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 port routed among routers along end- is forwarded to router end path from source host to output port destination host values in arriving two control-plane approaches: packet header traditional routing algorithms: implemented in routers software-defined networking(SDN): implemented in(remote)servers Network Layer: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 Control plane ▪ network-wide logic ▪ determines how datagram is routed among routers along endend path from source host to destination host 1 2 3 0111 values in arriving packet header ▪ two control-plane approaches: • traditional routing algorithms: implemented in routers • software-defined networking (SDN): implemented in (remote) servers Network Layer: 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 output plane values in arriving packet header 0111 Network Layer:4-7
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: 4-7
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:4-8
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: 4-8
Network service model Q:What service mode/for "channel"transporting datagrams from sender to receiver? example services for example services for a flow of individual datagrams: datagrams: guaranteed delivery in-order datagram delivery guaranteed delivery with guaranteed minimum bandwidth less than 40 msec delay to flow restrictions on changes in inter- packet spacing Network Layer:4-9
Network service model 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 Q: What service model for “channel” transporting datagrams from sender to receiver? Network Layer: 4-9
Network-layer service model Network Quality of Service(QoS)Guarantees Service Architecture Model Bandwidth Loss Order Timing Internet best effort none no no no Internet "best effort"service model No guarantees on: i.successful datagram delivery to destination ii.timing or order of delivery iii.bandwidth available to end-end flow Network Layer:4-10
Network-layer service model Network Architecture Internet ATM ATM Internet Internet Service Model best effort Constant Bit Rate Available Bit Rate Intserv Guaranteed (RFC 1633) Diffserv (RFC 2475) Bandwidth none Constant rate Guaranteed min yes possible Loss no yes no yes possibly Order no yes yes yes possibly Timing no yes no yes no No guarantees on: i. successful datagram delivery to destination ii. timing or order of delivery iii. bandwidth available to end-end flow Internet “best effort” service model Quality of Service (QoS) Guarantees ? Network Layer: 4-10