Www.ciscopress.com Copyright 2003 CCNA 4 Chapter 20 CCNA Certification Exam Review By Your Name. - презентация

1 Copyright 2003 CCNA 4 Chapter 20 CCNA Certification Exam Review By Your Name

2 Copyright 2003 OSI Model

3 Copyright 2003 Layer 1 Versus Layer 2

4 Copyright 2003 OSI Versus Ethernet Standards

5 Copyright 2003 Creating Subnets How to create a subnet Subnet planning

6 Copyright 2003 LAN Switching Full-duplex and half-duplex Ethernet operations Configuring both ends Configuring a router Mismatch between two switches

7 Copyright 2003 Comparing LAN Standards

8 Copyright 2003 LANs and Devices

9 Copyright 2003 Full Duplex and Half Duplex

10 Copyright 2003 The Data Link Layer Logical Link Control Ethernet Token Ring

11 Copyright 2003 Ethernet and IEEE Frame Formats Type (Ethernet) Specifies the upper-layer protocol to receive the data after Ethernet processing. Length (IEEE 802.3) The number of bytes of data that follows this field. Data (Ethernet) Ethernet version 2 does not specify any padding. Data (IEEE 802.3) Upper-layer protocol, is defined (LLC) in the data portion of the frame. If data is insufficient to fill the frame to the minimum 64-byte size, padding bytes are added. Preamble Alternating pattern of 1s and 0s (up to 31 pairs) tells receiving station that a data frame is coming.

12 Copyright 2003 MAC Addresses

13 Copyright 2003 Token Ring Frame Format

14 Copyright 2003 FDDI Frame Format

15 Copyright 2003 Ethernet Family Tree

16 Copyright 2003 LAN Segmentation

17 Copyright 2003 Layer 2 and Layer 3 Switching

18 Copyright 2003 Collision Domains

19 Copyright 2003 Symmetric Switching

20 Copyright 2003 Asymmetric Switching

21 Copyright 2003 Memory Buffering Port-based memory buffering –Packets are stored in queues that are linked to specific incoming ports. –It is possible for a single packet to block all other packets because its destination port is busy (even if the other packets could be delivered). Shared-memory buffering –All packets use a common memory buffer. –Packets in the buffer are then linked (mapped) dynamically to the appropriate destination port. –Helps balance between 10- and 100-Mbps ports.

22 Copyright 2003 Switching Methods

23 Copyright 2003 Redundancy and Loops Newer switched networks include redundant links to increase reliability and reduce single points of failure. With that comes the potential for data loops.

24 Copyright 2003 Spanning Tree Protocol Multiple paths to a destination provide redundancy and make a network robust. STP uses spanning-tree algorithm (STA). STP is a switched Ethernet network solution to deal with potential for data loops introduced by multiple paths. –Routers can manage multiple paths to avoid loops. –Hub networks would stop immediately with multiple paths. STP detects potential loops and blocks one path. –Blocked path can be quickly activated if other link fails. –Uses Layer 2 BPDUs (bridge protocol data units) to communicate between switches and detect potential loops.

25 Copyright 2003 Blocking –No frames forwarded, BPDUs heard Listening –No frames forwarded, listening for frames Learning –No frames forwarded, learning addresses Forwarding –Frames forwarded, learning addresses Disabled –No frames forwarded, no BPDUs heard Ports typically progress from Blocking > Listening > Learning > Forwarding. The Five STP States

26 Copyright 2003 WANs and Devices

27 Copyright 2003 WAN Physical Layer Standards

28 Copyright 2003 WAN Data Link Layer Protocols

29 Copyright 2003 WAN Encapsulation Formats (HDLC)

30 Copyright 2003 WAN Link Options

31 Copyright 2003 Point-to-Point Links Leased Lines

32 Copyright 2003 Packet-Switched Connections

33 Copyright 2003 Frame Relay

34 Copyright 2003 Circuit-Switched Connections

35 Copyright 2003 Dial-on-Demand Routing

36 Copyright 2003 ISDN