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WANs and RoutersWANs and Routers

Joanne WagnerJoanne WagnerCCNP, CCAI, Security+, CCSPCCNP, CCAI, Security+, CCSP

WAN OVERVIEWWAN OVERVIEW

Used to connect LANs that are separated Used to connect LANs that are separated by a large geographic areaby a large geographic area

WAN protocols differ from LAN protocols WAN protocols differ from LAN protocols mostly at the OSI Physical and Data Link mostly at the OSI Physical and Data Link LayersLayers

The figure shows the relationship between the common WAN technologies and the OSI model

WAN CHARACTERISTICSWAN CHARACTERISTICS

Uses the services of Regional Bell Uses the services of Regional Bell Operating Companies (RBOC) for Operating Companies (RBOC) for operational and functional connectionsoperational and functional connections

Unlike LANs, uses serial interfaces Unlike LANs, uses serial interfaces operating at lower speeds operating at lower speeds

WAN Line Types/BandwidthWAN Line Types/Bandwidth

WAN DevicesWAN DevicesWAN Devices include:

– RoutersRouters Router offer many services, including internetworking and WAN interface ports.

– SwitchesSwitches Switch in the WAN provide connectivity for voice, data, and video communication.

– ModemsModems Include interface voice-grade services, channel service units/digital service units (CSU/DSUs) that interface T1/E1 services,Terminal Adapters/Network Termination 1 (TA/NT1s)

– Communication serversCommunication servers Concentrate dial-in/dial-out user communication.

Introduction to WANsIntroduction to WANs

Organizations who provide us with most of our WAN standards and protocols:

International Telecommunications Union (ITU)International Telecommunications Union (ITU)

International Organization for Standards (ISO)International Organization for Standards (ISO)

Internet Engineering Task Force (IETF)Internet Engineering Task Force (IETF)

Electronic Industries Association (EIA)Electronic Industries Association (EIA)

WANs: Physical Layer WANs: Physical Layer

DTE (Data Terminal Equipment) DTE (Data Terminal Equipment) is the device at the user end of is the device at the user end of a user-network interface that a user-network interface that serves as a data source, serves as a data source, destination, or both.destination, or both.

DTE connects to a data network DTE connects to a data network through a DCE device and through a DCE device and typically uses clocking signals typically uses clocking signals generated by the DCE. generated by the DCE.

DTE includes such devices as DTE includes such devices as routers, computers, protocol routers, computers, protocol translators, and multiplexers. translators, and multiplexers.

WANs: Physical LayerWANs: Physical Layer

DCE - Data communications DCE - Data communications equipment (EIA expansion) or equipment (EIA expansion) or data circuit-terminating data circuit-terminating equipment (ITU-T expansion).equipment (ITU-T expansion).

The DCE provides a physical The DCE provides a physical connection to the network, connection to the network, forwards traffic, and provides a forwards traffic, and provides a clocking signal used to clocking signal used to synchronize data transmission synchronize data transmission between DCE and DTE between DCE and DTE devices. Ex: Modems and devices. Ex: Modems and CSU/DSUsCSU/DSUs

Hint: Use router# show controller serial 0/0to find out if a cable is a DTE or a DCE

WAN Physical Layer StandardsWAN Physical Layer Standards

EIA/TIA-232EIA/TIA-232EIA/TIA-449EIA/TIA-449V.24V.24V.35V.35X.21X.21ISDNISDNT1,T3, E1 and E3T1,T3, E1 and E3SONET (OC-3, OC-SONET (OC-3, OC-12, OC-48, OC-192)12, OC-48, OC-192)

WANs: DATA LINK LAYERWANs: DATA LINK LAYER

Define how frames are Define how frames are carried between systems carried between systems on a single data link:on a single data link:High-Level Data Link High-Level Data Link Control (HDLC)Control (HDLC)Frame RelayFrame Relay– LAPFLAPF

Point-to-Point (PPP)Point-to-Point (PPP)Integrated Services Integrated Services Digital Network (ISDN)Digital Network (ISDN)– LAPDLAPD– LAPBLAPB

X.25X.25

WAN Data Link Protocols: HDLCWAN Data Link Protocols: HDLC

The Cisco default The Cisco default serialserial line encapsulation type. line encapsulation type.

It is used when It is used when communicating with communicating with another Cisco device. another Cisco device.

If communicating with a If communicating with a non-Cisco device, non-Cisco device, synchronous PPP is a synchronous PPP is a viable option. viable option.

HDLC is normally HDLC is normally proprietary between proprietary between vendorsvendors. There is no . There is no windowing or flow control. windowing or flow control.

WAN DATA LINK PROTOCOLS: PPPWAN DATA LINK PROTOCOLS: PPP

Provides router-to-router (LAN to LAN) Provides router-to-router (LAN to LAN) and host-to-network connections over and host-to-network connections over synchronous and asynchronous circuitssynchronous and asynchronous circuits

Standardized so it supports vendor Standardized so it supports vendor interoperabilityinteroperability

Contains a protocol field to identify the Contains a protocol field to identify the network protocolnetwork protocol

WAN DATA LINK PROTOCOLS: PPPWAN DATA LINK PROTOCOLS: PPP

The Point-to-Point Protocol (PPP) is a The Point-to-Point Protocol (PPP) is a standard serial line encapsulation method standard serial line encapsulation method which includes:which includes:

Protocol type field Protocol type field

Link Control Protocol - This protocol can, among Link Control Protocol - This protocol can, among other things, check for link quality during other things, check for link quality during connection establishment. connection establishment.

Support for authentication through the Password Support for authentication through the Password Authentication Protocol (PAP) and the Challenge Authentication Protocol (PAP) and the Challenge Handshake Authentication Protocol (CHAP)Handshake Authentication Protocol (CHAP)

Comparing WAN Frame Encapsulation Comparing WAN Frame Encapsulation FormatsFormats

DATA LINK PROTOCOLS: ISDNDATA LINK PROTOCOLS: ISDN

A digital circuit-switched A digital circuit-switched service that transmits service that transmits voice and data over voice and data over existing telephone linesexisting telephone lines

ISDN applications include ISDN applications include high-speed image high-speed image applications, high-speed applications, high-speed file transfer, video file transfer, video conferencing, and voice conferencing, and voice

serviceservice

DATA LINK PROTOCOLS: ISDNDATA LINK PROTOCOLS: ISDN

ISDN services:ISDN services:

Basic Rate Interface Basic Rate Interface (BRI)(BRI)

Operates over most Operates over most copper twisted-pair copper twisted-pair telephone wiring in place telephone wiring in place today.today.

Delivers a total bandwidth Delivers a total bandwidth of a 144-kbps line into of a 144-kbps line into three separate channels.three separate channels.

Primary Rate Interface Primary Rate Interface (PRI)(PRI)

ISDN BRIISDN BRI

Two of the channelsTwo of the channels, called , called B (bearer) B (bearer) channelschannels, operate at , operate at 64 kbps64 kbps and are used and are used to to carry voice or data trafficcarry voice or data traffic. .

The The third channelthird channel, the , the D (data) channelD (data) channel, is , is a a 16-kbps signaling channel16-kbps signaling channel used to carry used to carry instructionsinstructions that tell the telephone network that tell the telephone network how to handle each of the B channels. how to handle each of the B channels.

Often referred to as “Often referred to as “2B+D2B+D.”.”

DATA LINK LAYER PROTOCOLS: DATA LINK LAYER PROTOCOLS: FRAME RELAYFRAME RELAY

Uses high quality digital Uses high quality digital facilities with no error facilities with no error correctioncorrection

More efficient than X.25More efficient than X.25

A packet-switched A packet-switched technology that enables technology that enables end stations to end stations to dynamically share the dynamically share the network medium and the network medium and the available bandwidthavailable bandwidth

Frame Relay:Frame Relay:

Designed withDesigned with higher higher speed. speed.

As a result, Frame Relay As a result, Frame Relay contains a limited amount contains a limited amount of error checking and of error checking and reliability features. reliability features.

Upper-layer protocols are Upper-layer protocols are expected to attend to expected to attend to these issues.these issues.

Most common packet-Most common packet-switched network typeswitched network type

DATA LINK LAYER PROTOCOLS: DATA LINK LAYER PROTOCOLS: FRAME RELAYFRAME RELAY

WAN CONNECTION TYPES:WAN CONNECTION TYPES:

WAN PROTOCOLS:WAN PROTOCOLS:

Dedicated connectivity, also referred to Dedicated connectivity, also referred to as leased lines, provides full-time as leased lines, provides full-time synchronous connections. synchronous connections.

Dedicated, full-time connectivity is Dedicated, full-time connectivity is provided by point-to-point serial links. provided by point-to-point serial links.

The cost of dedicated line solutions can The cost of dedicated line solutions can become significant when deployed to become significant when deployed to connect many sites, which is especially connect many sites, which is especially true if full meshing is desired. true if full meshing is desired.

Connection Type: Dedicated Connection Type: Dedicated (Leased)(Leased)

Leased lines of this type are ideal for Leased lines of this type are ideal for high-volume environments with a high-volume environments with a steady-rate traffic pattern. steady-rate traffic pattern.

Use of available bandwidth is a concern Use of available bandwidth is a concern because the cost of the line is paid even because the cost of the line is paid even when the connection is idle.when the connection is idle.


T1 is a dedicated WAN technology


Connection Type: DedicatedConnection Type: Dedicated(Leased)(Leased)

Dedicated leased lines are a reasonable design optionfor the core WAN

Used primarily to:Used primarily to:

connect remote usersconnect remote users

mobile usersmobile users to to corporate LANs. corporate LANs.

backup lines for backup lines for higher-speed circuits, higher-speed circuits, such as Frame Relay such as Frame Relay and dedicated lines.and dedicated lines.

Connection Type: Circuit-SwitchedConnection Type: Circuit-Switched

brought up when neededbrought up when needed

generally generally low bandwidthlow bandwidth

Basic Telephone Service Basic Telephone Service connections are generally connections are generally limited to 28.8 kbpslimited to 28.8 kbps without compression, without compression, ISDN to 64 or 128 kbpsISDN to 64 or 128 kbps..


There are There are two ISDN servicestwo ISDN services

Basic Rate Interface (BRI)Basic Rate Interface (BRI)

Primary Rate Interface (PRI)Primary Rate Interface (PRI)

ISDN BRIISDN BRI

operates over most of the copper operates over most of the copper twisted-pair telephone wiring in twisted-pair telephone wiring in place today. place today.

delivers a total bandwidth of a delivers a total bandwidth of a 144-kbps144-kbps line into line into three separate three separate channelschannels. .



ISDN provides ISDN provides great flexibilitygreat flexibility to the to the network designer because of its ability network designer because of its ability to to use each of the B channels for use each of the B channels for separate voice or data applicationsseparate voice or data applications::

– ExampleExample, a long document can be , a long document can be downloaded from the corporate downloaded from the corporate network over one ISDN 64-kbps B network over one ISDN 64-kbps B channel while the other B channel channel while the other B channel is being used to connect to is being used to connect to browse a World Wide Web page. browse a World Wide Web page.

– Care should be taken in the Care should be taken in the design phase to ensure that the design phase to ensure that the equipment selected has the equipment selected has the feature set that takes advantage feature set that takes advantage of ISDN’s flexibility. of ISDN’s flexibility.

Connection Type: Frame RelayConnection Type: Frame Relay

Information contained Information contained in packets or frames in packets or frames

Shares non-dedicated Shares non-dedicated bandwidth with other bandwidth with other WAN subscribers' WAN subscribers' frames. frames.

A WAN switch A WAN switch forwards Frame Relay forwards Frame Relay and X.25 traffic.and X.25 traffic.


X.25 can use Switched X.25 can use Switched Virtual Circuits (SVCs), Virtual Circuits (SVCs), with with some initial delaysome initial delay for for call setup, or Permanent call setup, or Permanent Virtual Circuits (PVCs) Virtual Circuits (PVCs) which which avoid delays for avoid delays for call setupcall setup. .

Frame Relay uses Layer Frame Relay uses Layer 2 identifiers 2 identifiers andand Permanent Virtual Permanent Virtual Circuits (PVCs).Circuits (PVCs).


Frame Relay defines the Frame Relay defines the connection between a connection between a customer DTE and a customer DTE and a carrier DCE.carrier DCE.

The DTE is typically a The DTE is typically a router or FRADrouter or FRAD ( (Frame Frame Relay access devices)Relay access devices)

The DCE is a Frame The DCE is a Frame Relay switch. Relay switch.

Frame Relay access is at:Frame Relay access is at:

56 kbps, 64 kbps, or 56 kbps, 64 kbps, or 1.544 Mbps1.544 Mbps

Frame Relay Cost Effective: Frame Relay Cost Effective:

A packet switched line is used to share a single point-to-point link to transport packets.

WAN CONNECTION TYPESWAN CONNECTION TYPESSUMMARY:SUMMARY:

WAN PROTOCOLSWAN PROTOCOLSSUMMARY:SUMMARY:

WAN link options are classified as dedicated and switched

WAN TECHNOLOGYWAN TECHNOLOGYSUMMARY:SUMMARY:

ROUTER OVERVIEWROUTER OVERVIEW

Internal Configuration Internal Configuration ComponentsComponents

WANs – The Router WANs – The Router

A router is a special type of computer. It hasA router is a special type of computer. It hasCPU CPU memory, memory, a system bus, a system bus, various input/output interfaces. various input/output interfaces.

Routers are designed to perform some very specific functions. Routers are designed to perform some very specific functions. routers connect and allow communication between two networks and routers connect and allow communication between two networks and determine the best path for data to travel through the connected determine the best path for data to travel through the connected networks. networks.

WANs – The Router WANs – The Router

A Routers Requires: A Routers Requires:

Internetwork Operating System software (IOS)Internetwork Operating System software (IOS)

CPUCPU

Configuration fileConfiguration file

Introduction to routers in a WANIntroduction to routers in a WANThe main internal components of the router are The main internal components of the router are

Random access memory (RAM), Random access memory (RAM), – Stores routing tables Stores routing tables – Holds ARP cache Holds ARP cache – Holds fast-switching cache Holds fast-switching cache – Performs packet buffering (shared RAM) Performs packet buffering (shared RAM) – Maintains packet-hold queues Maintains packet-hold queues – Provides temporary memory for the configuration file while the Provides temporary memory for the configuration file while the

router is powered on (router is powered on (stores running configuration filestores running configuration file))– Loses content when router is powered down or restartedLoses content when router is powered down or restarted

Nonvolatile random-access memory (NVRAM), Nonvolatile random-access memory (NVRAM), – Provides Provides storage for the startup configurationstorage for the startup configuration file which file which

contains the instructions that a router uses to control the contains the instructions that a router uses to control the flow of traffic through its interfacesflow of traffic through its interfaces

– Retains content when router is powered down, restarted, or Retains content when router is powered down, restarted, or power is lost.power is lost.

The main internal components (continued) The main internal components (continued) – Flash memory, Flash memory,

Holds or stores the Cisco operating system image (IOS) Holds or stores the Cisco operating system image (IOS) Allows software to be updated without removing and replacing Allows software to be updated without removing and replacing chips on the processor chips on the processor Retains content when router is powered down or restarted Retains content when router is powered down or restarted Can store multiple versions of IOS software Can store multiple versions of IOS software Is a type of electronically erasable, programmable ROM Is a type of electronically erasable, programmable ROM (EEPROM) (EEPROM)

– Read-only memory (ROM), and Read-only memory (ROM), and Maintains instructions for power-on self test (POST) diagnostics Maintains instructions for power-on self test (POST) diagnostics Stores bootstrap program and basic operating system software Stores bootstrap program and basic operating system software Requires replacing pluggable chips on the motherboard for Requires replacing pluggable chips on the motherboard for software upgrades software upgrades

– Interfaces. Interfaces. Network connection through which packets enter and leave the Network connection through which packets enter and leave the routerrouterConnect router to network for frame entry and exit Connect router to network for frame entry and exit Can be on the motherboard or on a separate module Can be on the motherboard or on a separate module Connects the router to LANs and WANsConnects the router to LANs and WANs

Introduction to routers in a WANIntroduction to routers in a WAN

Router LANs and WANs Router LANs and WANs Routers have both LAN and WAN Routers have both LAN and WAN interfaces. interfaces.

– While a router can be used to segment While a router can be used to segment LANs, its major use is as a WAN LANs, its major use is as a WAN device. device.

Routers are the backbone devices of Routers are the backbone devices of large intranets and of the Internet. large intranets and of the Internet.

– They operate at Layer 3 of the OSI They operate at Layer 3 of the OSI model, making decisions based on model, making decisions based on network addresses. network addresses.

The two main functions of a router are The two main functions of a router are – the selection of best path for and the selection of best path for and – the switching of frames to the proper the switching of frames to the proper

interface. interface.

Routers accomplish this by building Routers accomplish this by building routing tables and exchanging network routing tables and exchanging network information with other routers. information with other routers.

Router LANs and WANs (cont.)Router LANs and WANs (cont.)An administrator can maintain routing An administrator can maintain routing tables by tables by – configuring configuring static routesstatic routes, , – but generally routing tables are but generally routing tables are

maintained dynamically through the maintained dynamically through the use of a routing protocol that use of a routing protocol that exchanges network topology (path) exchanges network topology (path) information with other routers. information with other routers.

A correctly configured internetwork A correctly configured internetwork provides the following: provides the following: – Consistent end-to-end addressing Consistent end-to-end addressing – Addresses that represent network Addresses that represent network

topologies topologies – Best path selection Best path selection – Dynamic or static routing Dynamic or static routing – Switching Switching

Router internal components Router internal components

CPUCPU RAMRAM FlashFlash NVRAMNVRAM

• Buses • ROM • Interfaces • Power Supply

Router internal components Router internal components

CPUCPU – The Central Processing Unit (CPU) – The Central Processing Unit (CPU) executes instructions in the operating executes instructions in the operating system.system.

RAMRAM – Random-access memory (RAM) is – Random-access memory (RAM) is used for routing table information, fast used for routing table information, fast switching cache, running configuration, and switching cache, running configuration, and packet queues. packet queues.

RAM provides run time space for RAM provides run time space for executable Cisco IOS software and its executable Cisco IOS software and its subsystems. subsystems. RAM is usually logically divided into RAM is usually logically divided into main processor memory and shared main processor memory and shared input/output (I/O) memory. input/output (I/O) memory. Shared I/O memory is shared among Shared I/O memory is shared among interfaces for temporary storage of interfaces for temporary storage of packets. The contents of RAM are lost packets. The contents of RAM are lost when power is removed. when power is removed. RAM is generally dynamic random-RAM is generally dynamic random-access memory (DRAM) and can be access memory (DRAM) and can be upgraded by adding additional Dual In-upgraded by adding additional Dual In-Line Memory Modules (DIMMs). Line Memory Modules (DIMMs).

Router internal components (cont.)Router internal components (cont.)

FlashFlash – Flash memory is used for storage – Flash memory is used for storage of a full Cisco IOS software image. of a full Cisco IOS software image.

The router normally acquires the The router normally acquires the default IOS from flash. default IOS from flash. These images can be upgraded These images can be upgraded by loading a new image into flash.by loading a new image into flash. The IOS may be in The IOS may be in uncompressed or compressed uncompressed or compressed form. form. In most routers an executable In most routers an executable copy of the IOS is transferred to copy of the IOS is transferred to RAM during the boot process. RAM during the boot process. In other routers the IOS may be In other routers the IOS may be run directly from flash. run directly from flash. Adding or replacing the flash Adding or replacing the flash Single In-Line Memory Modules Single In-Line Memory Modules (SIMMs) or PCMCIA cards can (SIMMs) or PCMCIA cards can upgrade the amount of flash. upgrade the amount of flash.


NVRAMNVRAM – Nonvolatile random-access memory – Nonvolatile random-access memory (NVRAM) is used to store the startup configuration. (NVRAM) is used to store the startup configuration.

– In some devices, NVRAM is implemented In some devices, NVRAM is implemented using separate electronically erasable using separate electronically erasable programmable read-only memory (EEPROMs) programmable read-only memory (EEPROMs) in some devices. in some devices.

– In other devices it is implemented in the same In other devices it is implemented in the same flash device from which the boot code is flash device from which the boot code is loaded. loaded.

– In either case these devices retain contents In either case these devices retain contents when power is removed. when power is removed.

BusesBuses – Most routers contain a system bus and a – Most routers contain a system bus and a CPU bus. CPU bus.

– The system bus is used for communication The system bus is used for communication between the CPU and the interfaces and/or between the CPU and the interfaces and/or expansion slots. This bus transfers the packets expansion slots. This bus transfers the packets to and from the interfaces. to and from the interfaces.

– The CPU bus is used by the CPU for The CPU bus is used by the CPU for accessing components from router storage. accessing components from router storage. This bus transfers instructions and data to or This bus transfers instructions and data to or from specified memory addresses. from specified memory addresses.


ROMROM – Read-only memory (ROM) is used for – Read-only memory (ROM) is used for permanently storing startup diagnostic code permanently storing startup diagnostic code (ROM Monitor). (ROM Monitor).

– The main tasks for ROM are hardware The main tasks for ROM are hardware diagnostics during router bootup and diagnostics during router bootup and loading the Cisco IOS software from flash loading the Cisco IOS software from flash to RAM. to RAM.

– Some routers also have a scaled down Some routers also have a scaled down version of the IOS that can be used as an version of the IOS that can be used as an alternative boot source. alternative boot source.

– ROMs are not erasable. They can only be ROMs are not erasable. They can only be upgraded by replacing the ROM chips in upgraded by replacing the ROM chips in the sockets. the sockets.

Power SupplyPower Supply – The power supply provides the – The power supply provides the necessary power to operate the internal necessary power to operate the internal components. components.

– Larger routers may use multiple or modular Larger routers may use multiple or modular power supplies. power supplies.

– In some of the smaller routers the power In some of the smaller routers the power supply may be external to the router.supply may be external to the router.


Router internal components (cont.)Router internal components (cont.)InterfacesInterfaces – The interfaces are the router – The interfaces are the router connections to the outside. connections to the outside.

– The three types of interfaces are The three types of interfaces are – local-area network (LANs), local-area network (LANs),

The LAN interfaces are usually either The LAN interfaces are usually either Ethernet or Token Ring. Ethernet or Token Ring. These interfaces have controller chips These interfaces have controller chips that provide the logic for connecting that provide the logic for connecting the system to the media. the system to the media. The LAN interfaces may be a fixed The LAN interfaces may be a fixed configuration or modular. configuration or modular.

– wide-area network (WANs), wide-area network (WANs), The WAN interfaces include serial, The WAN interfaces include serial, ISDN, and integrated Channel Service ISDN, and integrated Channel Service Unit (CSUs). Unit (CSUs). As with LAN interfaces, WAN As with LAN interfaces, WAN interfaces also have special controller interfaces also have special controller chips for the interfaces. chips for the interfaces. The WAN interfaces may be a fixed The WAN interfaces may be a fixed configuration or modular. configuration or modular.

– Console/AUX. Console/AUX. The Console/AUX ports are The Console/AUX ports are serial serial portsports used primarily for the initial used primarily for the initial configuration of the router. configuration of the router. These ports These ports are not networking portsare not networking ports. . They are They are used for terminal sessionsused for terminal sessions from the communication ports on the from the communication ports on the computer or through a modem. computer or through a modem.

Router physical characteristics Router physical characteristics It is not critical to know the It is not critical to know the location of the physical location of the physical components inside the components inside the router to understand how router to understand how to use the router. to use the router. However in some However in some situations, such as adding situations, such as adding memory, it can be very memory, it can be very helpful.helpful. The exact components The exact components used and their location used and their location varies between router varies between router models. Figure identifies models. Figure identifies the internal components the internal components of a 2600 router. of a 2600 router. Figure shows some of the Figure shows some of the external connectors on a external connectors on a 2600 router.2600 router.

Router external connections Router external connections The three basic types of connections on a router are LAN interfaces, WAN The three basic types of connections on a router are LAN interfaces, WAN interfaces, and management ports. interfaces, and management ports. – LAN interfaces – LAN interfaces –

LAN interface allow the router to connect to the Local Area Network LAN interface allow the router to connect to the Local Area Network media. This is usually some form of Ethernet. media. This is usually some form of Ethernet. However, it could be Token Ring or Asynchronous Transfer Mode (ATM). However, it could be Token Ring or Asynchronous Transfer Mode (ATM).

– WAN interfaces – WAN interfaces – Wide Area Network connections provide connections through a service Wide Area Network connections provide connections through a service provider to a distant site or to the Internet. provider to a distant site or to the Internet. These may be serial connections or any number of other WAN interfaces. These may be serial connections or any number of other WAN interfaces. With some types of WAN interfaces, an external device such as a CSU is With some types of WAN interfaces, an external device such as a CSU is required to connect the router to the local connection of the service required to connect the router to the local connection of the service provider. provider.

– Management interfaces – Management interfaces – The management port provides a text-based connection for the The management port provides a text-based connection for the configuring, monitoringconfiguring, monitoring and and troubleshootingtroubleshooting of the router. of the router. The common management interfaces are the console and auxiliary ports. The common management interfaces are the console and auxiliary ports. These are EIA-232 asynchronous serial ports. These are EIA-232 asynchronous serial ports.

Management port connections Management port connections The The console portconsole port and the and the auxiliary (AUX) auxiliary (AUX) portport are management ports. These are management ports. These asynchronous serialasynchronous serial ports are ports are not not designed as networking portsdesigned as networking ports. .

One of these two ports is required for the One of these two ports is required for the initial configuration of the router. The initial configuration of the router. The console port is recommended for this console port is recommended for this initial configuration. initial configuration. – When the router is first put into When the router is first put into

service, there are no networking service, there are no networking parameters configured. parameters configured.

– To prepare for initial startup and To prepare for initial startup and configuration, attach an RS-232 configuration, attach an RS-232 ASCII terminal, or a computer ASCII terminal, or a computer emulating an ASCII terminal, to the emulating an ASCII terminal, to the system console port. system console port.

– Then configuration commands can be Then configuration commands can be entered to set up the router. entered to set up the router.

Not all routers have an auxiliary port. Not all routers have an auxiliary port.

Management port connectionsManagement port connections

Once this initial configuration is entered Once this initial configuration is entered into the router through the console or into the router through the console or auxiliary port, the router can then be auxiliary port, the router can then be connected to the network for connected to the network for troubleshooting or monitoring. troubleshooting or monitoring.

The router can also be configured from a The router can also be configured from a remote location by dialing to a modem remote location by dialing to a modem connected to the console or auxiliary port connected to the console or auxiliary port on the router. on the router.

The console port is also preferred over the The console port is also preferred over the auxiliary port for troubleshooting. auxiliary port for troubleshooting. – This is because it displays router This is because it displays router

startup, debugging, and error startup, debugging, and error messages by default. messages by default.

– The console port can also be used The console port can also be used when the networking services have when the networking services have not been started or have failed. not been started or have failed.

– Therefore, the console port can be Therefore, the console port can be used for disaster and password used for disaster and password recovery procedures.recovery procedures.

Connecting console interfaces Connecting console interfaces To connect to the console port, a rollover To connect to the console port, a rollover cable and a RJ-45 to DB-9 adapter are used cable and a RJ-45 to DB-9 adapter are used to connect a PC. to connect a PC.

– Cisco supplies the necessary adapter to Cisco supplies the necessary adapter to connect to the console port. connect to the console port.

The PC or terminal must support VT100 The PC or terminal must support VT100 terminal emulation. Terminal emulation terminal emulation. Terminal emulation software such as HyperTerminal is usually software such as HyperTerminal is usually used. used. To connect the PC to a router: To connect the PC to a router:

1.1. Configure terminal emulation software on Configure terminal emulation software on the PC for: the PC for:

– The appropriate com port The appropriate com port – 9600 baud 9600 baud – 8 data bits 8 data bits – No parity No parity – 1 stop bit 1 stop bit – No flow controlNo flow control

2.2. Connect the RJ-45 connector of the rollover Connect the RJ-45 connector of the rollover cable to the router console port. cable to the router console port.

3.3. Connect the other end of the rollover cable Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter. to the RJ-45 to DB-9 adapter.

4.4. Attach the female DB-9 adapter to a PC. Attach the female DB-9 adapter to a PC.

Connecting console interfaces Connecting console interfaces

When connected using the console interface, the computer is acting as a “dumb terminal”.

<Router Output>



<Router Output><Router Output>

Connection LAN interfaces Connection LAN interfaces In most LAN environments, the In most LAN environments, the router is connected to the LAN using router is connected to the LAN using an Ethernet or Fast Ethernet an Ethernet or Fast Ethernet interface. interface. The router is a host that The router is a host that communicates with the LAN via a communicates with the LAN via a hub or a switch. A straight-through hub or a switch. A straight-through cable is used to make this cable is used to make this connection. connection. A 10/100BaseTX router interface A 10/100BaseTX router interface requires Category 5 or better, requires Category 5 or better, unshielded twisted-pair (UTP) unshielded twisted-pair (UTP) regardless of the router type. regardless of the router type. In some cases the Ethernet In some cases the Ethernet connection of the router is connection of the router is connected directly to the computer connected directly to the computer or to another router. For this type of or to another router. For this type of connection, a crossover cable is connection, a crossover cable is required. required.

Connecting WAN interfaces (cont.)Connecting WAN interfaces (cont.)Perhaps the most commonly used router interfaces for Perhaps the most commonly used router interfaces for WAN services are serial interfaces. Selecting the proper WAN services are serial interfaces. Selecting the proper serial cable is as easy as knowing the answers to four serial cable is as easy as knowing the answers to four questions: questions:

– What is the type of connection to the Cisco device? What is the type of connection to the Cisco device?

The interface on the left is a Smart Serial The interface on the left is a Smart Serial interface. interface. The interface on the right is a DB-60 The interface on the right is a DB-60 connection. connection.

– Is the network system being connected to a DTE or Is the network system being connected to a DTE or DCE device? DCE device?

DTE and DCE are the two types of serial DTE and DCE are the two types of serial interfaces that devices use to communicate. interfaces that devices use to communicate. The key difference between these two is that The key difference between these two is that the DCE device provides the clock signal for the DCE device provides the clock signal for the communications on the bus. the communications on the bus.

– What signaling standard does the device require? What signaling standard does the device require? For each different device, a different serial For each different device, a different serial standard could be used. Each standard standard could be used. Each standard defines the signals on the cable and specifies defines the signals on the cable and specifies the connector at the end of the cable. the connector at the end of the cable.

– Is a male or female connector required on the Is a male or female connector required on the cable?cable?

If the connector has visible projecting pins, it is If the connector has visible projecting pins, it is male. male. If the connector has sockets for projecting If the connector has sockets for projecting pins, it is female. pins, it is female.

WANS operate over large geographic areas

WAN protocols and standards differ from LAN protocols mostly at the Physical and Data Link Layer of the OSI Model

WANS use routers, switches, modems, and communication servers

Console and/or Auxiliary ports on the router are used for initial configuration

The Console port is used for debugging, password recovery, and troubleshooting

Terminal emulation software (hyper terminal) is used to establish the connection between the router and PC for initial configuration

To establish a connection between the PC and router use a rollover cable, DB-9 connector and a RJ-45 connector

Points to RememberPoints to Remember

Management connections are non-network connections, are used for initial configuration, and are asynchronous serial ports.

Management connections are used for troubleshooting problems and monitoring the system

RAM stores routing tables, holds fast switching cache, stores the running configuration, holds ARP cache, and is lost when power is shut down

NVRAM stores the startup configuration and retains contents when powered down

FLASH memory stores the IOS software images. It may need to have memory added to hold multiple versions of the image

Interfaces connect the router to the network, connect LANs and WANs, and use the configuration files to control the flow of traffic through the interfaces

Points to Remember (con’t)Points to Remember (con’t)

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