An Overview of Routing Models for MPLS Networks

Transcription

1 An Overview of Routing Models for MPLS Networks Rita Girão Silva, José Craveirinha DEEC-FCTUC / INESC-Coimbra An Overview of Routing Models for MPLS Networks 1

2 Presentation Presentation Overview of routing models for MPLS networks QoS objectives and constraints Multicriteria routing models Inclusion of certain QoS objectives and constraints in a specific multiobjective routing model An Overview of Routing Models for MPLS Networks 2

3 Routing in MPLS networks Routing in MPLS networks Traffic can be represented in different levels in MPLS networks IP packets µ-flows traffic trunks LSPs Label Switched Paths An Overview of Routing Models for MPLS Networks 3

4 Routing models Generic properties Routing models Generic properties Traffic flow characterisation, including QoS features Network features Search for appropriate paths Different QoS objectives and constraints can be taken into account in the routing problem. An Overview of Routing Models for MPLS Networks 4

5 Routing models QoS objectives and constraints Routing models QoS objectives and constraints min {packet loss} min {packet delay} min {sensitivity to packet delay} Max {packet throughput} min {number of hops} min {number of paths} An Overview of Routing Models for MPLS Networks 5

6 Erbas et al - 1 Erbas et al min {traffic trunk delay} min {number of LSPs} Optimization of the resource utilization (by an appropriate distribution of the load in the network) An Overview of Routing Models for MPLS Networks 6

7 Erbas et al Erbas et al - 2 Different formulations and approaches to solve this problem Some objectives can be turned into constraints. The multiobjective functions are combined into a single objective function. An Overview of Routing Models for MPLS Networks 7

8 Erbas et al Erbas et al - 3 Different approaches Weighted sum of the o.f. Weighted lexicographic Chebyshev metric Paretooptimal solutions Evolutionary algorithm An Overview of Routing Models for MPLS Networks 8

9 Halinger et al - 1 Halinger et al min {maximal utilization of the links} (for an adequate load distribution) min {number of hops} (to minimize the packet delay and the fault probability of the path) An Overview of Routing Models for MPLS Networks 9

10 Halinger et al Halinger et al - 2 Heuristic to solve this problem Calculation of the least-cost path The cost of each link is updated by considering the utilization of the link (preference to the leastloaded links). An Overview of Routing Models for MPLS Networks 10

11 Elwalid et al Elwalid et al MATE MPLS Adaptive Traffic Engineering Single objective function: adaptive and balanced distribution of the load in the network The cost of a link is inversely proportional to its available bandwidth. Gradient projection algorithm An Overview of Routing Models for MPLS Networks 11

12 Franzke et al Franzke et al Single objective problem min {path weight} Each link has a weight related to the features of the flow (eg. bandwidth). Multicommodity network flow problem An Overview of Routing Models for MPLS Networks 12

13 Bourquia et al Bourquia et al Single objective problem min {load of the most loaded link of the network} Constraints on the flow conservation Branch-and-cut algorithm to solve the problem An Overview of Routing Models for MPLS Networks 13

14 Rombaut et al Rombaut et al Single objective problem min {load of the most loaded link of the network} Constraints on the number of different paths Modified Dijkstra algorithm to find paths increasingly worse and distribution of the flows in those paths An Overview of Routing Models for MPLS Networks 14

15 Knowles et al Knowles et al - 1 Routing in packet-switched networks min {maximal deviation between the routed traffic and the capacity of a link} min {maximal deviation from a specific value of the link utilization} min {cost of a path} (weighted by the offered traffic) An Overview of Routing Models for MPLS Networks 15

16 Knowles et al Knowles et al - 2 Problem solved by an evolutionary algorithm Solutions that minimize cost and solutions that minimize congestion Crossover of existing solutions to generate a new and improved solution An Overview of Routing Models for MPLS Networks 16

17 Widyono Widyono Real-time routing in packet networks Optimization of the resource utilization (by the minimization of a cost function that reflects the availability of resources) min {number of hops} Problem solved using a constrained Steiner tree An Overview of Routing Models for MPLS Networks 17

18 Pornavalai et al Pornavalai et al - 1 Routing in networks supporting multimedia applications min {number of hops} (to guarantee the use of a minimum of resources) min {cost of the path} (to guarantee an appropriate load distribution) considering the available bandwidth An Overview of Routing Models for MPLS Networks 18

19 Pornavalai et al Pornavalai et al - 2 Constraints on the bandwidth, the delay, the delay jitter and the number of hops of the path Heuristic to solve this problem: route composition, considering the paths obtained when only one metric is considered An Overview of Routing Models for MPLS Networks 19

20 Kochkar et al Kochkar et al Routing in networks carrying Best-Effort and QoS traffic min {cost of the path} (to guarantee an appropriate load distribution) considering the available bandwidth Concept of virtual residual bandwidth, which reflects the utilization of a link An Overview of Routing Models for MPLS Networks 20

21 using the notion of implied costs using the notion of implied costs The implied cost of a link represents the cost of carrying a call of a flow in the link, which includes the effects on the other flows of the network, resulting from the occupations in the other links of the path associated with the acceptance of a call. An Overview of Routing Models for MPLS Networks 21

22 using implied costs Marbukh using implied costs Marbukh Two-stage routing model 1st stage: each call tries a possible path; if not possible, try the 2nd stage 2nd stage: each call tries an alternate path, with minimum cost The cost of a path includes the implied cost and cannot exceed the revenue. An Overview of Routing Models for MPLS Networks 22

23 using implied costs Arvidsson et al using implied costs Arvidsson et al Max {revenue} The implied costs of transfering bandwidth units used by a flow to another flow are calculated. The cost of bandwidth is important in the allocation of bandwidth units to specific flows. An Overview of Routing Models for MPLS Networks 23

24 Outline of a multiobjective routing model - 1 Outline of a multiobjective routing model Hierarchical multiobjective routing model for a multi-service environment O.f. at the network level: Max {revenue} min {maximal blocking probability for all flows} min {total average packet delay} The delay can be weighted in terms of bandwidth or carried traffic of each flow. An Overview of Routing Models for MPLS Networks 24

25 Outline of a m.o. routing model - 2 Outline of a m.o. routing model O.f. at the service level: min {average blocking probability of a flow} min {maximal blocking probability of a flow} min {average packet delay in a flow} min {maximal packet delay in a flow} Network objectives have priority over service objectives. Constraints: equations to calculate the blocking probabilities (in terms of the offered traffic and the routing plan) and the packet delay An Overview of Routing Models for MPLS Networks 25

26 Outline of a m.o. routing model - 3 Outline of a m.o. routing model Dynamic routing model (on-line and periodic: the routes are regularly updated) Some difficulties of the model: Extremely complex Interdependencies among the o.f. Need to develop an appropriate traffic model Resolution approaches An Overview of Routing Models for MPLS Networks 26