iLab Basics Benjamin Hof hof@in.tum.de Lehrstuhl fr - - PowerPoint PPT Presentation

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Apr 07, 2023 31 likes •246 views

iLab Basics Benjamin Hof hof@in.tum.de Lehrstuhl fr Netzarchitekturen und Netzdienste Fakultt fr Informatik Technische Universitt Mnchen Lab 1 15ss 1 Outline Internet protocol architecture MAC addresses Internet protocol

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iLab

Basics Benjamin Hof hof@in.tum.de

Lehrstuhl für Netzarchitekturen und Netzdienste Fakultät für Informatik Technische Universität München

Lab 1 – 15ss

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution

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Layer model

application presentation session transport network data link physical application transport network link 7. 6. 5. 4. 3. 2. 1. DNS, DHCP, HTTP TCP, UDP, SCTP IPv6, ICMP, IPSec Ethernet, WLAN ISO/OSI concept Internet example protocols

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Example: HTTP communication in a local area network

browser TCP IP Ethernet driver HTTP server TCP IP Ethernet driver

HTTP protocol TCP protocol IP protocol Ethernet protocol

Ethernet

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Example: two networks connected with a router

wireless LAN browser TCP IP HTTP server TCP IP Ethernet driver WLAN driver IP Ethernet driver WLAN driver

HTTP protocol TCP protocol IP protocol IP protocol Ethernet protocol WLAN protocol

Ethernet router

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Encapsulation of data in the protocol stack

user data application header user data TCP header application data IP header TCP header application data

Ethernet header

IP header TCP header application data

Ethernet trailer

segment packet/datagram frame

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Terminology

IP header network layer SDU

Ethernet header

data link layer SDU

Ethernet trailer

network layer PDU data link layer PDU

◮ Protocol Data Unit ◮ Sercie Data Unit ◮ Interface: service access point (SAP) 9

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Design decisions

◮ no state between sender and destination ◮ end-to-end principle ◮ separation of packet forwarding and routing 10

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution

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Layer 2 addresses/frame

◮ MAC addresses, “physical address” ◮ specific for medium ◮ Ethernet/WLAN: 48 bit

◮ vendor and product information

◮ not hierarchical

Why are MAC addresses not used for addressing devices on the Internet?

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Ethernet layer 2

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destination address source address type service data unit

❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤ ❤

. . .

                          

46-1500

ctets

frame check sequence

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Layer 2 traffic

PC 0 PC 1 PC 2 switch A B C

PC 0 transmits:

1. destination MAC PC 1
2. destination MAC FF:FF:FF:FF:FF:FF

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution

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Internet Protocol

◮ packet switched ◮ best effort ◮ connectionless ◮ unreliable ◮ no flow control 16

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IPv6 header

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version traffic class flow label payload length next header hop limit source destination extension headers or payload

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IPv4 header

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version hdr len DSCP/ECN total length identification flags fragment offset time to live protocol header checksum source address destination address

ptions or payload

Flags will be used for fragmenting packets.

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Internet control message protocol

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type code checksum depends

◮ IPv6 next header: 58 ◮ IPv4 protocol: 1 ◮ similarities between ICMPv6 and ICMPv4 ◮ kind of on L3

purpose, e.g.,

◮ destination unreachable ◮ time to live exceeded ◮ neighbour discovery 19

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution

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