Connection setup ,s 3rd important function in some network architectures: ATM, frame relay, X25 before datagrams flow, two end hosts and intervening routers establish virtual connection routers get involved network vs transport layer connection service: network: between two hosts(may also involve intervening routers in case of Vcs) transport: between two processes Network Layer 4-7
Network Layer 4-7 Connection setup ❖ 3rd important function in some network architectures: ▪ ATM, frame relay, X.25 ❖ before datagrams flow, two end hosts and intervening routers establish virtual connection ▪ routers get involved ❖ network vs transport layer connection service: ▪ network: between two hosts (may also involve intervening routers in case of VCs) ▪ transport: between two processes
Network service model Q: What service mode/ for " channel transporting datagrams from sender to receiver example services for example services for individual a flow of datagrams. datagrams: quaranteed deliver . s in-order datagram .s guaranteed delivery deliver with less than 40 msec quaranteed minimum d bandwidth to flow .. restrictions on changes in inter- packet spacing Network Layer 4-8
Network Layer 4-8 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 interpacket spacing
Network layer service models Network Service Guarantees Congestion Architecture Model Bandwidth Loss Order Timing feedback Internet best effort none no no no(inferred via loss ATM CBR constant yes yes yes no rate congestion ATM VBR guaranteed yesyes yes no rate congestion ATM ABR guaranteed no yes no yes minimum ATM UBR none yes no no Network Layer 4-9
Network Layer 4-9 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 ?
Chapter 4: outline 4.1 introduction 4.5 routing algorithms 4.2 virtual circuit and link state datagram networks distance vector 4.3 what's inside a router hierarchical routing 4.4 IP: Internet protocol 4.6 routing in the datagram format Internet IPv4 addressing RIP ICMP OSPF IPv6 BGP 4.7 broadcast and multicast routing Network Layer 4-10
Network Layer 4-10 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 Chapter 4: outline
onnection connection-ess service datagram network provides network-layer connection/ess service virtual-circuit network provides network- layer connection service ,o analogous to TCP/ UDP connecton-oriented 7 connectionless transport-layer services but a service: host-to-host no choice: network provides one or the other implementation: in network core Network Layer 4-11
Network Layer 4-11 Connection, connection-less service ❖ datagram network provides network-layer connectionless service ❖ virtual-circuit network provides networklayer connection service ❖ analogous to TCP/UDP connecton-oriented / connectionless transport-layer services, but: ▪ service: host-to-host ▪ no choice: network provides one or the other ▪ implementation: in network core