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