Comparison of sdn and gmpls control techniques in optical transport networks by Name: Muhammad Atif Yaqub Reg #: ms(EE)-sp13-008 In Partial Fulfillment of Requirements

These interfaces are in between control and forwarding planes, which clearly separate these two important fields. Open flow field has made it very easy for the investors to help them invest in the new technologies that can integrate multiple different types of equipment.

Southbound interface performs some important actions. It shares the information with control plane when the data port of forwarding device is changed, other is the traffic information is also shared with the controller and the third is that it share the information of data for which the data plane has no information about its forwarding.

2.2.8.3 Network hypervisors

The new latest computer networks are using a new technique of simulations. It has been made effective in last few years. The resources are used based on simulated hardware not the physical hardware resources.

This layer asks for the use of these simulated resources instead of asking for the physical resources. The user demands for resources only when there is the requirement. It is great benefit regarding revenue as the resources are always shared between users. This technology has the important benefit that these shared resources can be shifted from any physical machine to any other physical hardware which provides flexible network nature. But still right now it is not freely used and the old physical fixed resources are used in networks.

The capacity of any network can be calculated with its structure and the available place to have network information. The network layers of different type require different types of network resources. The layers can be Layer-2, Layer-3 etc. One network structure cannot provide all kinds of requirements. The simulated networks are used to have best use of the resources. The IPv6 will have limitations for use as machines may be using IPv4 scheme.

It is observed that the old types of networks have the operating systems with them which can only work with basic level of equipment and operate them with vendor specific software. In addition to that some special commands with different programming techniques are used to further better use these devices.

Different vendors have developed their own network operating systems which are very well in the use and are fulfilling the requirements in better way as per service demand. The research is there to have common control of the whole diverse networks with the routing protocols which work with different kinds of network equipment.

Software defined networking has provided a common network operating system which gives protocols that are used by all kinds of network. There is no requirement to see for the details of data that is forwarded between devices in this operating system.

The control plane is run by this network operating system. The major classification of the control planes is done in 02 categories. The one is the common and other is divided.

The common control software is a one source to manage all the network entities. It has one software source and there may be any resource limitations in this kind of network. The common resources have very high limit for data forwarding and thousands of data forwarding can be managed with these controllers in one second.

The other one which is dispersed software is made as to handle a short or big network. It may be centrally managed or physically distributed. The first one which is centralized can be used for condensed data networks. The other is much hard to the different kinds of failures. The separated control planes have the advantage that when a system is failed, then the other system takes load of this faulty one. In a single control system, we have only one system to perform control actions and all control function will be affected when there is fault to this controller.

The controller performs important functions. It performs running of a program, activities based on commands, service safety in case of any network failure. In addition to that the network structure, control of devices in the network, data sending on smaller path and data safety is also managed by controllers.

The north bound interfaces are performing the operations of abstraction and implement languages to program. There are different programming languages available for this purpose. One program used Linux language which used Virtual file system application. It is helpful for systems that are working on layer-1&2. The programming is different for each operation as the applications like data forwarding, routing and protection and different for each other.

Some applications are based on involvement of the applications in the systems. There are certain rules which work for these applications. The network resources are allocated automatically when there is demand for a particular service. When there is a requirement of voice and data services then it is possible that unique bandwidth is allocated to that service as per service requirement. There is also check to verify that the bandwidth allocated does not surpass the set one by the network manager.

2.2.8.6 Language based virtualization

Virtualization has the ability to provide the service thought and also ensures the qualities like protection. It shows the idea of one large switch which shows adding many forwarding equipment which forward the data. Such centralized approach reduces the complexity in data forwarding as becomes easy to make the network.

One such kind of language has the idea of objects. Each object has its own requirements of data forwarding. The objects do not share the information with each other for any particular service.
2.2.8.7 Programming languages

The research based on moveable program is quite latest in the latest computer networks. The High level codes are helpful to resolve many issues faced on low levels. The high level has following important aspects.

• 
  The codes required to program the devices (which forward the data) are more simplified.
  
• 
  The programming is much problem resolution oriented which becomes quite easy for the peoples involved in coding.
  
• 
  It enables to reuse the code as per requirement.
  
• 
  Makes the network virtualization possible
  

The important benefit of this programming is its ability to build for virtual structure. The idea of object oriented is also the same. It enables the programmers to consider only the requirements and not think about the type of data used and how to manage this data.

High level languages serve the purpose of software defined networking with qualities like its modular approach, composition covering whole network and data verifications. The low level design has many challenges and to cover these challenges the high level is used with approach as mentioned below.

1. 
   This does not manage the service configuration on each system and focuses on the whole network. Such issues also observed in old systems.
   
2. 
   Management work is made easy with the network structure.
   
3. 
   Different jobs for data forwarding are not connected with each other.
   
4. 
   Resolves issues which avoid data forwarding with dynamic approach.
   
5. 
   Reducing the time for data forwarding.
   
6. 
   Immediate addressing of any kind of fault.
   

It is taken as the network core. Particular control information is changed into the form of instructions that further driver the devices which are used to send the traffic from one end to the other. The idea in it is that the path is defined between the source and destination. For this purpose a special instruction if followed by all systems from source to destination.

SDN is used for any type of network which may be small or large. These old systems can perform the other applications of the networks like the Laye-2 and Layer-3 protocols. But special features can be performed with the SDN network only. Software defined networking has important features like Optimization of data forwarding, data protection and interconnectivity about devices.

Very important application of Software defined networking is to balance the load in network. It combines the multiple requests from different users and does not need control function for every request. It is quite useful to balance the load as per network requirements. It avoids exerting load on a single network element or link.

In software defined networking it is possible to have routers configured dynamically. It helps routers to have less data base of routing tables and routers are configured when there is some data transmission required.


Chapter-3
3. Differences between GMPLS and SDN

1. 
   Distributed and Centralized control
   

While the centralized one has the facility to use the network in more optimized way. The distributed control cannot manage the efficiency of the routes from source to destination and the same is possible with Software defined networking. In this control technique all the network related information like paths, connectivity of nodes and bandwidth available is stored in common software. It computes the path for the services centrally and can manage in a better way as it has full picture of the network. The bandwidth requirement if also fulfilled as the service path changing is done as per demand. With this the network is used in efficient manner. Since it has complete information of the network so centralized control plane provides opportunity to control the issue of delay in data transmission due to long path usage. With this technique we can use the optimum path to avoid delay in data transmission.

Software defined networking has 02 important interfaces. One is for the demand of network resources from the network and other is for connectivity to Network management systems which has full authority to use the network. One disadvantage of the centralized control plane is that it is not as fast as GMPLS control plane when the changes in network are observed. When any node is down or any connectivity between nodes is disturbed the same cannot be instantly conveyed to the centralized control plane. GMPLS has distributed control and is efficient in this scenario.

In Software defined networking, control domain is not placed at the same location as it may be apart from each other for protection of the services. Each separate control domain needs to be in close connectivity with all other control domains so that all information between these controllers is shared and no ambiguity observed in the network. It is alos possible that each separate control domain may be of different brand and company. The control systems should be able to arrange communication between them even if they are not of same type.

The difference in these two control techniques is as under.

Fig-12 (a) SDN control plane with centralized control (b) GMPLS control plane with distributed control

2. 
   Complication of control plane
   

Network complication is reduced with the use of Software defined networking. In it there are no Open shortest path first and Reservation protocols and the unified interface of Open Flow is used along with many operating systems which are interconnected with each other.

In GMPLS there is no option available for resilience to the use of control plane that is new in the network. The people who are to operate the network do not find it easy to us the new control plane with the existing. It takes a long time when the new control plane can synchronize with the needs of the network. Therefore it is the continuous process that the network operators should be looking for the new plane that is very much close in process to the existing.

In SDN we use to add the control plane with a new technique in which the new control plane is placed among the already working control planes. This control plane then divides the circuit plane into many parts. Each part is then controlled by a different control plane. The network operator has only control over the data plane that has not been divided, while all the other divided data planes are controlled by the separate control planes. With this division there is also benefir that the control plane does not take packet and circuit switching separately and only one data plane is considered if controlled by a single control plane.

3. 
   Different services provisioning
   

GMPLS provides services of optical virtual private network. In this network each user is sharing the optical fiber resources between the nodes. Each user is allocated separate media resources in the GMPLS network which make them independent in service provisioning as well as operation and maintenance.

Fig-13 Connectivity of OVPN users in a network

As per above mentioned diagram, the different optical virtual private network users are connected to one management server. Both the users have different links for operation and maintenance of the network. These users can manage their GMPLS services from the network. Each network management user first allocates resources in form of bandwidth to the customer. After that it monitors the traffic associated with that customer and performs necessary operations when there is further requirement of media resources for that particular customer.

Another important GMPLS service is user network interface (UNI) service which is provided through the GMPLS network. When a user connect to the GMPLS systems through this interface then it automatically send the GMPLS request to the network to get the services. In this service each user who is asking for connectivity to the other user sends all information regarding the source node address and sink node address. The nodes on receiving this information change the node addresses into their identification numbers. After that the path is calculated and the end to end trail is made. The service level is also available in the message information generated by the user. After that the path is identified as per service level.

3. 
   Industrial application of SDN
   

Software defined networking is providing following important features to Telecom industry which were not provided by GMPLS and old Transport technologies.

The important benefits gained by SDN over GMPLS is telecom industry as below.

The old transport technologies like SDH, DWDM, ASON and GMPLS in transport network were not having any features to use special software tools to properly plan the telecom network. The planning was done only using the manual approach. Software defined networking has given the good features to plan the network using a software tool. Also all the planning was done prior to commissioning of the network. So it did not provide the real time application. When there was some abnormality in the real time working of the systems then it was not handled by old systems. SDN gives real time solution to the problems using proper coordination between the tools.

2. 
   Combined management
   

SDN provides an important feature that it provides the synchronization between transport equipments of different vendors, which was not possible in legacy transport technologies. Along with this SDN provides the synchronization between the core network and the transmission network to have a single control plane. It gives a simple understanding that managing a single control plane is easy other than to work on different control planes of different vendors.

The flexibility of the SDN planes makes it possible for interconnection of devices that are using multi-layer services. The Multi-layer devices make it possible to work together with a common control plane of SDN.

This is the important feature available in SDN that it gives direction that any vendor equipment can be connected to any other vendor equipment using the unified control architecture.

All these important features are available in one of the top vendor in Telecommunication vendors in the world. This is ZTE Technologies which has this important feature.

ZTE is the now the leading company to provide the transport equipments in different parts of the world.

ZTE has developed the important features of SDN which are well beyond the scope of legacy transport networks. The important features used by ZTE are shown below in detail.
3.5.2 ZTE SDN special features

ZTE provides following special features with the use of SDN.

Since SDN is using the important feature of centralized controller, therefore it is possible that a common centralized controller can well manage the network to provide services from one end to the other. Since all type of the systems are controlled by this common controller, so this controller has the database of all the available resources of the network. It cannot be possible to provide such dynamic services using the distributed control plane of the old transport technologies.

The distributed control system of GMPLS gives following drawbacks which reduce efficiency of the transport equipments.

• 
  The distributed control system is used to cover only the faults of specific areas and is unable to cover the whole network. Since the whole network comprises of multiple vendors or multiple technologies, therefore proper synchronization of different distributed control planes is not possible.
  
• 
  When a new network is going to be established or existing networking is expanded then it can be done using the information to plan the network for service configurations. After using a planning tool the available data is exported to the network management system. After that configuration is done. All this long process reduces the system efficiency.
  
• 
  When the new routes are discovered for new service provisioning and the data is shared with the NMS, then the services can be created on the network. This also reduces the efficiency of the network as consumes too much time from network planning to service provisioning.
  

When any fault is observed on working or protection label switched path of any trail service then the corresponding network elements ask centralized control plane for the restoration of the services. The centralized controller finds the most feasible route for the new path. The new path is then forwarded to the specific network elements. The NEs get this information and then configure the services.

This restoration of the services is makes the network more efficient. The controller has all the information about the network. Therefore the rerouting of the services becomes quite fast.

The service rerouting can be done based on the priority as well. It gives the planning information based on the priorities.

Fig. Restoration of services through centralized controller

Transport SDN has the option to prompt about the chance of any fault occurrence in the network. It gives analysis about any fault occurrence. It uses simulation to check for the network status during any fault occurrence. Through simulation the SDN control plane gives real time warning about the network survival.

The user performs the simulation to check the result of fault. When the fault is created then SDN control plane checks the available resources and calculates that which services will be interrupted. It computes the path of the services which will be rerouted and highlights those services which will not be restored.

Fig. Analysis to check survival of resources