Today's Topic This part of the lecture is about Service(s) & - PowerPoint PPT Presentation

Lic.(Tech.) Marko Luoma (1/30) Lic.(Tech.) Marko Luoma (2/30) Today's Topic This part of the lecture is about Service(s) & � HSS'2004: Quality of Service in Internet Differentiated Services architecture Customers Service Level Agreement [SLA] Service Architecture Service Level Lecture I: Differentiated Services Specification TC [SLS] PDB Conditioning Actions Relay actions PHB 9.8.2003 Policy Information Management Information Base [PIB] Base [MIB] Network Device(s) Input Processors Output Processors Lic.(Tech.) Marko Luoma (3/30) Lic.(Tech.) Marko Luoma (4/30) Internet today Best Effort Service Current Internet: � Ideological background � � 'Best Effort'-service � Network is used only with good intent and need � Equal opportunities (competitive resource sharing) Turned to battle field � � Equal missouries (uncontrolled delays and packet losses) � As fast and soon as possible Trend: � Customer model � � Internet is becoming commercial network with services leveling the � Access to the 'Internet' commercial incentives � Possibility to use shared information resources Basis � � Connectionless packet forwarding

Lic.(Tech.) Marko Luoma (5/30) Lic.(Tech.) Marko Luoma (6/30) Best Effort Router Differentiated Services Packets are forwarded based on their Is combination of mechanisms presented � � destination address in last wednesday Policy Control Admission Control Scheduling and queueing Physically, nothing more than Best Effort � � Control Plane � FCFS Logically, number of parallel Best Effort � networks Equal treatment Scheduling Differentiated Service Models � Services Packet is destined to one of the parallel � Routing networks Queue Management Application demands � Packet per packet processed quality Forwarder Scheduler of service User Plane � Connectionless architecture is still preserved Each parallel network uses same routing � topology (not neccesarily) Lic.(Tech.) Marko Luoma (7/30) Lic.(Tech.) Marko Luoma (8/30) Differentiated Services DiffServ Router Identification of which parallel best � Packets are forwarded based on the � Versio Hlen TOS Length effor network packet is destined, is destination address and class Ident Flags Offset coded in each packet TTL Protocol Checksum information SourceAddr � IPv4 ToS field is reformatted Scheduling and queueing is done � Control Plane DestinationAddr � No routing nor precedence based on the class information Options (variable) PAD Policy � Generic class identifier Control Routing Prec. TOS 0 Classifier Forwarder Scheduler DSCP CU User Plane

Lic.(Tech.) Marko Luoma (9/30) Lic.(Tech.) Marko Luoma (10/30) DiffServ Router DiffServ Conditioner DiffServ router has one additional Traffic Conditioner is constructed a � Meters � � element in datapath compared to set of � Responsible of rate metering basic Best Effort router: � Classifiers of logical streams � Conditioner � Responsible of logical � Markers Control Plane separation of packet streams Control plane of a DiffServ router � � Responsible of actions based Policy has one extra element ie policy on metering results and Control controller, which is responsible of Routing predefined thresholds internal management and Traffic Conditioning Block [TCB] configuration of conditioner and Conditioner Forwarder Scheduler FA Conditioning BA Conditioning scheduler FA BA Marking User Plane Marking Marking Marking 1:M BA 1:N FA MF classifier FA Metering BA classifier BA Metering Shaping Shaping Dropping Dropping Lic.(Tech.) Marko Luoma (11/30) Lic.(Tech.) Marko Luoma (12/30) DiffServ PHB DiffServ terminology Per hop behavior is block which � Workload in DiffServ is divided Edge routers are responsible of � � EF PHB contains queue management methods between two inherently different conditioning actions which required to implement desired types of routers eventually determine the logical AF1 AF13 AF12 AF11 service network where packet is to be � Edge routes AF2 AF23 AF22 AF21 forwarded � Queues � Core routers � Queue space management Edge routers are on the domain edge � P drop Max OUT Max IN algorithms interfacing 1 � Schedulers Operator 1 Operator 2 � Customer DS Access router � Other ISP Max P[OUT] DS Core router Max P[IN] DS border router AVG Min OUT Min IN Max QSIZE

Lic.(Tech.) Marko Luoma (13/30) Lic.(Tech.) Marko Luoma (14/30) DiffServ terminology DiffServ Logical network is concatenation of PHBs which interact together. Service decission in edge router can Core routers do nothing but � � � be based on: forwarding of packets based on the These logical networks have target service called per domain behavior (PDB). � extra information in DSCP field of � Metering result Target service is loose definition for the goal of the logical network when it is � packets � Rate based provisioned and configured in a predefined way. Requires � � Predefined set of filters Edge router chooses PDB for each packet which comes from the customer � � Classifier to detect DSCP fields � IP address ie customer � Marks packet with DSCP of PHB used to implement PDB � PHB to implement forwarding � TCP/UDP port ie application behaviors � User request � Precoded DSCP � RSVP signaling Lic.(Tech.) Marko Luoma (15/30) Lic.(Tech.) Marko Luoma (16/30) Service classes Expedited Forwarding (EF) [RFC2598] Differentiated Services is alligned � Leased line emulation � Egress point between Best Effort and IntServ � From destined ingress point to Variability of SLA There is counterpart for each IntServ destined egress point � service class in DiffServ IntServ IntServ Per Connection � End-to-end service with GS CL � Guaranteed Service <-> � Low loss Expedited Service Poorly � Low latency provisioned EF � Controlled Load <-> Assured � Low jitter Poorly Forwarding EF + AF + Dynamic provisioned AF BB BB � Assured bandwidth EF AF BE Static Ingress point Guarantee of QoS Strict Firm Relative Loose

Lic.(Tech.) Marko Luoma (17/30) Lic.(Tech.) Marko Luoma (18/30) EF EF Service commitment is only assured Leased Line Control of service guarantee � � � � Resources inside EF class are � Dedicated resources � Access control shared � Rate control � Full isolation � Amount of other EF traffic � No room for overflow � User control influences to the value of � Provisioning Virtual Leased Line � delay, jitter and loss � At least sum of contracted rates is � Shared resources � Path is freely chosen allocated to EF traffic � Partial isolation � Delay constraint can not be � High priority in the network � From other than leased held as the delay of paths are � Scheduled ahead of other traffic line traffic inherently different � Starvation of lower priorities ? � Can accommodate overflow � No reservation is done � Only small fraction of total � Vague service guarantee � Provisioning is in the key link capacity (10-30%) role Lic.(Tech.) Marko Luoma (19/30) Lic.(Tech.) Marko Luoma (20/30) Assured Forwarding (AF) [RFC2597] AF Four independent service classes Precedence No end-to-end semantics � � Precedence -> drop probability � All packets of a flow are � Service can be deployed as any destined to one of the classes to any service AF13 AF23 AF33 AF43 AF13 AF23 AF33 AF43 � No association of service level � Like today What is the between the classes AF12 AF22 AF32 AF42 � Uncontrollable resource usage AF12 AF22 AF32 AF42 differentiation ? Three precedences in each class inside the network � AF11 AF21 AF31 AF41 AF11 AF21 AF31 AF41 � Very vague QoS � Flow can have packets with different precedences Class � Class / precedence in contrast to Class � Order of packets in al flow is not service guarantee ??? allowed to change � Precedence can not be used to scheduling decissions inside the class