Presentation is loading. Please wait.

Presentation is loading. Please wait.

Transport Layer3-1 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet.

Published byClyde Page Modified over 8 years ago

Similar presentations

Presentation on theme: "Transport Layer3-1 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet."— Presentation transcript:

1 Transport Layer3-1 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet Protocol m Datagram format m IPv4 addressing m ICMP m IPv6 r 4.5 Routing algorithms m Link state m Distance Vector m Hierarchical routing r 4.6 Routing in the Internet m RIP m OSPF m BGP r 4.7 Broadcast and multicast routing

2 Transport Layer3-2 A B G D E c F A B G D E c F (a) Broadcast initiated at A (b) Broadcast initiated at D

3 Transport Layer3-3 A B G D E c F 1 2 3 4 5 (a)Stepwise construction of spanning tree A B G D E c F (b) Constructed spanning tree

4 Multicast Routing: Problem Statement r Goal: find a tree (or trees) connecting routers having local mcast group members m tree: not all paths between routers used m source-based: different tree from each sender to rcvrs m shared-tree: same tree used by all group members Shared tree Source-based trees

5 Transport Layer3-5 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet Protocol m Datagram format m IPv4 addressing m ICMP m IPv6 r 4.5 Routing algorithms m Link state m Distance Vector m Hierarchical routing r 4.6 Routing in the Internet m RIP m OSPF m BGP r 4.7 Broadcast and multicast routing

6 Transport Layer3-6 The Internet Network layer forwarding table Host, router network layer functions: Routing protocols path selection RIP, OSPF, BGP IP protocol addressing conventions datagram format packet handling conventions ICMP protocol error reporting router “signaling” Transport layer: TCP, UDP Link layer physical layer Network layer

7 Transport Layer3-7 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet Protocol m Datagram format m IPv4 addressing m ICMP m IPv6 r 4.5 Routing algorithms m Link state m Distance Vector m Hierarchical routing r 4.6 Routing in the Internet m RIP m OSPF m BGP r 4.7 Broadcast and multicast routing

8 Transport Layer3-8 IP datagram format ver length 32 bits data (variable length, typically a TCP or UDP segment) 16-bit identifier Internet checksum time to live 32 bit source IP address IP protocol version number header length (bytes) max number remaining hops (decremented at each router) for fragmentation/ reassembly total datagram length (bytes) upper layer protocol to deliver payload to head. len type of service “type” of data flgs fragment offset upper layer 32 bit destination IP address Options (if any) E.g. timestamp, record route taken, specify list of routers to visit. how much overhead with TCP? r 20 bytes of TCP r 20 bytes of IP r = 40 bytes + app layer overhead

9 Transport Layer3-9 IP Fragmentation & Reassembly r network links have MTU (max.transfer size) - largest possible link-level frame. m different link types, different MTUs r large IP datagram divided (“fragmented”) within net m one datagram becomes several datagrams m “reassembled” only at final destination m IP header bits used to identify, order related fragments fragmentation: in: one large datagram out: 3 smaller datagrams reassembly

10 Transport Layer3-10 IP addresses: how to get one? Q: How does host get IP address? r hard-coded by system admin in a file m Wintel: control-panel->network->configuration- >tcp/ip->properties m UNIX: /etc/rc.config r DHCP: Dynamic Host Configuration Protocol: dynamically get address from as server m “plug-and-play”

11 Transport Layer3-11 IP addressing: the last word... Q: How does an ISP get block of addresses? A: ICANN: Internet Corporation for Assigned Names and Numbers m allocates addresses m manages DNS m assigns domain names, resolves disputes

12 Transport Layer3-12 NAT: Network Address Translation 10.0.0.1 10.0.0.2 10.0.0.3 10.0.0.4 138.76.29.7 local network (e.g., home network) 10.0.0/24 rest of Internet Datagrams with source or destination in this network have 10.0.0/24 address for source, destination (as usual) All datagrams leaving local network have same single source NAT IP address: 138.76.29.7, different source port numbers

13 Transport Layer3-13 NAT: Network Address Translation r Motivation: local network uses just one IP address as far as outside word is concerned: m no need to be allocated range of addresses from ISP: - just one IP address is used for all devices m can change addresses of devices in local network without notifying outside world m can change ISP without changing addresses of devices in local network m devices inside local net not explicitly addressable, visible by outside world (a security plus).

14 Transport Layer3-14 NAT: Network Address Translation Implementation: NAT router must: m outgoing datagrams: replace (source IP address, port #) of every outgoing datagram to (NAT IP address, new port #)... remote clients/servers will respond using (NAT IP address, new port #) as destination addr. m remember (in NAT translation table) every (source IP address, port #) to (NAT IP address, new port #) translation pair m incoming datagrams: replace (NAT IP address, new port #) in dest fields of every incoming datagram with corresponding (source IP address, port #) stored in NAT table

15 Transport Layer3-15 NAT: Network Address Translation 10.0.0.1 10.0.0.2 10.0.0.3 S: 10.0.0.1, 3345 D: 128.119.40.186, 80 1 10.0.0.4 138.76.29.7 1: host 10.0.0.1 sends datagram to 128.119.40, 80 NAT translation table WAN side addr LAN side addr 138.76.29.7, 5001 10.0.0.1, 3345 …… S: 128.119.40.186, 80 D: 10.0.0.1, 3345 4 S: 138.76.29.7, 5001 D: 128.119.40.186, 80 2 2: NAT router changes datagram source addr from 10.0.0.1, 3345 to 138.76.29.7, 5001, updates table S: 128.119.40.186, 80 D: 138.76.29.7, 5001 3 3: Reply arrives dest. address: 138.76.29.7, 5001 4: NAT router changes datagram dest addr from 138.76.29.7, 5001 to 10.0.0.1, 3345

16 Transport Layer3-16 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet Protocol m Datagram format m IPv4 addressing m ICMP m IPv6 r 4.5 Routing algorithms m Link state m Distance Vector m Hierarchical routing r 4.6 Routing in the Internet m RIP m OSPF m BGP r 4.7 Broadcast and multicast routing

17 Transport Layer3-17 ICMP: Internet Control Message Protocol r used by hosts & routers to communicate network-level information m error reporting: unreachable host, network, port, protocol m echo request/reply (used by ping) r network-layer “above” IP: m ICMP msgs carried in IP datagrams r ICMP message: type, code plus first 8 bytes of IP datagram Type Code description 0 0 echo reply (ping) 3 0 dest. network unreachable 3 1 dest host unreachable 3 2 dest protocol unreachable 3 3 dest port unreachable 3 6 dest network unknown 3 7 dest host unknown 4 0 source quench (congestion control - not used) 8 0 echo request (ping) 9 0 route advertisement 10 0 router discovery 11 0 TTL expired 12 0 bad IP header

18 Transport Layer3-18 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet Protocol m Datagram format m IPv4 addressing m ICMP m IPv6 r 4.5 Routing algorithms m Link state m Distance Vector m Hierarchical routing r 4.6 Routing in the Internet m RIP m OSPF m BGP r 4.7 Broadcast and multicast routing

19 Transport Layer3-19 IPv6 r Initial motivation: 32-bit address space soon to be completely allocated. r Additional motivation: m header format helps speed processing/forwarding m header changes to facilitate QoS IPv6 datagram format: m fixed-length 40 byte header

20 Transport Layer3-20 Transition From IPv4 To IPv6 r Not all routers can be upgraded simultaneous m How will the network operate with mixed IPv4 and IPv6 routers? r Tunneling: IPv6 carried as payload in IPv4 datagram among IPv4 routers

21 Transport Layer3-21 Tunneling A B E F IPv6 tunnel Logical view: Physical view: A B E F IPv6 C D IPv4 Flow: X Src: A Dest: F data Flow: X Src: A Dest: F data Flow: X Src: A Dest: F data Src:B Dest: E Flow: X Src: A Dest: F data Src:B Dest: E A-to-B: IPv6 E-to-F: IPv6 B-to-C: IPv6 inside IPv4 B-to-C: IPv6 inside IPv4

Download ppt "Transport Layer3-1 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks r 4.3 What’s inside a router r 4.4 IP: Internet."

Similar presentations

CPSC 441 - Network Layer4-1 IP addresses: how to get one? Q: How does a host get IP address? r hard-coded by system admin in a file m Windows: control-panel->network->configuration-

CPSC Network Layer4-1 IP addresses: how to get one? Q: How does a host get IP address? r hard-coded by system admin in a file m Windows: control-panel->network->configuration-
CS 457 – Lecture 16 Global Internet - BGP Spring 2012.

CS 457 – Lecture 16 Global Internet - BGP Spring 2012.
4: Network Layer4a-1 IP Addressing: introduction r IP address: 32-bit identifier for host, router interface r interface: connection between host, router.

4: Network Layer4a-1 IP Addressing: introduction r IP address: 32-bit identifier for host, router interface r interface: connection between host, router.
8-1 Last time □ Network layer ♦ Introduction forwarding vs. routing ♦ Virtual circuit vs. datagram details connection setup, teardown VC# switching forwarding.

8-1 Last time □ Network layer ♦ Introduction forwarding vs. routing ♦ Virtual circuit vs. datagram details connection setup, teardown VC# switching forwarding.
Introduction 1-1 1DT066 Distributed Information System Chapter 4 Network Layer.

Introduction 1-1 1DT066 Distributed Information System Chapter 4 Network Layer.
Lecture 18 Network Layer (Internet Protocol)

Lecture 18 Network Layer (Internet Protocol)
Announcement r Recitation tomorrow on Project 2 r Midterm Survey at the end of this class.

Announcement r Recitation tomorrow on Project 2 r Midterm Survey at the end of this class.
Week 5: Internet Protocol Continue to discuss Ethernet and ARP –MTU –Ethernet and ARP packet format IP: Internet Protocol –Datagram format –IPv4 addressing.

Week 5: Internet Protocol Continue to discuss Ethernet and ARP –MTU –Ethernet and ARP packet format IP: Internet Protocol –Datagram format –IPv4 addressing.
Introduction 1-1 1DT014/1TT821 Computer Networks I Chapter 4 Network Layer.

Introduction 1-1 1DT014/1TT821 Computer Networks I Chapter 4 Network Layer.
Network Layer 4-1 4.1 introduction 4.2 virtual circuit and datagram networks 4.3 what’s inside a router 4.4 IP: Internet Protocol  datagram format  IPv4.

Network Layer introduction 4.2 virtual circuit and datagram networks 4.3 what’s inside a router 4.4 IP: Internet Protocol  datagram format  IPv4.
The Network Layer Chapter 5. The IP Protocol The IPv4 (Internet Protocol) header.

The Network Layer Chapter 5. The IP Protocol The IPv4 (Internet Protocol) header.
Network Layer4-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley,

Network Layer4-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley,
Chapter 5 The Network Layer.

Chapter 5 The Network Layer.
N/W Layer Addressing1 Instructor: Anirban Mahanti Office: ICT 745 Class Location: ICT 121 Lectures: MWF 12:00 – 12:50 Notes.

N/W Layer Addressing1 Instructor: Anirban Mahanti Office: ICT Class Location: ICT 121 Lectures: MWF 12:00 – 12:50 Notes.
NAT: Network Address Translation 10.0.0.1 10.0.0.2 10.0.0.3 10.0.0.4 138.76.29.7 local network (e.g., home network) 10.0.0/24 rest of Internet Datagrams.

NAT: Network Address Translation local network (e.g., home network) /24 rest of Internet Datagrams.
Network Layer4-1 Chapter 4: Network Layer Chapter goals: r understand principles behind network layer services: m routing (path selection) m dealing with.

Network Layer4-1 Chapter 4: Network Layer Chapter goals: r understand principles behind network layer services: m routing (path selection) m dealing with.
Network Layer Overview and IP

Network Layer Overview and IP
11- IP Network Layer4-1. Network Layer4-2 The Internet Network layer forwarding table Host, router network layer functions: Routing protocols path selection.

11- IP Network Layer4-1. Network Layer4-2 The Internet Network layer forwarding table Host, router network layer functions: Routing protocols path selection.
Announcement r Project 3 out, due 3/10 r Homework 3 out last week m Due next Mon. 3/1.

Announcement r Project 3 out, due 3/10 r Homework 3 out last week m Due next Mon. 3/1.
Network Layer4-1 IP: Internet Protocol r Datagram format r IPv4 addressing r DHCP: Dynamic Host Configuration Protocol r NAT: Network Address Translation.

Network Layer4-1 IP: Internet Protocol r Datagram format r IPv4 addressing r DHCP: Dynamic Host Configuration Protocol r NAT: Network Address Translation.

Similar presentations

Ads by Google