Chapter 4 Computer Networking Network Layer: ATO中DOWN APPROACH 华NTHEDITION The Data Plane KUROSE·ROSS 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 see the animations;and can add,modify. and delete slides (including this one)and slide content to suit your needs. They obviously represent a lot of work on our part.In return for use,we only ask the following: Computer If you use these slides (e.g.,in a class)that you mention their source (after all,we'd like people to use our book!) Networking:A Top If you post any slides on a ww site,that you note that they are adapted from(or perhaps identical to)our slides,and note our copyright of this Down Approach materal. 7th edition Thanks and enjoy!JFK/KWR Jim Kurose,Keith Ross A material copyight19-2016 Pearson/Addison Wesley J.F Kurose and K.W.Ross.All Rights Reserved April 2016 Network Layer:Data Plane 4-1
Computer Networking: A Top Down Approach 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 see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: ▪ If you use these slides (e.g., in a class) that you mention their source (after all, we’d like people to use our book!) ▪ If you post any slides on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright 1996-2016 J.F Kurose and K.W. Ross, All Rights Reserved 7 th edition Jim Kurose, Keith Ross Pearson/Addison Wesley April 2016 Chapter 4 Network Layer: The Data Plane Network Layer: Data Plane 4-1
Chapter 4:outline 4.I Overview of Network 4.4 Generalized Forward and SDN layer 。natch ·data plane ·action 。control plane OpenFlow examples of match- 4.2 What's inside a router plus-action in action 4.3 IP:Internet Protocol ·datagram format ·fragmentation ·lPv4 addressing ·network address translation ·IPv6 Network Layer:Data Plane 4-2
4.1 Overview of Network layer • data plane • control plane 4.2 What’s inside a router 4.3 IP: Internet Protocol • datagram format • fragmentation • IPv4 addressing • network address translation • IPv6 4.4 Generalized Forward and SDN • match • action • OpenFlow examples of matchplus-action in action Chapter 4: outline Network Layer: Data Plane 4-2
Chapter 4:network layer chapter goals: understand principles behind network layer services,focusing on data plane: network layer service models forwarding versus routing ·how a router works generalized forwarding instantiation,implementation in the Internet Network Layer:Data Plane 4-3
Chapter 4: network layer chapter goals: ▪ understand principles behind network layer services, focusing on data plane: • network layer service models • forwarding versus routing • how a router works • generalized forwarding ▪ instantiation, implementation in the Internet Network Layer: Data Plane 4-3
Network layer transport segment from ata lin sending to receiving host etwork network on sending side data link data link physical physical data link encapsulates segments physical data link data link into datagrams physical physica on receiving side,delivers network data link data link physical physical segments to transport data link layer physical application network network layer protocols data link network physical data link data link in every host,router data link physical physical router examines header fields in all IP datagrams passing through it Network Layer:Data Plane 4-4
Network layer ▪ transport segment from sending to receiving host ▪ on sending side encapsulates segments into datagrams ▪ on receiving side, delivers segments to transport layer ▪ network layer protocols in every host, router ▪ router examines header fields in all IP datagrams passing through it application transport network data link physical application transport network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical network data link physical Network Layer: Data Plane 4-4
Two key network-layer functions network-layer functions: analogy:taking a trip forwarding:move packets forwarding:process of from router's input to getting through single appropriate router output interchange routing:determine route taken by packets from routing:process of source to destination planning trip from source ·routing algorithms to destination Network Layer:Data Plane 4-5
Two key network-layer functions network-layer functions: ▪forwarding: move packets from router’s input to appropriate router output ▪routing: determine route taken by packets from source to destination • routing algorithms analogy: taking a trip ▪ forwarding: process of getting through single interchange ▪ routing: process of planning trip from source to destination Network Layer: Data Plane 4-5
Network layer:data plane,control plane Data plane Control plane local,per-router function network-wide logic determines how datagram determines how datagram is arriving on router input routed among routers along port is forwarded to end-end path from source host router output port to destination host forwarding function two control-plane approaches: traditional routing algorithms: values in arriving packet header implemented in routers software-defined networking 0111 (SDN):implemented in (remote)servers Network Layer:Data Plane 4-6
Network layer: data plane, control plane Data plane ▪ local, per-router function ▪ determines how datagram arriving on router input port is forwarded to router output port ▪ forwarding function Control plane ▪ network-wide logic ▪ determines how datagram is routed among routers along end-end path from source host to destination host ▪ two control-plane approaches: • traditional routing algorithms: implemented in routers • software-defined networking (SDN): implemented in (remote) servers 1 2 3 0111 values in arriving packet header Network Layer: Data Plane 4-6
Per-router control plane Individual routing algorithm components in each and every router interact in the control plane Routing Algorithm control plane data header plane output 0100 values in arriving packet header 0111 Network Layer:Control Plane 5-7
Per-router control plane Routing Algorithm Individual routing algorithm components in each and every router interact in the control plane data plane control plane Network Layer: Control Plane 5-7 1 2 0111 values in arriving packet header 3
Logically centralized control plane A distinct(typically remote)controller interacts with local control agents(CAs) Remote Controller control plane data plane CA values in arriving packet header 0111 Network Layer:Control Plane 5-8
data plane control plane Logically centralized control plane A distinct (typically remote) controller interacts with local control agents (CAs) Remote Controller CA CA CA CA CA Network Layer: Control Plane 5-8 1 2 0111 3 values in arriving packet header
Network service model Q:What service model for "channel"transporting datagrams from sender to receiver? example services for example services for a flow individual datagrams: of datagrams: guaranteed delivery in-order datagram guaranteed delivery with delivery less than 40 msec delay guaranteed minimum bandwidth to flow restrictions on changes in inter-packet spacing Network Layer:Data Plane 4-9
Network service model Q:What service model for “channel” transporting datagrams from sender to receiver? example services for individual datagrams: ▪ guaranteed delivery ▪ guaranteed delivery with less than 40 msec delay example services for a flow of datagrams: ▪ in-order datagram delivery ▪ guaranteed minimum bandwidth to flow ▪ restrictions on changes in inter-packet spacing Network Layer: Data Plane 4-9
Network layer service models: Network Service Guarantees Congestion Architecture Model Bandwidth Loss Order Timing feedback Internet best effort none no no no no (inferred via loss】 ATM CBR constant yesyes yes no rate congestion ATM VBR guaranteed yesyesyes no rate congestion ATM ABR guaranteed no yes no yes minimum ATM UBR none no yes no no Network Layer:Data Plane 4-10
Network layer service models: Network Architecture Internet ATM ATM ATM ATM Service Model best effort CBR VBR ABR UBR Bandwidth none constant rate guaranteed rate guaranteed minimum none Loss no yes yes no no Order no yes yes yes yes Timing no yes yes no no Congestion feedback no (inferred via loss) no congestion no congestion yes no Guarantees ? Network Layer: Data Plane 4-10