Introduction of Basic IP Service

Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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TCP/IP and OSI Model

Application Layer

Presentation Layer Application Layer

Conversation Layer

Transport Layer Transport Layer

Network Layer Network Layer

Data Link Layer Data Link Layer

Physical Layer Physical Layer

OSI Model TCP/IP Model

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TCP/IP Protocol Stack

Application HTTP, Telnet, FTP, Provide application program

Layer TFTP, Ping, etc. network interfaces

Establish terminal to
Transport
Layer TCP/UDP terminal connection

Network ICMP Addressing and route selecting

Layer IP
ARP/RARP
Data Link Ethernet, 802.3, PPP, Physical media access
Layer HDLC, FR, etc.

Physical Interfaces and Binary data flow transmission

Layer wires/cables

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Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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Ethernet Frame Structure

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Switches & Hub

 OSI model 의 Layer 2 에서 동작

 Forwarding & Flooding Domain
 Hub : Collision domain 을 구분
 Switch : Broadcast domain 구분

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 Issues in a Poorly Designed Network

 Unbounded failure domains

 Large broadcast domains

 Large amount of unknown

MAC unicast traffic

 Unbounded multicast traffic

 Management and
support challenges

 Possible security
vulnerabilities

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VLAN Overview

 Segmentation

 Flexibility

 Security

VLAN = Broadcast Domain = Logical Network (Subnet)

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802.1Q Frame

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Contents

1. OSI 7 Layers
2. Ethernet
 VLAN Overview
 Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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Loops

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Spanning Tree Protocol

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Spanning-Tree Operation

 One root bridge per broadcast domain.

 Broadcast domain 당 하나의 Root Bridge
 One root port per nonroot bridge.
 Non-root bridge 당 하나의 Root Port
 One designated port per segment.
 하나의 segment 당 하나의 designated port
 Nondesignated ports are unused.
 Nondesignated port 는 사용하지 않음

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STP Root Bridge Selection

 BPDU (default = sent every 2 seconds)

 Root bridge = bridge with the lowest bridge ID

Bridge MAC
 Bridge ID = Priority Address

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Spanning-Tree Port States

Spanning tree transits each port through several different states:

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Spanning-Tree Recalculation

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Rapid Spanning Tree Protocol

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Per VLAN Spanning Tree

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Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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IP Header Format

32bits
8 8 8 8
Version Header Type of Service Total Length
(4bits) Length (8bits) (16bits)

Identifier Flags
Fragmented Offset
(16bits) (3bits)

Time to Live Protocol Header Checksum

(8bits) (8bits) (16bits)

Source IP Address
(32bits)

Destination IP Address
(32bits)

Options
(Variable Length)

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IP Address

 32bit 의 길이로 구성
 32bit 내에서 network ID 와 Host ID 로 구성

 Network portion
 물리적 / 논리적 Link 로 구성되어 있는 하나의 Network 을 구분

 Host portion
 Network 내부에 있는 각 Device 를 구분하기 위하여 사용

 Generally, use dotted-decimal to represent it

 For example: 10.1.1.1, 192.168.1.1, etc.

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Classification of IP Address

First Octet Rule

1.0.0.0~ Network
126.255.255.255 0 Host(24bits) Class A
(7bits)

128.0.0.0~
191.255.255.255 1 0 Network(14bits) Host(16bits) Class B

192.0.0.0~
223.255.255.255 1 1 0 Network(21bits) Host(8bits) Class C

224.0.0.0~
239.255.255.255 1 1 1 0 Multicast Address Class D

240.0.0.0~
255.255.255.255 1 1 1 1 0 Reserved Class E

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Subnet Mask

Network ID 와 Host ID 를 구분하기 위한 수단

32-bit string, represented by dotted-decimal format

–Mask for class A: 255.0.0.0

–Mask for class B: 255.255.0.0
–Mask for class C: 255.255.255.0

IP address
192 168 1 1
IP subnet segment
“And” 192 168 1 0
Subnet mask
255 255 255 0

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Subnets and Subnet Masks

IP address: 192.168.1.17
11000000 10101000 00000001 00010001

Subnet mask: 255.255.255.240

11111111 11111111 11111111 11110000

Network Part Subnet Part Host Part

(n bits) (m bits)
IP Subnet: 192.168.1.17 255.255.255.240 or 192.168.1.17/28
Subnet numbers: 2n ( n=4, 24=16)
Host numbers: 2m-2 ( m=4, 24 – 2 = 14)

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Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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Host-to-Host Packet Delivery (1 of 22)

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Host-to-Host Packet Delivery (2 of 22)

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Host-to-Host Packet Delivery (3 of 22)

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Host-to-Host Packet Delivery (4 of 22)

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Host-to-Host Packet Delivery (5 of 22)

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Host-to-Host Packet Delivery (6 of 22)

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Host-to-Host Packet Delivery (7 of 22)

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Host-to-Host Packet Delivery (8 of 22)

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Host-to-Host Packet Delivery (9 of 22)

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Host-to-Host Packet Delivery (10 of 22)

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Host-to-Host Packet Delivery (11 of 22)

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Host-to-Host Packet Delivery (12 of 22)

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Host-to-Host Packet Delivery (13 of 22)

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Host-to-Host Packet Delivery (14 of 22)

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Host-to-Host Packet Delivery (15 of 22)

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Host-to-Host Packet Delivery (16 of 22)

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Host-to-Host Packet Delivery (17 of 22)

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Host-to-Host Packet Delivery (18 of 22)

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Host-to-Host Packet Delivery (19 of 22)

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Host-to-Host Packet Delivery (20 of 22)

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Host-to-Host Packet Delivery (21 of 22)

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Host-to-Host Packet Delivery (22 of 22)

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Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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Host-to-Host Packet Delivery (1 of 10)

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Host-to-Host Packet Delivery (2 of 10)

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Host-to-Host Packet Delivery (3 of 10)

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Host-to-Host Packet Delivery (4 of 10)

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Host-to-Host Packet Delivery (5 of 10)

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Host-to-Host Packet Delivery (6 of 10)

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Host-to-Host Packet Delivery (7 of 10)

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Host-to-Host Packet Delivery (8 of 10)

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Host-to-Host Packet Delivery (9 of 10)

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Host-to-Host Packet Delivery (10 of 10)

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Contents

1. OSI 7 Layers
2. Ethernet
1. VLAN Overview
2. Spanning-Tree Protocol

3. IP address Structure
4. Subnetting
5. Packet Flow
1. Host-to-Host
2. Switches
3. Routers

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Host-to-Host Packet Delivery (1 of 17)

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Host-to-Host Packet Delivery (2 of 17)

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Host-to-Host Packet Delivery (3 of 17)

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Host-to-Host Packet Delivery (4 of 17)

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Host-to-Host Packet Delivery (5 of 17)

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Host-to-Host Packet Delivery (6 of 17)

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Host-to-Host Packet Delivery (7 of 17)

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Host-to-Host Packet Delivery (8 of 17)

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Host-to-Host Packet Delivery (9 of 17)

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Host-to-Host Packet Delivery (10 of 17)

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Host-to-Host Packet Delivery (11 of 17)

Destination Next Hop Interface

192.168.3.0/24 Connected fa 0/0

192.168.4.0/24 Connected fa 0/1

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Host-to-Host Packet Delivery (12 of 17)

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Host-to-Host Packet Delivery (13 of 17)

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Host-to-Host Packet Delivery (14 of 17)

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Host-to-Host Packet Delivery (15 of 17)

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Host-to-Host Packet Delivery (16 of 17)

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Host-to-Host Packet Delivery (17 of 17)

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