Offline SD-SF MappingJay Mehta and Dinesh Ram Evana

NaaS – Network as a Service• Network as a Service (NaaS) is a modern option for enterprises to

consume and utilize different networking services and network functions away from their campus.

Network Function Virtualization (NFV)• Network Function Virtualization (NFV) is a core concept which enables

NaaS. NFV aims to address the problems faced by large NaaS providers’ networks. NFV is a network architecture concept. Using the technologies of IT virtualization, NFV virtualizes all the functions that are performed by traditional hardware appliances.• NFV decouples hardware from software.• Using concepts of NFV we can implement the network functions on

high-volume servers, storage and switches in a very flexible manner.

Virtualized Network Function (VNF)• The software implementations of the network functions that were

done by hardware is called Virtualized Network Function.

Service Function Chaining (SFC)• A Service Function Chain (SFC) request is received by the NaaS

provider which consists of a number of functions nodes, computation and bandwidth requirement and dependencies among these function nodes. The datacenters which serve the clients with network functions are called as Telecom Clouds (TC).

• A set of VNAs interconnected by virtual links, is referred to as a service function chain (SFC). The topology of an SFC can be as simple as a linear array (chain) or an irregular mesh that provides services for multiple packet flows (PFs).

Split Dependency:There are some cases that the traffic after one VNF will be split into two or more streams.One good example for this type is the load balancer (LB). When the LB is one of the VNFs in the chain it splits the incoming traffic into different branches to balance traffic.

Objective• Mapping of SFC request to SN.• Minimizing total bandwidth usage while doing so.• Minimize the number of utilized nodes.

SFC Request RepresentationGiven• List of 3-tuple for representing the chain of VNFs with bandwidth

requirement.• 3-tuple for representing the split dependency .• If more than 1 split dependencies in the request we’ll have a List.• Table for storing computation requirements with columns

Example SFC Representation

1. Request Chain = 2. Split Function = 3. Computation requirements table =

VNF 1

VNF 2

VNF 3

VNF 3

VNF 3

Substrate Network RepresentationGiven• Substrate network will be represented as a graph where is the nodes

and is the links.• Every node will have some computation capacity • Every link will have a cost and bandwidth and respectively.• Every node will be doing a virtualized network function .

Example SN Representation

N1 f130

N2 f310

N4 f2100

N5 f320

N3 f280

Algorithm Idea• The algorithm will start by mapping the that has maximum

bandwidth requirement. This way we’ll make sure that function that requires maximum bandwidth does get mapped and is not left unmapped in which case SFC request will not be served. If two have same bandwidth requirement then the one with higher will be mapped first. • For the substrate nodes, in case two nodes have the same

functionality then the node with less CPU available will be mapped.• Less Hops and Neighborhood first policy is used to minimize the total

bandwidth consumption across the substrate network.

Algorithm Steps1. Sort Request Chain in descending order of bandwidth requirement.2. Loop through the sorted request chain start nodes until all VNFs are

mapped on the substrate network.3. Map the VNFs to substrate nodes based on the neighborhood first

policy.4. Choose the lowest Computation Capacity Node which can perform

the Virtualized Network Function.5. Choose path which involves minimum hops, cost and bandwidth.

Algorithm applied on Example

N1 f130

N2 f310

N4 f2100

N5 f310

N3 f280

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2

Mapping VNF2 on Substrate Node

N1 f130

N2 f310

N4 f2100

N5 f310

N3 f280

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2

Mapped VNF2 to N3

N1 f130

N2 f310

N4 f2100

N5 f310

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2

Mapping VNF3 on Substrate Node

N1 f130

N2 f310

N4 f2100

N5 f310

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2Cost = 1 BW = 8

Cost = 4 BW = 8

Mapped VNF3(1st split) to N2

N1 f130

N2 f310-5

N4 f2100

N5 f310

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2Cost = 1 BW = 8-2

Cost = 4 BW = 8

Mapped VNF3(2nd Split) to N2

N1 f130

N2 f3

10-10

N4 f2100

N5 f310

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2Cost = 1 BW = 8-4

Cost = 4 BW = 8

Mapped VNF3(3rd Split) to N5

N1 f130

N2 f3

10-10

N4 f2100

N5 f310-5

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2Cost = 1 BW = 8

Cost = 4 BW = 8-2

Mapped VNF1 to N1

N1 f1

30-10

N2 f3

10-10

N4 f2100

N5 f310-5

N3 f2

80-20

VNF 110

VNF 220

VNF35

VNF35

VNF35

122

2Cost = 1 BW = 8-4

Cost = 4 BW = 8-2

One Possibility• If the user/client just provides with a request of network functions

that are required to be done and not the chain.• Our Algorithm will place the Split Function at the start of the chain

and followed by decreasing BW requirements.• This approach will minimize the overall bandwidth consumption of

our substrate network, because since the data streams will be split from the start, the low BW links on substrate network can be utilized.

VNF 2

VNF

VNF 1

VNF 1

VNF 3

VNF 3

VNF 3

Thank You