Todays Topic This lecture is about Differentiated Service(s) & - PowerPoint PPT Presentation

Lic.(Tech.) Marko Luoma (1/20) Lic.(Tech.) Marko Luoma (2/20) Today’s Topic This lecture is about Differentiated Service(s) & � Services architecture Customers Service Level Agreement [SLA] S−38.180 Palvelunlaatu Internetissä Service Architecture Service Level Specification BB S−38.180 Quality of Service in Internet [SLS] SLS Luento 9: Differentiated Services II Conditioning Actions Relay actions PHB Lecture 9: Differentiated Services II Policy Information Management Information Base [PIB] Base [MIB] Network Device(s) Input Processors Output Processors Lic.(Tech.) Marko Luoma (3/20) Lic.(Tech.) Marko Luoma (4/20) Best Effort semantics Differentiated Services semantics Best Effort −service Differentiated Services � � � All packets are treated equally � Packets are differentiated to N parallel Best Effort networks � Forwarding is based on the destination address � Each parallel network operates like basic Best Effort network with the exeption that there can be priorities and other semantics associated to � Packets are queued into single FIFO queue the service. � During the time of congestion packets are dropped � ’QoS’ based network service is sold to the customer � From the tail of the queue » When there is no space in the queue » When agerage queue length goes above threshold � Access to the network is sold to the customers

Lic.(Tech.) Marko Luoma (5/20) Lic.(Tech.) Marko Luoma (6/20) EF semantics AF semantics ’End−to−end’ service No end−to−end semantics Precedence −> drop probability � � � Single domain end−to−end � Service can be deployed � Quality is defined by two constrains: � Point−to−point AF13 AF23 AF33 AF43 � Provisioning � Any−to−any AF12 AF22 AF32 AF42 � Class should be provisioned � Uncontrollable resource usage with enough resources to inside the network AF11 AF21 AF31 AF41 handle worst case aggregate � Problem of commons � Sharing Class � No resource reservation for individual flows. � Under and overflows possible � Timing and delays can not be held or guaranteed Lic.(Tech.) Marko Luoma (7/20) Lic.(Tech.) Marko Luoma (8/20) What a customer wants ... End−to−end service Lets face the music What prohibits ??? � � � Customer is only interested in the perceived quality � Structure of DiffServ is based on local control (policies) � How things are rolling compared � Classification based on the policies at the edge of the network � Minute ago � Forwarding based on the policies in the core of the network � Year ago � We can stretch through single domain (ISP) with EF � Customer is not interested in the novel technology which is behind the � We may stretch through single domain (ISP) with AF service End−to−end � � This means end−to−end service quality � Is not within single ISP � It is between source and destination

Lic.(Tech.) Marko Luoma (9/20) Lic.(Tech.) Marko Luoma (10/20) Let us strech a little bit ... Still stretching ... If we want to have end−to−end Lets modify CBQ heuristics: � � semantics to the AF: � If class green is unsatisfied and � We need to control resources and class turquoise is unsatisfied but offered load hand in hand at the scale of the network only class green is unsatisfied we � Load to a single link in some allow only green to borrow. class increases Is this possible ? � Can we adjust � W 1 scheduling � Not with the logic which we W 2 W 3 � Do we need to reroute have today build inside DiffServ W 4 some of the classes � Single router does not know » Class and constraint network scale situation based routing � No state information associated Lic.(Tech.) Marko Luoma (11/20) Lic.(Tech.) Marko Luoma (12/20) Still a little bit further Bandwidth Broker What if we have intelligence (bandwidth broker) outside the network which Outside intelligence which controls the network provisioning � � would control the scheduling of classes � Makes possible to offer end−to−end semantics � Domain wide � Thats what we just talked about (however there are still some caps W 1 in the story) W 2 W 3 � Inter−domain W 4 Change w 1 to 0.4, w 2 to 0.1 w 3 to 0.2 and w 4 to 0.3 � We need to » translate domain specific service attributes at the border of two domains (pretty fixed) » Dynamically adjust resource requests to the other domain...

Lic.(Tech.) Marko Luoma (13/20) Lic.(Tech.) Marko Luoma (14/20) Inter−domain issues Other issues Inter−domain traffic forwarding is based on bilateral of multilateral peering What is potential problem in this scenario: � � agreements Corporate A � These tend to be business of lawyers and therefore rather static ISP B � 100Mbps LAN � 2.4Gbps DiffServ net � Our demand is varying rapibly and therefore we need to be dynamic � 2Mbps WAN � Peering agreements must change to more flexible � Rule of thumb: more money −> more lawyers −> more static � We need to brake that rule by defining peering more dynamically » One idea: charging should be based on the aggregate traffic in the classes and rate of change requests Lic.(Tech.) Marko Luoma (15/20) Lic.(Tech.) Marko Luoma (16/20) Other issues IntServ / DiffServ co−existence 2Mbps access link is eaily overloaded when both sides have higher capacities We need to be able to pass reservation attributes to and from IntServ cloud. � � � Access link is not DiffServ if ISP does not deliver customer premises � IntServ cloud may be equipements. � Corporation Corporate LAN may cause service degradation to the traffic passing out the � � Outbound / inbound traffic is delivered as guaranteed traffic corporate LAN » Mapping to DiffServ classes based on policy � Solution is to use some mechanism to guarantee that traffic is not degraded � Other ISP having IntServ as backbone inside high speed LAN � Mapping between IntServ and DiffServ classes � IntServ IntServ DiffServ

Lic.(Tech.) Marko Luoma (17/20) Lic.(Tech.) Marko Luoma (18/20) IntServ / DiffServ co−existence Reality check Bandwidth Broker can be used to do this also Are we rotating things back to IntServ ? � � � Edge router has dual capabilities � BB:s require knowledge from the network (offered load, provisioning) � Passes RSVP messages to the BB to be processed to the domain � By measuring itself specifig weight and filter modifications � By signaling from the users � BB:s modify conditioning and forwarding actions of network routers What is the difference to the IntServ ? � Bandwidth Broker � If we provide end−to−end service we need fixed routes and resources that at the minimum match the requirements RAR RAR RAR � We need state information somewhere COPS � Centralized − DiffServ BB:s RSVP RSVP Local Network Provider Network Local Network � Distributed − IntServ routers (IntServ) (DiffServ) (IntServ) Lic.(Tech.) Marko Luoma (19/20) Lic.(Tech.) Marko Luoma (20/20) Reality check Conclusion Is it so that we tend to re−invent the Differentiated Services is service architecture which allows to build N locically � � wheel separated Best Effort networks into a single physical network � Sometimes it may not be bad Differentiated Services provides tools to offer QoS which is only assured � thing Differentiated Services does not provide end−to−end semantics to the services � � Sometimes we dare to say it which are build upon it straight to the people End−to−end semantics are only achieved with outside intelligence − like � bandwidth brokers http://www.caspiannetworks .com