Internet Lab (iLab1) Basics Minoo Rouhi ilab1@net.in.tum.de Chair - - PowerPoint PPT Presentation

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Internet Lab (iLab1) Basics Minoo Rouhi ilab1@net.in.tum.de Chair - - PowerPoint PPT Presentation

Jan 21, 2024 362 likes •614 views

Chair of Network Architectures and Services Department of Informatics Technical University of Munich Internet Lab (iLab1) Basics Minoo Rouhi ilab1@net.in.tum.de Chair of Network Architectures and Services Department of Informatics Technical

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Chair of Network Architectures and Services Department of Informatics Technical University of Munich

Internet Lab (iLab1) Basics

Minoo Rouhi ilab1@net.in.tum.de

Chair of Network Architectures and Services Department of Informatics Technical University of Munich

Lab 1 – WiSe 2018

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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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. ISO/OSI concept Internet example protocols DNS, DHCPv6, HTTP , Tor, . . . TCP , UDP IPv6, ICMP , IPSec Ethernet, WLAN

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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/datagram packet/datagram frame 6/22

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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
  • Service Data Unit
  • Interface: service access point (SAP)

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Design decisions

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

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Destinations

  • unicast
  • broadcast
  • multicast

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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Layer 2 addresses/frame

  • MAC addresses, “physical address”
  • specific for medium
  • Ethernet/WLAN: 48 bit
  • 1 bit invividual/group (multicast or broadcast)
  • 1 bit globally (factory default)/locally administered
  • vendor and product information
  • not hierarchical

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

11/22

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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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Layer 2 traffic

PC 0 PC 1 PC 2 switch A B C

switch table:

port address A MAC PC 0

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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Internet Protocol

  • packet switched
  • best effort
  • connectionless
  • unreliable
  • no flow control

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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

7 8 15 16 31

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
  • neighbor discovery

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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Neighbor Discovery Protocol

PC 0 2001:DB8::1 PC 1 2001:DB8::2 PC 2 2001:DB8::3 A B C

Request/response protocol flow

  • Neighbor Solicitation (NS): What is the MAC of 2001:DB8::2?
  • Neighbor Advertisement (NA): MAC of 2001:DB8::2 is MACPC1.

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Outline

Internet protocol architecture MAC addresses Internet protocol L3 address resolution Next Steps

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Next steps

  • You should now have access to the Basics prelab
  • Enter your lab slot preference until tomorrow noon!
  • Results will be published tomorrow after the deadline has passed

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