Physical Implementations

• Many physical implementations carry traffic across the WAN

• Needs vary, depending on the:– distance of the equipment from the service– speed, and– actual service

WAN Physical Layer

HD

LC

PP

P

Fram

e

Relay ISDN BRI (with PPP)

EIA/TIA-232

EIA/TIA-449

X.21 V.24 V.35

HSSI

RJ-45

NOTE: Pinouts are different than RJ-45

used on campus

Serial Connections

Serial connections used to support WAN services are:

• Leased lines running Point-to-Point Protocol (PPP)

• High-Level Data Link Control (HDLC)

• Frame Relay encapsulations at Layer 2

Serial Line Speeds

Speeds of serial connections typically range from:

• 56 Kbps to

• T1/E1 1.544/2.048 Mbps

ISDN

ISDN BRI (Basic Rate Interface) is composed of

• Two 64 Kbps Bearer channels for data

• One Delta channel at 16 Kbps for signaling, and other link-management tasks

WAN Serial Connection

CSU/DSUDCE (Data Circuit-Terminating

Equipment)

DTE (Data Terminal Equipment

End User Device

Service

Provider

Router Connections

• EIA/TIA-232

• EIA/TIA-449

• V.35

• X.21

• EIA-530

Distance ComparisonsData in bps Distance

(Meters)

EIA/TIA-232

Distance (Meters)

EIA/TIA-232

2400 60 1,250

4800 30 625

9600 15 312

19,200 15 156

38,400 15 78

115,200 3.7 N/A

T1 (1,544,000 bps N/A 15

Connector Types

• In addition to determining cable type, it is necessary to determine whether DTE or DCE connectors are required

• DTE is the endpoint of the user’s device on the WAN link

• DCE is end point where responsibility for delivering data passes into hands of service provider

Router is DTE

DTE DCE

Modem

CSU/DSU

DTE DCE DCE DTE

SS

S

SS

S

Router connecting directly to a service provider

Router connecting to a device that will perform signal clocking

Router is DCE

If back-to-back routers are configured in a test environment – one of the routers is a DCE and the other is a DTE

Serially Connected Routers

When cabling routers for serial connectivity, routers will either have a fixed or modular port

• Fixed Ports– Figure 2-14, Page 59 of the ICND book shows fixed serial ports

Serial 1 and Serial 2– Configure with <port type> <port number>, such as “serial 0” or

“serial 1”

• Modular Ports– Figure 2-15, Page 61 shows modular serial ports– Configure using <port type><slot number>/<port number>, such

as “serial 1/0”

Other Serial Conventions

• 7500 series routers can have a virtual processor

• Designation of these ports would include VIP slot:<port type><slot number>/<port adapter number>/<port number>

• Example is serial 1/0/0

ISDN BRI

• With BRI, the following two types of interfaces can be used:– BRI S/T– BRI/U

• To determine which type you need, first determine whether you or the service provider will provide NT1 device

NT1 Device

• NT1 is an intermediate device between router and service provider’s ISDN switch

• It is used to connect four-wire subscriber wiring to the conventional two-wire loop

• NT1 refers to network termination type 1 device • In North America, NT1 is normally provided by

customer• In the rest of the world, service provider provides

NT1 device

U and S/T Interfaces

• If you need to provide NT1 device, use ISDN BRI with U interface

• If provider suplies an external NT1 device, router needs iSDN BRI S/T interface

• You need to determine which interface is needed when router is purchased

• Determine which type of ISDN connector is needed by looking at port label (see Figure 2-16)

Caution

• ISDN BRI uses voltages that can seriously damage non-ISDN devices

• Connect cable from ISDN BRI port only to– ISDN jack– ISDN switch

Console Connections

• In order to configure Cisco devices, a management connection is necessary directly to the device

• Management attachment is called a console port• Console port enables monitoring and configuring

of:– hub

– switch

– router

Console Configuration

PC

Device with console

RJ-45 to RJ-45

Rollover Cable

RJ-45 to DB-9 Adaptor

Labeled Terminal

Rollover Cable• Rollover cable has different pinouts than straight-

through or crossover RJ-45 cables used with Ethernet or ISDN BRI

• Pinout for rollover is:1 – 82 – 73 – 64 – 55 – 46 – 37 – 28 – 1

Caution

• Not all Cisco devices use a rollover cable to connect a console port to a PC

• Rollover is most common and is used with:– Router series: 1600, 2500, 2600, and 3600– Switch series: 1900 and 2820

• CHECK YOUR DOCUMENTATION RATHER THAN MAKE ANY ASSUMPTIONS!

Console Setup

• Step 1: Cable device using rollover cable – An RJ-45 to DB-9 or RJ-to DB-25 adapter may be necessary

• Step 2: Configure terminal emulation application with following COM port settings: 9600 bps, 8 data bits, no parity, 1 stop bit, no flow control – This provides out-of-band console access