網路技術管理進階班---網路連結 講師 : 陳鴻彬 國立東華大學 電子計算機中心

講師簡介 陳鴻彬 國立東華大學 電算中心 系統維修工程師 Tel : 03-8662500 ext 1505 Fax: 03-8662509 hbc@cc.ndhu.edu.tw http://www.ndhu.edu.tw/~hbc

內容大綱 簡介 訊號增益器(Repeater) 集訊器(Hub) 橋接器(Bridge) 第二層交換器(L2 Switch) 路徑器(Router) 第三層交換器(L3 Switch) 網路閘門(Gateway)

Interconnection Techniques Interconnect Directly Interconnect with WAN (Wide Area Networks) Interconnected via WAN (Wide Area Networks) Hierarchical Structure

Interconnection Techniques Internetworking Devices Repeaters Hub Bridges L2 Switch Routers L3 Switch Gateways

Interconnect Directly Interconnect two or more LANs directly via an internetworking unit. 區域網路 1 區域網路 2 5 6 7 1 2 3 4

Connect LANs to the WAN and be part of the WAN. Interconnect with WAN Connect LANs to the WAN and be part of the WAN. 區域網路 1 5 6 7 廣域網路 1 2 3 4

Interconnected via WAN LANs are interconnected via the WAN. 區域網路 1 區域網路 2 1 2 3 5 6 7 4 廣域網路

Hierarchical Structure 區域網路 1 廣域網路 2 3 大都會網路 4 8 9 10 11 12 13 14 15 16 17 5 6 7

Internetworking Devices

Internetworking Devices

Repeaters Physical Layer devices. Protocol Independent. Interconnect two or more network segments (with the same type) to be a larger network segment. Regenerates the received digital signals. Does not process the received frames.

Repeaters 1 2 3 4 網路區段 1 網路區段 2 訊號增益器

Bridges MAC Layer devices. Protocol Independent. Interconnect two or more LANs with different physical layers to be a logical LAN. Each LAN can still operate independently and parallel. Process received frames based on the MAC addresses.

Bridges Addressed Learning Function Frames Filtering Function Frames Forwarding Function 1 2 3 4 區域網路 1 區域網路 2 橋接器

10BaseT -- 10Base5 Bridges -- Examples 1 2 10BASET 網路 橋接器 10BASE5 網路 F H C A B D 1 橋接器 2 10BASET 網路 10BASE5 網路 10BaseT -- 10Base5

Bridges -- Examples CSMA/CD -- Token Ring 1 2 3 4 5 橋接器 LLC Token-Ring 區域網 CSMA/CD 區域網路 CSMA/CD -- Token Ring

CSMA/CD -- Wireless Lan Bridges -- Examples 1 2 3 Wireless Lan CSMA/CD Lan 4 Bridge 5 CSMA/CD -- Wireless Lan

Bridges 4 區域網路 1 橋接器 1 橋接器 3 橋接器 2 區域網路 2 區域網路 3 區域網路 4 5 1 2 3 LANs interconnected via multiple bridges might include several loops. For simple network, a tree based structure is suggested.

L2 Switch L2 Switch VS Bridge Process MAC Layer Bridge use Forwarding scheme Switch use Cut-Through Switching Scheme Both two have Filtering Function Multiple L2 Switchs should be connected as tree structure

L2 Switch 交換平台 Switch Fabric A B C D E F G H Port 1 Port 8 控制 處理機 位址對照表 (Routing Table) 工作站 埠 A 1 C 3 控制 處理機 (Control Processor) F 6 G 7 Port 1 Port 8 A B C D E F G H

L2 Switch Switch 1 Switch2 Switch3

Router PHY & LINK Layer can be different CSMA/CD <--->FDDI CSMA/CD <--->PPP or HDLC (WAN) Network Layer need to be the same IP IPX Apple Talk DECNet ……

Router Higher Layer also to be the same TCP UDP Example telnet, ftp, http, smtp……

Router B C 工作站 A 工作站 D 高層通訊協定 網路層 區域網路 1 (CSMA/CD) 區域網路 2 (FDDI or WAN HDLC or PPP) 路徑器 t2 t3 t4 t5 t6 t7 t8 t1 t9 t10 高層資料 N-H D-H t1, t10 t2, t5, t6, t9 t3, t4, t7, t8 D-T 鏈結層2 實體層2 鏈結層1 實體層1 鏈結層 1 實體層 1 鏈結層 2 實體層 2

Router Each frame contain two addresses Destination WS address (Layer3 address) Next Router/WS address (Layer2 address)

Router 5 2 5 2 5 2 5 2 5 2 5 2 5 2 4 5 1 2 3 Router1 Router2 Router3 5 2 Higher Layers 4 區域網路 1 區域網路 2 區域網路 3 5 1 2 3 D1 PH1 Network Layer 5 2 R1 S 2 5 2 D1 D2 Higher Layers PH1 PH3 Router1 5 2 R3 R1 D2 PH2 5 2 Network Layer Router2 D2 D3 Router3 5 2 PH2 PH3 S5 R3 Higher Layers D3 5 2 PH3

Router Routing Table Routing Protocols Static (Fixed) Routing Table Dynamic Routing Table Routing Protocols RIP (Routing Information Protocol) RIPII OSPF (Open Shortest Path First) EGP IGRP ……

Router Static Routing Table 1 2 3 4 5 6 7 路徑器 1 路徑器 3 路徑器 4 路徑器 5 區域網路 D 區域網路 E 5 6 7 1 2 3 區域網路 F 區域網路 G 路徑器 3 路徑器 4 路徑器 5 路徑器 2 路徑器 6 路徑器 7 1 2 6 5 7 3 4 A B C D E F G A B C D E F G 目的地區域網路 原始 區域 網路

Router 路徑器 1 路徑選擇表 路徑器 2 路徑選擇表 路徑器 3 路徑選擇表 路徑器 4 路徑選擇表 路徑器 5 路徑選擇表 由網路 B 來 欲往 轉至 由網路 D 來 欲往 轉至 B B A A C - C A D B D - E B E - F - F A G - G A A - A B C - B B D D C B E - E B F - F B G - G B 路徑器 1 路徑選擇表 由網路 A 來 由網路 C 來 B - A A C C B A D - D A E - E A F C F - G C G - 由網路 E 來 A - A - C - B B D - C - E E D B F - F - G - G - 欲往 轉至 欲往 轉至 由網路 F 來 由網路 G 來 A - A C B - B C D - C C E - D C F F E C G - G C A - A C B - B C D - C C E - D C F - E C G G F C B - A A C - B - D - C A E E D - F - F A G - G A 路徑器 2 路徑選擇表 路徑器 3 路徑選擇表 路徑器 4 路徑選擇表 路徑器 5 路徑選擇表 路徑器 6 路徑選擇表 路徑器 7 路徑選擇表

Router WAN Protocol HDLC PPP …...

When to use Bridges Locally to exploit high performance Many different network layer protocols which co-exist on the same LAN Have unroutable protocols Less skilled Network Management Administrator

When to use Bridges Lower cost requirements Have a single small, centralized network Want easy installation and maintenance

When to use Routers Interconnect LANs over WAN (Leased lines, X.25) Heterogeneous MAC layer interconnection Heavy broadcast/multicast traffic A few well defined, well behaved network level protocols

When to use Routers Skilled Network Management Administration Need network segmentation Better management on faults, speed mismatch

Structure of IP Address Network Segmentation Structure of IP Address 4 bytes address Network id + Host id Network Id Host id 32bits

IP Address Classing Network Segmentation Class A -------> 00 0 ~ 127 Network Id Host Id 1 Byte 3 Bytes

IP Address Classing Network Segmentation Class B -------> 10 127 ~ 191 Network Id Host Id 2 Bytes 2 Bytes

IP Address Classing Network Segmentation Class C -------> 11 192 ~ Network Id Host Id 3 Bytes 1 Byte

Planning Subnets in a Class C Network Network Segmentation IP Subnet Mask Scheme 203.64.88.11------>11001011.01000000.01011000.00001011 255.255.255.0----> 11111111.11111111.11111111.00000000 203.64.88.0-------> 11001011.01000000.01011000.00000000 Planning Subnets in a Class C Network

Gateways Interconnect two or more LANs with different types. Different protocols may be used at any or all of the network layers. The gateway handles any conversions that necessary to go from one set of protocols to the other.

Gateways Message Format Conversion Address Translation Different message format Maximum message sizes Character codes Address Translation Different addressing structure

Gateways Protocol Conversion Replace control information Message segmentation and reassembly Data flow control Error detection and recovery Gateway offers the greatly flexibility in network interconnection.

Gateway Gateways are correspondingly more complex and more expensive to develop. 區域網路 1 網路閘門 1 2 3 區域網路 2 或廣域網路 應用層 1 表達層 1 會議層 1 傳輸層 1 網路層 1 鏈結層 1 實體層 1 應用層 2 表達層 2 會議層 2 傳輸層 2 網路層 2 鏈結層 2 實體層 2

Ｔhe End 國立東華大學