Mapping Between intserv and CR-LDP Services in Visual C#.NET

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This section defines translation mechanisms between intserv and CR-LDP traffic parameters The target is to obtain a service inside the MPLS domain that is as similar as possible to that provided by the intserv areas The ingress LSR receives the QoS parameters inside the Flowspec object of the Resv message This LSR is responsible for translating these intserv values into traffic parameters TLV that the ingress LSR will forward inside a Label Request message The intserv Working Group has defined three services that specify different packet treatments The Null (N) service enables applications to identify themselves to network QoS policy agents using RSVP signaling After this, packets are treated according to the diffserv architecture When performing a reservation request, an application specifies the service s number and the values of the parameters it has chosen CR-LDP uses peak rate, committed rate, and service granularity to describe the traffic characteristics of a path In the following paragraphs, rules to create the traffic parameters TLV starting from the intserv parameters are defined for each ToS Controlled-Load Service The controlled-load service provides the application with service closely equivalent to that provided to best-effort traffic under lightly loaded conditions A controlled-load service request is characterized by five parameters (p, r, b, M, and m) An ingress LSR sets CR-LDP traffic parameters (described in 5, Motivations, Drivers, Approaches, and Advantages of Voice over MPLS ) using the following rules: PDR PBS CDR CBS EBS p M r b 0

The PDR is equal to the peak rate (p) controlled-load value The PBS is equal to the maximum packet size (M) because this way we control the maximum size of the IP packets Packets larger than M bytes can never enter this token bucket The CDR is the average rate of the link and is equal to the data rate (r) of the controlled-load service The CBS is defined as the maximum size of a burst; hence, it is equal to the bucket size (b) The EBS value is set to 0 because this service does not have an equivalent parameter in the controlled-load service This does not prevent an ingress LSR to choose a value different from 0

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Guaranteed Service Guaranteed service provides firm bounds on endto-end datagram queuing delays The guaranteed service makes it possible to provide a service that guarantees both delay and bandwidth A guaranteed service request is characterized by seven parameters (p, r, b, M, m, R, and S) An ingress LSR sets CR-LDP traffic parameters using the following rules: PDR PBS CDR CBS EBS p M R' b 0

This mapping is very similar to those of the previous section; the only difference is that the CDR is set to R' R' may be equal to the Rate (R) parameter To keep delay for packets below the bounds posed by the guaranteed service, the ingress LSR (like all RSVP routers) must set the CR-LDP data rate higher than the traffic data rate (r) According to RFC 2212,18 the R value guarantees that the end-toend delay for each packet is not larger than the requested one R' may be smaller than R (but bigger than r) only if a non-null slack term is present The R' value and the new slack term must be calculated as RFC 2212 specifies Nonconformant Packets Nonconformant packets are those that do not conform traffic specifications The ingress LSR may treat these packets in the following ways (each solution has pros and cons, but there is not enough experience with QoS to suggest an optimal choice; the best choice depends on the characteristics of the domain):

Reducing the service to all packets The ingress LSR labels all the conforming and nonconforming packets with the label associated with the setup CR-LSP LSRs internal to the domain may be able to forward the traffic with a QoS similar to that contracted or not Each LSR may use its own rules to treat nonconforming packets This means that the decision associated with the treatment of nonconformant packets is shifted to internal LSRs Assigning a best-effort treatment The ingress LSR sorts the flow s packets into a conformant set and a nonconformant set Those on the conformant set are given the label of the setup CR-LSP; those on the nonconformant set are given the label of the best-effort LSP, which connects the ingress LSR and the egress LSR Internal LSRs are not aware of nonconforming traffic; they simply serve them with the best-

Quality of Service (QoS)