Home > Articles > Certification > Cisco Certification > CCNA

  • Print
  • + Share This
This chapter is from the book

Understanding WAN Cabling

Just as several types of physical layer implementations for LANs exist, various kinds of serial and router connections can also be used in a WAN environment, depending on the network requirements.

Learning about the different types of WAN serial and router connections and their functions can help you understand more about how a WAN works.

WAN Physical Layer

Many physical implementations carry traffic across the WAN. Needs vary, depending on the distance of the equipment from the services, the speed, and the actual service itself. Figure 4-15 shows a subset of physical implementations that support some of the more prominent WAN solutions today.

Figure 15Figure 4-15 WAN at the Physical Layer

Serial connections support WAN services such as dedicated leased lines that run the Point-to-Point Protocol (PPP) or Frame Relay. The speed of these connections ranges up to E1 (2.048 Mbps).

Other WAN services, such as ISDN, offer dial-on-demand connections or dial backup services. An ISDN BRI is composed of two 64-kbps bearer channels (B channels) for data, and one 16-kbps data channel (D channel) for signaling and other link-management tasks. PPP is typically used to carry data over the B channels.

With the increasing demand for residential broadband high-speed services, DSL and cable modem connections are beginning to dominate. For example, typical residential DSL service can offer a speed of up to 1.5 Mbps over the existing telephone line. Cable services, which work over the existing coaxial cable TV line, also offer high-speed connectivity matching or surpassing that of DSL.

WAN Serial Connections

For long-distance communication, WANs use serial transmission. Serial transmission is a method of data transmission in which bits of data are transmitted sequentially over a single channel. This one-at-a-time transmission contrasts with parallel data transmission, which transmits several bits at a time. To carry the bits, serial channels use a specific electro-magnetic or optical frequency range.

Figure 4-16 shows all the different serial connector options available for Cisco routers.

Figure 16Figure 4-16 Serial Connectors

Serial ports on Cisco routers use a proprietary 60-pin connector or smaller "smart serial" connector. The type of connector on the other end of the cable is dependent on the service provider or end-device requirements.

Frequencies, described in terms of their cycles per second (Hz), function as a band or spectrum for communication. For example, the signals transmitted over voice-grade telephone lines use up to 3 kHz. The size of this frequency range is called the bandwidth. Another way to express bandwidth is to specify the amount of data in bits per second that can be carried using two of the physical layer implementations (EIA/TIA-232 and EIA/TIA-449). Table 4-4 compares physical standards for these two WAN serial connection options.

Table 4-3 Comparison of Physical Serial Standards

Data Rates in bps

EIA/TIA-232 Distance in Meters

EIA/TIA-449 Distance in Meters

2400

60

1250

4800

30

625

9600

15

312

19,200

15

156

38,400

15

78

115,200

3.7

N/A

1,544,000 (T1)

N/A

15


Several types of physical connections allow you to connect to serial WAN services. Depending on the physical implementation that you choose or the physical implementation that your service provider imposes, you need to select the correct serial cable type to use with the router.

Serial Connections

In addition to determining the cable type, you need to determine whether you need data terminal equipment (DTE) or data circuit-terminating equipment (DCE) connectors for your WAN equipment. The DTE is the endpoint of the user's device on the WAN link. The DCE is typically the point where responsibility for delivering data passes into the hands of the service provider.

As shown in Figure 4-17, if you are connecting directly to a service provider, or to a device (like a channel/data service unit [CSU/DSU]) that performs signal clocking, the router is a DTE and needs a DTE serial cable. This situation is typically the case for routers.

Figure 17Figure 4-17 DTE and DCE Connections

In some cases, the router needs to be the DCE. For example, if you are performing a back-to-back router scenario in a test environment, one of the routers is a DTE, and the other is a DCE. Figure 4-18 shows a back-to-back router configuration. To implement this, you need a DTE cable for one router, and a DCE cable for another router. You might also be able to buy a special back-to-back cable, which is wired with a DTE side and DCE side.

Figure 18Figure 4-18 Back-to-Back Router Connections

When you are cabling routers for serial connectivity, the routers have either fixed or modular ports. The type of port being used affects the syntax that you use later to configure each interface.

Figure 4-19 shows an example of a router with fixed serial ports (interfaces). Each port is given a label of port type and port number, for example, Serial 0. To configure a fixed interface, specify the interface using this convention.

Figure 19Figure 4-19 Fixed Serial Ports

Figure 4-20 shows examples of routers with modular serial ports. Usually, each port is given a label of port type, slot (the location of the module), and port number. To configure a port on a modular card, it is necessary to specify the interface using the convention "port type slot number/port number." For example, given serial 1/0, the type of interface is a serial interface, the slot number where the interface module is installed is slot 1, and the port referenced on that serial interface module is port 0.

Figure 20Figure 4-20 Modular Serial Portsts

ISDN BRI Connections

With ISDN BRI, you can use two types of interfaces: BRI S/T and BRI U, which are reference points for user connectivity. To determine the appropriate interface, you need to verify whether you or the service provider provides a Network Termination 1 (NT1) device.

An NT1 device is an intermediate device between the router and the service provider ISDN switch (cloud) that connects four-wire subscriber wiring to the conventional two-wire local loop. In North America, the customer typically provides the NT1, while in the rest of the world, the service provider provides the NT1 device.

You might find it necessary to provide an external NT1 if an NT1 is not integrated into the router. Looking at the labeling on the router interface is the easiest way to determine if the router has an integrated NT1. A BRI interface with an integrated NT1 is labeled BRI U, and a BRI interface without an integrated NT1 is labeled BRI S/T. Because routers can have multiple ISDN interface types, you must determine the interface needed when the router is purchased. You can determine the type of ISDN connector that the router has by looking at the port label.

Figure 4-21 shows the different port types for the ISDN interface. To interconnect the ISDN BRI port to the service-provider device, use a UTP Category 5 straight-through cable.

Figure 21Figure 4-21 ISDN Interface Types

WARNING

It is important to insert a cable running from an ISDN BRI port only to an ISDN jack or an ISDN switch. ISDN BRI uses voltages that can seriously damage non-ISDN devices.

DSL Connections

Routers can also be connected to an asymmetric digital subscriber line (ADSL). The Cisco 827 ADSL router has one ADSL interface. To connect an ADSL to the ADSL port on a router, one end of the phone cable is connected to the ADSL port on the router. The other end of the phone cable is connected to the external wall phone jack.

To connect a router for DSL service, you need a phone cable with RJ-11 connectors. The RJ-11 connector is the same one used on a traditional telephone connection and is slightly smaller than a RJ-45 connector. Figure 4-22 shows a connection to a phone jack with DSL services. DSL works over standard telephone lines. It uses only two pins on the RJ-11 connector.

Figure 22Figure 4-22 DSL Connection

Cable Connections

The Cisco uBR905 cable access router provides high-speed network access on the cable television system to residential and small office/home office (SOHO) subscribers. The uBR905 router has an F-connector coaxial cable interface that can be connected to a cable system.

To connect the Cisco uBR905 cable access router to the cable system, a cable splitter/directional coupler can be installed, if needed, to separate signals for TV and computer use. If necessary, you can also install a high-pass filter to prevent interference between TV and computer signals.

The coaxial cable is connected to the F connector of the router, as shown in Figure 4-23.

Figure 23Figure 4-23 Cable Connection

Asynchronous Router Connections

All Cisco devices also have at least one asynchronous connection that is used for management purposes. In some cases, these devices might also have an auxiliary asynchronous device that can be used for management or dialup network connections. When configuring and managing Cisco devices, you must be aware of how to connect to these ports.

Console Port Connections

To initially configure the Cisco device, you must provide a management connection, also known as a console connection, directly to the device. For Cisco equipment, this manage-ment attachment is called a console port. The console port allows monitoring and configuring of a Cisco hub, switch, or router.

The cable used between a terminal and a console port is a rollover cable, with RJ-45 connectors as illustrated in Figure 4-24.

Figure 24Figure 4-24 Connecting a Device with a Console Cable

The rollover cable, also known as a console cable, has a different pinout than the straight-through or crossover RJ-45 cables used with Ethernet or the ISDN BRI. The pinout for a rollover cable is as follows:

1–8
2–7
3–6
4–5
5–4
6–3
7–2
8–1

To set up the connection between your terminal and the Cisco console port, you must perform the following:

Step 1

Cable the device to the PC using a rollover cable. You might need an RJ-45- to-DB-9 or and RJ-45-to-DB25 adapter for your PC or terminal.

Step 2

Configure terminal emulation software for the PC with the following COM port settings: 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control.


This connection to the console port provides you with access to the device's executive process command-line interface (CLI). From there, you can configure the device.

NOTE

Many PCs and laptops are no longer manufactured with a 25- or 9-pin (legacy) serial connector. Instead, most devices now ship with USB connectors. If you are working with a USB connector, you need to obtain a USB-to-DB-9 converter cable to connect to the console.

Auxiliary Connections

The auxiliary (AUX) port is another asynchronous connection that can provide out-of-band management—management not using the network bandwidth—through a modem. To provide out-of-band management, you can connect a modem directly to the AUX port. When you dial the modem, you are connected to the AUX port and the executive process CLI. The AUX port must be configured using the console port before it can be used in this manner.

The AUX port can also be used as a dial-on-demand WAN port for passing user traffic.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020