# Last time. Transitioning to IPv6. Routing. Tunneling. Gateways. Graph abstraction. Link-state routing. Distance-vector routing. Dijkstra's Algorithm

Save this PDF as:

Size: px
Start display at page:

Download "Last time. Transitioning to IPv6. Routing. Tunneling. Gateways. Graph abstraction. Link-state routing. Distance-vector routing. Dijkstra's Algorithm"

## Transcription

1 Last time Transitioning to IPv6 Tunneling Gateways Routing Graph abstraction Link-state routing Dijkstra's Algorithm Distance-vector routing Bellman-Ford Equation 10-1

2 This time Distance vector link cost changes Hierarchical routing Routing protocols 10-2

3 Distance Vector: link cost changes Link cost changes: node detects local link cost change updates routing info, recalculates distance vector if DV changes, notify neighbours x 1 4 y 50 1 z good news travels fast At time t 0, y detects the link-cost change, updates its DV, and informs its neighbours. At time t 1, z receives the update from y and updates its table. It computes a new least cost to x and sends its neighbours its DV. At time t 2, y receives z s update and updates its distance table. y s least costs do not change and hence y does not send any message to z. 10-3

4 Distance Vector: link cost changes Link cost changes: good news travels fast bad news travels slow - count to infinity problem! 44 iterations before algorithm stabilizes: see text Poisoned reverse: If Z routes through Y to get to X : Z tells Y its (Z s) distance to X is infinite (so Y won t route to X via Z) Will this completely solve count to infinity problem? 60 x 4 y 50 1 z 10-4

5 Comparison of LS and DV algorithms Message complexity LS: with n nodes, E links, O(nE) msgs sent DV: exchange between neighbours only convergence time varies Speed of Convergence LS: O(n 2 ) algorithm requires O(nE) msgs may have oscillations DV: convergence time varies may be routing loops count-to-infinity problem Robustness: what happens if router malfunctions? LS: node can advertise incorrect link cost each node computes only its own table DV: DV node can advertise incorrect path cost each node s table used by others error propagates through network 10-5

6 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 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 10-6

7 Hierarchical Routing Our routing study thus far - idealization all routers identical network flat not true in practice scale: with 200 million destinations: can t store all destinations in routing tables! routing table exchange would swamp links! administrative autonomy internet = network of networks each network admin may want to control routing in his or her own network 10-7

8 Hierarchical Routing Aggregate routers into regions, autonomous systems (AS) Routers in same AS run same routing protocol intra-as routing protocol routers in different AS can run different intra-as routing protocol Gateway router Direct link to router in another AS 10-8

9 Interconnected ASes 3c 3a 3b AS3 1a 1c 1d 1b Intra-AS Routing algorithm AS1 Forwarding table Inter-AS Routing algorithm 2a 2c AS2 2b Forwarding table is configured by both intraand inter-as routing algorithm Intra-AS sets entries for internal destinations Inter-AS & Intra-AS sets entries for external destinations 10-9

10 Inter-AS tasks Suppose router in AS1 receives datagram whose destination is outside of AS1 Router should forward packet towards one of the gateway routers, but which one? AS1 needs: to learn which destinations are reachable through AS2 and which through AS3 to propagate this reachability info to all routers in AS1 Job of inter-as routing! 3c 3a 3b AS3 1a 1c 1d 1b AS1 2a 2c AS2 2b 10-10

11 Example: Setting forwarding table in router 1d Suppose AS1 learns (via inter-as protocol) that subnet x is reachable via AS3 (gateway 1c) but not via AS2. Inter-AS protocol propagates reachability info to all internal routers. Router 1d determines from intra-as routing info that its interface I is on the least cost path to 1c. Puts in forwarding table entry (x,i). 3c 3a 3b AS3 1a 1c 1d 1b AS1 2a 2c AS2 2b 10-11

12 Example: Choosing among multiple ASes Now suppose AS1 learns from the inter-as protocol that subnet x is reachable from AS3 and from AS2. To configure the forwarding table, router 1d must determine towards which gateway it should forward packets for destination x. This is also the job of the inter-as routing protocol! 3c 3a 3b AS3 1a 1c 1d 1b AS1 2a 2c AS2 2b 10-12

13 Example: Choosing among multiple ASes Now suppose AS1 learns from the inter-as protocol that subnet x is reachable from AS3 and from AS2. To configure the forwarding table, router 1d must determine towards which gateway it should forward packets for destination x. This is also the job of the inter-as routing protocol! Hot potato routing: send packet towards closest of two routers. Learn from inter-as protocol that subnet x is reachable via multiple gateways Use routing info from intra-as protocol to determine costs of least-cost paths to each of the gateways Hot potato routing: Choose the gateway that has the smallest least cost Determine from forwarding table the interface I that leads to least-cost gateway. Enter (x,i) in forwarding table 10-13

14 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 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 10-14

15 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) 10-15

16 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 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 10-16

17 RIP ( Routing Information Protocol) Distance vector algorithm Included in BSD-UNIX Distribution in 1982 Distance metric: # of hops (max = 15 hops) From router A to subsets: z u A C B D v y w x destination hops u 1 v 2 w 2 x 3 y 3 z

19 RIP: Example w x y A D B z C Destination Network Next Router Num. of hops to dest. w A 2 y B 2 z B 7 x Routing table in D 10-19

20 RIP: Example Dest Next hops w - 1 x - 1 z C Advertisement from A to D w x y A D B z C Destination Network Next Router Num. of hops to dest. w A 2 y B 2 z B A 7 5 x Routing table in D 10-20

21 RIP: Link Failure and Recovery If no advertisement heard after 180 sec --> neighbour/link declared dead routes via neighbour invalidated new advertisements sent to neighbours neighbours in turn send out new advertisements (if tables changed) link failure info quickly propagates to entire net poison reverse used to prevent ping-pong loops (infinite distance = 16 hops) 10-21

22 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 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 10-22

23 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 OSPF advertisement carries one entry per neighbour router Advertisements disseminated to entire AS (via flooding) Carried in OSPF messages directly over IP (rather than TCP or UDP 10-23

24 OSPF advanced features (not in RIP) Security: all OSPF messages authenticated (to prevent malicious intrusion) Multiple same-cost paths allowed (only one path in RIP) For each link, multiple cost metrics for different TOS (e.g., satellite link cost set low for best effort; high for real time) Integrated uni- and multicast support: Multicast OSPF (MOSPF) uses same topology data base as OSPF Hierarchical OSPF in large domains

25 Hierarchical OSPF 10-25

26 Hierarchical OSPF Two-level hierarchy: local area, backbone. Link-state advertisements only in area Each node has detailed area topology; only knows direction (shortest path) to nets in other areas. Area border routers: summarize distances to nets in own area, advertise to other Area Border routers. Backbone routers: run OSPF routing limited to backbone. Boundary routers: connect to other AS s

27 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 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 10-27

28 Internet inter-as routing: BGP BGP (Border Gateway Protocol): the de facto standard BGP provides each AS a means to: Obtain subnet reachability information from neighbouring ASs. Propagate reachability information to all ASinternal routers. Determine good routes to subnets based on reachability information and policy. allows subnet to advertise its existence to rest of Internet: I am here 10-28

29 BGP basics Pairs of routers (BGP peers) exchange routing info over semi-permanent TCP connections: BGP sessions BGP sessions need not correspond to physical links. When AS2 advertises a prefix to AS1, AS2 is promising it will forward any datagrams destined to that prefix towards the prefix. AS2 can aggregate prefixes in its advertisement 3c 3a 3b AS3 1a AS1 1c 1d 1b 2a AS2 2c 2b ebgp session ibgp session 10-29

30 Distributing reachability info With ebgp session between 3a and 1c, AS3 sends prefix reachability info to AS1. 1c can then use ibgp do distribute this new prefix reach info to all routers in AS1 1b can then re-advertise new reachability info to AS2 over 1bto-2a ebgp session When router learns of new prefix, creates entry for prefix in its forwarding table. 3c 3a 3b AS3 1a AS1 1c 1d 1b 2a AS2 2c 2b ebgp session ibgp session 10-30

31 Path attributes & BGP routes When advertising a prefix, advert includes BGP attributes. prefix + attributes = route Two important attributes: AS-PATH: contains ASs through which prefix advertisement has passed: AS 67 AS 17 NEXT-HOP: Indicates specific internal-as router to next-hop AS. (There may be multiple links from current AS to next-hop- AS.) When gateway router receives route advertisement, uses import policy to accept/decline

32 BGP route selection Router may learn about more than one route to some prefix. Router must select route. Elimination rules: 1. Local preference value attribute: policy decision 2. Shortest AS-PATH 3. Closest NEXT-HOP router: hot potato routing 4. Additional criteria 10-32

33 BGP messages BGP messages exchanged using TCP. BGP messages: OPEN: opens TCP connection to peer and authenticates sender UPDATE: advertises new path (or withdraws old) KEEPALIVE keeps connection alive in absence of UPDATES; also ACKs OPEN request NOTIFICATION: reports errors in previous msg; also used to close connection 10-33

34 Recap Distance vector link cost changes Count-to-infinity, poisoned reverse Hierarchical routing Autonomous Systems Inter-AS, Intra-AS routing Routing protocols Intra-AS RIP OSPF Inter-AS BGP 10-34

35 Next time BGP policy Broadcast / multicast routing ATM / MPLS Link virtualization Router internals 10-35

### Chapter 4: Network Layer

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 IPv4 addressing ICMP IPv6 4.5 Routing algorithms

### Hierarchical Routing. Our routing study thus far - idealization all routers identical network flat not true in practice

Hierarchical Routing Our routing study thus far - idealization all routers identical network flat not true in practice scale: with 200 million destinations: can t store all destinations in routing tables!

### Hierarchical Routing. Our routing study thus far - idealization all routers identical network flat not true in practice

Hierarchical Routing Our routing study thus far - idealization all routers identical network flat not true in practice scale: with 200 million destinations: can t store all destinations in routing tables!

### Chapter 4: Network Layer, partb

Chapter 4: Network Layer, partb The slides are adaptations of the slides available by the main textbook authors, Kurose&Ross Network Layer 4-1 Interplay between routing, forwarding routing algorithm local

### CSCE 463/612 Networks and Distributed Processing Spring 2018

CSCE 463/612 Networks and Distributed Processing Spring 2018 Network Layer IV Dmitri Loguinov Texas A&M University April 12, 2018 Original slides copyright 1996-2004 J.F Kurose and K.W. Ross 1 Chapter

### Inter-AS routing and BGP. Network Layer 4-1

Inter-AS routing and BGP Network Layer 4-1 Review: intra-as routing v Also known as interior gateway protocols (IGP) v Most common intra-as routing protocols: RIP: Routing Information Protocol, distance

### Internet rou)ng. V. Arun CS491G: Computer Networking Lab University of MassachuseFs Amherst

Internet rou)ng V. Arun CS491G: Computer Networking Lab University of MassachuseFs Amherst Slide material copyright 1996-2013 J.F Kurose and K.W. Ross, All Rights Reserved Graph abstraction 5 graph: G

### Chapter 4 Network Layer

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). They re in PowerPoint form so you see the animations; and

### CS 43: Computer Networks Internet Routing. Kevin Webb Swarthmore College November 16, 2017

CS 43: Computer Networks Internet Routing Kevin Webb Swarthmore College November 16, 2017 1 Hierarchical routing Our routing study thus far - idealization all routers identical network flat not true in

### Network Layer: Routing

Network Laer: Routing Instructor: Anirban Mahanti Office: ICT 74 Email: mahanti@cpsc.ucalgar.ca Class Location: ICT Lectures: MWF :00 :0 hours Notes derived Computer Networking: A Top Down Approach Featuring

### Chapter 4: Network Layer. TDTS06 Computer networks. Subnets. Subnets. Subnets. IP Addressing: introduction

hapter 4: Network Layer TDTS06 omputer s Lecture 6: Network layer III Routing in the Internet Jose M. Peña, jospe@ida.liu.se ID/DIT, LiU 2009-09-16 4. 1 Introduction 4.2 Virtual circuit and datagram s

### CS 457 Networking and the Internet. Shortest-Path Problem. Dijkstra s Shortest-Path Algorithm 9/29/16. Fall 2016

9/9/6 S 7 Networking and the Internet Fall 06 Shortest-Path Problem Given: network topology with link costs c(x,y): link cost from node x to node y Infinity if x and y are not direct neighbors ompute:

### CMPE 150/L : Introduction to Computer Networks. Chen Qian Computer Engineering UCSC Baskin Engineering Lecture 14

CMPE 150/L : Introduction to Computer Networks Chen Qian Computer Engineering UCSC Baskin Engineering Lecture 14 1 Two notes on routing algorithm Do not believe ou can understand an routing protocol, e.g.,

### Chapter 4: Network Layer

Chapter 4: Network Laer 4. Introduction 4. Virtual circuit and datagram networks 4. What s inside a router 4.4 IP: Internet Protocol Datagram format IPv4 addressing ICMP IPv6 4. Routing algorithms Link

### Chapter 5 Network Layer: The Control Plane

Chapter 5 Network Layer: The Control Plane A note on the use of these Powerpoint slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you

### COMP211 Chapter 5 Network Layer: The Control Plane

COMP211 Chapter 5 Network Layer: The Control Plane All material copyright 1996-2016 J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top Down Approach 7 th edition Jim Kurose, Keith

### Computer Networks. Instructor: Niklas Carlsson

Computer Networks Instructor: Niklas Carlsson Email: niklas.carlsson@liu.se Notes derived Computer Networking: A Top Down Approach, b Jim Kurose and Keith Ross, Addison-Wesle. The slides are adapted and

### Chapter 4: outline. 4.5 routing algorithms link state distance vector hierarchical routing. 4.6 routing in the Internet RIP OSPF BGP

Chapter 4: outline 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 addressing ICMP IPv6 4.5 routing algorithms link

### 5.1 introduction 5.5 The SDN control 5.2 routing protocols plane. Control Message 5.3 intra-as routing in Protocol the Internet

Chapter 5: outline 5.1 introduction 5.5 The SDN control 5.2 routing protocols plane link state 5.6 ICMP: The Internet distance vector Control Message 5.3 intra-as routing in Protocol the Internet t 5.7

### UNIT III THE NETWORK LAYER

UNIT III THE NETWORK LAYER Introduction-Virtual Circuit and Datagram Networks- Inside a Router- The Internet Protocol (IP): Forwarding and Addressing in the Internet-Routing Algorithms Routing in the Internet-Broadcast

### Inter-Domain Routing: BGP

Inter-Domain Routing: BGP Richard T. B. Ma School of Computing National University of Singapore CS 3103: Compute Networks and Protocols Inter-Domain Routing Internet is a network of networks Hierarchy

### Network Layer: Control Plane 5-2

Network Laer: Control Plane EECS34 8-03-05 4- Chapter 5: network laer control plane chapter goals: understand principles behind network control plane traditional routing algorithms SDN controlllers Internet

### Interplay between routing, forwarding

Chapter 4: outline 4. introduction 4. virtual circuit and datagram networks 4. what s inside a router 4.4 IP: Internet Protocol datagram format IPv4 addressing ICMP IPv6 4.5 routing algorithms link state

### CS 204: BGP. Jiasi Chen Lectures: MWF 12:10-1pm Humanities and Social Sciences

CS 204: BGP Jiasi Chen Lectures: MWF 12:10-1pm Humanities and Social Sciences 1403 http://www.cs.ucr.edu/~jiasi/teaching/cs204_spring17/ 1 Overview AS relationships Inter-AS routing BGP Example Paper discussion

### CSC 4900 Computer Networks: Routing Algorithms

CSC 4900 Computer Networks: Routing Algorithms Professor Henry Carter Fall 2017 Last Time Subnets provide granularity for address assignment and ease management. What is 192.168.8.0? 192.168.32.0? 192.168.8.0:

### CMPE 80N: Introduction to Networking and the Internet. Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 20

CMPE 80N: Introduction to Networking and the Internet Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 0 Announcements Final exam: June 7 th at 4pm. Comprehensive. Photo id required.

### Data Communications & Networks. Session 7 Main Theme Networks: Part II Circuit Switching, Packet Switching, The Network Layer

Data Communications & Networks Session 7 Main Theme Networks: Part II Circuit Switching, Packet Switching, The Network Layer Dr. Jean-Claude Franchitti New York University Computer Science Department Courant

### Network Layer: Routing. Routing. Routing protocol. Graph abstraction for routing algorithms: graph nodes are routers graph edges are physical links

Network Layer: Routing A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you can add, modify, and delete

### Initial motivation: 32-bit address space soon to be completely allocated. Additional motivation:

IPv6 Initial motivation: 3-bit address space soon to be completel allocated. Additional motivation: Header format helps speed processing/forwarding Header changes to facilitate QoS (service classes) Reduction

### CS321: Computer Networks Unicast Routing

CS321: Computer Networks Unicast Routing Dr. Manas Khatua Assistant Professor Dept. of CSE IIT Jodhpur E-mail: manaskhatua@iitj.ac.in Introduction The goal of the network layer is deliver a datagram from

### EECS 3214: Computer Networks Protocols and Applications

EECS 3214: Computer Networks Protocols and Applications Suprakash Datta datta@cse.yorku.ca Office: CSEB 3043 Phone: 416-736-2100 ext 77875 Course page: http://www.cse.yorku.ca/course/3214 These slides

### Department of Computer and IT Engineering University of Kurdistan. Computer Networks II Border Gateway protocol (BGP) By: Dr. Alireza Abdollahpouri

Department of Computer and IT Engineering University of Kurdistan Computer Networks II Border Gateway protocol (BGP) By: Dr. Alireza Abdollahpouri Internet structure: network of networks local ISP Tier

### Dynamic Routing. The Protocols

Dynamic Routing The Protocols Desirable Characteristics of Dynamic Routing Automatically detect and adapt to topology changes Provide optimal routing Scalability Robustness Simplicity Rapid convergence

### Shortest Paths Algorithms and the Internet: The Distributed Bellman Ford Lecturer: Prof. Chiara Petrioli

Shortest Paths Algorithms and the Internet: The Distributed Bellman Ford Lecturer: Prof. Chiara Petrioli Dipartimento di Informatica Rome University La Sapienza G205: Fundamentals of Computer Engineering

### CNT Computer and Network Security: BGP Security

CNT 5410 - Computer and Network Security: BGP Security Professor Kevin Butler Fall 2015 Internet inter-as routing: BGP BGP (Border Gateway Protocol): the de facto standard BGP provides each AS a means

### ETSF05/ETSF10 Internet Protocols Routing on the Internet

ETSF05/ETSF10 Internet Protocols Routing on the Internet 2014, (ETSF05 Part 2), Lecture 1.1 Jens Andersson Circuit switched routing 2014 11 05 ETSF05/ETSF10 Internet Protocols 2 Packet switched Routing

### EE 122: Intra-domain routing

EE : Intra-domain routing Ion Stoica September 0, 00 (* this presentation is based on the on-line slides of J. Kurose & K. Rose) Internet Routing Internet organized as a two level hierarchy First level

### The Internet network layer

The Internet network layer host, router network layer functions: transport layer: TCP, UDP network layer routing protocols path selection RIP, OSPF, BGP forwarding table link layer physical layer IP protocol

### Module 3 Network Layer CS755! 3-1!

Module 3 Network Layer CS755 3-1 Please note: Most of these slides come from this book. Note their copyright notice below A note on the use of these ppt slides: We re making these slides freely available

### Internet inter-as routing: BGP

Internet inter-as routing: BGP BGP (Border Gateway Protocol): the de facto standard BGP provides each AS a means to: 1. Obtain subnet reachability information from neighboring ASs. 2. Propagate the reachability

### Network service model. Network service model. Network Layer (part 1) Virtual circuits. By the end of this lecture, you should be able to.

Netork Layer (part ) y the end of this lecture, you should be able to. xplain the operation of distance vector routing algorithm xplain shortest path routing algorithm escribe the major points of RIP and

### Routing Protocols. Autonomous System (AS)

Routing Protocols Two classes of protocols: 1. Interior Routing Information Protocol (RIP) Open Shortest Path First (OSPF) 2. Exterior Border Gateway Protocol (BGP) Autonomous System (AS) What is an AS?

### Computer Networking. Intra-Domain Routing. RIP (Routing Information Protocol) & OSPF (Open Shortest Path First)

Computer Networking Intra-Domain Routing RIP (Routing Information Protocol) & OSPF (Open Shortest Path First) IP Forwarding The Story So Far IP addresses are structured to reflect Internet structure IP

### Network Protocols. Routing. TDC375 Winter 2002 John Kristoff - DePaul University 1

Network Protocols Routing TDC375 Winter 2002 John Kristoff - DePaul University 1 IP routing Performed by routers Table (information base) driven Forwarding decision on a hop-by-hop basis Route determined

### COMP 3331/9331: Computer Networks and Applications

OMP /9: omputer Networks and pplications Week 9 Network Layer: Routing Reading Guide: hapter 4: Sections 4.5 Network Layer nnouncements v Labs Lab 4 ongestion ontrol Lab 5 Simple Router (start up for ssignment,

### CSCE 463/612 Networks and Distributed Processing Spring 2018

CSCE 463/612 Networks and Distributed Processing Spring 2018 Network Layer V Dmitri Loguinov Texas A&M University April 17, 2018 Original slides copyright 1996-2004 J.F Kurose and K.W. Ross Chapter 4:

### Routing on the Internet! Hierarchical Routing! The NSFNet 1989! Aggregate routers into regions of autonomous systems (AS)!

Routing on the Internet! Hierarchical Routing! Aggregate routers into regions of autonomous systems (AS)! In the beginning there was the ARPANET:! route using GGP (Gateway-to-Gateway Protocol)," a distance

### Routing on the Internet. Routing on the Internet. Hierarchical Routing. Computer Networks. Lecture 17: Inter-domain Routing and BGP

Routing on the Internet Computer Networks Lecture 17: Inter-domain Routing and BGP In the beginning there was the ARPANET: route using GGP (Gateway-to-Gateway Protocol), a distance vector routing protocol

### Routing Protocols. The routers in an internet are responsible for receiving and. forwarding IP datagrams through the interconnected set of

Routing Protocols MITA DUTTA The routers in an internet are responsible for receiving and forwarding IP datagrams through the interconnected set of sub-networks from source to destination. Routing protocols

### Routing(2) Inter-domain Routing

Routing(2) Inter-domain Routing Information Network I Youki Kadobayashi 1 Outline! Distance vector routing! Link state routing! IGP and EGP Intra-domain routing protocol, inter-domain routing protocol!

### Inter-domain Routing. Outline. Border Gateway Protocol

Inter-domain Routing Outline Border Gateway Protocol Internet Structure Original idea CS 640 2 Internet Structure Today CS 640 3 Route Propagation in the Internet Autonomous System (AS) corresponds to

### COMPSCI 314: IP routing

COMPSCI 314: IP routing Nevil Brownlee with thanks to Brian Carpenter n.brownlee@auckland.ac.nz Lecture Topics Routing the problem Approaches (K&R 4.1.1) Shay 10.4 Algorithms (K&R 4.) Dijkstra (K&R 4..1)

### Chapter 4 Network Layer

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). They re in PowerPoint form so you see the animations; and

### OSPF (Open Shortest Path First)

OSPF (Open Shortest Path First) Open : specification publicly available RFC 1247, RFC 2328 Working group formed in 1988 Goals: Large, heterogeneous internetworks Uses the Link State algorithm Topology

### CS 457 Networking and the Internet. The Global Internet (Then) The Global Internet (And Now) 10/4/16. Fall 2016

CS 457 Networking and the Internet Fall 2016 The Global Internet (Then) The tree structure of the Internet in 1990 The Global Internet (And Now) A simple multi-provider Internet 1 The Global Internet Some

### Computer Networking. Rou1ng Algorithms. Rou1ng Algorithms. Interplay between rou1ng, forwarding. routing algorithm

Computer Networking Interpla between roung, forwarding routing algorithm local forwarding table header alue output link 000 00 0 00 alue in arriing packet s header 0 Graph abstracon Graph: G = (N,E) u

### CS 640: Introduction to Computer Networks. Intra-domain routing. Inter-domain Routing: Hierarchy. Aditya Akella

CS 640: Introduction to Computer Networks Aditya Akella Lecture 11 - Inter-Domain Routing - BGP (Border Gateway Protocol) Intra-domain routing The Story So Far Routing protocols generate the forwarding

### Review for Chapter 4 R1,R2,R3,R7,R10,R11,R16,R17,R19,R22,R24, R26,R30 P1,P2,P4,P7,P10,P11,P12,P14,P15,P16,P17,P22,P24,P29,P30

Review for Chapter 4 R1,R2,R3,R7,R10,R11,R16,R17,R19,R22,R24, R26,R30 P1,P2,P4,P7,P10,P11,P12,P14,P15,P16,P17,P22,P24,P29,P30 R1. Let s review some of the terminology used in this textbook. Recall that

### CSC 401 Data and Computer Communications Networks

CSC 40 Data and Computer Communications Networks Network Layer NAT, Routing, Link State, Distance Vector Prof. Lina Battestilli Fall 07 Chapter 4 Outline Network Layer: Data Plane 4. Overview of Network

### cs/ee 143 Communication Networks

cs/ee 143 Communication Networks Chapter 5 Routing Text: Walrand & Parakh, 2010 Steven Low CMS, EE, Caltech Warning These notes are not self-contained, probably not understandable, unless you also were

### Chapter 4 Network Layer

Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 Slides adopted from original ones proided by the textbook authors. Network

### Chapter 4 Network Layer

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). They re in PowerPoint form so you can add, modify, and delete

### Chapter 7 Routing Protocols

Chapter 7 Routing Protocols Nonroutable Protocols In the early days of networking, networks were small collections of computers linked together For the purposes of sharing information and expensive peripherals

### Architectures and Protocols for Integrated Networks. Intra-domain and Inter-domain Routing Protocols

Architectures and Protocols for Integrated Networks Intra-domain and Inter-domain Routing Protocols How is the routing table built? Path finding Paths from a device to any other device. Aggregated according

### OSPF (Open Shortest Path First)

OSPF (Open Shortest Path First) Open : specification publicly available RFC 1247, RFC 2328 Working group formed in 1988 Goals: Large, heterogeneous internetworks Uses the Link State algorithm Topology

### Module 8. Routing. Version 2 ECE, IIT Kharagpur

Module 8 Routing Lesson 27 Routing II Objective To explain the concept of same popular routing protocols. 8.2.1 Routing Information Protocol (RIP) This protocol is used inside our autonomous system and

### Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley

Intra- AS Rou-ng h0p://kcd.com/85/ Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesle Some materials copright 1996-2012 J.F Kurose and K.W. Ross, All Rights Reserved

### Forelesning nr 5, m andag 16. sept em ber Chapt er 4, Net w ork Layer and Rout ing. Datakom høsten

Dat ak om m unik asjon høst en 2002 Forelesning nr 5, m andag 16. sept em ber Chapt er 4, Net w ork Layer and Rout ing Datakom høsten 2002 1 Øvingsoppgaver ] Oppgaver 1 CIDR og subnetting ] IP Address

### Routing Protocols of IGP. Koji OKAMURA Kyushu University, Japan

Routing Protocols of IGP Koji OKAMURA Kyushu University, Japan Routing Protocol AS (Autonomous System) Is operated autonomous in the organization. 6bit IGP (Interior Gateway Protocol) Routing Control inside

### Top-Down Network Design, Ch. 7: Selecting Switching and Routing Protocols. Top-Down Network Design. Selecting Switching and Routing Protocols

Top-Down Network Design Chapter Seven Selecting Switching and Routing Protocols Copyright 2010 Cisco Press & Priscilla Oppenheimer 1 Switching 2 Page 1 Objectives MAC address table Describe the features

### Politecnico di Milano Scuola di Ingegneria Industriale e dell Informazione. 06 Routing protocols. Fundamentals of Communication Networks

Politecnico di Milano Scuola di Ingegneria Industriale e dell Informazione 06 Routing protocols Fundamentals of Communication Networks Topics o Routing basics o Routing algorithms (Bellman-Ford, Dijkstra)

### Internetworking Part 2

CMPE 344 Computer Networks Spring 2012 Internetworking Part 2 Reading: Peterson and Davie, 3.2, 4.1 19/04/2012 1 Aim and Problems Aim: Build networks connecting millions of users around the globe spanning

### Telecomunicazioni. Docente: Andrea Baiocchi DIET - Stanza 107, 1 piano palazzina P. Piga Via Eudossiana 18

University of Roma La Sapienza Telecomunicazioni Docente: Andrea Baiocchi DIET - Stanza 07, piano palazzina P. Piga Via Eudossiana 8 E-mail: andrea.baiocchi@uniroma.it Corso di Laurea in Ingegneria Gestionale

### Introduction to Routing

1 Introduction to Routing Session 2 Presentation_ID.scr 1 Agenda Addressing Concepts Routing Protocols Statics and Defaults 3 ISO OSI Reference Model Routing Information Protocol (RIP and RIPv2) L7 L6

### Networking: Network layer

control Networking: Network layer Comp Sci 3600 Security Outline control 1 2 control 3 4 5 Network layer control Outline control 1 2 control 3 4 5 Network layer purpose: control Role of the network layer

### Chapter 4 Network Layer

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). They re in PowerPoint form so you see the animations; and

Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ Chapter 4 Network Layer Computer Networking: A Top Down Approach, 5 th edition. Jim Kurose, Keith Ross Addison-Wesley, April 2009. All

### ECE 428 Internet Protocols (Network Layer: Layer 3)

ECE 428 Internet Protocols (Network Layer: Layer 3) 1 Done so far MAC protocols (with PHYsical layer) Transport bits from one node to another. Key element: Determine WHEN to transmit DLC protocol (running

### Routing Protocol Type Primarily IGP or EGP RIP Distance-Vector IGP EIGRP OSPF IS-IS BGP

Appendix D Memory Tables Chapter 1 Table 1-2 Routing Protocol Characteristics Routing Protocol Type Primarily IGP or EGP RIP Distance-Vector IGP EIGRP OSPF IS-IS BGP Chapter 3 Table 3-2 Hexadecimal/Binary

### KR_4. Strato di rete

INFO-COM Dpt. Dipartimento di Scienza e Tecnica dell Informazione e della Comunicazione Università degli Studi di Roma La Sapienza KR_4. Strato di rete TELECOMUNICAZIONI per Ingegneria Informatica (secondo

### Announcement. Project 2 extended to 2/20 midnight Project 3 available this weekend Homework 3 available today, will put it online

Announcement Project 2 extended to 2/20 midnight Project 3 available this weekend Homework 3 available today, will put it online Outline Introduction and Network Service Models Routing Principles Link

### Internet Interconnection Structure

Internet Interconnection Structure Basic Concepts (1) Internet Service Provider (ISP) Provider who connects an end user customer with the Internet in one or few geographic regions. National & Regional

Link State Routing In particular OSPF Karst Koymans Informatics Institute University of Amsterdam (version 16.3, 2017/03/09 11:25:31) Tuesday, March 7, 2017 Link State Protocols Basic ideas Problems and

### CS519: Computer Networks. Lecture 4, Part 5: Mar 1, 2004 Internet Routing:

: Computer Networks Lecture 4, Part 5: Mar 1, 2004 Internet Routing: AS s, igp, and BGP As we said earlier, the Internet is composed of Autonomous Systems (ASs) Where each AS is a set of routers, links,

### COMP/ELEC 429 Introduction to Computer Networks

COMP/ELEC 429 Introduction to Computer Networks Lecture 11: Inter-domain routing Slides used with permissions from Edward W. Knightly, T. S. Eugene Ng, Ion Stoica, Hui Zhang T. S. Eugene Ng eugeneng at

### Overview. Problem: Find lowest cost path between two nodes Factors static: topology dynamic: load

Dynamic Routing Overview Forwarding vs Routing forwarding: to select an output port based on destination address and routing table routing: process by which routing table is built Network as a Graph C

### Introduction to IP Routing. Geoff Huston

Introduction to IP Routing Geoff Huston Routing How do packets get from A to B in the Internet? A Internet B Connectionless Forwarding Each router (switch) makes a LOCAL decision to forward the packet

### Chapter 4 Network Layer

Chapter 4 Network Layer Modified form the following All material copyright 1996-2012 J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith

### Routing. Routing. Overview. Overview. Routing vs. Forwarding. Why Routing

Routing Dr. Arjan Durresi Department of Computer Science Louisiana State University Overview Routing vs. Forwarding Routing Algorithms, Distance Vector, Link State Dijkstra s Algorithm ARPAnet Routing

### Distance Vector: Link Cost Changes. Interdomain Routing. Distance Vector: Count to Infinity Problem. Distance Vector: Poisoned Reverse

istance Vector: Link ost hanges 7 loop: Interdomain Routing 8 wait (until sees a link cost change to neighbor V 9 or until receives update from neighbor V) 0 if ((, V) changes by d) for alldestinations

### Introduction to OSPF

Introduction to OSPF 1 OSPF Open Shortest Path First Link state or SPF technology Developed by OSPF working group of IETF (RFC 1247) OSPFv2 standard described in RFC2328 Designed for: TCP/IP environment

### Chapter IV: Network Layer

Chapter IV: Network Laer UG3 Computer Communications & Networks (COMN) Mungjin Lee mungjin.lee@ed.ac.uk Slides copright of Kurose and Ross IP addresses: how to get one? Q: How does a host get IP address?

### Presentation On Routing Protocol

Presentation On Routing Protocol By Muhammad Siddiqui ISNM2003 28th Jan 2004 Networks A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area

### ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE. Link State Routing. Jean Yves Le Boudec 2015

ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE Link State Routing Jean Yves Le Boudec 2015 1 Contents 1. Link state 2. OSPF and Hierarchical routing with areas 3. Dynamic metrics and Braess paradox 2 1. Link

### IP Forwarding Computer Networking. Graph Model. Routes from Node A. Lecture 11: Intra-Domain Routing

IP Forwarding 5-44 omputer Networking Lecture : Intra-omain Routing RIP (Routing Information Protocol) & OSPF (Open Shortest Path First) The Story So Far IP addresses are structured to reflect Internet

### Interdomain Routing Reading: Sections P&D 4.3.{3,4}

Interdomain Routing Reading: Sections P&D 4.3.{3,4} EE122: Intro to Communication Networks Fall 2006 (MW 4:00-5:30 in Donner 155) Vern Paxson TAs: Dilip Antony Joseph and Sukun Kim http://inst.eecs.berkeley.edu/~ee122/

### Introduction to OSPF

Introduction to OSPF ISP/IXP Workshops ISP/IXP Workshops 1999, Cisco Systems, Inc. 1 OSPF Dynamic Routing Protocol Link State technology Runs over IP, protocol 89 Designed by IETF for TCP/IP Supports VLSM

### Dynamics of Hot-Potato Routing in IP Networks

Dynamics of Hot-Potato Routing in IP Networks Jennifer Rexford AT&T Labs Research http://www.research.att.com/~jrex Joint work with Renata Teixeira (UCSD), Aman Shaikh (AT&T), and Timothy Griffin (Intel)