Internetworking - 1
Internetworking Techniques
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without prior written permission of Professor Nen-Fu Huang (E-mail: [email protected]).
Internetworking - 2
Interconnection Techniques
Interconnect Directly Interconnect with WAN (Wide Area
Networks) Interconnected via WAN (Wide Area
Networks) Hierarchical Structure Internetworking Units
Repeaters Bridges Routers Gateways
Internetworking - 3
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
Internetworking - 4
Interconnect with WAN
Connect LANs to the WAN and be part of the WAN.
區域網路 1
56
7
廣域網路
1 2 3 4
Internetworking - 5
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
Internetworking - 6
Hierarchical Structure
區域網路
1
廣域網路
2 3
大都會網路 大都會網路
4 89
區域網路
區域網路
10 11 12 13
14 15 16 17
5
6 7
Internetworking - 7
Internetworking Devices
網路閘門
路徑器
橋接器
訊號增益器
連結設備 通訊協定
實體層 鏈結層 網路層以上 MAC LLC
相同
不同
相同 相同 相同
不同
不同
不同 相同 相同
不同 不同 相同
不同 不同 不同
網路閘門
路徑器
橋接器
訊號增益器
連結設備 實際網路個數 邏輯網路個數
1 1
1N
N
N
N
N
Internetworking - 8
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.
網路區段 1
1 2
網路區段 2
3 4
訊號增益器
Internetworking - 9
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. Addressed Learning Function Frames Filtering Function Frames Forwarding Function
區域網路 1
1 2
區域網路 2
3 4
橋接器
Internetworking - 10
Bridges -- Examples
FE G
HC
A
B D
1橋接器 2
10BASET 網路
10BASE5 網路
1 23
4橋接器
5
LLCToken-Ring 區域網路
LLC CSMA/CD 區域網路
10BaseTx -- 10Base5
CSMA/CD -- Token Ring
Internetworking - 11
Bridges
LANs interconnected via multiple bridges might include several loops.
For simple network, a tree based structure is suggested.
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
Internetworking - 12
Routers Structure工作站 A
B C
工作站 D
高層通訊協定
網路層 網路層 網路層
高層通訊協定
區域網路 1 區域網路 2
路徑器
t2
t3t4
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 N-H D-T
高層資料
高層資料
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
Internetworking - 13
Router Characteristics
Network Layer Routing Network layer protocol dependent Filter MAC broadcast and multicast packets Easy to support mixed media Packet fragmentation and reassembly Filtering on network addresses and information Accounting
Direct Communication Between Endpoints and Routers
Highly configurable and hard to get right Handle speed mismatch Congestion control and avoidance
Internetworking - 14
Router Characteristics (Continued)
Routing Protocols Interconnect layer 3 networks and exploit arbitrary
topologies Determine which route to take Static routing Dynamic routing protocol support Provides reliability with alternate routes
Router Management Troubleshooting capabilities Name-Address mapping services
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Router Protocol Needs
IP ARP, RARP, ICMP, RIP, EGP, IGRP OSPF, IS-IS
DECNET XNS and Variations
NOVELL IPX BANYAN
ISO CLNS (Connectionless Network Service)
APPLETALK OTHERS
APOLLO DOMAIN PUP CHAOSNET
Internetworking - 16
Differences Between Bridges and Routers
Bridges RoutersOperation at Layer 2 Operation at Layer 3Protocol Independent Protocol DependentAutomatic Address Learning/Filtering Administration Required for Addre
ss,Interface and Routes
Pass MAC Multicast/Broadcast MAC M/B can be FilteredLower Cost Higher CostNo Flow/Congestion Control Flow/Congestion ControlLimited Security Complex SecurityTransparent to End Systems Non-TransparencyWell Suited for Simple/Small Networks For WAN, Larger NetworksNo Frames Segmentation/Reassembly Frames Segmentation/Reassembl
ySpanning Tree Based Routing Optimal Routing and Load Sharing Plug and Play Requires Central Administrator
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When to use Bridges ?
Locally to exploit high performance Many different network layer protocols which co-exist on t
he same LAN Have unroutable protocols Less skilled Network Management Administrator Lower cost requirements Have a single small, centralized network Want easy installation and maintenance
Internetworking - 18
When to use Routers ?
Interconnect LANs over WAN (private lines, X.25) Heterogeneous MAC layer interconnection Heavy broadcast/multicast traffic A few well defined, well behaved network level
protocols Skilled Network Management Administration Need network segmentation Better management on faults, speed mismatch
Internetworking - 19
Router-Based Network Example
4
區域網路 1
路徑器 1
區域網路 2
區域網路 3
5
1 2
3
路徑器 2路徑器 3
D2 D3PH2 PH3
網路層
D1
PH1
應用層表達層會議層傳輸層網路層
D1 D2PH1 PH3
網路層
R1S2 25
25
R3R1 25
25
R3 25S5
25
25
D2
PH2
應用層表達層會議層傳輸層網路層
D3
PH3
應用層表達層會議層傳輸層網路層
Internetworking - 20
Routing
Fixed Routing Table Dynamic Routing Table Routing Protocols -- The protocols used between routers
to exchange the routing information, such as routing tables and network status.
Internet Routing Protocols Examples RIP (Routing Information Protocol) OSPF (Open Shortest Path First)
Internetworking - 21
Fixed Routing Example
Fixed Routing Table
1 1 1
1 1 1
2 2 2
2 2 2
2
6
6
6 6 6 6 6
5 5 5 5 5 5
7
7 7 7 7
3 3 3 3 3
3
3 4 4
4 5
A B C D E F GABCDEFG
目的地區域網路
原始區域網路
4
區域網路 A
路徑器 1
區域網路 B 區域網路 C
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
Internetworking - 22
Fixed Routing Example
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 - 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 來欲往 轉至
由網路 B 來欲往 轉至
由網路 A 來欲往 轉至
由網路 C 來欲往 轉至
B - A A C C B A D - D A E - E A F C F - G C G -
由網路 B 來欲往 轉至
由網路 E 來欲往 轉至
A - A - C - B B D - C - E E D B F - F - G - G -
由網路 A 來欲往 轉至
由網路 E 來欲往 轉至
由網路 C 來欲往 轉至
由網路 F 來欲往 轉至
由網路 C 來欲往 轉至
由網路 G 來欲往 轉至
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
Internetworking - 23
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. Message Format Conversion
Different message format Maximum message sizes Character codes
Address Translation Different addressing structure
Protocol Conversion Replace control information Message segmentation and reassembly Data flow control Error detection and recovery
Gateway offers the greatly flexibility in network interconnection.
Internetworking - 24
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
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
Internetworking - 25
Inter-LAN Networks
Inter-LAN Networks can be built by directly interconnecting various LANs with bridges, routers, or gateways, depending on how similar the networks are at the various layers.
Another approach that can be used with inter-LAN networks is to use a backbone network.
A backbone network is a central network to which other networks connect. Users are not attached directly to the backbone network: They are connected to the Access networks which in turn connect to the backbone.
A backbone network requires a high bandwidth and the ability to transmit across long distances.
Optical Fiber Links Microwave-Based Links
Backbone network offers several advantages: Greater processing efficiency (parallel operation) More reliable Better traffic control (Filter traffic) Optimized different networks (Different requirements)
Internetworking - 26
Backbone Network Example
...
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校園網路 (FDDI)
...
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路徑器
路徑器
路徑器
廣域網路
橋接器
區域網路
區域網路
橋接器
橋接器區域網路
區域網路
區域網路