《计算机网络 Computer Networking》课程PPT教学课件（A Top Down Approach，8th edition）Chapter 5 The Network Layer - Control Plane

Chapter 5 James F.Kurose Keith W.Ross Network Layer: 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 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. COMPUTER In return for use,we only ask the following: NETWORKING If you use these slides(e.g.,in a class)that you mention their A TOP-DOWN APPROACH 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. Computer Networking:A For a revision history,see the slide note for this page. Top-Down Approach Thanks and enjoy!JFK/KWR 8th edition All material copyright 1996-2020 Jim Kurose,Keith Ross J.F Kurose and K.W.Ross,All Rights Reserved Pearson,2020

Computer Networking: A Top-Down Approach 8 th edition Jim Kurose, Keith Ross Pearson, 2020 Chapter 5 Network Layer: 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 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. For a revision history, see the slide note for this page. Thanks and enjoy! JFK/KWR All material copyright 1996-2020 J.F Kurose and K.W. Ross, All Rights Reserved

Network layer control plane:our goals -understand principles instantiation,implementation behind network control in the Internet: plane: ·OSPE,BGP traditional routing algorithms OpenFlow,ODL and ONOS ·SDN controllers controllers 。network management,. Internet Control Message configuration Protocol:ICMP ·SNMP,YANG/NETCONF Network Layer:5-2

Network layer control plane: our goals ▪understand principles behind network control plane: • traditional routing algorithms • SDN controllers • network management, configuration ▪ instantiation, implementation in the Internet: • OSPF, BGP • OpenFlow, ODL and ONOS controllers • Internet Control Message Protocol: ICMP • SNMP, YANG/NETCONF Network Layer: 5-2

Network layer:"control plane"roadmap ■introduction ■routing protocols ■link state ■distance vector intra-ISP routing:OSPF routing among ISPs:BGP network management, -SDN control plane configuration Internet Control Message ·SNMP Protocol ·NETCONF/YANG Network Layer:5-3

Network layer: “control plane” roadmap ▪ network management, configuration • SNMP • NETCONF/YANG ▪ introduction ▪ routing protocols ▪ link state ▪ distance vector ▪ intra-ISP routing: OSPF ▪ routing among ISPs: BGP ▪ SDN control plane ▪ Internet Control Message Protocol Network Layer: 5-3

Network-layer functions forwarding:move packets from router's data plane input to appropriate router output routing:determine route taken by control plane packets from source to destination Two approaches to structuring network control plane: per-router control (traditional) logically centralized control (software defined networking) NetworkLayer:5-4

Two approaches to structuring network control plane: ▪ per-router control (traditional) ▪ logically centralized control (software defined networking) Network-layer functions Network Layer: 5-4 ▪ forwarding: move packets from router’s input to appropriate router output data plane control plane ▪ routing: determine route taken by packets from source to destination

Per-router control plane Individual routing algorithm components in each and every router interact in the control plane Routing Algorithm control plane data header output plane values in arriving packet header 0111 Network Layer:5-5

Per-router control plane Individual routing algorithm components in each and every router interact in the control plane Routing Algorithm data plane control plane 1 2 0111 values in arriving packet header 3 Network Layer: 5-5

Software-Defined Networking(SDN)control plane Remote controller computes,installs forwarding tables in routers Remote Controller control plane data plane CA values in arriving packet header 0111 NetworkLayer:5-6

Software-Defined Networking (SDN) control plane Remote controller computes, installs forwarding tables in routers data plane control plane Remote Controller CA CA CA CA CA 1 2 0111 3 values in arriving packet header Network Layer: 5-6

Network layer:"control plane"roadmap ■introduction routing protocols link state ■distance vector intra-ISP routing:OSPF routing among ISPs:BGP -network management, SDN control plane configuration Internet Control Message ·SNMP Protocol ·NETCONF/YANG Network Layer:5-7

Network layer: “control plane” roadmap ▪ network management, configuration • SNMP • NETCONF/YANG ▪ introduction ▪ routing protocols ▪ link state ▪ distance vector ▪ intra-ISP routing: OSPF ▪ routing among ISPs: BGP ▪ SDN control plane ▪ Internet Control Message Protocol Network Layer: 5-7

Routing protocols mobile network national or global ISP Routing protocol goal:determine good"paths (equivalently,routes), from sending hosts to receiving host, application transport through network of routers network link physical path:sequence of routers packets traverse from given initial source host to final destination host ■"good":least"cost","fastest",“least datacenter network congested" application routing:a"top-10"networking transport network challenge! enterprise link network physical NetworkLayer:5-8

Routing protocol goal: determine “good” paths (equivalently, routes), from sending hosts to receiving host, through network of routers ▪ path: sequence of routers packets traverse from given initial source host to final destination host ▪ “good”: least “cost”, “fastest”, “least congested” ▪ routing: a “top-10” networking challenge! Routing protocols mobile network enterprise network national or global ISP datacenter network application transport network link physical application transport network link physical network link physical network link physical network link physical network link physical network link physical Network Layer: 5-8

Graph abstraction:link costs Cob:cost of direct link connecting a and b 3 -W- e.g,Cwz=5,Cuz=∞ cost defined by network operator: could always be 1,or inversely related to bandwidth,or inversely related to congestion graph:G=(N,E) N:set of routers={u,v,w,x,y,z} E:set of links={(u,v以(u,x,(,x,(,w,(xw,x,y，以(w,yl,(w,z,(y,z)} Network Layer:5-9

Graph abstraction: link costs Network Layer: 5-9 u x y v w z 2 2 1 3 1 1 2 5 3 5 graph: G = (N,E) ca,b: cost of direct link connecting a and b e.g., cw,z = 5, cu,z = ∞ cost defined by network operator: could always be 1, or inversely related to bandwidth, or inversely related to congestion N: set of routers = { u, v, w, x, y, z } E: set of links ={ (u,v), (u,x), (v,x), (v,w), (x,w), (x,y), (w,y), (w,z), (y,z) }

Routing algorithm classification global:all routers have complete topolegy,link cost info ("link state"algorithms How fast dynamic:routes change do routes static:routes change more quickly change? slowly over time periodic updates or in response to link cost changes decentralized:iterative process of computation,exchange of info with neighbors routers initially only know link costs to attached neighbors "distance vector"algorithms global or decentralized information? Network Layer:5-10

Routing algorithm classification Network Layer: 5-10 global or decentralized information? global: all routers have complete topology, link cost info • “link state” algorithms decentralized: iterative process of computation, exchange of info with neighbors • routers initially only know link costs to attached neighbors • “distance vector” algorithms How fast do routes change? dynamic: routes change more quickly • periodic updates or in response to link cost changes static: routes change slowly over time