武汉大学计算机学院：《多媒体技术及应用》 Chapter 7 protocols for Qos Support

Chapter 7 Protocols for Qos Support 7.0 Increased demands o Need to incorporate bursty and stream traffic in TCP/IP architecture ◆ ncrease capacity Faster links, switches, routers Intelligent routing policies End-to-end flow control ◆ Multicasting o Quality of Service( Qos) capability o Transport protocol for streaming

1 Chapter 7 Protocols for QoS Support 7.0 Increased Demands Need to incorporate bursty and stream traffic in TCP/IP architecture Increase capacity ◼ Faster links, switches, routers ◼ Intelligent routing policies ◼ End-to-end flow control Multicasting Quality of Service (QoS) capability Transport protocol for streaming

71 Resource reservation Unicast Prevention as well as reaction to congestion required e Can do this by resource reservation ◆ Unicast End users agree on Qos for task and request from network May reserve resources a Routers pre-allocate resources If Qos not available, may wait or try at reduced Qos

2 7.1 Resource Reservation - Unicast Prevention as well as reaction to congestion required Can do this by resource reservation Unicast ◼ End users agree on QoS for task and request from network ◼ May reserve resources ◼ Routers pre-allocate resources ◼ If QoS not available, may wait or try at reduced QoS

7.1 Resource Reservation- Multicast o Generate vast traffic High volume application like video Lots of destinations ◆ Can reduce load Some members of group may not want current transmission ◆“ Channels” of video Some members may only be able to handle part of transmission Basic and enhanced video components of video stream o Routers can decide if they can meet demand 3

3 7.1 Resource Reservation – Multicast Generate vast traffic ◼ High volume application like video ◼ Lots of destinations Can reduce load ◼ Some members of group may not want current transmission  “Channels” of video ◼ Some members may only be able to handle part of transmission  Basic and enhanced video components of video stream Routers can decide if they can meet demand

Resource reservation problems on an internet Reservations must follow chan o Must interact with dynamic routin langes in route o Soft state-a set of state information at a router that expires unless refreshed End users periodically renew resource requests

4 Resource Reservation Problems on an Internet Must interact with dynamic routing ◼ Reservations must follow changes in route Soft state – a set of state information at a router that expires unless refreshed ◼ End users periodically renew resource requests

7.1.1 Resource Reser Vation Protocol (RSVP) Design Goals o Enable receivers to make reservations Different reservations among members of same multicast group a allowed o Deal gracefully with changes in group membership Dynamic reservations, separate for each member of group o Aggregate for group should reflect resources needed Take into account common path to different members of group o Receivers can select one of multiple sources(channel selection) o Deal gracefully with changes in routes Re-establish reservations o Control protocol overhead o Independent of routing protocol 5

5 7.1.1 Resource ReSerVation Protocol (RSVP) Design Goals Enable receivers to make reservations ◼ Different reservations among members of same multicast group allowed Deal gracefully with changes in group membership ◼ Dynamic reservations, separate for each member of group Aggregate for group should reflect resources needed ◼ Take into account common path to different members of group Receivers can select one of multiple sources (channel selection) Deal gracefully with changes in routes ◼ Re-establish reservations Control protocol overhead Independent of routing protocol

RSVP Characteristics Unicast and multicast Simplex f Unidirectional data flow Separate reservations in two directions ◆ Receiver initiated i Receiver knows which subset of source transmissions it wants o Maintain soft state in internet Responsibility of end users o Providing different reservation styles a Users specify how reservations for groups are aggregated Transparent operation through non-RSVP routers o Support IPv4 (Tos field) and IPv6(Flow label field) 6

6 RSVP Characteristics Unicast and Multicast Simplex ◼ Unidirectional data flow ◼ Separate reservations in two directions Receiver initiated ◼ Receiver knows which subset of source transmissions it wants Maintain soft state in internet ◼ Responsibility of end users Providing different reservation styles ◼ Users specify how reservations for groups are aggregated Transparent operation through non-RSVP routers Support IPv4 (ToS field) and IPv6 (Flow label field)

7.12 Data flows Session e Data flow identified by destination Resources allocated by router for duration of session ◆ Defined by Destination IP address ◆ Unicast or multicast IP protocol identifier ◆ TCP, UDP etc Destination port May not be used in multicast

7 7.1.2 Data Flows - Session Data flow identified by destination Resources allocated by router for duration of session Defined by ◼ Destination IP address  Unicast or multicast ◼ IP protocol identifier  TCP, UDP etc. ◼ Destination port  May not be used in multicast

Flow Descriptor ◆ Reservation Request Flow spec Desired Qos Used to set parameters in node's packet scheduler Service class, Rspec(reserve), Tspec(traffic) a Filter spec Set of packets for this reservation Source address, source prot

8 Flow Descriptor Reservation Request ◼ Flow spec  Desired QoS  Used to set parameters in node’s packet scheduler  Service class, Rspec (reserve), Tspec (traffic) ◼ Filter spec  Set of packets for this reservation  Source address, source prot

Treatment of packets of one session at one router packets that Packet scheduler s packets of one session flowspec Qas delivery (addressed to one destination) espec Best-effo other packets delivery

9 Treatment of Packets of One Session at One Router

RSVP Operation Diagram (a) Data distrubution to a multicast group b)Filtering by Source (c)Filtering a Substream (d) Merged Resv Messages 10

10 RSVP Operation Diagram