mule: multi-layer virtual network embeddingsr2chowd/papers/cnsm17_mule...mule: multi-layer virtual...

MULE: Multi-Layer Virtual Network Embedding

Shihabur R. Chowdhury, Sara Ayoubi, Reaz

Ahmed, Nashid Shahriar, Raouf Boutaba

Jeebak Mitra,Liu Liu

Virtual Network Embedding (VNE)

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Virtual Network Embedding (VNE)

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Extensive Literature, mostly focused on single-layer substrate

Multi-Layer IP-over-Optical Network

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IP Network

Packet Switched

Flexible addressing, traffic engineering, resource allocation


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Circuit switched

High capacity (Terabits of bandwidth/link)

Optical Network


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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.

Multi-Layer IP-over-DWDM Network

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Multi-Layer IP-over-DWDM Network

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IP Links are tunneled over

a single wavelength light-path

Multi-Layer IP-over-OTN Network

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OTN Links are logical,

routed over wavelengths, and

can multiplex bandwidth

of multiple IP Links

Topological Flexibility of Multi-Layer Network

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Topological Flexibility of Multi-Layer Network

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New IP Links can be

created on-the-fly

Question:

How can we leverage the topological flexibility

of multi-layer networks for VN embedding?

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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

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The Problem

Multi-Layer Virtual Network Embedding (MULE)

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In the most resource efficient way, jointly determine

The Problem


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Creation of New IP links (if necessary)


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The Problem


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VN Embedding on the IP Layer


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The Problem


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VN Embedding on the IP Layer

Embedding of new IP Links on Optical

Layer


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Context

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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

MULE: Example

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Multi-Layer Substrate Network

Given

MULE: Example

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Logical

IP Layer

Physical

Optical

Layer

Given

MULE: Example

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Logical

IP Layer

Physical

Optical

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Given

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Virtual Network (VN)

Location

Constraint

MULE: Example

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Embed the VN on the IP Layer

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MULE: Example

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Create new IP links (if necessary)


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MULE: Example

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Embed the new IP links on Optical

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MULE: Example

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Embed the new IP links on Optical

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Objective: Minimize bandwidth allocation cost on both layers

Our Contributions

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OPT-MULE FAST-MULE

ILP-based Optimal Solution

(NP-hard)

Three Step Heuristic: Collapse, Extract, Embed

A suit of solutions to MULE

State-of-the-art

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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.

OPT-MULE:

ILP model for optimal solution to MULE that

minimizes bandwidth allocation cost for

embedding VN and provisioning new IP links

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OPT-MULE*

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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

OPT-MULE*

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Decision Variables


Constraints






OPT-MULE*

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Decision Variables


Constraints






OPT-MULE*

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Decision Variables


Constraints






OPT-MULE*

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Decision Variables


Constraints

Virtual links can be mapped to existing or newly created IP links




OPT-MULE*

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Decision Variables


Constraints





OPT-MULE*

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Decision Variables


Constraints





OPT-MULE*

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Decision Variables


Constraints





FAST-MULE: Challenges

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Joint Embedding on IP and Optical Layer

Challenge - I


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Challenge - I Solution

Collapse IP and Optical Layer into a single layer


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Joint embedding of virtual nodes and virtual links


Challenge - I

Challenge - II

Solution



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Joint embedding of virtual nodes and virtual links


Challenge - I

Challenge - II

Solution


Solution

Embed star subgraphs from VN in a single shot using

min-cost max-flow

FAST-MULE: 3-Phase Algorithm

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Phase-I (Collapse): Collapse IP and Optical Layers into a single layer collapsed graph


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Phase-II (Extract): Extract star subgraphs from VN


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Phase-II (Extract): Extract star subgraphs from VN

Phase-III (Embed): Jointly embed nodes and links of each star subgraph on the collapsed graph

Phase-I: Collapse

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Phase-I: Collapse

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Place as many direct links as the

number of ports of an IP node to

the corresponding OTN node (set

bandwidth to port capacity)

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Phase-I: Collapse

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• 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.

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Phase-II: Extract

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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.

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Phase – III: Embed

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Star subgraph from VN

Collapsed Graph

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We reduce star-subgraph

embedding to solving min-cost

max-flow on collapsed graph.

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Phase – III: Embed

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Map center node of star to one of

its location constraint IP node.

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Phase-III: Embed

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Add meta-node for each other Vnode.

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Phase-III: Embed

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Add link from a VNode‘s location

constraint nodes to its meta-node.

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Phase-III: Embed

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Add a sink node (t). Add unit capacity

link from all meta-nodes to sink node.

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Phase-III: Embed

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Set cap. of other links to: max. number

of VLinks that can be placed on that link

Phase-III: Embed

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Solve min-cost max-flow to obtain joint

node and link embedding.

Evaluation: Setup

FAST-MULE compared with OPT-MULE and D-VNE*

OTN15 – 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.

FAST-MULE Performance Highlights

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Optimal for star shaped VN*

* Proof is in the paper


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67% better than D-VNE on avg.




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Within ~47% of optimal on avg.





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Within ~47% of optimal on avg.

2-3 Orders of magnitude faster than OPT-MULE




Summary

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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

What’s Next?

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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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Backup Layer

FAST-MULE: Complexity

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𝑂( 𝑉′ 𝑉 𝐸 2 log 𝑉)

V’ = Number of Virtual nodes

V = Number of nodes in collapsed graph

E = Number of links in collapsed graph

Conflict Resolution using “Referee Node”

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Add meta link:

Conflicting nodereferee nodemeta-node

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Impact of Virtual Node Ordering

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Fixed substrate size

Why MULE?

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Why MULE?

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mule: multi-layer virtual network embeddingsr2chowd/papers/cnsm17_mule...mule: multi-layer virtual...

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