Integrated Services (RFC 1633) r Architecture for providing QoS guarantees to individual application sessions r Call setup: a session requiring QoS guarantees must reserve sufficient resources at each router on its path before transmitting data r A session must: m declare its QoS requirement using R-spec m characterize traffic it will send into network using T-spec r A signaling protocol is needed to carry R-spec and T-spec to routers r Router must determine whether or not it can admit the call r Router must maintain per-flow state (allocated resources, QoS requests)

RSVP r RSVP: a signaling protocol for applications to reserve resources (link bandwidth and buffer space) m Make reservations for both unicast and multicast transmissions m Receiver-oriented m Can reserve resources for heterogeneous receivers r Sender sends a PATH message to the receiver specifying R- spec and T-spec r Receiver responds with a RESV message to request resources for the flow m An intermediate router can reject or accept the request of the RESV message m A router may merge the reservation messages arriving from downstream

Intserv Service Models Guaranteed service: r Provide firm bounds on end-to- end datagram queuing delays. r Provide bandwidth guarantee r Token-bucket-policed source + WFQ WFQ token rate, r bucket size, b per-flow rate, R D = b/R max arriving traffic Controlled load service: r Provide a quality of service closely approximating the QoS that the same flow would receive from an unloaded network element. m A very high percentage of transmitted packets will be successfully delivered to the destination. m A very high percentage of transmitted packets will experience a queuing delay close to 0.

Differentiated Services (RFC 2475) Concerns with Intserv: r Scalability: router need to process resource reservations and maintaining state for each flow. r Flexible Service Models: not allow relative service distinctions. Diffserv approach: r Goal: provide the ability to handle different classes of traffic in different ways r Scalable: simple functions in network core, relatively complex functions at network edge r Flexible: don’t define specific service classes, provide functional components to build service classes

Diffserv Architecture Edge router: -Packets are marked -The mark of a packet identifies the class of traffic to which the packet belongs Core router: -Packet forwarded to the next hop according to the per-hop behavior (PHB) associated with that packet’s class -PHB determines buffering and scheduling at the routers - Routers needn’t maintain states for individual flows

Classification and Marking at Edge-Router r Classification: packets classified based on packet header fields (source/destination IP address, source/destination port, protocol ID) r Marking: packet marked based on per-flow profile m Traffic profile: pre-negotiated rate A, bucket size B m Meter used to compare the incoming packet flow with the traffic profile m In-profile packet receive priority marking, out-of-profile packets might be marked differently, shaped (i.e. delayed), or dropped

Packet Marking r Packet is marked in the DS field of the IP packet header (Type of Service (TOS) field in IPv4, and Traffic Class field in IPv6) m 6 bits used for Differentiated Service Code Point (DSCP) and determine PHB that the packet will receive m 2 bits are currently unused r All packets with the same DSCP are referred to as a behavior aggregate

Forwarding (PHB) r PHB is “a description of externally observable forwarding behavior of a Diffserv node applied to a particular Diffserv behavior aggregate”. m A PHB can result in different classes of traffic receiving different performance. m A PHB does not specify what mechanisms to use to achieve required behaviors m Differences in performance must be observable and hence measurable r Examples: m Class A gets x% of outgoing link bandwidth over time intervals of a specified length m Class A packets leave before class B packets

Service Level Agreements r A customer must have a Service Level Agreement (SLA) with its ISP. r A SLA specifies the service classes supported (traffic profile, performance metrics, actions for non-conformant packets) and the amount of traffic allowed in each class. m Static SLA: pre-provisioned m Dynamic SLA: signaled on demand r Boundary routers mark, drop, shape packets based on SLA r When a packet enters one domain from another domain, its DS field may be re-marked, as determined by the SLA between the two domains.

Example Diffserv Services r Premium Service: low delay and low jitter service r Assured Service: better reliability than Best Effort Service r Olympic Service: three tiers of services: Gold, Silver and Bronze, with decreasing quality.