MULE: Multi-Layer Virtual Network Embedding

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MULE: Multi-Layer Virtual Network Embedding Shihabur R. Chowdhury, Sara Ayoubi, Reaz Ahmed, Nashid Shahriar, Raouf Boutaba Jeebak Mitra, Liu Liu

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Virtual Network Embedding (VNE) 2 10 a b c 10 10 10 12 10 d e f 20 20 20 5 5 C A B D E F G H 60 80 55 50 70 65 85 90 22 15 12 10 15 17 17 20 25 a b c e d f

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Virtual Network Embedding (VNE) 3 10 a b c 10 10 10 12 10 d e f 20 20 20 5 5 C A B D E F G H 60 80 55 50 70 65 85 90 22 15 12 10 15 17 17 20 25 a b c e d f Extensive Literature, mostly focused on single-layer substrate

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Multi-Layer IP-over-Optical Network 4 A D E C B IP Network  Packet Switched  Flexible addressing, traffic engineering, resource allocation

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Multi-Layer IP-over-Optical Network 5 1 3 2 4 6 5 7 9 8  Circuit switched  High capacity (Terabits of bandwidth/link) Optical Network

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Multi-Layer IP-over-Optical Network 6 A D E C B 1 3 2 4 6 5 7 9 8 IP overlay on Optical Network  IP routers are directly connected to optical switches  IP links are logical and tunneled over optical paths  Best of two worlds  High capacity combined with flexible addressing, routing, traffic engineering, resource allocation.

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Multi-Layer IP-over-DWDM Network 7 A D E C B 1 3 2 4 6 5 7 9 8 1 3 5 A D

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Multi-Layer IP-over-DWDM Network 8 A D E C B 1 3 2 4 6 5 7 9 8 1 3 5 A D IP Links are tunneled over a single wavelength light-path

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Multi-Layer IP-over-OTN Network 9 A D E C B 1 3 2 4 6 5 7 9 8 1 3 5 A D OTN Links are logical, routed over wavelengths, and can multiplex bandwidth of multiple IP Links

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Topological Flexibility of Multi-Layer Network 10 A D E C B 1 3 2 4 6 5 7 9 8 1 3 5 A D

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Topological Flexibility of Multi-Layer Network 11 A D E C B 1 3 2 4 6 5 7 9 8 1 3 5 A D New IP Links can be created on-the-fly

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Question: How can we leverage the topological flexibility of multi-layer networks for VN embedding? 12

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(One Possible) Answer: If IP network does not have sufficient capacity for VN embedding, then we can increase capacity, by creating new IP links 13

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The Problem Multi-Layer Virtual Network Embedding (MULE) 14 In the most resource efficient way, jointly determine

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The Problem Multi-Layer Virtual Network Embedding (MULE) 15 Creation of New IP links (if necessary) In the most resource efficient way, jointly determine A D E C B ?

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The Problem Multi-Layer Virtual Network Embedding (MULE) 16 Creation of New IP links (if necessary) VN Embedding on the IP Layer In the most resource efficient way, jointly determine d f e A D E C B ? A D E C B d f e

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The Problem Multi-Layer Virtual Network Embedding (MULE) 17 Creation of New IP links (if necessary) VN Embedding on the IP Layer Embedding of new IP Links on Optical Layer In the most resource efficient way, jointly determine d f e 1 3 2 4 6 5 7 9 8 A D E C B ? A D E C B d f e A D E C B

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Context 18 Multi-Layer IP-over-OTN Network OTN is static and OTN Links are already provisioned on light-paths in DWDM layer. No multi-path embedding; No node capacities

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MULE: Example 19 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Multi-Layer Substrate Network Given

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MULE: Example 20 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Multi-Layer Substrate Network Logical IP Layer Physical Optical Layer Given

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MULE: Example 21 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Multi-Layer Substrate Network Logical IP Layer Physical Optical Layer Given 0 2 1 {C} {A, B} {D, E} 15 15 15 Virtual Network (VN) Location Constraint

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MULE: Example 22 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Embed the VN on the IP Layer 0 2 1

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MULE: Example 23 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Create new IP links (if necessary) Embed the VN on the IP Layer 0 2 1

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MULE: Example 24 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Create new IP links (if necessary) Embed the VN on the IP Layer Embed the new IP links on Optical Layer 0 2 1

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MULE: Example 25 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000 Create new IP links (if necessary) Embed the VN on the IP Layer Embed the new IP links on Optical Layer 0 2 1 Objective: Minimize bandwidth allocation cost on both layers

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Our Contributions 26 OPT-MULE FAST-MULE ILP-based Optimal Solution (NP-hard) Three Step Heuristic: Collapse, Extract, Embed A suit of solutions to MULE

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State-of-the-art 27 No Optimal Solution ILP-based Optimal Solution Two step virtual node and virtual link embedding D-VNE* MULE Jointly embeds virtual nodes and links as much as possible Collapses multiple layers into one with information loss Collapses multiple layers into one without information loss * Zhang, et al. "Dynamic virtual network embedding over multilayer optical networks“, Journal of Optical Communications and Networking 7(9): 918-927, 2015.

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OPT-MULE: ILP model for optimal solution to MULE that minimizes bandwidth allocation cost for embedding VN and provisioning new IP links 28

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OPT-MULE* 29 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Typical VN Embedding constraints for VN to IP Layer Mapping  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes  Capacity constraint for OTN links, * Details are in the paper

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OPT-MULE* 30 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Typical VN Embedding constraints for VN to IP Layer Mapping  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes  Capacity constraint for OTN links, * Details are in the paper

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OPT-MULE* 31 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Typical VN Embedding constraints for VN to IP Layer Mapping  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes  Capacity constraint for OTN links, * Details are in the paper

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OPT-MULE* 32 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Typical VN Embedding constraints for VN to IP Layer Mapping  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes  Capacity constraint for OTN links, * Details are in the paper

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OPT-MULE* 33 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Virtual links can be mapped to existing or newly created IP links  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes * Details are in the paper

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OPT-MULE* 34 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Virtual links can be mapped to existing or newly created IP links  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes * Details are in the paper

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OPT-MULE* 35 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Virtual links can be mapped to existing or newly created IP links  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes * Details are in the paper

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OPT-MULE* 36 Decision Variables Creation of new IP Links, IP Layer to Optical Layer Embedding for new IP links, Virtual Node and Link mapping Constraints  Virtual links can be mapped to existing or newly created IP links  Newly created IP links must be embedded on the Optical layer  Port constraint for IP nodes * Details are in the paper

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FAST-MULE: Challenges 37

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FAST-MULE: Challenges 38 Joint Embedding on IP and Optical Layer Challenge - I

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FAST-MULE: Challenges 39 Joint Embedding on IP and Optical Layer Challenge - I Solution Collapse IP and Optical Layer into a single layer

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FAST-MULE: Challenges 40 Joint embedding of virtual nodes and virtual links Joint Embedding on IP and Optical Layer Challenge - I Challenge - II Solution Collapse IP and Optical Layer into a single layer

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FAST-MULE: Challenges 41 Joint embedding of virtual nodes and virtual links Joint Embedding on IP and Optical Layer Challenge - I Challenge - II Solution Collapse IP and Optical Layer into a single layer Solution Embed star subgraphs from VN in a single shot using min-cost max-flow

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FAST-MULE: 3-Phase Algorithm 42

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FAST-MULE: 3-Phase Algorithm 43 Phase-I (Collapse): Collapse IP and Optical Layers into a single layer collapsed graph

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FAST-MULE: 3-Phase Algorithm 44 Phase-I (Collapse): Collapse IP and Optical Layers into a single layer collapsed graph Phase-II (Extract): Extract star subgraphs from VN

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FAST-MULE: 3-Phase Algorithm 45 Phase-I (Collapse): Collapse IP and Optical Layers into a single layer collapsed graph Phase-II (Extract): Extract star subgraphs from VN Phase-III (Embed): Jointly embed nodes and links of each star subgraph on the collapsed graph

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Phase-I: Collapse 46 A D E C B 1 3 2 4 6 5 7 9 8 15 10 10 10 15 1000 985 990 990 990 985 1000

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Phase-I: Collapse 47 A D E C B 1 3 2 4 6 5 7 9 8 1000 985 990 990 990 985 1000 Place as many direct links as the number of ports of an IP node to the corresponding OTN node (set bandwidth to port capacity) A 1 20 20 20 60 60 60 60 60

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Phase-I: Collapse 48 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15 • Place IP links between OTN nodes where the link’s IP endpoints are. • Keep IP link cost as is, set OTN link cost to very high. 60 60 60 60 60

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Phase-II: Extract 49 0 2 1 {C} {A, B} {D, E} 15 15 Extract star-shaped subgraph from VN Embedding a star-shaped subgraph in one-shot corresponds to jointly embedding a virtual node and all its incident virtual links. 15 0 2 1 {C} {A, B} {D, E} 15 15 2 1 {A, B} {D, E} 15

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50 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15 0 Phase – III: Embed 2 1 {C} {A, B} {D, E} Star subgraph from VN Collapsed Graph 15 15 We reduce star-subgraph embedding to solving min-cost max-flow on collapsed graph. 60 60 60 60 60

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51 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15 Phase – III: Embed 0 2 1 {C} {A, B} {D, E} 0 Map center node of star to one of its location constraint IP node. 15 15 60 60 60 60 60

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52 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15 Phase-III: Embed 0   Add meta-node for each other Vnode. 0 2 1 {C} {A, B} {D, E} 15 15 60 60 60 60 60

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53 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15 Phase-III: Embed 0   Add link from a VNode‘s location constraint nodes to its meta-node. 0 2 1 {C} {A, B} {D, E} 15 15 60 60 60 60 60

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Phase-III: Embed 54 A D E C B 1 3 2 4 6 5 7 9 8 10 15 1000 985 990 990 990 985 1000 10 10 15  t  3 3 3 3 3 1 1 1 1 1 1 Add a sink node (t). Add unit capacity link from all meta-nodes to sink node. 0 2 1 {C} {A, B} {D, E} 0 15 15

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Phase-III: Embed 55 A D E C B 1 3 2 4 6 5 7 9 8 0 1 66 65 65 65 65 65 66 0 0 1  t  3 3 3 3 3 1 1 1 1 1 1 0 0 2 1 {C} {A, B} {D, E} 15 15 Set cap. of other links to: max. number of VLinks that can be placed on that link

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Phase-III: Embed 56 A D E C B 1 3 2 4 6 5 7 9 8 0 1 66 65 65 65 65 65 66 0 0 1  t  3 3 3 3 3 1 1 1 1 1 1 0 0 2 1 {C} {A, B} {D, E} 1 2 15 15 Solve min-cost max-flow to obtain joint node and link embedding.

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Evaluation: Setup  FAST-MULE compared with OPT-MULE and D-VNE*  OTN 15 – 100 nodes  IP Network ~60% the size of the OTN Virtual Network  4 – 8 nodes  20 VNs for each IP/OTN combination 57 * Zhang, et al. "Dynamic virtual network embedding over multilayer optical networks“, Journal of Optical Communications and Networking 7(9): 918-927, 2015.

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FAST-MULE Performance Highlights 58 Optimal for star shaped VN* * Proof is in the paper

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FAST-MULE Performance Highlights 59 67% better than D-VNE on avg. Optimal for star shaped VN* * Proof is in the paper

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FAST-MULE Performance Highlights 60 Within ~47% of optimal on avg. 67% better than D-VNE on avg. Optimal for star shaped VN* * Proof is in the paper

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FAST-MULE Performance Highlights 61 Within ~47% of optimal on avg. 2-3 Orders of magnitude faster than OPT-MULE 67% better than D-VNE on avg. Optimal for star shaped VN* * Proof is in the paper

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Summary 62 We address VNE problem for Multi-Layer IP-over- OTN Network Two Solutions to MULE: OPT-MULE, FAST-MULE FAST-MULE performs ~47% better than the optimal (empirically); allocates ~66% less resources than the state-of-the-art

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What’s Next? 63 Can we exploit topological flexibility for failure recovery? What is the impact of fragmentation? How challenging is it to address MULE for other Optical network technologies (e.g., Elastic Optical Networks)?

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65 Backup Layer

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FAST-MULE: Complexity 66 ( ′ 2 log ) V’ = Number of Virtual nodes V = Number of nodes in collapsed graph E = Number of links in collapsed graph

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Conflict Resolution using “Referee Node” 67 A D E C B 1 3 2 4 6 5 7 9 8 0 1 66 65 65 65 65 65 66 0 0 1  t  3 3 3 3 3 1 1 1 1 1 0 0 2 1 {C} {A, B} {A, E} 15 15 Add meta link: Conflicting nodereferee nodemeta-node r 1 1 1