Virtual Routing

Chapter 2

Literature Review

PREAMBLE: This part of the dissertation documentation is to gather and to put forward the required information to focus on the idea of network virtualization in order to get an idea on the concept of virtual routing. It also focuses on the need for Virtualization of hardware resources in the network and benefits of implementation of Virtual Routing concept in the Computer Networks. It also discusses the basic routing algorithms used and other fundamental concepts of networking to get an idea about virtual routing.


As the need for more communication and data sharing grow, more and more networks are being deployed. A computer network is a group of computers or peripheral devices that are interconnected to each other. When the numbers of computer users increased, more networks are deployed. Computer network is used in small, medium and large organizations also.

The main problem with the VPN(Virtual Private Network) is that if the network is to be expanded or re-organized, then hardware costs will be increased. Virtual routing implementation on networks helped to overcome this issue in VPN. ISPs were forced to take a new form of network design which is called the MPLS design. This design enables ISPs to provide internet to their customers with high quality of service and greater speeds


Making the computer resources virtual is said to be a good thing as it reduces the complexity of the system and it called as virtualization. Computers and other devices are taking advantages of this concept with many components adopting the virtualization on their devices. Before getting to know about the virtualization on network, the definition of virtual according to “TheFreeDictionary” is

“Computer system created, simulated, or carried (…) or computer system designed so as to extend the potential of a finite system beyond its immediate limits (...).”(Thefreedictionary, 2008)

The main objective of virtualization is that integrate the existing network with virtualized network devices. The networks were become very complex, when we increase the organization expansion. According to Inkra Systems, virtualization in networks is stated as

“Virtualization is a concept that separates a function from physical reality (Inkra, 2003). “

Though virtualization was considered as a big task, but the introduction of advanced microprocessors and inexpensive PCs have given a hope for the virtualization.

2.3 Types of Network Virtualization:

There are two types of network virtualization, they are:

* Data path Virtualisation: This virtualization refers to the virtualization of the network path instead of devices. After the virtual path has been created, the network traffic can easily shared among the paths created. Interconnection path between devices is also virtualized through the creation of multiple tunnel paths. This concept is called as Generic Routing Encapsulation (GRE).

* Device Virtualisation: This virtualization creates the logical device within the physical device. It also replicates full functionality of the original physical device. This virtualisation is the basis of virtual routing.

2.4 Why go for virtual routing? :

Sending the information from source to destination without any delay is called routing(Steinbach, 2006). In routing sometimes hardware components may be used for faster communications. According to Andreas's posts, routing is defined as

“Controlling the flow of network traffic to an optimal path between two nodes (Antonopoulos. 2008)”

The purpose for selecting virtual routing concept is that concentrating on the issues that the conventional routing creates. Increasing IP addressing size was the idea formulated by network analysts and a new protocol called IPv6, which is the next generation protocol for internet has 128 bits of address space as compared to the currently running IPv4 which has only 32 bits addressing space (Das K, 2008)(Deering and Hinden,1998). But that doesn't solve the problem, as according to the survey analysts Joan and Svein Nordbotten, the numbers of internet users registered to their local ISP during 1999 and 2000 have increased five folds around the world. (Joan and Svein, 2002).

Growth in registered users

(Source: )

Virtual routing reduces the addition of extra hardware components that improve the network routing. Jenifer Liscom, a principle analyst have quoted about Virtual routing concept as

“Virtual routing concept feature creates a paradigm shift in today's requirements to insert and deliver value-added services at the edge of the network. This unique capability reduces service providers' capital investment and operational costs, dramatically changing network economics and enabling new wholesale services ” (Lawitzke, 2004).

Virtual routing concept also holds another proposal of creating a new virtual path. Instead of routing all the traffic in the same line and enabling congestion, create a separate new parallel path and redirect the traffic into that route.

2.5 Virtual routing Basics:

The main idea of virtual routing is to route the traffic in a faster and efficient manner, if the original path is congested. The following specifications are achieved in order to implement the virtual network.

* Each Virtual Router in the VPN must function independent to any other Virtual Router in the VPN.

* All the virtual routers in a specific VPN network must share the same VPN-ID.

* Various routing protocols such as BGP, Static routing or RIP can be used by the virtual router to route traffic.

* The VPN architecture must be designed in such a way that it must accommodate different data at different levels of the architecture.

* To increase the security and rigidness, addition of authentication and encryption services for VPNs are necessary.

* Each Virtual router should contain separate individual RIB (Routing Information Base) and FIB (Forward Information Base) for each supported technology. (IPv4, IPv6, MPLS etc).

* It must support overlapping of VPN addresses in a particular Virtual private network.

* Virtual router deployment and management must be managed by the network administrator.

* Routing of the traffic can be done using virtual router (software) or using the normal router (hardware). The tasks of the router include isolation of frames, including Address Resolution Protocol*, exploring new routes, detecting and avoiding congestion etc.

2.6 Benefits of Virtual Routing:

The following are the benefits of virtual routing:

* The added benefits of Virtual Private network with implementation of virtual routing is to increase security in the network.

* Since the software application emulates the router making it virtual router, costs is much reduced.

* Deployment and management of the network can be done faster with software rather than hardware, since moving of hardware within the network might produce unpredictable effects on the network,

* Highly scalable approach with minimal supervision and maintenance.

* Virtual router application installed in an existing router is said to be stable and accurate.

* Maintenance costs and upgrades to maintain the router is reduced. For example one router can be upgraded along with its virtual routers, which is easy rather than upgrading hundreds of individual routers without virtual routers in the network.

2.7 Features of Virtual Routing:

The virtual routing concept helps not only the network administrators but also in the areas of business.

* Each Virtual router consists of separate RIB and FIB (routing information table) similar to the hardware router and the routing information of virtual router will same in original router, therefore supports overlapping of IP addresses.

* Virtual router can use routing algorithms to route and simulate traffic in the network.

* Implementation of Virtual router in the VPNs will reduce maintenance, software upgrades and increase security in the network.

* Inclusion of API (Application Programming Interface) allows the administrators to configure the network dynamically.

* Usage of better protocols enhances the security and reduces the complexity of the protocol stack.

* Uses VRF (Virtual Routing and Forwarding Protocol) in setting up multiple virtual routers on a single network platform. (ipinfusion, 2002).

* The deployed virtual router should allow the network administrator to configure the VPN network. The tasks that can performed on the network by network administrator are:

ð Creating/ deleting new Virtual Routers

ð Adding services by applying protocols to the existing VR.

ð Adding authenticated and authorised users to the Virtual routers to enhance security.

2.8 Router Virtualization Technologies:

Router virtualization is the partitioning and isolation of h/w and s/w resources within a single router. There is actually a dispute about the technology that virtually creates the existing routers into virtual routers, which is called as Virtual Routing approach and another approach called as the BGP/MPLS approach where a single router sits in between the ISP and the customer VPNs. Both the concepts are simple and effective, according to network analyst Alice Barrett Mark.

2.8.1 Virtual Routing:

Virtual Routing provides strong security features like encryptions and authentications. The concept of virtual routing is simple, instead of using multiple routers. without virtual routing

Source: < >

Each router has a routing table that holds all the address of devices. Multiple routers in a network have some difference in the routing table, but its routing mechanisms and firewall capabilities are same. The above figure shows the conventional routing in compare with the virtual routing. virtual concept defined

Source: < >

The problem with the virtual routing is encryption, where packets are encrypted at the starting router and must be decrypted at the egress router.

2.8.2 BGP/MPLS:

BGP/MPLS maintains a single routing table called as VRF table (Virtual Routing and Forwarding), with all the updates are done on a single table. MPLS devices in the network determine the optimal path for the packet. The main advantages of this approach, they are:

* It is a highly scalable approach. I.e. this type of network configuration can process high volumes network traffic.

* The network using this approach will allow network administrators to expand the network easily.

* IPSec, the authentication, encryption of packet stream is optional in this type of network configuration.

* In VPN tunnelling concept, a tunnel or a private network path is created to access the resources outside the VPN, Each client who has VPN have one, but this technology enables shared Tunnelling, which allows multiple clients to use the same tunnel.

* Enables Virtual sites, i.e. uses sub interfaces to connect to multiple VPNs. (Welcher, 2000).

2.9 Comparison of routing technologies:

These technologies are almost similar. The comparison of the routers virtualisation is based on how the technology is deployed and used. The comparison does not find the capabilities that lack in the technology but gives an overview. Alice Barret Mack, a principle technical marketing manager at Eriksson IP infrastructure, has studied and researched about these routing technologies and compared based on the vital network routing features.

The comparison chart has been shown below,


Virtual Routing





Ease of provisioning new services


High security requirement


Requirement for a "securable" network



Support for many subscribers


MPLS/BGP installation not feasible





End-to-end QoS




Reduction in CPE complexity



Reduction in CPE processing


Comparison of features between Virtual Routing and BGP/MPLS technology.

It is clear that Virtual routing is considered to be flexible and appropriate if there is a need to maintain high level security in the WAN topology, on the other hand, BGP/MPLS is better for less secure networks and the data processing is very fast.

2.10 Routing Algorithms used:

Setting the network consider several network performance parameters such as delay, efficiency, speed, load, stress etc. In this project, we focus on two network performance metrics they are delay and efficiency of the router.

Network routers may use single or different algorithms based on the algorithm complexity, this project discusses the most basic five algorithms, they are:

1. Hot-Potato

2. Source Routing

3. Distance Vector (Bellman-Ford)

4. RIP (Routing Information Protocol)

5. Link state Routing Algorithm

The artefact based on these algorithms efficiency calculates the delay and the efficiency of a particular routing algorithm. If the delay is less than the efficiency is more, where as if the delay is more than the efficiency is low. They are inversely proportional to each other.

2.11 Software Development life cycle:

The SDLC is very important for the development of any software artefact. There are several SDLC designs such as Waterfall model, RAD model, the fountain model, the Spiral model etc are some the SDLC design lifecycles. The software life cycle model used in the development of this artefact is Waterfall Model. The Waterfall model is a top down, since the process flow in a step by step fashion in form of a waterfall; hence the model has been named as Waterfall model.

Source : < >

There are 5 stages in the Waterfall model, they are

1. Requirement Analysis and Testing

2. System and Software Design

3. Implementation and Unit Testing

4. Integration and System Testing

5. Operation and Maintenance.

These five stages may be used based on the time constraints of the projects. This SDLC waterfall model is generally used by Small or Medium software projects, since it offers

* Rigidness.

* Testing and verifying is done at each and every stage.

* Step by Step Scheduling.

* The process phases are more visible.

* A document driven approach, i.e. document is presented at completion of each stage. (Steinbach, 2006)

Please be aware that the free essay that you were just reading was not written by us. This essay, and all of the others available to view on the website, were provided to us by students in exchange for services that we offer. This relationship helps our students to get an even better deal while also contributing to the biggest free essay resource in the UK!