Ospf, eigrp with cisco products over isp level network 2009

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1.1 Overview

Network pioneers attempted to build multi-protocol networks in the early 1990s were faced with a lot of problems. Most of the protocols are running in enterprise network had no scalable routing protocols that enabled the network engineer to build reliable large networks. The grown-up and established routing protocols like RIP (Routing Information Protocol) or IGRP (Interior Gateway Routing Protocol) were reliable, slow and the newer up-and-coming routing protocol, like OSPF (Open Shortest Path First) were difficult and not confirmed in the field at that time. Cisco Systems decided to overcome the gap between the existing technologies with a latest routing protocol, named Enhanced Interior Gateway Routing Protocol (EIGRP) that combined the simplicity and reliability of the previous routing protocols.

The purpose of this project is to check stability, performances in OSPF and EIGRP protocols with CISCO based large scale network. Network architects recommend mix protocols for large network. My attempt is to prove and find changes in OSPF and EIGRP configurations. This will help us to do select best configuration and it will avoid potentially expensive network outages.

1.2 Objectives

Attempting to achieve following objectives in CISCO based large scale network. This network contains OSPF, BGP and EIGRP protocols. The OPNET Technology is using to do following things

  1. Examination link utilizations and routing path.
  2. Test network performance with help of flow analysis.
  3. Visualize network to determine overloaded links.
  4. Deploy application and investigate impact on network.
  5. Identify network failover recovery by performing failure analysis.

1.3 History of CISCO System

Sandy Lerner and Len Bosack are married couple and Richard Troiano worked together at Stanford University as a computer operation staff. They were founded Cisco Systems in 1984. Lerner started doing full time work to Cisco in 1987 at Schlumberger. The name "Cisco" was extracted from the city name, San Francisco.

The Cisco System has stated sell routers supporting multiple network protocols. It was commercially success in that time. They were the pioneer in this technology. The Internet Protocol (IP) became widely accepted, the importance of multi-protocol routing had refused. At present, Cisco's largest routers, switches are primarily used to deliver routing (edge, core, and access), IPTV, switching, security and web conferencing etc.

In March 2000, at the peak of the dot-com bubble (covering roughly 1998 to 2001), Cisco was the most valuable and respectable company in the world. They have market capitalization of more than US$500 billion. Today (In July 2009), they are reaching a market capitalization of about US$108.03 billion. It is still one of the most prestigious company in I.T industry. The CISCO was selected stock of the decade on American Stock Exchange. The Cisco 7500 Series router was voted 3rd in the product of the last decade 1990-2000 after the Mosaic web browser and the Novell LAN manager.

Today, Cisco Systems, Inc is a multinational corporation with more than 65,000 staff and annual revenue of more than US$ 36.10 billion as of 2009.

The Cisco systems vision is "Changing the Way We Work, Live, Play and Learn". Cisco's current mission is "Welcome to the human network".

1.4 Why CISCO?

Today, Cisco System has big name in the network world. They have important hardware products and software products. Most of network architects, pioneers, engineers recommend Cisco products for their customers. Cisco covers all network segments such as routing, switching, wireless LAN etc. This is the one and only company covering all the network sectors and they have over 50 percent market share in all segments.

Cisco System has own routing protocols like EIGRP for their products. These protocols do not support to other technologies but still they are leaders in the network industry.

Cisco's market leadership is the “best kept secret” in management services. It has over 50 percent market leadership across all divisions. Here is the market leadership percentage wise

  • Storage Area Networks -20 Percent

  • Web conferencing - 45 Percent
  • Routing Edge / Core / Access - 57 Percent
  • Digital Video IPTV - 65 Percent
  • Wireless LAN - 60 Percent
  • Networked Home - 44 Percent
  • Switching - 73 Percent
  • Security - 38 Percent
  • Voice - 28 Percent

1.5 Summary

Throughout this chapter I discussed the background and the purpose of the project. Later chapters, I am going to explain the link utilization, network performances and so on.

Then I went through the Cisco System history. Now, Cisco is a huge company and they are earning over US$ 36.10 billion profit.

Then, I explained the reason for the selection of Cisco company products for my development. They have over 50 percent market leadership across all the divisions. Including routing edge, switching, web conferencing, wireless LAN, digital video IPTV etc.

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OSPF, EIGRP with CISCO Products over ISP Level Network

2009

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OSPF, EIGRP with CISCO Products over ISP Level Network

2009

CHAPTER

§ Principles for choosing a routing protocol

§ What is IP Routing?

§ Multi-Protocols Routing

§ OSPF v2

§ EIGRP

§ Summary

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OSPF, EIGRP with CISCO Products over ISP Level Network

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OSPF, EIGRP with CISCO Products over ISP Level Network

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2.1 Principles for choosing a routing protocol

With the fast growth of I.T Industry, TCP/IP protocol suit has been in top of the protocol hierarchy. Many different types of vendors make routers to exchange most important information through network. To achieve this objective, routers should communicate with each other therefore routers need routing protocols or common language to communicate with each other. When we design a large scale network we need to select good, efficiency routing protocols that is very important. Normally used routing protocols contain RIP v1, RIP v2, IS-IS, BGP as well Cisco proprietary protocols of IGRP and EIGRP. You have to select different routing protocols according to your network requirement.

Connectivity, network topology and network management are most basic requirement of IP network. In addition to following factors we can consider for choosing routing protocol.

Compatibility of protocols -When we are selecting a routing protocol we need to make sure compatibility issues because today, there are so many manufacture making different networking products.

Topology of network - Topology of network has straight pressure on protocol selection. For example RIP v2 is not good for complicated large scale network, because it has restricted coverage. Thus we need more complicated routing protocols. Like OSPF and EIGRP.

Strong and Stable - The routing protocols should be strong and stable because other protocols need to ensure network connectivity. Many types of disturbances will come into view in the network such as hardware or software errors or load balancing problems. Routers are doing some kind of decision making of the network, if routers have hardware or software errors, they may generate unpredictable network performance. Routing protocols must be able hold various disturbances for a long time.

Best path selecting -Routing protocols main objective is finding the best path in the network and make sure its connectivity. Each routing protocol has different kind of standard to evaluate a route quality (the evaluating constraint contains hop number, holding time, bandwidth and delay etc). We must select suitable configuration for different network environments to make sure the best network path.

Management and security -When weare making the autonomous systems, different areas will increase the possibility of route unreachable and reduce route cycle. It allows us to management of network more easily and efficiently. We also need to consider security and policy of routing information exchanging.

2.2 What is IP Routing?

IP routing sometimes known as IP forwarding is just process of getting an IP packet, making a result of where to send the packet next destination and then sending the packet. The sending process needs to be comparatively straightforward, or at least smooth, for a router to send huge volumes of packets. Ignoring the details of several Cisco optimizations to the sending process for an instant, the internal sending logic in a router works basically as shown in Figure 2-1.

Source - B6 Chapter 6

The following list reviews the main steps shown in Figure 2-1.

  1. A router collects the frame and checks the obtained frame check sequence (FCS). If errors arise, the frame is discarded. The router not attempt to pick up or recover the lost packet.
  2. If no errors arise, the router validates the “Ethernet Type” field for the packet type and takes out the packet. Now, the Data Link header and trailer no needed and can be discarded.
  3. Assuming an IP packet, the router checks its IP forwarding table for the most exact prefix equal of the packet's target IP address.
  4. The equivalent routing table entry contains the outgoing interface and next-hop router. This information points the router to the adjacency information wanted to make a new Data Link frame.
  5. The router updates the IP header TTL field, linking a recompilation of the IP header checksum before making a new frame.
  6. The router encapsulates the IP packet in a newly made Data Link header with the destination address and trailer with FCS to make a latest frame.

2.3 Multi Protocols Routing

Multiprotocol routing includes characteristics for different routing protocols. For example, EIGRP and interior or internal routing protocol can support routing tables for TCP/IP, IPX/SPX, and others. That is a separate routing table is made for each protocol but using only one routing protocol.

Multiprotocol routing means the ability to route (receiving /sending) different protocols at the same time. Multiprotocol routing will boost the amount of routing update information or data on the network because the routers will broadcast each routing protocol separately.

2.4OSPF v2

Internet Engineering Task Force has invented OSPF (Open Shortest Path First) in the mid 1980s. OSPF is a routing protocol, capable of serving large heterogeneous network. The OSPF protocol is a link state protocol based on cost instead of hopes. Network Architect had done many research efforts, including Bolt, Newman and Beranek's SPF (Dijkstra) algorithm in 1978, area routing in 1986, Dr. Radia fault tolerant broadcasting of routing and an early version of IS-IS (Intermediate System to Intermediate System) routing protocol.

OSPF protocol has two main characteristics. The first main characteristic is that protocol specification or requirement is in the public domain. The OSPF requirement published on RFC 1247. This is called “OPEN”. The second characteristic is SPF algorithm occasionally is referred to as the “Dijkstra” algorithm to respect for the person for his outstanding creation.

The OSPF is grouping to link state routing protocol group that calls for the forwarding of link state advertisements (LSAs) to all other routers within the similar area. OSPF LSAs information contains attached interfaces, metrics and other variables. OSPF routers collect link state information and use the SPF algorithm to evaluate the shortest path to each router. Routers with distance vector algorithm send all or a part of their routing tables with routing update messages to their neighbors.

The OSPF is a hierarchical protocol. The top most entity is autonomous system (AS) which is a collection of OSPF networks running according to common administration and share a common routing strategy. An autonomous system further divided into number of areas. Areas include contiguous network and end users, hosts etc.

2.4.1 OSPF Features

Recently, OSPF routing protocol has been well developed because it is fitting for many types of networks, especially large scale network. OSPF has many types of features. Such as

OSPF is a loop free routing protocol and this feature comes from the shortest path first algorithm and with the link state protocol.

Second feature is fast convergence, sending and receiving routing information via entire autonomous system and compute route path in very small time.

OSPF routing protocol has equal cost load balancing ability.

OSPF has many areas inside the single autonomous system but it depends on the topology. Each area separated from the router, named area border router (ABR). This ABR sending and receiving routing information to other area routers and makes LSA information. This will reduces the complexity of routing calculation, number of autonomous system as well as size of the LSA information. Therefore always generating small number of routing information when network expanding.

According to network engineers overloading is a big problem in OSPF but it become minimum because of hello packet including only changes of routing information thus it become very smaller, OSPF accept multicast address in broadcast network thus it minimizes noisiness to other routers or switches which is not run OSPF routing protocol, In large scale multi access network with maintain two or more routers then they are maintain DR and BDR routers to minimize network bandwidth usage, routing limited to AS no communication with other area, BDR use router aggregation and reduces routing information transmission between areas, In point to point network, OSPF will not send hello packet if there is no big changes.

OSPF has two types of authentication type one is common clear text authentication other one is ciper text authentication mode with MD5 encryption algorithm.

OSPF can handle any size of network it support one router contain network to thousand routers contain network but you have to configure it properly.

OSPF support traffic engineering concept because of link state algorithm.

OSPF routing protocol has four classes router. Such as internal routing, inter area routing, type of external routing and type two external routing. It provides reliable transmission to OSPF network.

2.4.2 OSPF Operations

OSPF routing protocol first establish adjacencies with their neighbor routers. It use “HELLO” packet to acquire neighbors. The OSPF routing protocol send and receive “HELLO” packets to establish and keep lives the router.

  1. The first thing is to find neighbors. A router sends and receives “HELLO” packets to its neighboring routers. The destination address that is normally used is a multicast address. Through this Hello packet OSPF identify neighbor is in same AS and area.
  2. Designated Router (DR) / Backup Designated Router (BDR) election will occur. After that all the other routers become adjacencies with the designated routers.
  3. After the connection establishment then need to synchronize their Link State Database (LSDB). They are exchanging Link State Acknowledgement (LSA) and the receipt of all LSAs from neighbor routers.
  4. After the update and synchronize of all router LSDBs, the SPF algorithm is run against the information and place best routing path on routing table.
  5. If there is any change to the network then a latest LSA must be synchronized throughout the network to update all routers.

2.4.3 SPF Algorithm

In OSPF best path selection based on information collected in the routing database and the SPF algorithm. Each router in an area building a tree, where the router is the top and all other network are branches. This tree contains only networks belong to same area. If router has separate areas then separate trees will be created. OSPF use a metric called cost. Cost has default value defined in RFC 2338 but Cisco has own method to calculate OSPF cost.

2.4.4 OSPF drawbacks and benefits

The OSPF has two o three main disadvantages, first one is OSPF takes more memory and processing power to update topology tables. Topology tables are similar in all of routers in an area and it holds all the information for every router and link in the area. Second disadvantage is OSPF use more options and millions of configurations.

OSPF has the capacity to balance massive networks and get them down to a manageable size. The

network ability to organized into areas. The amount of routing data or overhead for an OSPF network is radically reduced compared to distance vector protocol. OSPF protocols can reduce the overhead of the SPF calculations by dividing the network into areas. In other words OSPF does not support unequal load balance.

The OSPF configuration is little bit more complex. It has more complex network attributes and dividing areas etc. The network administrators, network engineers should have solid understanding, knowledge of computer network and data communication to do high quality configuration as well to ensure OSPF is working well. Everyday OSPF is getting popular among network engineer thus this problem is not considered as a big problem.

2.5EIGRP

Enhanced Interior Gateway Routing Protocol (EIGRP) is invented by Cisco Systems in 1992 to overcome limitations of RIP v1. EGIRP is a distance vector protocol, classless and it offer more features capabilities than other distance vector family. It has features and capabilities from both link state and distance vector protocol.

EGIRP is very easy to configure, it is similar to IGRP. EGRP is an advanced distance vector protocol because it has link state protocol features like dynamic neighbor discovery. EGIRP use DUAL (Diffused Update Algorithm) therefore protocol categorized under hybrid category. This DUAL feature is allowed rapid coverage and the guarantee of loop free topology.

2.5.1 EGIRP Features

EGIRP has advantages of IGRP. Correctly, calculate routing load and heterogeneous (mixed) network protocols support features available on EGIRP. EGIRP computes routes according to data such as network routing bandwidth, network path reliability, total delay, path loading and so on. Thus router table is perfect. EGIRP supports IPX, IGRP and Apple talk.

EIGRP is not uses much network resources. Throughout the day today operation, consumption of network resource is very low level. Only hello packets are sent and received on a steady network. If changes happened only routing tables changes are forwarded to respective locations but not entire routing table. This will reduces the load the routing protocols to respective memory. EIGRP has ability to control the packet propagation and reduces the consumption of bandwidth. Thus no one can avoid or prevent to transmission of information.

Third one is loop free and fast convergence. EIGRP has special algorithm, named DUAL allow transmitting only routing changes. Here one route is update neighbor route and next router updates their neighbor router and so on.

Forth one is related to EIGRP security. The cipher text based authentication use with support of MD5 algorithm.

EIGRP support Variable Length Subnet Mask (VLSM) like RIP v2 and IGRP. This will minimize traffic of routing information and keep down the bandwidth usage.

EGIRP comes with load balancing feature. The equal cost and unequal cost use to balance the network. EIGRP can do transmission over unequal cost path but this is not recommended by Cisco Systems.

Last feature, like other protocols configuration is very simple. There are no complicated things to configure but you must give extra care when you are configuring with different protocols and different vendors.

2.5.2 EGIRP Operations

As I said earlier, EGIPR is a hybrid protocol because includes both distance vector and link state protocol features, classless and Cisco proprietary protocol which means it support only for Cisco products. It has autonomous system features like IGRP and contains subnet mask when updating routers but this feature not available on IGRP.

OSPF send link state packets but EGIRP doesn't send link state packets. It sends distance vector updates but the important thing is EGIRP works like a link state protocol, it synchronize routing table between neighbors at start up. EGIRP supports max hop counting 255.

EGIRP has following powerful features

  • Support for IPv4 and IPv6 through protocol dependent modules
  • Classless protocol like OSPF
  • Support for VLSM
  • Support for router summaries and discontinuous networks
  • Very efficient neighbor discovery
  • Communication using Reliable Transport Protocol (RTP)
  • Best path selection passing through Diffusing Update Algorithm (DUAL)

2.5.3 Neighbor Discovery

First, need to discover neighbors before start EIGRP routing process. There are 3 conditions to find neighbors such as “HELLO” packed and Acknowledgement send and receive, AS number match and identical metrics.

EGIRP is following OSPF process to maintain their neighbor relationships. If router belongs to different AS, then routing information never share with that router. This is very useful when maintaining large scale network. When routers receive neighbor updates, they stored that information in a topology table. This table includes all known routers and neighbor information.

2.5.4 Reliable Transport Protocol (RTP)

The Cisco Systems has another proprietary protocol, named Reliable Transport Protocol (RTP) use to communicate with EGIRP configured routers. This RTP increase the reliability of communication.

When EGIRP forward multicast traffic, each EIGRP routers know the neighbors are, and it maintains a list of neighbor details. After 16 attempts, they aware the neighbor is dead. This process called reliable multicast.

2.5.5Diffusing Update Algorithm(DUAL)

Diffusing Update Algorithm is used to aware and maintain best path to each router. This algorithm gives, backup router information, support VLSM, dynamic routing and alternative routing path.

This DUAL allows fastest covergency time compared to other routing protocols. EIGRP maintain copy of all neighbor router tables and calculate best path. If it is going wrong check the routing table again and select new best path. If there is no good alternatives then checked with their neighbor router for help with direction. This quality called “diffusing”.

“HELLO” packets use to find neighbors, RTP provides smooth communication and DUAL is managing best path.

2.5.6EIGRP drawbacks

EIGRP does not have area concept,thus it may arise some problematic situation when configuring or dealing with high scale hierarchy network. Specially, when running OSPF on an enterprise level network, we are making the high scale network hierarchy by dividing the network into smaller areas. Clearly, EIGRP is not an excellent selection for an ISP level or enterprise level network. EGIRP has some limitations of a distance vector routing protocol such as RIP v1, RIP v2. Anyhow, if you select EIGRP as a routing protocol for a large scale network then you must divide the network into not equal EIGRP domain and then relocate or import routing table to each other. Keep in mind, this is not best network architecture and you can make only few networks like this but you cannot make large scale network.

EGIRP is not support to Dial on Demand (DoD). An EGIRP protocol exchange “HELLO” packets periodically to maintain the neighbor relationships when doing this process dial up link is up. “HELLO” packets can bring the dial link up but this is not the purpose of dial up link. The dial up link is only for the backup purpose. We have alternative configuration to avoid this thing. We can configure dialer group and dialer list on the routing interface then “HELLO” packet will not up the dial link. But the problem is we are wasting valuable router resources to avoid this thing. The OSPF takes benefit at this case providing DoD support.

The EIGRP DUAL algorithm provides fast convergence and loop free characteristics. Fundamentally, the DUAL algorithm is working by sending information to its neighbor regarding the active routes (doubtful routes), then convergence is receiving the reply. If the routes are doubtful or active routes for its neighbor too, then neighbor also send information to their neighbor. This process will be carry on and on till obtain the successful reply or after a period of time, the particular routes will be decided not available and get discarded from the routing table. However in some situations, the active routes will be put into active status for after long period of time. This situation is very badly affected the fast convergence feature. OSPF has not this kind of situation at all but EGIRP is still provides fast convergence among other routing protocols. EGIRP is little bit slow in following cases, in a long narrow network, if something has changed it takes long time to send the “HELLO” packet from one routing side to other routing side.

Let say like this, EGIRP configured to fully mesh with neighbor relationship and communicate to other routers, exchange information within all routers, but if it is broadcasting network that means EIGRP kill a lot of bandwidth. In OSPF select DR and BDR routers and only wants to configure adjacency with DR then exchange link state advertisement within the network. This will save lot of bandwidth resources.

Cisco Systems introduced this EIGRP protocol, It is a proprietary protocol and not a open standard protocol. An only Cisco products can run on this EIGRP protocol and Cisco System has the fully right to use this protocol and do modifications. They do not need anyone's approval to change or modify this protocol. If they have done changes without inform to customers or other product vendors, then it may create more problematic situation because Cisco system has the market leadership. But OSPF is other hand, OSPF comes with IETF and it is open standard routing protocol. Most of products support to this protocol without any problem and there are no much compatibility issues with this protocol.

2.6 Summary

Throughout this chapter I have discussed principles of selecting routing protocols, routing, multiprotocol routing, OSPF and EIGRP. I hope now you have some idea of routing, background of routing protocols and so on.

Selection of routing protocol tropic, I have discussed main consideration things when we are choosing a routing protocol. Routing protocols use to exchange routing information with each other routers. Today, Information and communication Technology is rapidly developing thus we need to select good routing protocol to do efficient and accurate communication. We need to consider so many tropics such as compatibility of protocols, topology of network, storage and stability, best path selection and management security etc.

IP Forwarding tropic explain how packet are sending and receiving throughout the network. Figure 2-1 used to explain this routing process. In addition to step by step I explained the function of routing process. How packets are exchanging between two or more routers, logic of routing and behind the screen process.

Multiprotocol means more than one protocols running on the network. I just discussed this tropic because it will help you to understand future tropics.

I have discussed more details things in OSPF such as history, operations, advantages and drawbacks. Mid 1980, Engineering Task Force invented OSPF. It contains two main characteristics one is specification of public domain other one is SPF algorithm. OSPF operation has given the idea of OSPF process, such as HELLO packets, DR / BDR process etc.

OSPF has lot of features. Such as loop free routing comes with SPF algorithm, fast convergence, equal cost load balancing ability, autonomous systems and area concept reduce the complexity of topology, overloading minimum because of exchanging only changed information, two types of authentication type one is common clear text authentication other one is ciper text authentication mode with MD5 encryption algorithm and OSPF routing protocol has four classes router provides reliable transmission to OSPF network.

After that we discussed OSPF operation. First, establish adjacencies with their neighbor routers, “HELLO” packets to find neighbors, DR and BDR election process, exchanging LSDB, other routing information, run SPF to find best path and send LSA information if any changes will occurred.

The OSPF has some disadvantages first one is OSPF takes more memory and processing power to update topology tables and OSPF use more options and millions of configurations.

OSPF has the capacity to balance massive networks and get them down to a manageable size and can reduce the overhead of the SPF calculations by dividing the network into areas. It has more complex network attributes and dividing areas etc. The network administrators, network engineers should have solid understanding, knowledge of computer network and data communication to do high quality configuration.

Then I went through EIGRP. Then I went through EIGRP. Invented by Cisco Systems in 1992, it has features and capabilities from both link state and distance vector protocol, easy to configure, similar to IGRP.

EGIRP has several features. Correctly, calculate routing load and heterogeneous (mixed) network protocols support features available on EGIRP, is not uses much network resources. Throughout the day today operation, consumption of network resource is very low level. Only hello packets are sent and received on a steady network. Next one is loop free and fast convergence. EIGRP has special algorithm, named DUAL allow transmitting only routing changes. It use cipher text based authentication use with support of MD5 algorithm. EIGRP support VLSM. This will minimize traffic of routing information and keep down the bandwidth usage. Again, EGIRP comes with load balancing feature. Last feature, configuration is very simple.

The Cisco Systems has another proprietary protocol, named Reliable Transport Protocol (RTP) use to communicate with EGIRP configured routers. This RTP increase the reliability of communication.

Diffusing Update Algorithm is used to aware and maintain best path to each router. This algorithm gives, backup router information, support VLSM, dynamic routing and alternative routing path.

At last we discussed the drawbacks of EIGRP, EIGRP does not have area concept, thus it may arise some problematic situation when configuring or dealing with high scale hierarchy network, It is not support to Dial on Demand (DoD).

The DUAL algorithm is working by sending information to its neighbor regarding the active routes (doubtful routes), then convergence is receiving the reply. If the routes are doubtful or active routes for its neighbor too, then neighbor also send information to their neighbor. This process will be carry on and on till obtain the successful reply or after a period of time, the particular routes will be decided not available and get discarded from the routing table. However in some situations, the active routes will be put into active status for after long period of time. This will effect to fast coveragencies feature.

The EGIRP configured to fully mesh with neighbor relationship and communicate to other routers, exchange information within all routers, but if it is broadcasting network that means EIGRP kill a lot of bandwidth. The Cisco has the full right to do modification.

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OSPF, EIGRP with CISCO Products over ISP Level Network

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OSPF, EIGRP with CISCO Products over ISP Level Network

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CHAPTER

§ OSPF Configurations

§ EIGRP Configurations

§ Comparing OSPF & EIGRP

§ Migrating EIGRP to OSPF

§ BGP

§ Redistribution

§ Summary

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OSPF, EIGRP with CISCO Products over ISP Level Network

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3.1 OSPF Configuration

OSPF configuration little bit difficult compared to other routing protocols like RIP, EIGRP. Here I am going to explain single area configuration to get small idea.

Source - B7 Chapter 7

Here “ospf 1” 1 means OSPF process id. This value is a unique number 1to 65,535. The Process id use to identify specific routing process. You can run different routing process same time on the same router.

After the routing process you need to discover the interfaces that you want to enable. The keyword, named “network” use to define a network (10.0.0.0) and the wildcard mask (0.0.0.255). The arrangement of this two numbers use to recognize interface and the keyword is “area” use to define the area router belongs.

3.1.2 Verify OSPF Configurations

There are so many commands to verify OSPF configurations. I will explain some of them to take quick understand

“show ip route” command

Source - B7 Chapter 7

This command shows entire routing table. Here “O” represents OSPF network. OSPF use bandwidth to find out the best routing path.

“show ip ospf” command

Source - B7 Chapter 7

Above command shows all the ospf processes running on the router.

“show ip ospf database” command

Source - B7 Chapter 7

This command will display all the routers information and neighbor router id. This is called topology table.

In addition to there are so many commands use to verify and debug routing process. Which are as follows

  • show ip ospf interface
  • show ip ospf neighbor
  • sShow ip protocols
  • debug ip ospf packets
  • debug ip ospf hello
  • debug ip ospf adj

3.2 EIGRP Configuration

However EGIRP support IP, IPv6, IPX and AppleTalk protocols. That means we can configured EGIRP with this protocols. EGIRP has two configuration modes, named router configuration mode and interface configuration mode. Router configuration mode allows set global characteristics and recognizes type of network run on EGIRP. Interface configuration mode use to modify metrics, timers and bandwidth. EGIRP configuration is easier than OSPF configuration.

Source - B7 Chapter 7

This example EGIRP configured to autonomous system 20 and router linked with two networks. Which are network 172.16.0.0 and network 10.0.0.0. Autonomous System number can be any number in between 1 to 65535.

3.2.2 Verify EGIRP Configurations

EGIRP includes so many commands to verify, debug and troubleshoot the process. Here I am going to explain two or three commands to get basic idea.

“show ip route” command

Source - B7 Chapter 7

Again this command uses to shows the routing table. EGIRP use letter “D” in routing table. OSPF use letter “O” and directly connect interfaces use letter “C”.

“show ip eigrp neighbour” command

Source - B7 Chapter 7

Here “H” field shows the sequence of neighbor identified. Hold timer, say waiting time for “HELLO” packet. This command helps you to find the IP addresses, intervals and queue counts.

“show ip eigrp topolgy”

Source - B7 Chapter 7

Here “P” represents passive state and “A” represent active state. If it is active state means connection lost and looking for a new connection. Using this command you can able to see entire topology table.

In addition to above commands there are so many other commands. Which are as follows

  • debug egirp packet - Able to see transmission between neighbor routers
  • debug ip egirp notification - Changes and updates on an EIGRP network

3.3 Comparing OSPF & EIGRP

OSPF and EIGRP are both brilliant routing protocols and every one provides a distinctive set of benefits for implementing and designing a large scale network such as ISP level network. These two protocols can be used for a generous range of networks from small, campus, regional networks to large enterprise, global level network systems. The common question is frequently, asked is, "Which protocol is the best? Either OSPF or EGIRP" This is good and complicated question, as both protocols (EIGRP and OSPF) have their own benefits. This chapter evaluates EIGRP and OSPF and provides condition to contrast the two protocols, either EIGRP or OSPF and decide which is the most appropriate for your network requirement. The following conditions have been considered so that main discriminating features can be evaluated when choosing the routing protocol which one is the best match to your network requirements. This chapter and chapter 2 covered the basic operations, functions and features of each protocol. It evaluates the related things of each protocol.

Network Design - EGIRP doesn't need hierarchical network topology but OSPF needs it. It is good design habit to building EIGRP hierarchically but it is not necessary. As a result, EIGRP is more flexible from a topology point of view but still you must careful when design the network properly. Occasionally all the adaptability of EIGRP makes unacceptable network design, while OSPF points you to build in a backbone of a network. OSPF also has restrictions in number of routers in an OSPF area (max 50 depends on the design) and number of areas per router (up to 3 may be vary according to design). Therefore building an OSPF network could be more challenging and restricting than building an EIGRP network.

Ease of Use - Because OSPF wants a hierarchical structure, needs a reviewed address structure, and needs physically configured outline addresses. It has to be harder to implement. In addition, the special rules for the many types of areas and LSA types are theoretically more complex to realize. Though, all these requirements can be attractive and support a large scalable network (ISP Level), when ended appropriately. EIGRP can also need some complex and advanced configuration when to configure special features. However, many people sense EIGRP is bendier than OSPF and network plans are easier to apply using EIGRP.

Neighbors - EIGRP forms adjacencies (neighbor) and send / receive (exchanging) routing updates with each neighboring router. While OSPF does an election process for a DR (Designated Router) and BDR (Backup DR) which operate as a "distribution" location for routing information. In OSPF, routers only structure a full adjacency to the DR and BDR (there is only one DR / BDR per network area). This means that all things being equal OSPF can more resourcefully maintain a full interconnect of neighboring routers per interface. This point is particularly valid on high speed WAN and LAN media. As a guideline of thumb, this concern gets to be important at about 20 neighbors per routing interface, but depends on routing table, size of routing table, routing platform (ISO version), router utilization etc.

Although, lots of network plans do not have a huge number of neighbors per routing interface. They have a millions of neighbors per router. In these situations, there are design restrictions concerning the number of routers in an OSPF area and the number of areas maintained per router (Max 50 depends on the configuration). It is essential to note that both OSPF and EIGRP have planning concerns regarding neighbors. These planning concerns depend on lot of factors contain routing table, size of routing table, routing platform (ISO version), router utilization, etc. but a normal rule of thumb is that OSPF may have more neighbors per interface. While EIGRP allocates more design adaptability for lot of neighbors per router.

Route Filtering and Redistribution - Filtering router processes is not easy in OSPF contain router. "Distribute-list in" feature does not operate in OSPF routing processes. The "Distribute-list out" operates only on the routes with configured redistribute function from other routing processes into OSPF. Furthermore, OSPF route distribution may only be carried out at AS boundaries or OSPF area. The EIGRP information could be filtered and distributed at all interface and at every bit boundary. Hypothetically allocating several hierarchies based on routing topology. Thus EIGRP is much more flexible and easier to operate when performing route filtering and redistribution. As well as EIGRP is far better quality to OSPF in inbound route and outbound route filtering on an each interfaces.

Route Summarization and Configuration - By default, EIGRP perform an automatic summarization process but OSPF needs to configure each and every summary address. As we talk about earlier, EIGRP can be easier to configure and implement. Although in many large scale networks (ISP level or more) with meshed networks and / or redistribution ends, no need much careful consideration to summarization process. Otherwise it can reason for routing loops and constancy troubles. You have to carefully consider the routing topology and addresses schema, faulty auto summarization is a regularly encountered trouble to lots of end users. Of course, you can get more or less these troubles in EIGRP with interface summary address commands or OSPF configuring area range commands but it gets additional steps, good practice and some more information of how the routing protocol operates. OSPF needs all manual summary commands and hence wants more consideration to this routing process. With EIGRP, careful concerns should also be given to summarization process even if you are using the automatic summarization options. Not operating summarization correctly with either protocol can reason severe network crisis.

Convergence - To improve a network routing topology alterations, EIGRP comes with DUAL technology (Diffusing Update Algorithm) which make available rapid convergence if a feasible successor is available. OSPF forwards a LSA and calculates it again the SPF algorithm (sometimes known as Diskjtra). From this viewpoint, EIGRP may convergence speed than OSPF and may require less CPU processing time. Although convergence is not independent factor, it requires one or many factors including topology database, routing metric, type of failure etc. so an ultimate conclusion / ending cannot be made here. When a feasible successor does not available, EIGRP will start query neighboring routers for the lost route which then asking their neighbors building a growing tree or network hierarchy of queries until the route is established or considered to be not available. In this situation, the speed of convergence requires on so many things including the network routing topology and it is not possible to clearly state which protocol is faster.

Memory and CPU - EIGRP forwards limited (partial) updates and if routing topology change occurred, it will start sending this updates otherwise not send any update. This is the one and only time you can get update from the EIGRP routing topology. The availability of a "feasible successor" in EIGRP restricts the result of routing database changes to directly affected routers and other routes. The OSPF multicasts LSAs to all EIGRP routers in the area leading a routing database change and forward periodic routing database updates. Memory and CPU consumption come into account when reflecting the EIGRP routing table size, number of neighbors and how regularly the EGIRP routing protocol is actively running it is DUAL algorithm. OSPF is normally more CPU exhaustive on the DR router and this router must have more memory and CPU power to hold this task. Also, OSPF may need more CPU and memory resources on other routers with or without OSPF in the network.

Vendor Compatibility - OSPF is carried by lot of router vendors such as Cisco, Nokia etc. and as I said earlier, is an industry standard RFC 1583 but EIGRP is a proprietary protocol introduced by Cisco System. EGIRP is not a vendor independent protocol and it is supports only Cisco products. Although, you have to be careful when inter connecting OSPF with different vendor routers because each and every vendor's OSPF implementations is not similar, sometimes it may not be able to handle large OSPF routing table sizes (some vendors supports 200 maximum routes including 4 neighbors but it may be vary according to vendor to vendor). It should also be distinguished that multiple routing protocols could be supported on a router if it is possible to configure EIGRP and still inter connect with OSPF routers by adding another separate routing process.

Route Selection - OSPF makes the interface cost (cost, use several techniques different vendors but all are very similar) to decide the shortest path. EIGRP uses a routing database and calculate shortest paths taking link bandwidth and delay as condition. EIGRP offers more flexibility, manage and control in choosing the best routing path.

Routing Overhead - OSPF communicate with routing database each and every 30 minutes and update Link State Advertisements (LSA) at any time a routing database change take placed. EIGRP uses a topology database which does not have to be periodically update and does not send LSAs when the network topology amendments. As an alternative, EIGRP forwards out queries only when an acceptable "feasible successor" not available to an attempt to find a route. Therefore, depending on the network routing topology, routing state, and router configuration, EIGRP is a well organized than OSPF by reducing routing information exchanged.

Link Bandwidth Conservation - OSPF utilizes whatever bandwidth it wants. EIGRP will use only 50% (default value) of a link bandwidth in a bad situation. In EIGRP, you can configure bandwidth consumption parameters but OSPF does not provide this kind of facility. Also, EIGRP allow you to change “hello timers” and “hold down timers” on particular interfaces to limit the bandwidth used and to boost network convergence and reliability. EIGRP additionally save WAN bandwidth by suppressing ACKs and sending unicast data packets to this task. Therefore EIGRP is much more suitable for WAN applications where connection bandwidth is valued.

Reliable Delivery of Routing Information - EIGRP gives more reliable delivery of routing information, update, and acknowledgement and reply packets to make sure routing query is not lost. OSPF multicasts send information and accept acknowledgments for the packets. Both protocols support reliable mechanism to communicate routing information.

Security - OSPF gives message digest authentication key security and password for routing information. EIGRP also gives authentication sending an encrypted key. Both protocols have a excellent security features available.

3.4 Migrating OSPF & EIGRP

Migration an EGIRP routing network to an OSPF routing network efficiently without interruption to the existing network is not an easy task. You have to give an extra concern to rearrange or upgrade EIGRP routing to OSPF routing. The easiest technique is removing the EIGRP routing protocol and implement OSPF protocol. Although, this is not and recommended way and it breaks the existing network. Second thing it takes network down time. Different vendors introduced different techniques to migrate EIGRP to OSPF. Huwavi, Juniper Networks and network architectures carried out following technique.

In reality, smooth migrate an EIGRP routing protocol to OSPF routing protocol or other hand is not that much difficult. If we follow the right procedure, guidelines we can make an ideal migration without breaching the present network and what we have to to do is the proper design changes.

The most important initiative is migrating a network protocol to another different network protocol is using the different preference of different routing protocol (example Huwavi use Huawei VRP and Cisco use Cisco IOS, This Huawei VRP and Cisco IOS like an OS in a particular routers where the routing protocol run). When we run many types of routing protocols on a network, the functioning routing protocol is pulled out by their priority the better and the less. The following is the rules and guidelines of migration.

First you need to complete pre migration stage. During this phase you have to get comprehensive knowledge of existing network including IP address range, network topology, edge infrastructure, router CPU usage, memory usage, network traffic inbound and network traffic outbound etc.

A Planning of the OSPF networks including how many areas, routing rules, subnet, IP addressing ranges, network topology etc.

Build up OSPF routing protocol on the EIGRP network and give the administrative distance of EIGRP higher than administrative distance of OSPF, then make the interfaces into OSPF areas.

At this moment, the priority of EIGRP is greater than OSPF and the EIGRP configured routers contains on the routing table. Still OSPF configured routers do not come to the routing table that means OSPF does not function.

Now make sure everything is working properly and changes the priority of EIGRP and OSPF. Change the priority of OSPF greater than EIGRP. Then OSPF will start the working and routing table change to OSPF. Now EIGRP is not a routing protocol in this network.

If everything is working properly then delete EIGRP configuration. Do more OSPF changes and smooth the routing process. Now migration complete.

If something goes wrong, we can do rollback by changing the administrative distance of OSPF routing table. We don't need down time to do this configuration changes or migration process. Only do some priority changes and we can change the OSPF configured routing tables to EIGRP configured routing table or other side. The main advantage is if something goes wrong we can do rollback very easily.

The main issues with this approach are expensive migration strategy, require additional equipments and resources to build up a parallel network, require IP address rearrangement and careful designing and summarization techniques.

3.5BGP

The Border Gateway Protocol (BGP) is the advanced routing protocol applied to send receives routing information over the internet. It allows Internet Service Provider (ISP) to attach each other and it makes end users to link more than one ISP. BGP is the one and only protocol that can having ability to connect with a network of the large scale or Internet's size and the one and only protocol that is planned to having more than one links to separated routing domains.

In 1989, The RFC 1105 was defined BGP as an Internet standard. BGP4 is the latest version of this protocol. The RFC 4271 was defined this version in 1995.

BGP has established to be stable, scalable and provides the technology needed to carry difficult routing policies. When IT engineers chat about "BGP" today, they completely mean latest version BGP4. There is not necessitated to mention the BGP 4 version number because all people use latest versions, and very small number of manufacture even still maintain or support them to earlier version.

The Border Gateway Protocol (BGP) is an Inter Autonomous System routing protocol. The main purpose of a BGP is to send and receive network routing information with other BGP systems. The network routing information or reachability information contains information on the register of Autonomous Systems that network routing information go over. This information is enough to build up graph of Autonomous System connectivity including prune routing loops and other mandatory policy decisions at the Autonomous System stage.

Latest BGP gives set of technologies for achieving Classless Inter Domain Routing (CIDR) mentioned in RFC 4632. These technologies contain support for promoting a set of end points as an IP technology and preventing the theory of network “class” inside the BGP. Latest BGP version is established technologies which help aggregation of routers and AS paths.

The destination based forwarding model comes via BGP to exchanged routing information. This believes that a router sends a packet based exclusively on the destination address accepted in the IP header of the packet. This send the set of policy decisions that can or cannot be forced using BGP. BGP may help only the policies proving to the destination based forwarding concept.

A unique AS number (ASN) is assigned to each AS to apply with BGP routing. The numbers are allocated by Regional Internet Registries (RIR) and the IANA. Two authorities that have the power of assign IP address. There are two ranges of IP addresses public and private. Public IP range is used on the internet and the series of IP address from 1 to 64511. Private IP range is from 64512 to 65535. This can be supported inside an organization.

3.6Redistribution

Redistribution is a process of sharing routing protocols. It is allowing you to distribute only routing information. You can also distribute static router, interface and default router. Two types of routers commonly use one is one way distribution and other one is mutual distribution. One way distribution means one routing protocol does share routing information to other routers but other routers does not share routing information. Mutual distribution means both routing protocols do share routing information between two routers.

EIGRP redistribution is not much difficult. It is like IGRP redistribution. EIGRP is a classless routing protocol and it needs specify a metric. But it is not necessary if distribution take place between IGRP routing protocol or EGIRP routing protocol. If metrics value is not available then it will assign default value “0”. “redistribute” keyword use to configure redistribution process.

OSPF redistribution process does not require metric value. If a metric not set then it will take default value “20”. OSPF has classless routing feature and it can also redistribute to classful routing protocol

3.7Summary

OSPF configuration is little bit difficult and configuration example discussed earlier. Here, some commands use to verify OSPF configuration “show ip route”, “show ip ospf”,” show ip database” ,” show ip ospf”etc.

EIGRP configuration is very easy similar to IGRP configuration. We use “show ip eigrp neighbour”, “show ip route”, “debug egirp packet” commands to verify EGIRP process.

OSPF and EIGRP are both brilliant routing protocols and every one provides a distinctive set of benefits for implementing and designing a large scale network such as ISP level network.

Network Design - EGIRP doesn't need hierarchical network topology but OSPF needs

Ease of Use - Because OSPF wants a hierarchical structure, needs a reviewed address structure, and needs physically configured outline addresses. EIGRP can also need some complex and advanced configuration when to configure special features. However, many people sense EIGRP is bendier than OSPF.

Neighbors - EIGRP forms adjacencies (neighbor) and send / receive (exchanging) routing updates with each neighboring router. While OSPF does an election process for a DR (Designated Router) and BDR (Backup DR) which operate as a "distribution" location for routing information.

Route Filtering and Redistribution - Filtering router processes is not easy in OSPF contain router. "Distribute-list in" feature does not operate in OSPF routing processes. The EIGRP information could be filtered and distributed at all interface and at every bit boundary. Hypothetically allocating several hierarchies based on routing topology.

Route Summarization and Configuration - By default, EIGRP perform an automatic summarization process but OSPF needs to configure each and every summary address.

Convergence - To improve a network routing topology alterations, EIGRP comes with DUAL technology (Diffusing Update Algorithm) which make available rapid convergence if a feasible successor is available. OSPF forwards a LSA and calculates it again the SPF algorithm (sometimes known as Diskjtra). From this viewpoint, EIGRP may convergence speed than OSPF and may require less CPU processing time.

Memory and CPU - EIGRP forwards limited (partial) updates and if routing topology change occurred, it will start sending this updates otherwise not send any update.OSPF is normally more CPU exhaustive on the DR router and this router must have more memory and CPU power to hold this task.

Vendor Compatibility - OSPF is carried by lot of router vendors such as Cisco, Nokia etc. and as I said earlier, is an industry standard RFC 1583 but EIGRP is a proprietary protocol introduced by Cisco System.

Route Selection - OSPF makes the interface cost (cost, use several techniques different vendors but all are very similar) to decide the shortest path. EIGRP uses a routing database and calculate shortest paths taking link bandwidth and delay as condition.

Routing Overhead - OSPF communicate with routing database is each and every 30 minutes and update Link State Advertisements (LSA). EIGRP forwards out queries only when an acceptable "feasible successor" not available to an attempt to find a route.

Link Bandwidth Conservation - OSPF utilizes whatever bandwidth it wants. EIGRP will use only 50% (default value) of a link bandwidth in a bad situation.

Reliable Delivery of Routing Information - EIGRP gives more reliable delivery of routing information. OSPF multicasts send information and accept acknowledgments for the packets.

Security - OSPF gives digest security and password. EIGRP also gives authentication sending an encrypted key.

After wards I have discussed migration strategy. An EIGRP routing protocol to OSPF routing protocol or other

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