Network Technologies Network Design Routing Protocol Computer Science Essay

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I met some with simulation of networks designing scenarios according to my time schedule. Again my designing scenarios were getting long time to simulation. So I reduced some application traffic. When I was designing more network scenarios, OPNET drive space was full. Then I sent a mail to my supervisor to increase that space. Then I more enough space regards my supervisor.

Key word during next period

Next work is focusing; the simulation of designing networks scenarios and gets the statistical result. Give the brief description of each scenarios and comparing interior routing protocol towards statistical result. Sv823 4 MSc Project

RESEARCH AND LITERATURE REVIEW

At present, internet plays a vital role in many of our daily life. It made a dramatic revolution on communication which we enjoy today. The revolution offered web appliances, e-commerce, video conferences, online gaming and so on. All these became possible and operating on the backbone called networks.

On the first hand, before discussing about routing and routing protocols we'll go through and networking. Initially U.S. government funded researches on sharing information within computers for scientific and military[1] purposes. Though there were many contributed to the foundation of internet J. C. R. Licklider was the first among them. As a leader of Information Processing Technology Office (IPTO) he demonstrated the concept of time sharing and promoted the researches and concepts on networking. Time sharing made a major evolution in the IT world. It became the basis for networking as well. Lick's successors as leaders of IPTO, Ivan Sutherland and Bob Taylor influenced by "Intergalactic Network" lead the researches of Advanced Research Projects Agency (ARPA)'s IPTO. The three people Paul Baran, Leonard Kleinrock and Donald Davies developed fundamentals for ARPANET with their own concepts such as packet switching and so on. After continuous researches on implementation of networks, the first ARPANET interconnected and became success in 1969. Being limited for military and research purposes by universities ARPANET has gone through several modifications and adopted many mechanisms. By 1990 networks gradually became for public and from their several other technologies emerged based on networks.

When the networks used by general public, it began to grow massive and more complex. So there was a need for a man in the middle kind of device to handle the routes for networks. So that experts coined the device called "router". Router is a networking device used to forward the data to an interface to route the data towards its destination. Again the network administrator had to do a hectic job of adding static routes and updating each and every route in a network. For instance, if a link goes down all the routers should be updated manually to cope with it. So to handle these messy situations experts came up with the routing protocols. Though there were plenty of contributors and technology shifts in various occasions in the industry, the above paragraphs covers the milestones in the history. Sv823 5 MSc Project

Routing Concept

Routing is the process of directing a packet towards the destination with the help of router. The router receives a packet from one interface, determine which interface to be forwarded based on routing algorithm and destination address and then send the packet to the interface. To route a packet the router should satisfy at least following,

Router should know Destination address & subnet mask

Discover Neighbor routers where it can identify the routes for remote routers

Identify all possible routes for all remote networks

The best path for routing the packet

The process of maintaining and verifying the routing table and routing information

In general, routing can be categorized as static and dynamic routing. Static routing is the process of adding the routes manually in the router table. The Static routes have the administrative distance of 1 by default.

IP route 172.16.30.0 255.255.255.0 172.16.20.2

Dest n/w subnet mask next hope

Static routing has no overhead on router CPU or bandwidth of the link and secure compared to dynamic routing. However, static routing doesn't have fault tolerant and it's a tedious job to add routes manually. In a wide area network, adding all the routes is definitely a hardest job. Then again when a topology changes or a link goes down again the network administrator have to run all over the place to update. However in some scenarios, static routing remains handy. For instance, in stub networks where all the traffic routed towards a gateway static routing is inevitable with default routes. So static routing consume less resources, easy to configure, more secure and can handle multiple networks. Default routing is a category of static routing where only the exiting interface is specified.

IP route 0.0.0.0 0.0.0.0 serial1

Dest n/w Subnet Exit interface

Administrative distance for default routing is 0. Default routing is used to send packets to remote networks when the router doesn't have information about it on routing table.

The next crucial, widely used category is dynamic routing which is concerned in this project. Dynamic routing is the process of keeping the routing table up to date with instant updates from routing protocols. These protocols dynamically share the information and able to update the routing table when topology changes occur. Further, these protocols determine the Sv823 6 MSc Project

best path based on metric calculations. So that dynamic routing protocols remain crucial in large scale corporate networks to update their routing tables. Dynamic routing protocols provide fault tolerance by broadcasting updates when links goes down or server shutdown. To update the router tables the routing protocols define the rules for communicating with the neighbor routers. The rules specify the method and algorithm to exchange information between neighbors. All in all though dynamic protocols consume more CPU power and bandwidth when compared, they are robust and more reliable in networks, especially large scale. Routing protocols can be categorized in various ways based on their characteristics.

Initially, protocols can be divided into routing and routed protocols. Routed protocols are responsible for actual data transfer. The protocols under this category are TCP/IP, IPX/SPX, and apple talk. Routing protocols exchange the routing information between routers. They include RIP, RIP v.2, IGRP, EIGRP, OSPF BGP and so on.

Further dynamic protocols can be classified as,

Interior gateway protocols (IGP) and Exterior gateway protocol(EGP)

Classful and Classless

Distance vector ,Link-state and hybrid protocols

IGP and EGP are characterized based on autonomous system. Autonomous system (AS) is the collection of networks within one administrative domain. IGP protocols are used to exchange router information between same AS number and EGP is between different AS numbers. Rip, Rip v.2, IGRP, EGRP, OSPF, IS-IS come under IGP and BGP is under EGP.

Classful routing protocols do not advertise the subnet mask but classful address in advertisement. Classless protocols advertise subnet mask. RIP and IGRP are classful and RIP v.2 EIGRP, OSPF and IS-IS are classless.

The other important characterization is Distance vector, Link state and hybrid.

Distance vector protocols

Advertise periodically

Advertise full routing table

Advertise only for directly connected routers

High convergence time

Limited no of hops

Suffer from routing loop

Do not establish neighbor relationship

Protocols - RIP, IGRP

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Link state protocols

Advertise only when network triggered

Advertise only the update

Flood the advertisement

Convergence is low

No limits in hop count and suitable for large network

No routing loops

Establish neighbor relation in formal way

Protocols - OSPF & IS-IS

Hybrid protocols

It's a combination of both Distance vector and Link-state. EIGRP share such routing characteristics.

Dynamic routing Protocols

Routing Information Protocol (RIPv1)

Routing information protocol version 1 known as RIP is the initial routing protocol to be implemented in ARPANET in 1967. As classified before RIP is a classful, distance vector and interior gateway protocol (IGP). RIP was developed based on Bellman-Ford algorithm and use hop count as the metric value. It uses the lowest hop count to calculate the best path. Rip limits the number of hosts it supports in a network to prevent routing loops and maintain stability. It supports a maximum of 15 hops in a network. 16th hop is defined as in infinite administrative distance and they become unreachable and unshareable. It uses broadcast address 255.255.255.255 to send updates between routers. Administrative distance for RIP is 120.

Rip use several timers in the advertising and updating process. Routing update timer, route timeout timer, and route flush timer are the timers used by RIP. Routing update timer is used to determine the time interval between each update from rip implemented router. Usually a full update is sent every 30 seconds from router. This became a problem when all the routers simultaneously try to send updates every 30 seconds and consuming the bandwidth since they are synchronized. So that when the timer is reset random time is added in addition to the 30 seconds to prevent such congestion. Route timeout timer is the time frame until a record remains valid before it gets an update with same record. If the router doesn't get the update again within the time frame router marks the record for deletion and hold it until the Sv823 8 MSc Project

flush time expire. After the flush time expires the record will be purged permanently from the table.

Rip protocol preserve stability by limiting the number of hops to prohibit routing loops propagation. RIP implements split horizon, route poisoning and timing mechanisms to prevent erroneous information propagation. However, limitation on number of hops becomes a setback in large scale networks. Limiting only to classful advertising is another drawback in RIP. Further, routing updates are not capable for authentication process which is a security concern with version1. Despite rip being emerged ages ago it still exists in routers. Because it is easy to configure, stable, suits well for stub networks and widely used.

Routing Information Protocol (RIPV2)

Rip version 2 was standardized and released in 1993 due to lack of some important features in version 1 as mentioned above. Version 2 is an enhancement for variable length subnet masking (VLSM). Ripv2 designed to support classless routing with subnet masks which was a critical update from earlier version. Version2 updates carry more information with simple authentication enabled on it. It uses multicast address 224.0.0.9 to send updates. Multicasting avoids the hosts which are not part of routing from receiving update. This version also maintains the maximum number of hops to 15.

Open Shortest Path First (OSPF) Routing Protocol

Open shortest past first (OSPF) plays a key role in IP networks for several reasons. It was drafted to be used with the internet protocol suite with high functionality as a non proprietary protocol. OSPF is an interior gateway routing protocol which routes packets between the same autonomous systems. It has an administrative distance of 110. It is designed to fully support VLSM (Variable Length Subnet Masking) or CIDR (Classless Inter-Domain Routing).Also it supports for manual summarized advertisement. It's a link state protocol. So it scales well[2], converges quickly and offer loop free routing. On a topology change or link down it converges quick enough to provide a new loop free route.

It uses cost to calculate the metric value. The shortest path is calculated based on Dijkstra algorithm to find the best path. OSPF use multicast addresses for updates. The addresses are, 224.0.0.5 is for sending updates and 224.0.0.6 is to receive updates. OSPF maintains three types Sv823 9 MSc Project

of tables namely, routing table, neighbor table and database table. It uses Hello protocol to establish neighbor relation and maintain a neighbor table. Hello protocols attributes are,

Router ID

Priority (default 1)

Hello interval (10 sec)

Dead interval (40 sec)

Authentication bit

Stub area flag

Process ID

The relationship is established based on the router ID. To establish a neighbor relationship timers (hello &dead), network mask, area ID and authentication password should be same.

It uses area to communicate among routers. OSPF can be configured as single area or multi-area network. Areas are introduced to constrain the flooding of update into a single area. An OSPF domain is split into areas and labeled with 32 bit identifiers to limit the updates and calculation of best path with Dijkstra algorithm into one area. Areas should be carefully designed and configured to group the hosts and routers to a logical area. Each area maintains its own link state database which is distributed via a connecting router to other networks. Such design reduces the traffic flow between areas and keeps the topology anonymous to other areas. In single area OSPF the entire interface in that network belongs to same network. The diagram below explains a configuration in single area OSPF.

In multi-area, all other areas must connect to the back bone area (area 0) directly or virtually. The diagram below is a sample of multi-area configuration.

A multiple area OSPF must contain at least one backbone / zero area and may have several non-backbones. Zero area remains as the core area for all the other areas. All the other areas connect to backbone area to get updated. OSPF allows configuring stub networks as well. In OSPF stub networks external updates are not flooded in to the stub area. This will result in reducing the size of database size and thereby memory consumption. When stub network area is configured default routing will be used to connect to the external areas. OSPF defines the following router states,

Area border router (ABR)

Autonomous system boundary router (ASBR)

Internal router (IR)

Backbone router (BR)

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The routers could play one or more roles as mentioned above in an OSPF network. The router identifier should be defined in a dotted decimal format to associate each OSPF instance with an ID. If it is not explicitly specified, the highest logical IP will be assigned as the router ID.

Area border router (ABR) is the common router which placed on the edge of the backbone area to connect other areas via its interfaces. The ABR keeps a copy of the link state databases of both the backbone and of the areas which it is connected to in its memory.

Autonomous system boundary router (ASBR) is the router which connects an autonomous system and a non-OSPF network. ASBR remains as a gateway to connect an AS to other routing protocol networks such as EIGRP, RIP, BGP, static and so on. It also used to exchange routes which it learned from other AS number through its own AS number.

The router which has all its interfaces and neighbor relationship within an area is called as Internal Router (IR). All the routers which are part of the backbone area are backbone router (BR). It may be a backbone internal router or an area border router. ABR is also a BR since it is connected to backbone via a physical or logical link.

From OSPF configurations the routers elect designated router (DR) and backup designated router (BDR). A designated router (DR) is elected on a multi-access network segment to exchange routing information with other routers. The job of the DR is multicasting the router update which it received to the other routers. So other routers listen only to the DR instead of listening to broadcast. DR elected to act as one-to-many instead of many-to-many routing update. So updates are sent only to the DR router and it updates all the routers within the segment. This election mechanism reduces the network traffic a lot. The router with the highest priority among the routers will be elected as the Designated Router. If more than one router has same priority Router ID will be used as the tie breaker. In multi access networks Backup designated router (BDR) must be elected next. BDR is a standby router for DR if DR becomes unavailable. The router which becomes the second in the election process will be the BDR. If both become unavailable the election process will be held again. The BDR receives updates from adjacent routers but doesn't multicast them. OSPF adjacency is established to share the routing updates directly to each other. Establishing adjacency depends on the OSPF configuration in routers.

From OSPF configuration point of view networks can be categorized as,

Broadcast multi-access - In broadcast multi-access networks routers have direct access to all the routers via direct links. Some of the examples for Broadcast multi-access are Ethernet, and Token ring. Through Ethernet multiple devices are allowed to access the same network. So when an OSPF packet is sent on the network it'll be broadcasted and

Sv823 11 MSc Project

all the routers will receive it. With OSPF DR and BDR should be elected for broadcast multi-access network.

Non-broadcast Multi Access (NBMA) - NBMA network allows data transmission over a virtual link or across a switching device between the hosts in the network. Typical examples for NBMA are X.25, ATM and Frame relay. In NBMA, all the devices are connected through a shared medium. It doesn't support broadcast or multicast. Instead, OSPF sends the hello packet to each router in the network one at a time. As a result OSPF should be configured specially and the neighbor relationship should be specified properly. Power Line Communication (PLC) is also categorized as Non-broadcast Multiple Access network.

Point-to-point - In Point-to-point connections, both routers endpoints are connected point to point to provide a single path for communication. High-Level Data Link Control (HDLC) and Point-to-Point Protocol (PPP) could be the examples for P2P. In point to point network, it may be a serial cable connecting the endpoints directly or a virtual link which connects two routers apart in greater distance. But both scenarios eliminate the need for election of DR and BDR in OSPF implementation. The neighbors will be identified automatically with P2P.

Point-to-multipoint - Point-to-multipoint topology refers to connecting a single interface of a router to multiple destination routers. All the devices in Point-to-multipoint will be in a same network. Conventionally the routers could identify their neighbors automatically in broadcast network.

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Enhanced Interior Gateway Routing Protocol (EIGRP)

Enhanced Interior Gateway Routing Protocol (EIGRP) is a proprietary, hybrid protocol owned by Cisco. It was developed by CISCO as a successor of IGRP. Though it's not a version of IGRP; it's completely different. It behaves as both link state and distance vector protocol. It's a classless protocol as well. Administrative distance for EIGRP is 90. It exercises a different algorithm from previous protocols which is known as Diffusing update algorithm (DUAL). DUAL algorithm ensures to find the best path with faster convergence and loop free routing. EIGRP supports unequal cost balancing as well. It uses multicast address 224.0.0.0 to send updates. EIGRP also use autonomous system number. It maintains three types of tables,

Neighbor table - maintains data about the neighboring routers which are directly connected and accessible. Hello packets with timers are employed to keep the record with precision.

Topology table - The topology table contains all the destinations advertised by its neighbor routers. It maintains the table as an aggregation of all advertised routes with adjoining metrics. In addition from the aggregation a successor and feasible successor will be identified and stored. The successor path is the best path to reach a destination based on the least sum of advertised distance from a neighbor and the distance to reach that neighbor. This route will be installed in the router. The optional feasible successor has the metric higher than successor, which qualify to be the next successor. This route doesn't get installed but kept in the topology table as an alternative. The router will automatically add the feasible route as successor when the successor becomes unavailable. The state of a route for destination can be marked as active or passive in the table. When the router find successor unavailable with no backup routes it query the neighbor routers. This state is called as active and when it gets a reply it changes to passive state. This whole process ensures a loop free path for destinations.

Routing table - This table store the actual routes for all destinations. This table is build from the previous topology table calculation. A successor route and an optional feasible route will be stored in this table.

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Network Modelling

Basically Network modelling is a main concept of network deployment into network planning, designing and implementation. Modelling is used to describe concept of the project. Network analysis and network designing should be defined before create network modelling. Define the requirements, objectives and problem areas should be created in network analysis part. So at this stage describe about the router and routing concept towards how they are using routing protocol to route the packets and how to configure with those routing protocols. After this stage implementation part considers all fulfil requirements. Finally design part where we define appropriate network deployment. Network modelling is giving a lot of helps to think more ideas to create best possible network model. Because of that I selected OPNET simulator in this project to create network models.

OPNET Modeller 15.0 (Optimized Network Engineering Tools)

Currently OPNET is one of the best tools among many network modelling tools in the network technologies. It provides us to designing network model using all kind of network equipments. Networking designers are gained better understanding of designing before development process. It helps to reduce time manner and expense of prototyping hardware equipments. We can able to analyse, measure the performance and behaviour of proposed Model system from event simulations.

OPNET tool contains many features. There are main three editors in the OPNET

Project Editor:

It contains graphical interface of network topology nodes such as subnet, hub, switch, router, etc and much kind of links to communicate among those devices. All are designed with graphical user interface such as easy to end users.

Node Editor:

It is describe clear picture of internal architecture of the nodes by investigate the data flow between useful nodes. Node model can send, receive and create network traffic with other node model through the packets.

Process Editor:

It describes about the processes and events create by implementation of specific process operation on the network such as behaviour and functionality of the node model. During the simulation time each node model may create a process of any event, so that it gives the state of process and its functionality. Completely we can't compare simulated network with real world time traffic. But it will give some of information such as how much required bandwidth, where the jamming can occur and how to handle to avoid these problems. Sv823 14 MSc Project

Configuration and attributes of interior routing protocols in OPNET modeller

Description of Routing Information Protocol (RIP)

Basically RIP comes under distance vector routing protocol and used Bellman Ford algorithm to exchange routing information between network nodes. RIP contains various implemented features. RIP version1 (RIPv1) is a classful routing protocol with a metric of hop count and RIP version2 (RIPv2) is additional of RIP1 that supports classless routing with other features. Basically when we focus RIP on OPNET modeller, it can be configured by both ways such as go to the edit attribute and change the parameters which are we need to change. Another way right clicks on router select open virtual command line interface. When we use routers in OPNET, RIP is the default routing protocol on all routers. Mainly we can specify RIP protocol setting by simulation attributes and edit attribute parameters.

First make sure that RIP is the routing protocol specified for all interfaces in our network design Edit Attribute→ IP→IP Routing Parameters → Interface information →Routing protocol attribute.

Below picture is showing all important attributes on RIP routing. Edit Attribute → IP Routing Protocols → RIP Parameters → Process Parameters Table

RIP start time: is that first routing information updates will be broadcast over the interface on this node. First timer attribute, update interval timer that controls frequently router sends Sv823 15 MSc Project

updates. The router invalid attribute controls how long it will take to disable router. In this time if no update is received for router, it is down as unreachable and advertised. This time flash timer denotes the time it gets for route. Here the router is removed from routing table.

Failure Impact: Here there are two options such as Retain Routing Table and Clear Routing Table. If we choose Retain Routing Table that table will retain all the route information. If we choose Clear Routing Table that will be empty and it needs to rebuilt.

Version: These attribute which the version of RIP that we are going to configure on the interface. We can select either version or version2

Auto Summary: is disabled, subnetworks are advertised outside of their major network. RIPv1 don't support to advertise subnets information on routing updates. When auto summary is disabled we can have variable Length Subnets Masks (VLSM). So it reduces use of IP address space.

Send Style: it can be selected either Broadcast or Broadcast & Multicast. It controls how RIP network model router sends out RIP updates. When choose send version option is select to version 1& 2 from interface information table, in this case send style is set to Broadcast that can broadcast a RIPv2 Packet updates. Send style is set to Broadcast & multicast that can send both multicast RIPv2 updates and broadcast RIPv1 updates.

Redistribution: RIP can be configured to acknowledge routes that have redistributed from other routing protocols configured on the same router. So we can select witch protocols that will acknowledge redistributed routes and what metric contains with route received.

The above picture 0.0 is showing RIP parameters setting on interface information.

Silent Mode: if silent mode is enabled interface will receive and process RIP updates but not broadcast or multicast. Sv823 16 MSc Project

Advertisement Mode: controls any filtering used to RIP updates. The advertisement mode contains three options are Split Horizon, No Filtering and Split Horizon/Poison Reverse.

Triggered Extension:

The following network design describe variable-Length subnet mask (VLSMs) with both Version1 & Version2 of RIP protocols.

150.10.0.0/24

12.3.0.0/16

12.4.0.0/16

12.2.0.0/16

192.0.1.0/24

The above picture shows there are three main routers are connected between them and each router connects LAN network with different IP network to demonstration and among those both versions of routing information protocol. That is descried variable Length subnet mask (VLSMs) support problems or called discontiguos network problem has been simulated and analysed statistics. Focus the network topology contains different IP network addresses. Each interface of those routers has been configured by above IP address networks scheme with appropriate ports. Sv823 17 MSc Project

Secnario- RIP_version1

Above network topoloy has been configured using RIP version1 routing protocol for routing.

The above picture shows configuration of Router_A interface information table. In this node's interfaces has been configured such as serial interfaces IF10, IF11 and Ethernet interface IF0 are assigned by IP addresses 150.10.1.2, 12.3.0.1 and 12.4.0.1 respectively. Similarly Router_B's serial IF10 and Ethernet IF0 are configured by the IP addresses 150.10.1.1, 12.2.0.1 and Router_C's serial IF11 and Ethernet IF0 are configured by the IP addresses 12.3.0.2, 192.0.1.1. I have done some configuration of simulation attribute after all interfaces are configured.

The above 0.0 picture is showing simulation DES attributes. Here Global attribute→ IP → IP dynamic Routing Protocol is set to RIP and RIP Sim Efficiency is set to enabled, RIP Stop Time (Seconds) is set to 3600. RIP scenario with version1 has been run after completed configuration. Check the routing tables of those routers. Sv823 18 MSc Project

The above picture 0.0 is illustrating Router routing tables of Routers A, B and C. When we see the routing table of Router_A, This router advertises the directly connected networks 12.3.0.0, 12.4.0.0 and 150.10.1.0. Here RIP version1 of routing information protocol used so it advertises the major network only but not the sub network information. In this network topology the network address 12.0.0.0 is divided into sub nets such as 12.2.0.0, 12.3.0.0 and 12.4.0.0 and configured at different places. The split horizon doesn't accept counting to infinity problem. RIP Router_A advertise the networks 12.3.0.0 and 12.4.0.0 as major network 12.0.0.0 to the Router_B and the network 12.4.0.0 as same 12.0.0.0 to the Router_C. If any packet arrives with destination 12.4.0.2, those routers will conflict because they have more than one number of networks 12.0.0.0. So they can't find the destination and that packet will drop. Routing Protocol version1 doesn't advertise the sub network information with packets. If we use RIP version1 protocol to multi sub networks topology, it will come failure. Even after auto summary is disabled then also this variable Length Subnet Mask (VLSM) problems or discontiguos network problem still present. Because auto summary disable features don't support to routing information protocol verstion1. Sv823 19 MSc Project

Secnario- RIP_version2

Routing information protocol version2 has been enabled to solve this network problem. Here same network topology has been configured with Version2 and auto summary is disabled from RIP parameters attribute on each routers.

Here each routers they have routes for any network of this topology because routing information protocol version2 sends packets with subnets information.

Protocol Average RIP Traffic (bit/sec)

RIP_version1 86.72523

RIP_version2 154.0983

RIP version2 is giving more traffic then RIP version1 because version2 is created large routing table then version1.

Finally we can conclude both RIP version 1 & 2 are distance vector interior gateway routing protocol. Routing Information Protocol version1 doesn't support Variable Length Subnet mask IP networks even after auto summary is disabled. But routing Information Protocol version2 solves this discontiguos network problem by it carries subnet mask information. Normally RIP version1 can receive any updates information from version2 but RIP version2 can't receive any Sv823 20 MSc Project

updates information from version1. RIP uses a metric called a hop count, that maximum size of RIP network is limited hop count of 16. Always RIP version1 broadcast the routing table but version 2 broadcast updates packet, it is using 224.0.0.9 of multicast address to broadcast the packet.

Description of Enhanced Interior Gateway Routing Protocol (EIGRP)

EIGRP comes under distance vector routing protocol suite, designed to reduce the overhead state and provide a faster convergence in the network topology changes. It is a classless routing protocol to support VLSM IP network.

It can be configure each interface of each router individual to enable EIGRP as routing protocol. But all the router interfaces come under same IP sub network have to configure the same routing protocol.

If a network model doesn't have any topology change after a specific time of simulation ten it can run off the EIGRP activities. To do this modification, go to the simulation attributes setting "EIGRP Sim Efficiency" and "EIGRP Stop Time".

Each node mode has EIGRP attributes such as EIGRP Interface Table, EIGRP Metric Variance, DUAL, Load balancing, Traffic Sharing Hello Interval and EIGRP Start Time and etc to configure.

Scenario- EIGRP

The above scenario illustrates EIGRP's capability. That loading balancing is set to "packet based" sharing among three equal routes from client to sever with failure and recovery conditions as well. Here all routers that used in the network are Cisco 7500 series and all links are 10BaseT Sv823 21 MSc Project

Ethernet Links. Client can access the sever through three equally simple hop count routes such as,

Route: Client → Router 01 → Router 02 → Router X → Router 03 → Router 04

Route: Client → Router 01 → Router 02 → Router Y → Router 03 → Router 04

Route: Client → Router 01 → Router 02 → Router Z → Router 03 → Router 04

Initially EIGRP protocol has been enabled on all routers as routing protocol. The application traffic is generated through those three routes equally. After that Router X fails at 40minutes which configured from Recovery Failure node attribute → Node Recovery/Failure specification. This time rest of those two routers share recovery EIGRP process of Router X. That Diffusing Update Algorithm (DUAL) runs again to identify the specific destinations with each other's and update their routing table for the new network; it takes times called Convergence time. So some packet may drop and needs retransmissions when this failure of router and EIGRP process convergence completion time witch it can be seen on Open DES Log. Again link between Router Y to Router 04 fails at 1hour and recover again at 2hour. This time also same process happens. The network has been simulated with three hours. Sv823 22 MSc Project

The above pictures are showing routing table of the network Router 02 at different times such as 25minutes, 35minutes and 3hours. Here first table is showing three equal routes for 192.0.9.0 and 192.0.10.0. So client can access sever by those three paths until 30minutes. Then second table is showing at 35minutes after Router X failure, routing table updates only new routes for 192.0.6.0 network using X and Y routers and EIGRP process defines new two equal routes for between clients and sever. Finally table is showing, after completion link between Router X and Router 04 fail at 1hour and recover at 2houre. It have route for all destinations of the network. The Router X failure at 30minutes, EIGRP process updates the table. Sv823 23 MSc Project

Description of Open Shortest Path First (OSPF)

Open Shortest Path First (OSPF) comes under Link state hierarchical interior routing protocol. The network can be divided into multiple areas by OSPF routing protocol. The distance vector routing protocols are single area routing protocols, all routes in an area which are advertised everywhere. So number of routes is increasing in a single area. Its propagation and convergence time gets long, a limited route advertises by dividing the network into multiple areas. Every router advertises all routing information to every neighbour router in the area. This situation is possible for small networks but not for large networks. When we use single area, area number or router ID should be defining that 32bit number. Mainly OSPF networks are created using multiple areas. That can be support hierarchical and scalable network.

When we use OSPF protocol in multiple areas, area 0 or backbone area should be defined and all nonzero OSPF areas should be connected to the area 0 or backbone. OSPF doesn't advertise route similar distance vector routing protocol. It advertises link state by Link state advertisements (LSAs). Each area configured on an OSPF router which maintains OSPF database for each area to run Shortest Path First (SPF) algorithm. OSPF network topology can be divided into three parts such as Area Border Router (ABR), Autonomous System Boundary Router (ASBR) and Internal Router.

OSPF protocol can configure point to point network topology, broadcast multi area access network topology and broadcast multi access in multi areas network topology. Here this scenario explains multi area with virtual link between backbone and nonzero areas configuration.

Virtual Link

Area1

Area0

Area2

Area3

192.0.1.0

192.0.2.0

192.0.3.0

192.0.4.0

192.0.5.0

192.0.6.0

192.0.9.0

192.0.7.0

ASBR/ RIP Protocol

Network 192.0.0.0 Sv823 24 MSc Project

Above picture is showing OSPF configuration in multi area and OSPF protocol have connected, routes and redistributed with another protocol as RIP, is called Autonomous System Boundary Router (ASBR). Area3 network has been connected to backbone or area 0 networks via area 2 network using virtual link using those router IDs. Each interface of routers has been configured by appropriate IP address, area with specific protocol such as OSPF or RIP. Router ID and loopback interface also configured for each router. Routing information (RIP) protocol is enabled between Router A and Router B at 192.0.1.0 IP network and OSPF routing protocol is enabled among Router B, C, D, E, F and G with different IP networks. Router B's redistribution is enabled that redistribution of RIP to OSPF and OSPF to RIP.

The above picture illustrates OSPF protocol process parameter table for each router.

Router ID: that is identifies the router which is defined by loopback address

Start Time: this attribute define the OSPF protocol start distribution on all interface.

External Router Information: any static routing information can be defined by this attribute.

Area Summarization: it defines router's border route of areas. Sv823 25 MSc Project

Virtual Link: this attribute is connecting the router to another router. It should be configured both side routers.

Redistribution: if this attribute is enabled, specific route coming through other protocols can be advertised by OSPF protocol.

There are some attributes come under the OSPF timer.

The Hello timer default value is 10seconds; All OSPF routers connect a specific network whether it is a multi access or point to point network, hello time is same for any type of networks. Hello packet uses for detection of neighbour routers. If it is not received by neighbour until four packets sent, that neighbour is down. This time is the Router Dead Interval.

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