deploying multiple service chain (sc) instances per...

Deploying Multiple Service Chain

(SC) Instances per Service Chain

BY

ABHISHEK GUPTA

FRIDAY GROUP MEETING

JULY 14, 2017

Virtual Network Function (VNF) Service Chain (SC)

2

Multiple VNF SC Placement and Routing

3

Continued…

4

1 SC instance for each SC

s1

s2

s3

d1

d2

d3

s4d4

s5 d5

Single Instance Per SC

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Service Chain 1

1

5

98

6

3

2

12

7

11

14

13

4

10

SC2

SC1

2 Demand Requests SC1r1 = 14 𝟏, 𝑺𝑪𝟏r2 = 4 𝟕, 𝑺𝑪𝟏

2 Demand Requests SC2r3 = 14 𝟐, 𝑺𝑪𝟐r4 = 7 4, 𝑺𝑪𝟐

Service Chain 2

Multiple Instances per SC

6

1

5

98

6

3

2

12

7

11

14

13

4

10

SC1(1)

SC2 (1)

SC2 (2) SC1 (2)

2 Demand Requests SC1r1 = 14 𝟏, 𝑺𝑪𝟏r2 = 4 𝟕, 𝑺𝑪𝟏

2 Demand Requests SC2r3 = 14 𝟐, 𝑺𝑪𝟐r4 = 7 4, 𝑺𝑪𝟐

Service Chain 1

Service Chain 2

Inferences and Questions

• 1 SC instance per SC leads to suboptimal results

• Having SC instances replicated on every node will lead to

to optimal results

• Large capital expenditure to make all nodes NFV capable

• High Orchestration Overhead for large number of instances

• The question therefore becomes:

• How many SC instances to deploy to reduce bandwidth

consumption while also reducing nodes used?

7

Issue of symmetric flows

8

Service Chain

A B

A B

VNFs placed in different nodes

Continued…

9

A B

A B

VNFs placed in same node

Continued…

• Placing VNFs for SC at different nodes

• makes symmetric flow take longer path

• Placing VNFs for SC at one node

• symmetric flow takes shorter path

• placement and routing becomes easier

• chaining aspect is forgone

• Is this more realistic?

• Represents the case of a DC

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Configuration Type 1 – (ILP, CG)

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1

1

1

2 23

3

CG Model

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Configuration Type 2 – (2 Phase Model)

13

1

1

1

2 2

Phase 1 : Traffic flows are

clustered using SPTG

Phase 2 : Configurations of Type

2 are generated for clustered

traffic of Phase 1

Comparison (ILP, CG, 2 Phase Model)

14

Continued…

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Full Traffic Matrix, 1 SC deployment, 1 SC instance

16

1

5

98

6

3

2

12

7

11

14

13

4

10

SC instance location

All nodes are NFV-capable.

All node pairs have requests for the same service chain.

Grouping of traffic pairs

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Continued …

• Create traffic flow groups

• Assign dummy SC Id’s to traffic flow groups

• Big Question: How to do we make traffic groups?

• Model accounting for traffic groups becomes quadratic.

Subsequent, linearization reduced the scalability of the

model

• We, therefore, use a heuristic to do make the traffic

groups

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Grouping traffic flows around a node

• Betweenness Centrality

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Group around node pairs of the graph

• A and B can also be source and destination

• Done for each SC

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A B

s1

s2

s3

d1

d2

d2

Continued…

• Ordered node pair with highest traffic flow count passing

through on shortest paths

• Traffic flows which share sub-paths in common

• Deploying one SC instance for each such group

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Shortest Path Traffic Grouping

(SPTG)

• Given: the number of instances for a SC, the traffic flows

for the SC

• The heuristic will:

1. Find the node pair with highest number of flows

2. This becomes another (s, d) pair group/cluster

3. All flows in group/cluster are removed from global flow list

4. Repeat step 1 to 3 until number of instances is reached

5. Iterate through the remaining flows:

1. Find best group based on which path length through node pair

2. Add flow to that group/cluster

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Shortest Path Traffic Grouping

– Traffic Aware (SPTG-TA)

• Cluster around the heaviest/largest traffic flow

• The heuristic will:

1. Find the node pair with highest number of flows and the largest

flow

2. This becomes another (s, d) pair group/cluster

3. All flows in group/cluster are removed from global flow list

4. Repeat step 1 to 3 until number of instances is reached

5. Iterate through the remaining flows:

1. Find best group based on which path length through node pair

2. Add flow to that group/cluster

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2 Phase Model

• 1st

phase

• Apply SPTG/SPTG-TA for each SC and create the required number of

groups

• Assign dummy SC ids to groups of flows

• 2nd

phase

• Use the column generation model which decides on 1 SC instance

per SC

• Also we can control the number of nodes that can host VNFs, we

refer to this number as ‘K’

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Assumptions

• All nodes are capable of hosting VNFs

• No CPU constraints are enforced

• No link capacity constraints are enforced

• Only one SC instance per SC model

• All traffic pairs have 1Gb traffic flow

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NSFNET K=14

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NSFNET K=14,5,4,3,2,1

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Partitioning of Traffic Load

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Partitioning of CPU resources

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VNF Replica Constraints

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Correlation between ‘K’ and ‘VNF Replica Count’

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Mean Maximum Link Load

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Cluster Counts (Uniform Traffic – Same Load)

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ASP Bandwidth Variation (Uniform Traffic – Same

Load)

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Bandwidth Used (Uniform, Same Load, Across

Clusters and Traffic)

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Continued…

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Continued…

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Compare Cluster Counts (Skewed Traffic – Same Load)

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ASP Bandwidth Variation (Skewed Traffic – Same Load)

39

40

Bandwidth Used (Skewed, Same Load, Across

Clusters and Traffic)

Continued…

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Continued…

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Continued…

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Scenario 2 (4 Service Chains, 1 Tb Load)

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VNF 3 VNF 1 VNF 7 VNF 4 VNF 5

VNF 3 VNF 1 VNF 7 VNF 1 VNF 3

VNF 3

VNF 3

VNF 1

VNF 1

VNF 7

VNF 9

VNF 9

VNF 4

VNF 5

VNF 5

Web – 18.2%

VoIP – 11.8%

Video – 69.8%

Cloud Gaming - .2%

Continued…

45

VNF ID SC’s Traffic Load (Tbps)

3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

K = 2

46


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

Continued…

47


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

K=3

48


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

K=4

49


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

K=5

50


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

K=14

51


3 0,1,2,3 1.118

1 0,1,2,3 1.118

7 0,1,2 .998

5 0,2,3 .882

4 0,3 .184

9 2,3 .700

Scalability of 2 Phase Model

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Future Work Directions

• Cases where distribution of VNFs occur:

• Cases where CPU resources are constrained or VNF replicas (because

of licenses) are enforced

• Any additional cases?

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