Foundation Summary

Study Material For Cisco Ccna Ccnp And Ccie Students

Study Material For Cisco Students

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The "Foundation Summary" section of each chapter lists the most important facts from the chapter. Although this section does not list every fact from the chapter that will be on your CCNA exam, a well-prepared CCNA candidate should know, at a minimum, all the details in each "Foundation Summary" section before going to take the exam.

Figure 4-12 depicts some of those key concepts and terms used with point-to-point WAN leased lines.

Figure 4-12 Point-to-Point Leased Line—Components and Terminology

- Short Cables (Usually Less than 50 Feet) -

Long Cables (Can Be Several Miles Long)

Figure 4-12 Point-to-Point Leased Line—Components and Terminology

- Short Cables (Usually Less than 50 Feet) -

Long Cables (Can Be Several Miles Long)

Table 4-10 lists some of the standards for WAN speeds. Table 4-10 WAN Speed Summary

Type of Line

Name of Signaling Type

Bit Rate

56

DS0*

56 kbps

64

DS0

64 kbps

T1

DS1

1.544 Mbps (24 DS0s, plus 8-kbps overhead

T3

DS3

44.736 Mbps (28 DS1s, plus management overhead)

E1

ZM

2.048 Mbps (32 DS0s)

E3

M3

34.064 Mbps (16 E1s, plus management overhead)

J1

Y1

2.048 Mbps (32 DS0s; Japanese standard)

*DS0, with 1 robbed bit out of 8

*DS0, with 1 robbed bit out of 8

Table 4-11 lists the WAN data-link protocols, with comments about each. Table 4-11 List of WAN Data-Link Protocols

Correction?

Type Field?

Other Attributes

Synchronous Data Link Control (SDLC)

Yes

No

SDLC supports multipoint links. It assumes that the SNA header occurs after the SDLC header.

Link Access Procedure Balanced (LAPB)

Yes

No

LAPB is used mainly with X.25.

Link Access Procedure on the D Channel (LAPD)

No

No

LAPD is used by ISDN lines for signaling to set up and bring down circuits.

Link Access Procedurefor Frame Mode Bearer Services (LAPF)

No

Yes

This is a data-link protocol used over Frame Relay links.

High-Level Data Link Control (HDLC)

No

No

HDLC serves as Cisco's default on serial links.

Point-to-Point Protocol (PPP)

Supported but not enabled by default

Yes

PPP was meant for multiprotocol interoperability from its inception, unlike all the others.

Figure 4-13 depicts some of the terms and ideas related to basic Frame Relay. Figure 4-13 Frame Relay Components

Figure 4-13 depicts some of the terms and ideas related to basic Frame Relay. Figure 4-13 Frame Relay Components

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