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.

Slides:



Advertisements
Similar presentations
11-1 Last time □ Distance vector link cost changes ♦ Count-to-infinity, poisoned reverse □ Hierarchical routing ♦ Autonomous Systems ♦ Inter-AS, Intra-AS.
Advertisements

Introduction 1 Lecture 22 Network Layer (Broadcast and Multicast) slides are modified from J. Kurose & K. Ross University of Nevada – Reno Computer Science.
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.
Network Layer4-1 Hierarchical Routing scale: with 200 million destinations: r can’t store all dest’s in routing tables! r routing table exchange would.
Lecture 9 Overview. Hierarchical Routing scale – with 200 million destinations – can’t store all dests in routing tables! – routing table exchange would.
Data Communications and Computer Networks Chapter 4 CS 3830 Lecture 22 Omar Meqdadi Department of Computer Science and Software Engineering University.
Chapter 4: Network Layer 4. 1 Introduction 4.2 Virtual circuit and datagram networks 4.3 What’s inside a router 4.4 IP: Internet Protocol –Datagram format.
Network Layer4-1 Chapter 4 Network Layer A note on the use of these ppt slides: We’re making these slides freely available to all (faculty, students, readers).
CPE 400 / 600 Computer Communication Networks
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.
4a-1 CSE401: Computer Networks Hierarchical Routing & Routing in Internet S. M. Hasibul Haque Lecturer Dept. of CSE, BUET.
Network Layer4-1 Spanning trees r Suppose you have a connected undirected graph m Connected: every node is reachable from every other node m Undirected:
1 IP Multicasting. 2 IP Multicasting: Motivation Problem: Want to deliver a packet from a source to multiple receivers Applications: –Streaming of Continuous.
14 – Inter/Intra-AS Routing
Review r The Internet (IP) Protocol m Datagram format m IP fragmentation m ICMP: Internet Control Message Protocol m NAT: Network Address Translation r.
Routing Algorithms & Routing Protocols  Shortest Path Routing  Flooding  Distance Vector Routing  Link State Routing  Hierarchical Routing  Broadcast.
Network Layer 4-1 Chapter 4 Network Layer. Network Layer 4-2 Chapter 4: Network Layer 4. 1 Introduction 4.2 Virtual circuit and datagram networks 4.3.
1 ECE453 – Introduction to Computer Networks Lecture 10 – Network Layer (Routing II)
R OUTING IN THE INTERNET. A UTONOMOUS SYSTEM ( AS ) Collections of routers that has the same protocol, administative and technical control Intra-AS routing.
Transport Layer 3-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012  CPSC.
14 – Inter/Intra-AS Routing Network Layer Hierarchical Routing scale: with > 200 million destinations: can’t store all dest’s in routing tables!
Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A note on the use of these.
Chapter 22 Network Layer: Delivery, Forwarding, and Routing
What’s inside a router. Router architecture overview two key router functions:  run routing algorithms/protocol (RIP, OSPF, BGP)  forwarding datagrams.
1 Computer Communication & Networks Lecture 22 Network Layer: Delivery, Forwarding, Routing (contd.)
Network Layer4-1 R1 R2 R3R4 source duplication R1 R2 R3R4 in-network duplication duplicate creation/transmission duplicate Broadcast Routing r Deliver.
Multicast Sources: Kurose and Ross cast/addresstranslation_01.html.
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.
Introduction 1 Lecture 21 Network Layer (Routing Activity) slides are modified from J. Kurose & K. Ross University of Nevada – Reno Computer Science &
RSC Part II: Network Layer 6. Routing in the Internet (2 nd Part) Redes y Servicios de Comunicaciones Universidad Carlos III de Madrid These slides are,
Introduction 1 Lecture 19 Network Layer (Routing Protocols) slides are modified from J. Kurose & K. Ross University of Nevada – Reno Computer Science &
CS 3830 Day 29 Introduction 1-1. Announcements r Quiz 4 this Friday r Signup to demo prog4 (all group members must be present) r Written homework on chapter.
10-1 Last time □ Transitioning to IPv6 ♦ Tunneling ♦ Gateways □ Routing ♦ Graph abstraction ♦ Link-state routing Dijkstra's Algorithm ♦ Distance-vector.
CS 5565 Network Architecture and Protocols Godmar Back Lecture 22.
Homework 4 r Out: Fri 2/27/2015 r In: Fri 3/13/2015.
Network Layer4-1 Chapter 4: Network Layer r 4. 1 Introduction r 4.2 Virtual circuit and datagram networks  4.3 What ’ s inside a router r 4.4 IP: Internet.
Network Layer r Introduction r Virtual circuit and datagram networks r Routing algorithms m Link state m Distance Vector m Hierarchical routing r What’s.
Network Layer4-1 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.
IPv6. r Initial motivation: 32-bit address space soon to be completely allocated. r Additional motivation: m header format helps speed processing/forwarding.
Broadcast and multicast routing. R1 R2 R3R4 source duplication R1 R2 R3R4 in-network duplication duplicate creation/transmission duplicate Broadcast Routing.
1 Mao W07 Interdomain Routing Broadcast routing EECS 489 Computer Networks Z. Morley Mao Monday Feb 12, 2007.
Network Layer4-1 Intra-AS Routing r Also known as Interior Gateway Protocols (IGP) r Most common Intra-AS routing protocols: m RIP: Routing Information.
Network Layer4-1 Chapter 4 roadmap 4.1 Introduction and Network Service Models 4.2 Routing Principles 4.3 Hierarchical Routing 4.4 The Internet (IP) Protocol.
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.
Chapter 4: outline 4.1 introduction
Transport Layer3-1 Network Layer Every man dies. Not every man really lives.
Network Layer4-1 Routing Algorithm Classification Global or decentralized information? Global: r all routers have complete topology, link cost info r “link.
Network Layer4-1 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.
Network Layer4-1 Chapter 4 roadmap 4.1 Introduction and Network Service Models 4.2 Routing Principles 4.3 Hierarchical Routing 4.4 The Internet (IP) Protocol.
Network Layer4-1 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.
Network Layer4-1 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.
Border Gateway Protocol. Intra-AS v.s. Inter-AS Intra-AS Inter-AS.
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.
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.
Network Layer4-1 Chapter 4: Network Layer 4. 1 Introduction 4.2 Virtual circuit and datagram networks 4.3 IP: Internet Protocol Datagram format IPv4 addressing.
Ch4-2 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.
Application Layer 2-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A.
Application Layer 2-1 Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 A.
Routing in the Internet
14 – Inter/Intra-AS Routing
Chapter 4: Network Layer
Homework 4 Out: Fri 2/26/2016 In: Fri 3/11/2016.
Chapter 4: Network Layer
Chapter 4: outline 4.1 introduction
Chapter 4: Network Layer
Chapter 4: Network Layer
Chapter 4: Network Layer
Chapter 4: Network Layer
Optional Read Slides: Network Multicast
Presentation transcript:

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 addressing  ICMP  IPv6 4.5 routing algorithms  link state  distance vector  hierarchical routing 4.6 routing in the Internet  RIP  OSPF  BGP 4.7 broadcast and multicast routing Chapter 4: outline

Network Layer 4-2 Intra-AS Routing  also known as interior gateway protocols (IGP)  most common intra-AS routing protocols:  RIP: Routing Information Protocol  OSPF: Open Shortest Path First  IGRP: Interior Gateway Routing Protocol (Cisco proprietary)

Network Layer 4-3 RIP ( Routing Information Protocol)  distance vector algorithm  distance metric: # hops (max = 15 hops), each link has cost 1  DVs exchanged with neighbors every 30 sec in response message (aka advertisement)  each advertisement: list of up to 25 destination subnets (in IP addressing sense) D C BA u v w x y z subnet hops u 1 v 2 w 2 x 3 y 3 z 2 from router A to destination subnets:

Network Layer 4-4 RIP: example destination subnet next router # hops to dest wA2 yB2 zB7 x--1 ….…..... routing table in router D w x y z A C D B

Network Layer 4-5 w x y z A C D B destination subnet next router # hops to dest wA2 yB2 zB7 x--1 ….…..... routing table in router D A 5 dest next hops w - 1 x - 1 z C 4 …. …... A-to-D advertisement RIP: example

Network Layer 4-6 RIP table processing  RIP routing tables managed by application-level process called route-d (daemon)  advertisements sent in UDP packets, periodically repeated physical link network forwarding (IP) table transport (UDP) routed physical link network (IP) transprt (UDP) routed forwarding table

Network Layer 4-7 OSPF (Open Shortest Path First)  “open”: publicly available  uses link state algorithm  LS packet dissemination  topology map at each node  route computation using Dijkstra’s algorithm  advertisements flooded to entire AS  IS-IS routing protocol: nearly identical to OSPF

Network Layer 4-8 Internet inter-AS routing: BGP  BGP (Border Gateway Protocol): the de facto inter-domain routing protocol  “glue that holds the Internet together”  BGP provides each AS a means to:  eBGP: obtain subnet reachability information from neighboring ASs.  iBGP: propagate reachability information to all AS- internal routers.  determine “good” routes to other networks based on reachability information and policy.  allows subnet to advertise its existence to rest of Internet: “I am here”

Network Layer 4-9 BGP basics  when AS3 advertises a prefix to AS1:  AS3 promises it will forward datagrams towards that prefix AS3 AS2 3b 3c 3a AS1 1c 1a 1d 1b 2a 2c 2b other networks other networks  BGP session: two BGP routers (“peers”) exchange BGP messages:  advertising paths to different destination network prefixes (“path vector” protocol)  exchanged over semi-permanent TCP connections BGP message

Network Layer 4-10 BGP basics: distributing path information AS3 AS2 3b 3a AS1 1c 1a 1d 1b 2a 2c 2b other networks other networks  using eBGP session between 3a and 1c, AS3 sends prefix reachability info to AS1.  1c can then use iBGP do distribute new prefix info to all routers in AS1  1b can then re-advertise new reachability info to AS2 over 1b-to- 2a eBGP session  when router learns of new prefix, it creates entry for prefix in its forwarding table. eBGP session iBGP session

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 addressing  ICMP  IPv6 4.5 routing algorithms  link state  distance vector  hierarchical routing 4.6 routing in the Internet  RIP  OSPF  BGP 4.7 broadcast and multicast routing Chapter 4: outline

Network Layer 4-12 R1 R2 R3R4 source duplication R1 R2 R3R4 in-network duplication duplicate creation/transmission duplicate Broadcast routing  deliver packets from source to all other nodes  source duplication is inefficient:  source duplication: how does source determine recipient addresses?

Network Layer 4-13 In-network duplication  flooding: when node receives broadcast packet, sends copy to all neighbors  problems: cycles & broadcast storm  controlled flooding: node only broadcasts pkt if it hasn’t broadcast same packet before  node keeps track of packet ids already broadacsted  or reverse path forwarding (RPF): only forward packet if it arrived on shortest path between node and source  spanning tree:  no redundant packets received by any node

Network Layer 4-14 A B G D E c F A B G D E c F (a) broadcast initiated at A (b) broadcast initiated at D Spanning tree  first construct a spanning tree  nodes then forward/make copies only along spanning tree

Network Layer 4-15 A B G D E c F (a)stepwise construction of spanning tree (center: E) A B G D E c F (b) constructed spanning tree Spanning tree: creation  center node  each node sends unicast join message to center node  message forwarded until it arrives at a node already belonging to spanning tree

Network Layer 4-16 Multicast routing: problem statement goal: find a tree (or trees) connecting routers having local mcast group members  tree: not all paths between routers used  shared-tree: same tree used by all group members shared tree source-based trees group member not group member router with a group member router without group member legend  source-based: different tree from each sender to rcvrs

Network Layer 4-17 Approaches for building mcast trees approaches:  group-shared tree: group uses one tree  center-based trees  source-based tree: one tree per source  shortest path trees  reverse path forwarding

Network Layer 4-18 Center-based trees  single delivery tree shared by all  one router identified as “center” of tree  to join:  edge router sends unicast join-msg addressed to center router  join-msg “processed” by intermediate routers and forwarded towards center  join-msg either hits existing tree branch for this center, or arrives at center  path taken by join-msg becomes new branch of tree for this router

Network Layer 4-19 Center-based trees: example suppose R6 chosen as center: router with attached group member router with no attached group member path order in which join messages generated LEGEND R1 R2 R3 R4 R5 R6 R7

Network Layer 4-20 Shortest path tree  mcast forwarding tree: tree of shortest path routes from source to all receivers  Dijkstra’s algorithm i router with attached group member router with no attached group member link used for forwarding, i indicates order link added by algorithm LEGEND R1 R2 R3 R4 R5 R6 R s: source

Network Layer 4-21 Reverse path forwarding if (mcast datagram received on incoming link on shortest path back to center) then flood datagram onto all outgoing links else ignore datagram  rely on router’s knowledge of unicast shortest path from it to sender  each router has simple forwarding behavior:

Network Layer 4-22 Reverse path forwarding: example router with attached group member router with no attached group member datagram will be forwarded LEGEND R1 R2 R3 R4 R5 R6 R7 s: source datagram will not be forwarded

Network Layer 4-23 Reverse path forwarding: pruning  forwarding tree contains subtrees with no mcast group members  no need to forward datagrams down subtree  “prune” msgs sent upstream by router with no downstream group members router with attached group member router with no attached group member prune message LEGEND links with multicast forwarding P R1 R2 R3 R4 R5 R6 R7 s: source P P

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 addressing, ICMP, IPv6 4.5 routing algorithms  link state, distance vector, hierarchical routing 4.6 routing in the Internet  RIP, OSPF, BGP 4.7 broadcast and multicast routing Chapter 4: done!  understand principles behind network layer services:  network layer service models, forwarding versus routing how a router works, routing (path selection), broadcast, multicast  instantiation, implementation in the Internet