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



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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

For the Award of Degree of

Master of Science in Electrical Engineering

School of Electrical Engineering
Faculty of Engineering Sciences

The University of Faisalabad



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Declaration Form

It is certified that MS(EE) thesis titled " Comparison of SDN and GMPLS control techniques in optical transport network " prepared by Mr. Muhammad Atif Yaqub under Reg # MS(EE)-SP13-008 has been approved for submission.


Thesis Supervisor




Abstract






GMPLS (Generalized multi-protocol label switching) is the control plane that is derived from the IP/MPLS technique. The protocols used in GMPLS for routing (OSPF, IS-IS) and signaling (RSVP) are same that are used in IP/MPLS network. In IP/MPLS the Labels are used to distinguish between the LSPs but in GMPLS the LSPs are identified based on TDM signal, wavelength and fiber.
On the other hand SDN (Software defined networking) serves the main purpose of current requirements in optical transport network. It meets the requirement of dynamic, smart and price operative services with more optimized solutions. SDN uses a common control plane for all layers used in optical transport networks which make the control plane less complicated as compared to GMPLS. There may be multiple switching layers in SDN based on different vendors which may provide different services but the control plane is centralized for the whole multi-layer network.
In this paper we will have comparison on the control techniques used in GMPLS and SDN for the current requirements and the future trends in optical transport network. After that the recommendations and conclusions will be made based on the advantages of SDN control technique over GMPLS. Also the possible strengths of SDN will be discussed for future optical networks. Control plane is not quite easy to implement in optical network as we have to observe multiple parameters like optical power calculation, optical signal bandwidth and path calculation.


ACKNOWLEDGEMENT
First and foremost I would like to express my sincere gratitude to my thesis advisor, Dr. Syed Ali Mohsin, for his guidance, encouragements and unreserved help during my two years of study. He motivated me to start my master thesis during my third semester which allowed me to extend my research study this far. His office door was always opened for me to discuss long hours even during after office hours. His pursuit of high standard in research and his maturity in the field were the greatest source of my motivation.
My special thanks should go to the Mr. Muhammad Kashif for his in depth research guidance especially in the area of Optical fiber Communication. In my daily work I have been blessed with a friendly and supportive group of fellow students. I would like to thank all my friends who have provided constant help and encouragement and I gratefully acknowledge their support in many ways during two years of my study. Further my immense gratitude should go to all my professional colleagues for their research guidance, constructive criticisms and invaluable suggestions.
Finally I take this opportunity to embrace my beloved parents for everything they have done for me and I thank my family for their prayers and emotional support throughout my studies. I dedicate this thesis dissertation to my parents.

Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v


Table of contents
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Chapter-1 Introduction to GMPLS and issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

    1. Introduction of GMPLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

    2. GMPLS protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 GMPLS challenges and the way out . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.3.1 Division of Generalized label. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3.2 Formation of Label switched path in GMPLS. . . . . . . . . . . . . . . . . . . . . . 7

1.3.3 Mechanism for data Transmission variety . . . . . . . . . . . . . . . . . . . 9

1.3.4 Structuring of GMPLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.3.4.1 Proposed Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.3.4.2 Duplex Label switch path . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.3.5 Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

1.3.5.1 Forwarding Adjacency Label switch path . . . . . . . . . . . . . . .12

1.3.5.2 Categorized label switch path . . . . . . . . . . . . . . . . . . . . . . .13

1.3.5.3 Link Aggregations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.3.6 Consistency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.3.7 Efficient Use of available resources . . . . . . . . . . . . . . . . . . . . . . . 17

1.3.7.1 Numberless connections . . . . . . . . . . . . . . . . . . . . . . . . . . .18

1.4 GMPLS unresolved problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

1.4.1 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

1.4.2 Connectivity with other networks . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.4.3 Stability of network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

1.4.4 NMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Chapter-2 Software defined networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.1 What is SDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.2 SDN Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2.2.1 Data plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2.2.2 Control plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

2.2.3 Data forwarding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.4 Data distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.5 Network specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.6 Advantages of Decoupling of control and data planes . . . . . . . . . . . . 24

2.2.7 Interaction of SDN layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.2.7.1 Software defined networking core controller . . . . . . . . . . . . . . 25

2.2.7.2 Use of vendor based Network Software . . . . . . . . . . . . . . . . . 25

2.2.7.3 Use of Network Management System . . . . . . . . . . . . . . . . . . 25

2.2.8 SDN layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.2.8.1 Infrastructure layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

2.2.8.2 Southbound interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.2.8.3 Network hypervisors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.2.8.4 Network operating systems . . . . . . . . . . . . . . . . . . . . . . . . 28

2.2.8.5 Northbound interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.2.8.6 Language based virtualization . . . . . . . . . . . . . . . . . . . . . . . 30

2.2.8.7 Programming languages . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.2.8.8 Network applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3. Differences between GMPLS and SDN . . . . . . . . . . . . . . . . . . . . 31

3.1 Distributed and Centralized control . . . . . . . . . . . . . . . . . . . . . . 31

3.2 Complication of control plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33


    1. Non-Flexibility for new control plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

3.4 Different services provisioning . . . . . . . . . . . . . . . . . . . . . . . . . 34

3.5 Industrial application of SDN . . . . . . . . . . . . . . . . . . . . . . . . . . 35



      1. Important benefits in Telecom industry . . . . . . . . . . . . . . . . . . . . . . 35

3.5.1.1 Use of special software tools . . . . . . . . . . . . . . . . . . . . . . . . 36

3.5.1.2 Combined management . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

3.5.1.3 Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

3.5.1.4 Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

3.5.2 ZTE SDN special features . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.5.2.1 Dynamic extension of services . . . . . . . . . . . . . . . . . . . . . . 37

3.5.2.2 Restoration of services using common controller . . . . . . . . . . 39

3.5.2.3 Possibility of availability . . . . . . . . . . . . . . . . . . . . . . . . . . .40




List of Figures



Chapter-1
GMPLS
1.1 Introduction of GMPLS
This is the time of high speed internet that is requirement of each and every individual. Also the high definition and high quality video streaming has become quite important for use. All these services required high bandwidth allocations. For this purpose the transport network is very important which needs to have high bandwidth in it to fulfill the future and current requirements. The DWDM is the type of optical transport networks which covers the requirements in a better way. Also it is very important that the control on these DWDM systems should be well optimized for better use.
Internet Engineering Task Force (IETF) started working on the control planes of optical transport networks and developed Generalized Multi-protocol Label switching ( GMPLS). GMPLS works as a control technique in the optical transport networks to calculate the path between source and destination. The GMPLS control plane is for the old TDM type transport networks like SDH, PDH, wavelength and fiber switching techniques similar to MPLS that is used for IP traffic between switches and routers. GMPLS control plane works in such a way that it dynamically allocates the resources as per demand. Whenever there is demand for resource allocation, then the media resources are allocated and remain spare when no requirements. This dynamic approach of GMPLS has selected it as a better choice of control technique in the future transport networks.
MPLS has the benefit of being used for fast data transmission in data networks comprising of switches and routers. Since Internet protocol technique is a not connection oriented technique but when the MPLS is used it has information of both source and destination. This path in determined before the packets are transmitted from one station to the other. In order to further enhance the pace of data transmission in this type of system, a label is used to identify the forward path of the packet. It not used the IP addresses to check for the destination IP for path calculation. We can also provide the Quality of service to the traffic using MPLS with the tables. The combination of both the label and tables makes the LSP.
GMPLS uses the qualities of MPLS as a control plane. The protocols used in MPLS like routing and signaling protocols are used in GMPLS as well for different TDM, wavelength and fiber switched systems. The main purpose of using the MPLS techniques in GMPLS is to provide automatic service provisioning methods that require fewer loads on the management and dynamically uses the available network resources.
MPLS has good features for efficient routing and transmission of data in data networks and with other TDM switches and wavelength multiplexed systems also had the requirements to have a generalized control plane that can control the data transport dynamically through these old systems. For this purpose the GMPLS idea was used that is also using the LSPs that were used in MPLS network. The LSP not having labels in GMPLS as were in MPLS, but for TDM it is having time slots, for WDM it is having wavelength and also for fiber switching it is having fiber port in place of labels.
Very important feature that is quite new in optical transport networks and used in GMPLS is dynamic and automated network management. As we see in SDH all kinds of services are configured manuallay from one station to the other and we have to manullay create the path traversing all the systems in the path. Such process is too lengthy and creates a lot of load on the management system operations teams. If one ring is fully used and no more resource is available in the ring then it is essential to upgrade the ring. After that the wholebetwork will be informed manullay about this upgradation so that the resources are further used.
1.2 GMPLS protocols
All the routing protocols like OSPF, IS-IS and signaling protocols like RSVP, CR-LDP that were used in MPLS are now also used in GMPLS control plane. All these protocols cover the TDM like SDH and WDM for wavelength networks.
Another very important protocol for signaling puposes in link management protocol (LMP). It is used to have better conditions of control and data planes between the two nearby stations.
Below table-1 summarizes these protocols and the extensions for GMPLS.






Table-1. GMPLS protocols

Protocols

Description

Routing

OSPF-TE,
IS-IS-TE

These protocols are used for dynamic/auto discovery of the network, all the necessary information like the available bandwidth in the network is also shared with all network elements.

Also works to check for the protection paths availability. It shares some very important information which is as under.

It shares what kind of protection to the traffic is available (e.g 1 +1, 1 :1 or no protection)

In order to improve the quality it uses these new links

It broadcasts the information of links that are not having IP addresses but the IDs of the link NEs and the interface IDs of both ends.

It is also important to have calculated/identified the protection path in case of failure (which is shared risk link group).

Signaling

RSVP-TE,
CR-LDP

These protocols are very important, used for making the Label switched paths.

The important aspects are as below.

Since TDM, wavelength networks are used in GMPLS so generalized labels are required instead of labels in packer transport.

The generalized labels are always bi-directional.

Like routing protocols the signaling protocols also use protection path for backup recovery.

After that the labels are assigned using the

Expediting label assignment via proposed labels.



Link Management

LMP

These protocols have following aspects.

Link management with control-channel:

It shares link parameters, for example the frequency sends the information to other end to check the link status and also link strength using hello protocol. PING-test verification: The PING test is used to check the physical connectivity of the two joining systems so that link management is verified.



Correlation of link possessions: It will identify the properties of the link of all nodes connected together. The properties may be of protection scheme used by the nodes.

Fault Separation: It will separate a single or many faults of the optical domain.

All these protocols can be seen in below Fig-1.



GMPLS protocols.


1.3 GMPLS challenges and the way out
Since GMPLS has to cover different types of equipments with different switching types to provide a unified control plane, teherfore folliwng important issues are observed.


  1. Forwarding of the data is as not just related to packet. The GMPLS control plane should be able to provide the facility to forward the data of TDM, wavelength and fiber switching also as works with packets traffic.

  2. The data carried by packets has the facility that it cab be observed by the network NEs who carry this traffic. The packets receive the header of packet, check for label and then the output port having the forward path is determined and the packet moves to this direction. But when we talk about time and wavelength division systems then the packets are not identified in these systems as these systems are not made for this purpose.

  3. As we know in TDM, DWDM and frequency switching the bandwidth reservation of a label switched path is done as per fixed units. But when we see in packet networks the bandwidth of label switched path can be from 1 Mb/s to 100 Mb/s. Like is TDM we have optical data rates of STM-1, STM-4, STM-16, teherfeore the bandwidth allocation will be only as per earlier mentioned data rates. If we have a packet network that has LSP bandwidth requirement of 50 Mbps, so a fixed bandwidth pipe of STM-4 is more than the requirements. Therefore the requirements should be as per actual.

  4. It is essential that the network should be made such that is can cover all the network modification easily and quickly. Since the TDM and optical networks are very large networks as compared to those of packet switched systems, therefore it is required that the proper network change adaptability be ensured. The wavelength and fiber switched systems will have to use hundrds of wavelengths in it.

  5. It is not time saving job to have electronic and optical switches as takes more time when there are hundreds of output ports available for switching from input to output ports. All these types of networks create too much delay in setting up label switched path as mane input ports will be checked for switching to many output ports.

  6. Since in TDM networks like SDH we observe that the automatic protection is observed in these systsems in case of failure of any link. The restoration time is 50 ms. The GMPLS ssystems should also ensure that the fast recovery mechanism is also adopted in this system with dynamic/auto recovery process. The protection mechanism may be fixed or automatic/dynamic.

All these challenges are discussed in detail is the below section.


1.3.1 Division of Generalized label
Generalized switching is required in the GMPLS based systems that have time slots, wavelengths and fiver ports for switching. The generalized approach is used in it in which the data is forwarded to the next node without considering what kind of data it is and what kind of switching is involved. When we talk about generalized switch it can have a time slot, wavelength or fiber as a generalized label. GMPLS also carries the packet MPLS labels as well to carry packet traffic as well.

Following important data regarding lables is available in GMPLS.




  1. Label switched path need to be identified that what kind of label is used, for example packet, TDM or wavelength.

  2. Switching capability needs to be verified that what kind of switching ability (packet, wavelength of TDM) the NE possesses.

  3. It is important to know what kind of data/payload will be with the Label switched path (data may be of Ethernet, SDH, ATM etc).

Label switching router of the main upstream node send the lables to the last downstream node. The upstream node suggest labels for the downstream and ultimately it covers the whole path.



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