information Protocol) and can coexist with RIP on a network.
EIGRP (Enhanced Interior Gateway Routing Protocol)
An advanced distance-vector protocol developed by Cisco that combines some of the features of a link-state protocol and so is sometimes referred to as a hybrid protocol.
CRC error
An error statistic that indicates messages are being damaged in transit.
smartjack
An intelligent type of NIU (network interface unit) located at the customer's demarc that can provide diagnostic information about the interface.
DOCSIS (Data Over Cable Service Interface Specifications)
An international, cooperative effort orchestrated by Cable-Labs that standardized cable broadband service.
obsolete. However, the generic term exterior gateway protocol now refers to any routing protocol that routes information between autonomous systems.
An older routing protocol named Exterior Gateway Protocol is
GSM (Global System for Mobile Communications)
An open standard for cellular networks that uses digital communication of data separated by time slots on a channel.
RIPv2 (Routing Information Protocol, version 2)
An updated version of the original RIP routing protocol that generates less broadcast traffic and functions more securely than its predecessor. However
signals and providing coverage over three equidistant lobes. When a client passes from one coverage area to another, the mobile device begins communicating with a different antenna
Antennas are positioned at three corners of each cell, radiating their
SD-WAN (software-defined wide area network)
As you discuss the pending expenditure in these other countries with your IT team, you realize the need for centralized management of company network resources. MPLS connections all the way to Asia won't suffice to meet your company's needs over the coming years. Instead, your team suggests a newer solution called
private-direct connection
At first, the VPNs work well enough. Later in the year, as the cloud migration nears completion, it becomes obvious that a VPN will not be sufficient for the home office. Instead, your cloud provider recommends a
hexagons
At the base station, a controller assigns frequencies to mobile clients and manages communication with them. In network diagrams, cells are depicted as
With a fast convergence time and low network overhead, it's easier to configure and less CPU-intensive than OSPF. EIGRP also offers the benefits of supporting multiple protocols and limiting unnecessary network traffic between routers.
Benefits of EIGRP (Enhanced Interior Gateway Routing Protocol)
Cable broadband
Broadband Internet access provided over the coaxial cable wiring used for TV signals.
trusted edge router for some organization's AS, even if that organization is a large telecommunications company managing a portion of the Internet backbone.
But keep in mind that every router communicating over the Internet is a
LTE (Long Term Evolution) features
CDMA networks (such as Verizon's) still require SIM cards to use their
devices are compared against a whitelist, which is a database of subscribers that contains information on their subscriptions with the provider
CDMA networks do not require a SIM card in a cellular device because
70 Mbps download and 7 Mbps upload
Cable broadband service is typically offered at asymmetric speeds, such as up to
1000 feet to 12 miles in diameter
Cell sizes vary from roughly
1. each base station is connected to an MSC (mobile switching center), also called an MTSO (mobile telecommunications switching office), by a wireless link or fiber-optic cabling 2. At the MSC, the mobile network intersects with the wider wired network. Equipment at an MSC manages mobile clients, monitoring their location and usage patterns, and switches cellular calls. it assigns each mobile client an IP address 3. From the switching center, packets sent from cellular networks are routed to wired data networks through backbones using WAN technologies.
Cellular system Process
line-of-sight path from an unobstructed view of the sky.
Clients can exchange signals with satellites as long as they have a
limited distances without the help of repeaters. Also, the distance between the customer and the central office affects the actual throughput a customer experiences. (The farther away the customer's premises, the lower the throughput.)
DSL can support multiple data and voice channels over a single line, but it can span only
amplitude or phase modulation to alter the waves at higher frequencies to carry data.
DSL uses data modulation techniques at the physical layer of the OSI model to achieve extraordinary data throughput over regular telephone lines. Recall that modulation techniques can allow a single channel to carry more data per cycle of a signal. Depending on its version, a DSL connection might use a modulation technique based on
leased lines
Dedicated Internet bandwidth provided over fiber-optic connections.
services from the 1970s and 1980s were analog
Describe 1G (first generation) services
1990s paved the way for texting and media downloads on mobile devices transmission on 2G systems didn't exceed 240 Kbps
Describe 2G (second generation) services
early 2000s rates rose to 384 Kbps Two market leaders: GSM and CDMA GSM: uses digital communication of data separated by time slots on a channel USES TDMA (time division multiple access) where signals from several sources on a channel are separated by timeslots. CDMA: uses spread-spectrum technology, in which a signal is spread over a wide bandwidth so that multiple users can occupy the same channel.
Describe 3G Services
Description: A routing challenge caused when messages going in one direction in a conversation travel a different path than messages going in the other direction. This is typically unavoidable (especially when using BGP on the Internet) and is not a problem. However, it can cause issues for NAT (network address translation) and for firewalls that need to see traffic in both directions of a conversation to properly apply filtering rules. TroubleShoot: If some incoming traffic hits a different firewall than the one a server is configured to use for its outgoing messages, the firewall might incorrectly reject outgoing traffic that should have been approved. For organizations using multiple firewalls, thoughtful configuration of traffic flow and internal routing can be used to avoid problems with asymmetrical routing.
Describe and Troubleshoot Asymmetrical routing
Description: If no matching route exists for a message, the message will be dropped. when existing routes are not being advertised through routing protocols. TroubleShoot: a gateway of last resort should be configured to handle messages with no matching route. Add by using the command: ip default-gateway and ip default-network. Ip default-gateway (used when no routing is configured on the router), ip default-network (requires that routing is configured on the router and chooses a classful default route from existing routes), or ip route 0.0.0.0 0.0.0.0 (sets a default route for messages with no matching route in the routing table and requires that routing is configured on the router).
Describe and Troubleshoot Missing route
Description: A failure of a routing protocol that results in messages being transmitted continuously in a loop along the same paths and never reaching their destinations; commonly caused by making too many topology changes too quickly. TroubleShoot: A conservative TTL (time-to-live) can ensure these stray packets are dropped after so many hops. Limiitations on outers' ability to share their routing tables with neighbors so this sharing moves outward from each router without old information looping back on itself—this is called a split horizon routing timer ensures that all the routers in the system share their routing tables at the same time.
Describe and Troubleshoot Routing loop
BANDS- Verizon are focusing instead on higher-density but less widely available infrastructure that uses new and smaller millimeter-wave frequencies in a newly available higher band. These dense but weaker frequencies provide high speeds for short distances while offering much lower resilience across long distances or when crossing obstacles such as walls and landscaping. But that speed could plummet to closer to 4G speeds at 200-300 Mbps if you walk around the corner of a nearby building or stand behind a tree. CELL DENSITY- many small 5G antennas must be installed in close proximity to each other to get stronger signals CHANNELS- 5G works to increase speeds by using wider channels. EX: G can use up to eight 100-MHz channels in the high band, which ranges from 20 to 100 GHz. CLIENT VOLUME- must be placed closer together so millimeter-wave frequencies can reach clients, each cell site can support more clients.
Describe the factors that affect 5G Speeds.
QoS (quality of service) refers to a group of techniques for adjusting the priority assigned to various types of traffic. saves time and reduces latency by allowing you to set routes for traffic between sites so the ISP's routers don't have to stop and think with each packet where that packet should go next.
Despite the various service levels of each location's connection to the ISP, you can manage segmentation and QoS for different types of traffic across your entire network, even if your locations are spread hundreds or thousands of miles apart. These advantages are explained next:
multiplexed TDM signals all come from the same source (such as a router), while multiplexed TDMA signals come from several sources (such as several smartphones in the same vicinity).
Digital communication of data is separated by timeslots on a channel using TDMA (time division multiple access), which is similar to TDM (time division multiplexing). The primary difference is that
ecurity when traffic traverses the Internet, costs for underlying WAN connections (such as MPLS), and flexibility for cloud and mobile users.
Disadvantages of SD-WAN
, satellite services are typically asymmetrical, and bandwidth is shared among many subscribers Throughputs vary and are controlled by the service provider. Downlink speeds might reach 100 Mbps, while uplink rates are much slower Compared with other wireless WAN options, satellite services are slower and suffer more latency the inconsistent latency causes jitter problems, degrading signal quality
Disadvantages of satellite
entire routing tables with neighboring routers even if there's not been a change to a route, which requires the transfer of large amounts of data simply to keep routing tables updated
Distance-vector routing protocols periodically exchange their
BGP (Border Gateway Protocol)
Dubbed the "protocol of the Internet," this path-vector routing protocol is the only current EGP (exterior gateway protocol) and is capable of considering many factors in its routing metrics.
ntersects with the wider wired network
Each base station is connected to an MSC (mobile switching center), also called an MTSO (mobile telecommunications switching office), where the mobile network i
indicate the packet's next hop
Each router in the data stream's path revises the label to
network congestion, QoS indicators assigned to the messages, plus other criteria
Each router in the data stream's path revises the label to indicate the packet's next hop In this manner, routers on a network can take into consideration
changed by a network administrator when one protocol should take precedence over a previously higher-rated protocol on that network.
Each routing protocol is assigned a default AD, which is a number indicating the protocol's reliability, with lower values being given higher priority. This assignment can be
SDSL (symmetric DSL)
Equal download and upload speeds maxing out around 2 Mbps. Symmetrical transmission is suited to users who both upload and download significant amounts of data
if it is located on the customer's side of the demarc (demarcation point)
Equipment belonging to the ISP, despite its location on the customer's premises, should only be serviced by the ISP's technicians even
CPE (customer premises equipment)
Equipment located on the customer's premises, regardless of who owns it and who is responsible for it, is called
NIU (network interface unit)- Connects the ISP's local loop to the customer's network. The ISP is responsible for all wiring leading up to the NIU and for the NIU itself. The customer is responsible for everything past the NIU unless the equipment is owned by the ISP, such as with a line driver, CSU/DSU, or set-top box. Line driver— a repeater, a line driver can be installed either on copper lines (in which case, it is called a copper line driver) or fiber lines (in which case, it is called a fiber line driver) to boost the signal across greater distances CSU/DSU (channel service unit/data service unit)—This device serves as the endpoint for a dedicated connection between an ISP and a customer. Can be owned by either party, depending upon who is responsible for providing this device according to the terms of service. typically placed on the customer's side of the demarc between the demarc and the first ro
Equipment owned by the customer is the responsibility of the customer and will not be serviced by the ISP. The following list describes devices commonly found at or near the demarc: NIU LINE DRIVER CSU/DSU (channel service unit/data service unit)
a SmartJack acts as a multifunctional device in telecommunications, serving as a demarcation point, facilitating signal splitting, offering diagnostic capabilities, enabling remote monitoring, aiding in fault isolation, and enhancing network security. Its implementation is crucial in ensuring the efficient operation of telecommunications networks and maintaining clear lines of responsibility between service providers and customers.
Explain the purpose of a smartjack.
HSRP (Hot Standby Routing Protocol)
FHRP (First Hop Redundancy Protocol) Proprietary to Cisco.
ADSL (asymmetric DSL)
Faster download speeds than upload speeds and is the most common form of DSL. Asymmetrical communication is well suited to users who receive more information from the network than they send to it
VDSL (very high bit rate DSL or variable DSL)
Faster than ADSL and is also asymmetric,
5G (fifth generation)
Fifth-generation mobile phone standard requiring minimal throughput of 1 Gbps and maxing out at 20 Gbps download and 10 Gbps upload. Actual speeds vary greatly depending on the bands, cell density, channels, and client volume.
one of the most valued and sophisticated functions performed by a route
Finding the best route or best path for messages to take across networks is
separate the data signal from the voice signal before it reaches the terminal equipment (for example, the phone or the computer)
For ADSL, a splitter must be installed at the carrier and at the customer's premises to
uptime, service, and bandwidth are still not guaranteed.
For a higher premium, businesses can get faster broadband speeds and possibly one or more static IP addresses included in the package. However,
show ip interface brief (or sh ip int br)
For a more concise list of interfaces, IP addresses, and interface status, enter the command
4G (fourth generation)
Fourth-generation mobile phone service that is characterized by an all-IP network for both data and voice transmission and throughput of 100 Mbps up to 1 Gbps.
glbp command
GLBP (Gateway Load Balancing Protocol) Configurations are made using the
Router A examines all rows in its routing table. In each row, it uses information in the first two columns—the destination network's IP address and netmask—to calculate the range of IP addresses included in that network. If the message's destination IP address fits in the calculated range for a route, the router then reads the IP address of the gateway in the third column If it finds more than one possible route, the router uses routing metrics that two routes can reach the network printer on LAN D. Of these two routes, the router would select the one with the lower metrics value. In this scenario, router A finds two matches with LAN D's network information and chooses the best of these two options based on their respective routing metrics. Router A then determines that it should send the message out the port that faces router C.
Here's a breakdown of how the route-search process uses information for Printer A to LAN D.
1. Information must first be transmitted to the satellite from Earth in an uplink from an Earth-based transmitter. info is scrambled to avoid interception. 2. At the satellite, a transponder receives the uplink signal, then transmits it to an Earth-based receiver in a downlink. Each satellite uses unique frequencies for its downlink 3. Back on Earth, the downlink is picked up by a dish-shaped antenna. The dish shape concentrates the signal so that it can be interpreted by a receiver.
How satellite communication works
IPv4 like OSPF is, so it's easy to adapt to IPv6
IS-IS is not handcuffed to
detect the problems and reroute messages through a different path.
If congestion or failures affect the network, a router using dynamic routing can
shut down using the shutdown command or has encountered a configured limitation, such as a security breach. Bring it back up using the no shutdown (or no shut) command.
If the interface is "administratively down," it has been
BGP in depth.
If you maintain networks for an ISP or large telecommunications company, you will need to understand
Duplex and speed
Indicates if the link is operating in full-duplex mode, the link's bandwidth (such as 100 Mbps), and the physical connection type (such as RJ-45).
BW (bandwidth)
Indicates the link's supported bandwidth, which is used by routing protocols to calculate best paths
MTU
Indicates the maximum network-layer packet size the interface can support. The Ethernet standard MTU is 1500 bytes.
Link state
Indicates whether the interface is up or down
VRRP (Virtual Router Redundancy Protocol)
Industry standard across vendors for First Hop Redundancy Protocol)
scrambled (in other words, its signal is encoded) before transmission to prevent unauthorized interception
Information must first be transmitted to the satellite from Earth in an uplink from an Earth-based transmitter. Often, the uplink signal information is
show interface (or sh int)
Interface configuration, status, and statistics can all provide helpful information in troubleshooting a network connection problem. To get an overview of all the device's interfaces, enter the command
Send and receive traffic statistics
Interface statistics are tracked over time and can be cleared. Information here will indicate when the statistics were most recently reset. The next several lines indicate statistics that have been gathered since the most recent reset and include number of packets dropped due to queue overflow, average input and output rates, total number of packets and bytes received or sent by the system, and number of broadcast frames, runts, and giants received.
available bandwidth on an entire network
It's also possible to use a device that combines cable modem functionality with a SOHO router to share
geographically separate hardware and network media
Larger networks should also have multiple ISP connections with each using
dialing up a service provider to create the connection
Like DSL, cable broadband provides a dedicated and always-up, or continuous, connection that does not require
complex to configure and troubleshoot more processing power to incorporate information from throughout the network to build each device's routing table
Link-state routing protocols tend to adapt more quickly to changes in the network, but they can also be more
connectivity option for each site that makes sense while centrally managing bandwidth between each site.
MPLS allows you to use any
the less throughput available to each individual user. Cable companies counter this perceived disadvantage by rightly claiming that at some point (for example, at a remote switching facility), a telephone company's DSL bandwidth is also fixed and shared among a group of customers.
Moreover, the throughput of a cable line is fixed. As with any fixed resource, the more one person uses, the less that is left for others. In other words, the greater the number of users sharing a single line,
setting these paths. Consequently, MPLS offers potentially faster transmission than traditionally routed networks.
Network engineers maintain significant control in
customer's demarcation point where wires terminate at the NIU.
No matter what kind of media is used, the end of the local loop—and the end of the carrier's responsibility for the network—is the
Supports large network with no hop limits Calculates more efficient best paths than RIP Maintains a database of the other routers' links. If OSPF learns of the failure of a given link, the router can rapidly compute an alternate path. Demands more memory and CPU power for calculations, but keeps network bandwidth to a minimum with a very fast convergence time, often invisible to users. Uses algorithms that prevent routing loops. Supported by all modern routers. It is commonly used on autonomous systems that rely on a mix of routers from different manufacturers.
OSPF (Open Shortest Path First) is an IGP and a link-state routing protocol used on core or edge routers. It was introduced as an improvement to RIP and can coexist with RIP or RIPv2 on a network. Characteristics include the following:
Computer controlled, and nearly all the PSTN uses digital transmission and fiber for backbone connections
Originally, the PSTN carried only analog traffic. All its lines were copper wires, and switching was handled by operators who manually connected calls upon request. Today, switching is
VRRP (Virtual Router Redundancy Protocol)—Industry standard across vendors. The VIP points to the primary, active router, and all other routers stand by as potential backups. Configurations are made using the vrrp command. HSRP (Hot Standby Routing Protocol)—Proprietary to Cisco. The VIP points to the active router, a standby router is configured for auto failover, and other routers listen for indications the active and standby routers have both failed. Configurations are made using the standby command. GLBP (Gateway Load Balancing Protocol)—Also proprietary to Cisco devices. GLBP gateways are weighted according to priority, and traffic is load balanced among all gateways. Configurations are made using the glbp command.
Popular FHRPs include
routing metrics
Properties of a route used by routing protocols to determine the best path to a destination when various paths are available. may be calculated using any of several variables, including hop count, bandwidth, delay, MTU, cost, and reliability.
Advantages: SIMPLE Prevents routing loops from continuing indefinitely by limiting the number of hops a message can take between its source and its destination to 15. Disadvantages: Only considers the number of hops between nodes when determining the best path rather than other, more complex factors Broadcasts routing tables every 30 seconds to other routers, regardless of whether the tables have changed Might take several minutes for new information to propagate Slower and less secure Does not work well in very large network environments- Too many router jumps
RIP (Routing Information Protocol) Advantage and disadvatages
15 hops
RIPv2's packet forwarding is still limited to a maximum
redundant hardware, connections, services, and copies of data. For example, if one router fails, another router can take over. You might even have a cluster of routers so your network could tolerate the failure of multiple devices without losing service.
Recall that fault tolerance on a network is accomplished through using
investments by ISPs into their access-level fiber infrastructure. Traditionally, fiber investment focused on long-haul connections across hundreds and thousands of miles
Rising market demand for last-mile fiber service is causing increased
location on a network or the Internet and the routing protocols they use.
Routers are often categorized according to their
few, unique entries, including the default gateway and loopback address. However, routing tables on Internet backbone routers, such as those operated by ISPs, maintain hundreds of thousands of entries.
Routing tables on workstations typically contain no more than a
Can manage configurations regardless of method (broadband, leased line, MPLS, cellular, and others) offers active-active load balancing where it can choose the best physical WAN connection for different types of traffic according to traffic prioritization and current network conditions automatic failover SD-WAN can be used to optimally manage all available WAN connections and minimize the need for more expensive WAN services. A network admin can indicate in the controller's GUI their intent for traffic, such as limiting bandwidth for a specific application The edge device can be set up by a non technical person, the device will find and check with the remote SD-Wan Controller, then a technician can finish deployment,
SD-WAN offers the following benefits:
extra pair of wires contained in a telephone cable (which are otherwise typically unused)
SDSL cannot use the same wire pair that is used for voice signals. Instead, this type of DSL uses th
relay information from one point on Earth to another
Satellites are generally used to
IS-IS in their own networks because it's more scalable than OSPF, but OSPF is still more common.
Service providers generally prefer to use
route latency and other network traffic characteristics
Some distance-vector routing protocols factor only the number of hops to the destination, whereas others consider
Path-vector routing protocol—Communicates via BGP-specific messages that travel between routers over TCP sessions. Efficient—Determines best paths based on many factors. Customizable—Can be configured to follow policies that might, for example, avoid a certain router, or instruct a group of routers to prefer one route over other available routes.
Some special characteristics of BGP:
combined in the same device
The DTE communicates on the LAN, and the DCE communicates on the WAN. Sometimes the DTE and DCE are
Overhead
The burden placed on the underlying network to support a routing protocol.
DTE (data terminal equipment)
The customer's endpoint device on a WAN is called the
Connecting a city's police stations Connecting a hospital with its regional medical centers Connecting a home office with its branch offices and a warehouse location
The following list gives examples where MANs can be useful
FTTB (fiber-to-the-building) or FTTH (fiber-to-the-home)
The junction box at the demarc to your building
ADSL2+, which extends the reach of DSL to within two kilometers of the provider's location
The latest version of ADSL is
LTE-A (LTE-Advanced)
The latest version of LTE, with theoretical downlink rates approaching true 4G speeds up to 1 Gbps and uplink rates as high as 100 Mbps, although actual speeds are significantly less. Sometimes misleadingly called 5G E (5G Evolution).
ROUTING PROTOCOL/ TYPE / ALGORITHM USED RIP (Routing Information Protocol)/ IGP/ Distance-vector RIPv2 (Routing Information Protocol, version 2)/ IGP/ Distance-vector OSPF (Open Shortest Path First)/ IGP/ Link-state IS-IS (Intermediate System to Intermediate System)/ IGP/ Link-state EIGRP (Enhanced Interior Gateway Routing Protocol)/ IGP/ Advanced distance-vector BGP (Border Gateway Protocol)/ EGP/ Advanced distance-vector or path vector
The most common routing protocols with type and algorithm used
best path
The most efficient route from one network to another, as calculated by a router.
PSTN (public switched telephone network)
The network of lines and carrier equipment that provides wired telephone service to most homes and businesses.
10 Gbps downstream and 6 Gbps upstream, thus rivaling some fiber-optic Internet service options once experienced speeds start to approach the standard's defined maximums.
The newest DOCSIS standard, 4.0, theoretically allows for symmetric multi-gigabit speeds up to
RIP (Routing Information Protocol)
The oldest routing protocol that is still widely used. A distance-vector protocol that uses hop count as its routing metric and only allows up to 15 hops.
local loop
The part of a phone system that connects a customer site with a telecommunications carrier's switching facility.
different technologies and protocols have been developed to best serve each of these markets
The reason to make these distinctions between WANs, MANs, CANs, and LANs is because
bandwidth is broken up for different purposes.
The reason upstream and downstream bandwidth are different on a DSL line is because of the way the
gateway of last resort
The router on a network that accepts all unroutable messages from other routers.
C (connected)—Networks directly connected to the router's own interfaces are classified as C (connected). S (static)—Static routes are manually configured by a network admin. Protocol—Codes identify the routing protocol used to configure the route, such as R (RIP), B (BGP), D (EIGRP), and O (OSPF). Gateway of last resort—This route identifies the path for messages when another route doesn't apply.
The routing table lists several types of routes and other information about the routes. Some of the most used route types and information are described next:
Distance-vector routing protocols
The simplest type of routing protocols; used to determine the best route for data based on the distance to a destination. calculate the best path to a destination based on the distance to that destination
show startup-config (or sh start)
The startup-config file is not stored in RAM but instead is stored in NVRAM, which persists through a power cycle. To see the device's stored startup-config file, enter the command
Convergence time
The time it takes for routers on a network to recognize and adjust to configuration changes or a network outage.
Third-party entity similar to how owners of office buildings or malls lease out portions of their property to other businesses. Cellular providers lease space on the towers for their antenna arrays
The tower—the tall part you can easily see from a distance—is often owned by a
where the router should forward the message next and, sometimes, prioritization information
These MPLS labels include information about
FCC
These frequencies, as well as the satellite's orbit location, are assigned and regulated by the
routing protocols
To determine the best path, routers communicate with each other through
fixed dish antenna The dish antenna's receiver is connected via cable to a modem. This modem typically uses an Ethernet interface to connect with the subscriber's router or computer.
To establish a satellite Internet connection, each subscriber must have a
copy running-config startup-config (or copy run start)
To make your changes persist beyond a device's power cycle, you must copy the running-config file to the startup-config file with the command
100 Mbps download and up to 75 Mbps upload
Typical speeds now for LTE connections might reach
High-throughput, long-distance digital data exchange.
Unlike wireless LANs, wireless WANs are designed for
businesses located close to a telephone company's CO (for example, in the middle of a metropolitan area), but it won't work for most individuals.
VDSL Limitations are suited for
100 Mbps in both directions but drops off quickly at even shorter distances.
VDSL2 offers throughput speeds nearing
the vrrp command
VRRP (Virtual Router Redundancy Protocol) Configurations are made with
Linux or UNIX—Enter route at a shell prompt. Windows—Enter route print in a CLI. Cisco's IOS—Enter show ip route at the CLI using privileged EXEC mode.
What Utility allows you to view a host's routing table
Typically: Connect dissimilar networks, such as a LAN and a WAN, which use different types of protocols. Interpret layer 3 and often layer 4 addressing Determine the best path for data to travel from point A to point B. Reroute traffic if the path of first choice is down but another path is available. Optionally: Filter broadcast transmissions to alleviate network congestion. Acting as a simple firewall, prevent certain types of traffic from getting to a network, enabling customized segregation and security. Support simultaneous local and remote connectivity. Provide high network fault tolerance through redundant components such as power supplies or network interfaces. Monitor network traffic and report statistics. Diagnose internal or other connectivity problems and trigger alarms.
What can all routers do both Optionally and typically
Most hosts have a default gateway—a router or layer 3 switch—where they send all routable messages. Hosts can't communicate with other networks without a default gateway. Most routers have a default route as a backup route when no other route can be determined. The default route points to a gateway of last resort. A router's gateway of last resort is where it sends messages addressed to networks the router can't find in its routing table.
What's the difference between a default gateway, a default route, and a gateway of last resort?
the new router's routing tables are updated.
When a router is added to a network, dynamic routing ensures that
Interference- Intermittent problems or problems that affect unrelated portions of a network are common indicators of interference issues. DNS issues- Correct DNS server information and a functioning DNS server are critical requirements for enabling Internet access. Router misconfiguration- Routing tables with incorrect routes can result in dropped messages with no error feedback. blocked ports that should be open, speed or duplex mismatches, incorrect IP address range or subnet mask, or an incorrect default gateway.. Interface error- Misconfigured interfaces, such as an incorrect default gateway or missing DNS server addresses, can result in interface errors. switch to a different interface on the same device to fix it. For example, if your computer's wired connection is having problems, try connecting to the network using the computer's wireless interface.
When you lose Internet connectivity, a little troubleshooting can help determine the location of the problem and the party responsible for repairing the connection. The following list presents some common issues to look for on your own equipment:
Running-config file
Where is a router's hostname stored when you first change the name?
4G
Which cellular generation was the first to offer speeds up to 1 Gbps
route print
Which command will output your Windows computer's routing table?
CRC error
Which problem is most likely caused by a damaged cable?
RIPv2 / RIP
Which routing protocol is limited to 15 hops?
BGP
Which routing protocol runs between your network's edge router and your ISP's edge router?
Cable broadband
Which wired WAN service offers speeds most comparable to the highest satellite Internet speeds in a similar price range?
MPLS connections are highly scalable for businesses Customers can prioritize their own traffic across the WAN according to QoS attributes, such as giving VoIP traffic higher priority over email traffic. The ability to label traffic offers more reliability, predictability, and security (when properly implemented) than when using cheaper connections over the open Internet.
While MPLS does offer decreased latency, this benefit is not quite as noticeable today as it was when MPLS first became available. The primary benefits of MPLS today include the following:
Dedicated bandwidth—The customer pays for a specific bandwidth (such as 2 Gbps) and reserves that bandwidth for their sole use without having to share it with other customers. Throughput won't fluctuate in response to traffic demands from other customers. Symmetrical bandwidth—Leased line speeds are typically symmetrical, meaning upload and download speeds will be the same. SLA-backed guarantee—Performance is backed by SLA-enforced uptime, repair time, and possibly backup options (such as having a broadband connection available during an outage).
While a leased line's dedicated bandwidth might be listed at a lower speed than the maximum theoretical speeds advertised for fiber broadband services, a dedicated line offers the following advantages:
use of the networking media connecting these LANs
With MANs, many customers might own one or more of the connected LANs, and a single, third-party provider leases
placement between layer 3 and layer 2 information. For this reason, MPLS is sometimes said to belong to "layer 2.5." Next, the network's layer 2 protocol header
With MPLS, the first ISP router (the provider's edge router, also called the MPLS ingress router) receives a message in a data stream and adds one or more labels to the layer 3 packet. These MPLS labels together are sometimes called a shim because of their
all the connected LANs and most or all the networking media connecting those LANs
With a CAN, it's likely that a single organization (or group of organizations) owns
LANs within a single property or nearby properties, such as buildings belonging to a school where all the buildings and most or all the network media spanning those connections are confined within land owned by the school.
a CAN is a collection of
within a limited geographical area, such as a downtown area or even a city, county, or province
a MAN is a collection of LANs
RIP and RIPv2
are distance-vector routing protocols.
show ip interface (or sh ip int)
command focuses on detailed layer 3 information, such as IP addressing, helper address, accounting, compression, NAT, and many other settings.
onfigurations are made using the standby command.
command to configure HSRP (Hot Standby Routing Protocol)
handoff
communication might change frequencies or even carriers between cells. The transition, which normally happens without the user's awareness, is known as a
Multiple cells sharing borders
forms a network in a honeycomb pattern
WAN connections
fully digital connections are increasingly common, especially for businesses that rely heavily on
routing technology to figure out how to place and configure a router to the best advantage.
high-powered, multiprotocol routers can be a challenge to install on sizable networks. Typically, an engineer must be very familiar with
LANs connect nodes, such as workstations, servers, printers, and other devices, in a small geographical area on a single organization's network, whereas WANs use networking devices, such as routers and modems, to connect networks spread over a wide geographical area. LANs and WANs may differ at layers 1 and 2 of the OSI model in access methods, topologies, and, sometimes, transmission media. For example, the way DSL transmits bits over a WAN differs from the way Ethernet transmits bits over a LAN. Both LANs and WANs use the same protocols from OSI layers 3 and above. LANs are mostly owned and operated by the companies that use them. On the other hand, WANs are usually owned and operated by telcos (telecommunications carriers), also known as NSPs (network service
how a WAN differs and doesn't from a LAN:
The first portion, FastEthernet0/0, refers to the physical layer: Is a physical cable connected to the interface? The second portion, line protocol, refers to the data link layer: Are basic protocols functioning properly across the link, such as clocking and framing?
in a Link State, what do the second and first portions refer to?
Encapsulation
is always set to ARPA. The statement "loopback not set" does not refer to the loopback interface but to the interface's current mode. Loopback mode is sometimes used for testing.
BGP (Border Gateway Protocol)
is the only modern example of an exterior gateway protocol.
HSRP (Hot Standby Routing Protocol)
roprietary to Cisco. The VIP points to the active router, a standby router is configured for auto failover, and other routers listen for indications the active and standby routers have both failed.
independently assess network conditions two or more hops away. This limitation is sometimes called "routing by rumor," and it results in slow convergence and higher likelihood of persistent errors when network conditions change.
routers relying on Distance-vector routing protocols must accept the data they receive from their neighbors and cannot
Hop count, which is the number of network segments crossed Theoretical bandwidth and actual throughput on a potential path Delay, or latency, on a potential path, which decreases performance Load, which is the traffic or processing burden sustained by a router in the path MTU (maximum transmission unit), which is the largest IP packet size in bytes allowed by routers in the path without fragmentation (excludes the frame used by the local network) Routing cost, which is a value assigned to a particular route as judged by the network administrator; the more desirable the path, the lower its cost Reliability of a potential path, based on historical performance A network's topology
routing metrics used to determine the best path include the following:
A clothing manufacturer sells its products over the Internet to customers worldwide An automobile manufacturer in Detroit contracts its plastic parts manufacturing to a Delaware-based company. Regional sales representatives for a national pharmaceutical company need to submit their sales figures to a file server at the company's headquarters and receive email from the company's mail server. A bank with offices around the state needs to connect those offices with each other to gather transaction and account information into a central database.
scenarios that demonstrates a need for a WAN:
1. Workstation 1 commands a network printer and sees its on a different LAN so it forwards transmission to switch A to Router A. 2.Router A examines the destination IP from packet header and uses a routing table to determine where the message should go. 3. Before it forwards the message, router A decreases the number of hops tallied in the TTL (time to live) field of the packet header. It then sends the message to router C. 4. Router C decreases the packet's hop count by 1, reads the packet's destination IP address, searches its routing table for matching network information, and determines the message is destined for its own LAN D. 5. Using its ARP table, switch D matches the destination IP address with the printer's MAC address. Switch D then delivers the transmission to the printer, which picks up the message and begins printing.
suppose a workstation in LAN A wants to print to the network printer in LAN D. The following steps describe how routing tables would be used in this transmission:
DCE (data circuit-terminating equipment)
the carrier's endpoint device for the WAN is called th
terrain, EMI, and antenna radiation patterns. Some edges overlap and others don't meet up, leaving gaps in coverage
the division of a network into cells provides thorough coverage over any given area. In reality, cells are misshapen due to
use networking devices, such as routers and modems, to connect networks spread over a wide geographical area the way DSL transmits bits over a WAN differs from the way Ethernet transmits bits over a LAN use the same protocols from OSI layers 3 and above. Recall that layer 3 protocols are responsible for directing data between LANs. Usually owned and operated by telcos (telecommunications carriers), also known as NSPs (network service providers), such as AT&T, Verizon, Spectrum, and Comcast. Corporations lease WAN connections from these carriers, often with payments based on the amount of bandwidth used or reserved.
the major characteristics of WANs
BGP
the most complex of the routing protocols
the size of your network, your network's bandwidth needs, and the relative locations of your network's segments.
the tools you'll use to connect networks vary greatly according to
Geosynchronous earth orbiting satellites
the type used by the most popular satellite data service providers. Least expensive
Broadband
well-suited for residential customers, the cables (whether telephone, coaxial, or fiber) and available bandwidth are shared between multiple customers.
show running-config (or sh run)
when making a configuration change to a Cisco device, those changes are held in the running configuration file. You can see the device's running-config file with the command
52 Mbps in one direction and up to 16 Mbps in the opposite direction can extend only a maximum of 1.6 km before dropping to speeds similar to ADSL2+.
with faster download speeds than upload speeds. A VDSL line that carries up to
router types and their capabilities further
you plan to specialize in network design, engineering, or management, you should research
VoIP calls with customers and vendors E-commerce traffic to your website Sales activity from physical storefronts Upload and download traffic to exchange large graphic files with customers
you realize your broadband Internet connection can no longer provide the support your business needs. Instead of basic Internet access, you need to connect your three locations with higher and more reliable throughput speeds to support the following activities:
