PROJECT TRAINING REPORT ON SERVICE PROVIDER NETWORK

ACKNOWLEDGEMENT

The internship opportunity I had with company name was a great chance for learning and professional development. Therefore, I consider myself as a very lucky individual as I was provided with an opportunity to be a part of it. I am also grateful for having a chance to meet so many wonderful people and professionals who led me though this internship period.Bearing in mind I am using this opportunity to express my deepest gratitude and special thanks to Mr. xyz who in spite of being extraordinarily busy with his duties, took time out to hear, guide and keep me on the correct path and allowing me to carry out my project at their esteemed organization and extending during the training.I express my deepest thanks to him for taking part in useful decision & giving necessary advices and guidance and arranged all facilities to make it easier. I choose this moment to acknowledge his contribution gratefully.

TABLE OF CONTENTSContents

ACKNOWLEDGEMENT2CERTIFICATE3INTRODUCTION TO NETWORKING6Definition:-6Requirement of Networking7TYPES OF NETWORKS8LAN (Local Area Network)8WAN (Wide Area Network)9NETWORKING DEVICES10Network Interface Card10Hub10Switch11Bridge11Router11Comparison between Hub, Bridge, Switch & Router12OSI NETWORK MODEL13Application Layer13Presentation Layer14Session Layer14Transport Layer14Network Layer14Data Link Layer15Logical Link Control15Physical Layer15TCP/IP16The Process/Application layer17Host to Host layer Protocols18Internet Layer Protocols18Network access layer19NETWORKING MODELS-TERMINOLOGIES20IP ADDRESSING21PRIVATE IP22IP ACCESS LIST22MASKING23SUBNETTING23CLASSLESS INTER-DOMAIN ROUTING (CIDR)24IP TRAFFIC OVERVIEW25Broadcast25Unicast26Multicast27VIRTUAL LAN29ROUTING30Static Routing:31Default Routing:31Dynamic Routing:31ROUTING PROTOCOLS32Distance vector:32Link State:32Hybrid:32BORDER GATEWAY PROTOCOL33BGP Peers (Neighbours)34BGP (Best Path determination)34OSPF35SPF Calculation36IS-IS Fundamentals37The IS-IS Hierarchy38IS-IS vs. OSPF39RIP40RIP Timers40Multiprotocol Label Switching (MPLS)41LSR and LER42Label-Switched Paths (LSPs)42CISCO THREE LAYER HIERARCHIAL MODEL43Distribution layer:44Access Layer:44Core Layer:44

INTRODUCTION TO NETWORKINGDefinition:-

A network is a system that transmits any combination of voice, video and/or data between users. A network can be defined by its geographical dimensions and by which the users PC access it.

A network consists of a:

The network operating system (Windows NT/2000TM/XP) on the users PC (client) and server. The cables connecting all network devices (users PC, server, peripherals, etc.). All supporting network components (hubs, routers and switches, etc.).

Network computer devices that originate, route and terminate the data are called network nodes.Nodes can includesuch as personal computers,phones,serversas well asnetworking hardware. Two such devices are said to be networked together when one device is able to exchange information with the other device, whether or not they have a direct connection to each other.Requirement of Networking

Resource SharingTo make all programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource and the user.High ReliabilityAs all files could be replicated on two or three machines, so if one of them is unavailable (due to hardware failure), the other copies could be used.ScalabilityIt is the ability to increase system performance gradually as the workload grows just by adding more processors. A computer network can provide a powerful communication medium along widely separated employees. The use of networks to enhance human-to-human communication will probably prove more important than technical goals such as improved reliability.These are the requirement with respect to companies but computer networking is required even in the normal day to day life as we have to access the internet to get information about what all new happening in the world, to have communication with people staying far away using the e mail service.

TYPES OF NETWORKS

LAN (Local Area Network)

These are privately owned networks within a single building or campus of up to a few a kilometers in size.LANs are distinguished from other networks by three characteristics:1) Their size.2) Their transmission technology.3) Their topology.LANs are restricted in size, which means that the worst-case transmission time is bounded and known in advance.LANs often use a transmission technology consisting of a single cable to which all the machines are attached.LANs run at speeds of 10 to 100 Mbps, have low delays, and make very few errors. WAN (Wide Area Network)

It is a Computer network that spans a relatively large geographical area, often a country or continent. Typically a WAN consists of two or more Local Area Network.Computers connected to WAN are often connected through public networks such as telephone systems. They can also be connected through leased lines or satellites. The largest WAN in existence is Internet.WANs run at speed of maximum 2 to 10 Mbps.

WAN SETUPFor most WANs, the long distance bandwidth is relatively slow: on the order of kilobits per second (kbps) as opposed to megabits per second (Mbps) for local-area networks (LANs). For example, an Ethernet LAN has a 10 Mbps bandwidth; a WAN using part or all of a T1 carrier has a bandwidth of 1.544 Mbps .Three types of approaches are used to connect WANs:1) Circuit switching, which provides a fixed connection (at least for the duration of a call or session), so that each packet takes the same path. Examples of this approach include ISDN, Switched 56, and Switched T1.2) Packet switching, which establishes connections during the transmission process so that different packets from the same transmission may take different routes and may arrive out of sequence at the destination. Examples of this approach are X.25, frame relay, and ATM.3) Leased lines, which can provide a dedicated connection for private use

NETWORKING DEVICES

Networking devices do various kinds of jobs like transferring the data to signals, providing connectivity to different network devices, transferring the data in form of packets or frames form one device to other. These are the central connections for all the network equipments and handle a data type known as frame or packet. Actually frames/ packet contain data and the destination address of where it is going. When a frame is received, it is amplified and then transmitted on to port of destination PC. But different networking components do this job in diff form at diff layers.

Network Interface CardA Network Interface Card (NIC) is a circuit board that plugs into both clients and servers and controls the exchange of data between them (A specific software driver must be installed depending on the maker of the NIC. A physical transmission medium, such as twisted pair or coaxial cable interconnects all network interface cards to network hubs or switches. Ethernet and Token Ring are common network interface cards. Todays cards supports 10baseT and 100baseT with automatic recognition. HubWhen the need for interconnecting more than 2 devices together then a device known as hub comes to picture. Basically hub is a layer one device. i.e it operates on the physical layer of the OSI model. It is designed to do broadcasting i.e. when it gets any frame it broadcasts it to every port irrespective that whether it is destined for that port or not. Hub has no way of distinguishing which port a frame should be sent. Broadcasting results in lot of traffic on the network which lead to poor network response. If two PC simultaneously transmit there data packets and both are connected to a HUB, then collision will occur, so we can say, it creates a single collision domain. On the other hand all PCs connected to a hub will get a same message so a single broadcast domain will be created.A 100/1000 Mbps hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the max available bandwidth. If, however, multiple PCs are broadcasting, then that bandwidth will need to be divided between all of these systems, which will degrade the performance. They are usually Half - Duplex in nature.

Switch

Hubs are capable of joining more than two PC but having some demerits like if two PC would want to communicate at a time then there would be a collision and the both PC would have to send the data once again. This shortcoming of Hub is overcome by Switch. Switches are intelligent devices which work on the Layer2 of the OSI model. Basically a switch keeps a record of MAC addresses of all the devices connected to it. Using this information, it builds a MAC address table. So when a frame is received, it knows exactly which port to send it to, which increases the network response time.The switch supports broadcast. Hence we can call switches create single broadcast domain and multiple collision domains.A 100/1000Mbps switch will allocate a full 100/1000 Mbps to each of its ports. So regardless of the no of PCs transmitting user will always have access to max amt of bandwidth. They are usually Full-Duplex in nature.Bridge

Bridge is another device like switch which also operates basing on the MAC address. But the Basic difference between the bridge and the switch is that bridge works on software bases, but the switch works on hardware basic. The Switch works on ASICs (Application Specific Integrated Circuits)Router

Switch and the Hub can only interconnect devices in a single LAN. For interconnecting two LAN or two or more different networks anther device known as router is used. Its main job is to route (sends) packets to other networks and to do the routing (establishing paths between networks) it uses the IP address. A router is typically connected to at least two networks, commonly two LANs or WANs or a LAN and its ISPs network. Routers are located at gateways, the places where two or more networks connect. Routers to determine the best path for forwarding the packet are using forwarding tables. It is a layer 3 device i.e. it operates at network layer of OSI model. The working principle of the router is totally different from a switch. Router makes a table known as routing table, which contains all the IP address in the network, the information for IP address router obtains directly ( all configured IP address on it ) or indirectly ( from neighbor routers ). When a packet is received it compares the destination IP address of the packet with the available IP addresses in its Routing table. If the IP address is not available in the routing table then it simply discard the packet instead of flooding in all the ports like a switch.(Detailed Information about router in chap )

Comparison between Hub, Bridge, Switch & Router

FeatureHubBridgeSwitchRouter

Number of broadcast domainsSegment111 per router interface

Number of collision domains11 per bridge port1 per switch port1 per router interface

Forwards LAN broadcasts?1YesYesNo

Forwards LAN multicastsN/AYesYes; can be optimized for less forwardingNo

OSI layer used when making forwarding decisionN/ALayer 2Layer 2Layer 3

Internal processing variantsN/AStore-and- forwardStore-and-forward, cut-through, Fragment FreeStore-and- forward

Frame/packet fragmentation allowed?N/ANoNoYes

Multiple concurrent equal-cost paths to same destination allowed?N/ANoNoYes

OSI NETWORK MODEL

The OSI model describes how information makes its way from application programs through a network medium to another application program in other computer. It divides one big problem in to seven smaller problems. Each problem is addressed by one of the seven layers of the OSI model.

Application Layer Used for applications specifically written to run over the network Allows access to network services that support applications; Directly represents the services that directly support user applications Handles network access, flow control and error recovery Example apps are file transfer, e-mail, Net BIOS-based applications

Presentation Layer Translates from application to network format and vice-versa All different formats from all sources are made into a common uniform format that the rest of the OSI model can understand Responsible for protocol conversion, character conversion, data encryption / decryption, expanding graphics commands, data compression Sets standards for different systems to provide seamless communication from multiple protocol stacks Not always implemented in a network protocol

Session Layer Establishes, maintains and ends sessions across the network Responsible for name recognition (identification) so only the designated parties can participate in the session Provides synchronization services by planning check points in the data stream => if session fails, only data after the most recent checkpoint need be transmitted Manages who can transmit data at a certain time and for how long Examples are interactive login and file transfer connections, the session would connect and re-connect if there was an interruption; recognize names in sessions and register names in history

Transport Layer Additional connection below the session layer Manages the flow control of data between parties across the network Divides streams of data into chunks or packets; the transport layer of the receiving computer reassembles the message from packets "Train" is a good analogy => the data is divided into identical units Provides error-checking to guarantee error-free data delivery, with on losses or duplications Provides acknowledgment of successful transmissions; requests retransmission if some packets dont arrive error-free Provides flow control and error-handling TCP, ARP, RARP; Network Layer Translates logical network address and names to their physical address (e.g. computer name ==> MAC address) Responsible for addressing and determining routes for sending Managing network problems such as packet switching, data congestion and routing If router cant send data frame as large as the source computer sends, the network layer compensates by breaking the data into smaller units. At the receiving end, the network layer reassembles the data IP; ARP; RARP, ICMP; RIP; OSFP;

Data Link Layer Turns packets into raw bits 100101 and at the receiving end turns bits into packets. Handles data frames between the Network and Physical layers The receiving end packages raw data from the Physical layer into data frames for delivery to the Network layer Responsible for error-free transfer of frames to other computer via the Physical Layer This layer defines the methods used to transmit and receive data on the network. It consists of the wiring, the devices use to connect the NIC to the wiring, the signaling involved to transmit / receive data and the ability to detect signaling errors on the network media

Logical Link Control Error correction and flow control Manages link control and defines SAPs

Physical Layer Transmits raw bit stream over physical cable Defines cables, cards, and physical aspects Defines NIC attachments to hardware, how cable is attached to NIC.

One of the greatest functions of OSI specifications is to assist in data transfer between dis-separate hosts.For example that they enable us to transfer data between UNIX host and a PC or a MAC. The OSI is not a physical model though rather it is a set of guidelines that application developers can used to create and implement applications that run on network. It also provides a framework for creating and implementing networking standards devices and inter-networking schemes.The OSI has seven different layers divided into two groups. The top three layers define how the applications within end stations will communicate with each other and with others. The bottom four layers define how data is transmitted end to end. It allows multiple-vendor development through standardization of network components. It prevents changes in one layer from affecting other layers so it does not hamper development.It encourages industry standardization by defining what functions occur at each layer of model. It allows various types of network hardware and software to communicate.

TCP/IP

Transmission Control Protocol takes large block of information from an application and breaks them into segments. It numbers and sequences each segment so that destinations TCP stack can put the segment back into the order the application intended. The TCP/IP model was created by Department of Defense(DoD) to ensure and preserve data integrity.The model consists of four instead of seven layers: Process/Application layer Host to Host layer Internet layer Network access layer A vast array of protocols combine at TCP/IP models Process/Application to integrate the various activities and duties. The process/application layer defines protocols for node to node application communication and also controls user-interface specifications.The Host to Host layer parallels the functions of the OSIs transport layer, defining protocols for setting up the level of transmission service for application. It tackles issues such as creating reliable end to end communication and ensures the error free delivery of data. It handles packet sequencing and maintains data integrity.The Internet layer includes the logical transmission of packets over entire network. It takes care of addressing of hosts by giving them an IP address and it handles routing of packets among multiple networks.At the bottom Network access layer monitors data exchange between the host and the network. The equivalent of the data link and physical layer of the OSI model, the Network access layer oversees hardware addressing and defines protocols for physical transmission of data.

The Process/Application layer It includes following protocols:TelnetIt allows a user on a remote client machine called Telnet client to access resources of other machine, the Telnet Server.

File Transfer protocol: It is a protocol that actually let us transfer files between any two machines.Network File System: It is a jewel of a protocol specializing in file sharing. It allows two different types of file systems to interoperate.Simple Mail transfer Protocol:This protocol is used for delivering of messages to destination in e-mail.X-window: It is designed for client/server operations. X window defines a protocol for writing client/server applications based on graphical user interface.Host to Host layer ProtocolsThe purpose of this to shield the upper layer applications from the complexities of the network. It covers two protocols:Transmission Control Protocol:It is a transport protocol used for delivering of messages from one process to other. It takes large block of information from an application and breaks them into segments. It numbers and sequences each segment so that destination TCPs stack can put the segments back into the order the application intended. After these segments are sent, TCP waits for an acknowledgement of receiving ends TCP virtual circuit session retransmitting those that are not acknowledged. User Datagram Protocol:UDP is also a transport protocol used for delivering of messages from one process to other and add port address.UDP does not sequence the segments and does not care in which order the segments arrive at the destination. But after that UDP sends the segments off and forgets about them. Due to this it is an unreliable protocol.It does a fabulous job of transporting information that does not require reliable delivery and it does so using far fewer network resources.Internet Layer ProtocolsInternet Protocol:IP is essentially the internet layer. IP looks at each packets address. Then using a routing table it decides where packet is to be sent next choosing the best path.IP receives segments from host to host layer and fragments them into datagrams.IP receives segments from Host to Host layer and fragments them into datagrams if necessary IP then reassembles datagrams back into datagrams on the receiving side. Each datagram is assigned the IP address of the sender and of recipient. Each router (layer3 device) that receives a datagram makes routing decisions based on the packets destination IP address.Internet Control Message ProtocolICMP works at network layer and is used by IP for many different devices. ICMP is a management protocol and messaging service provider for IP.ICMP packets are encapsulated within IP datagrams.They can provide hosts with information about network problems.Address Resolution Protocol: It finds the hardware address of a host from a known IP address. When IP has datagram to send in it must inform Network access protocol such as Ethernet or Token Ring of destination hardware address on local network.Reverse Address Resolution ProtocolRARP is the reverse of ARP. It finds the IP address knowing its physical address by sending out a packet includes its MAC address and a request for the IP address assigned to that MAC address. A designated machine called RARP server responds with the answer and the identity crisis is over. RARP uses information it does know about the machines MAC address to learn its IP address and complete the machines ID portrait.Proxy Address Resolution Protocol:On a network your hosts cant have more than one default gateway configured. What if the default gateway happens to go down? The host wont just start sending to another router automatically. But proxy Arp can actually help machines on a subnet reach remote subnets without configuring routing or even a default gateway.Network access layerAt the bottom Network access layer monitors data exchange between the host and the network. The equivalent of the data link and physical layer of the OSI model, the Network access layer oversees hardware addressing and defines protocols for physical transmission of data.

NETWORKING MODELS-TERMINOLOGIES

Collision Domain- It is the group of PCs in which collision will occur when two PC will transmit data simultaneously. Broadcast Domain- It is the group of PCs those will receive same broadcast message.CSMA/CD (Carrier Sense Multiple Access/ Collision Detection)- In this protocol when a PC wants to transmit any packet it sense the carrier i.e. the path ,if no other PC is using the carrier then only it sends. If two PCs start sending data simultaneously collision will occur. Both PCs will wait for some random time and then initiate the same process.MAC (Media Access Control): The IEEE 802.3 (Ethernet) and 802.5 (Token Ring) are the MAC sub layers of these two LAN data-link protocols.Burned-in address: The 6-byte address assigned by the vendor making the card. It is usually burned in to a ROM or EEPROM on the LAN card and begins with a 3-byte organizationally unique identifier (OUI) assigned by the IEEE.Locally administered address: Through configuration, an address that is used instead of the burned-in address.Unicast address: Fancy term for a MAC that represents a single LAN interface.

IP ADDRESSING

Every machine on the internet has a unique identifying number, called an IP address. A typical IP address looks like this:

216.27.61.45IP ADDRESS is a 32-bit number, usually written in dotted decimal form that uniquely identifies an interface of some computer. This 32-bit number is divided into 4 octets each separated by a decimal. Out so many values certain values are restricted for use as typical IP address. For example, the IP address 0.0.0.0 is reserved for the default network and the address 255.255.255.255is used for broadcast.Each IP address is split into 2 sections:1) Network address2) Host addressIndividual IP address in same network all have a different value in the host part of address, but they have identical value in network part, just as in town there are different street address but same ZIP code.There are five IP classes:Class A This class is for very large networks, such as a major international company. IP addresses with a first octet from 1 to 126 are part of this class. The other three octets are each used to identify each host.

Loopback- The IP address 127.0.0.1 is used as the loopback address. This means that it is used by the host computer to send a message back to itself. It is commonly used for troubleshooting and network testing.

Class B- Class B is used for medium-sized networks. A good example is a large college campus. IP addresses with a first octet from 128 to191 are part of this class. Class B addresses also includes the second octet as part of the Net identifier. The other two octets are used to identify each host.

Class C- Class C addresses are commonly used for small to mid-size business. IP addresses with a first octet from192 to 223 are part of this class. Class C addresses also include the second and third octets as part of Net identifier. The last octet is used to identify each host.

Class D- It is used for multicast. It has first bit value of 1, second bit value of 1, third bit value of 1 and fourth bit value of 0. The other 28 bits are used to identify the group of computers the multicast messages is intended for.

Class E- It is used for experimental purpose only. Reserved for future. PRIVATE IPIt is not necessary that every time we make a network we are connected to some ISP (Internet Service Provider). So in that case we require some private IP also which can be used in indigenous networks .In each class a range of IP addresses have been defined for this purpose CLASS A 10.0.0.1 to 10.255.255.244CLASS B 172.16.0.1 to 172.34.255.254CLASS C 192.168.0.0/16IP ACCESS LIST

IP access lists cause a router to discard some packets based on criteria defined by the network engineer. The goal of these filters is to prevent unwanted traffic in the networkwhether to prevent hackers from penetrating the network, or just to prevent employees from using systems that they should not be using.Key features of access lists: Packets can be filtered as they enter an interface, before the routing decision. Packets can be filtered before they exit an interface, after the routing decision. Deny is the term used in Cisco IOS software to imply that the packet will be filtered. Permit is the term used in Cisco IOS software to imply that the packet will not be filtered. The filtering logic is configured in the access list. At the end of every access list is an implied deny all traffic statement. Therefore, if a packet does not match any of your access list statements, it is blocked.Access lists have two major steps in their logic: matching and action. Matching logic examines each packet and determines whether it matches the access-list statement. As soon as an access-list statement is matched, there are two actions to choose from: deny and permit. Deny means to discard the packet, and permit implies that the packet should continue on its way.

MASKINGComputers use a mask to define size of network and host part of an address. Mask is a 32-bit number written in dotted decimal form. It provides us the network address when we perform a Boolean AND of mask with the IP address. It also defines number of host bits in an address.Class of addressSize of network Part of address, in bitsSize of Host Part of address, in bits Default Mask for Each Class of Network

A824255.0.0.0

B1616255.255.0.0

C248255.255.255.0

SUBNETTING

Basically it is a process of subdividing networks into smaller subnets. In case we have 2-3 small networks but we cant buy IP address for each and every network. So here we use the basic concept of SUBNETTING i.e using one public IP address we will give them IP address and make them independent networks. For this we take some bits of host address and use them for network address so we have different independent networks.Advantages of Subnetting are: Reduced Network Traffic: We all appreciate less traffic. Networks are no different. With routers most traffic stay on local network; only packets destined for other networks will pass through routers. Router create broadcast domain. The more broadcast domains one create, the smaller the broadcast domains and less network traffic on each network segment. Optimized Network Performance: This is a result of reduced Network Traffic Simplified management: It is easier to identify and isolate network problems in a group of smaller connected networks than within one gigantic network. Facilitated spanning of large geographical distances: Because WAN links are considerably slower and more expensive than LAN links, a single large network that spans long distances can create problems in every area previously listed. Connecting multiple smaller networks makes the system more efficient.To create Subnets follow these steps:1) Determine the number of required network IDs: One for each subnet One for each wide area network connection2) Determine the number of required host IDs per subnet One for each TCP/IP host One for each router interface3) Based on above requirements create the following: One subnet mask for entire network A unique subnet ID for each physical segment A range of host ID for each subnet

CLASSLESS INTER-DOMAIN ROUTING (CIDR)

It is basically the method that internet service providers use to allocate a number of addresses to a company, a home-a customer. They provide addresses in a certain block size.When we receive a block of address from ISP it will look like: 192.168.10.32/28.This is telling what our subnet mask is. The slash notation (/) means how many bits are turned on(1s).Obviously the maximum could be /32 because a byte is 8 bits and there are 4 bytes in an IP address(4*8=32).The largest subnet mask available can only be a /30 because one has to keep at least 2 bits for host bits.Example:Subnet maskCIDR Value255.240.0.0 /12255.255.128.0 /17255.255.255.128 /25255.255.255.252 /30 IP TRAFFIC OVERVIEW

IP multicasting is an extension of the standard IP protocol and is described in Host Extensions for IP Multicasting. IP multicasting is the transmission of an IP datagram to a group identified by a single IP destination address. A multicast datagram is delivered to all members of its destination host group using User Datagram Protocol (UDP). Membership in these groups is unrestrictedhosts can be members of multiple groups, and they may join or leave at any time.IP multicast datagrams are handled by multicast routers. A host transmits an IP multicast datagram as a local network multicast that reaches a multicast router. The router examines the packet and begins to provide the host with the requested multicast traffic. If the router is not receiving the requested multicast traffic, it will pass the request to other multicast routers. IP traffic can travel the network in one of the ways: Broadcast Unicast MulticastBroadcast

In its simplest form, broadcast traffic consists of packets that reach every point of the network. In a typical network, broadcasts are stopped at the router. You can set the router to forward broadcasts, but doing so is not very efficientit creates a lot of traffic on the network and slows the end users machines. Every host on the network must process the packet to see if it is destined for that host. Data broadcasts are typically small frames used in the local networkso, the performance effect is negligible, unless there is a broadcast storm. In a broadcast storm, an incorrect packet is broadcast on the network. This causes most hosts to res-pond with incorrect answers, which in turn causes even more hosts to respond again. This process continues until the network can no longer carry any other traffic. A broadcast storm can also occur when there is more than one path through the network, allowing broadcasts to circle the network until there are so many that the network comes to a stop.Multimedia broadcasts, in contrast, can be huge packets. Processing these types of broadcasts can quickly use up all the available bandwidth on the network and bring the end station to a crawlparticularly if you are in a shared 10BaseT environment.

Broadcast traffic flow.Unicast

In Unicast, a single packet is sent from the source to the destination. It is a onetoone relationship: For every packet that reaches the destination, one packet was sent by the source. This process is fine if the source is having different conversations with only a few hosts. Now, imagine that same source talking to hundreds of hosts on the same conversationeach identical packet must be generated by the source and must travel on the network.Audio and video transmissions are so large that a highbandwidth link is consumed very quickly. A 100Mbps link can support about 60 to 70 fullscreen, fullmotion video streams if each stream uses approximately1.5Mbps of servertoclient bandwidth. You will need gigabitpersecond (Gbps) links between the server and the network in order to provide one audio/video broadcast to a couple hundred hosts. Unicast multimedia applications do not scale very well.

Unicast traffic flow.

Multicast

Multicast is a combination of broadcast and Unicast. It sends one copy of the packet to many hosts that requested it, thereby using less bandwidth. It also saves bandwidth by not sending the packet to the portion of the network whose hosts didnt request the transmission. Multicast accomplishes this task by transmitting to an identified group, called a multicast group, rather than to an individual host. Each interface/host can be a member of multiple multicast groups. The membership is dynamic; a host can leave and join any time it wants. The traffic is also not limited by any boundary; it can reach the farthest point of the Internet.

Multicast traffic flow.The characteristics of multicast enable it to take three different forms:OnetomanyOnetomany is the most common form of multicast traffic. Examples include database updates, live concerts, news, music/audio broadcasts, announcements, lectures, and many more.ManytooneManytoone multicasts are less common; they include data collection, auctions, and polling.ManytomanyManytomany multicasts are rare, but they are gaining popularity as programmers begin to utilize multicast in some imaginative ways. Chat groups, multimedia conferencing, concurrent processing, interactive music sessions, and collaboration are examples of manytomany multicasts. But dont forget the rising star (and my favorite): interactive multiplayer games.

VIRTUAL LAN

VLANs (Virtual LAN) are used to segment the network into smaller broadcast domains or segments. The primary reason to segment your network is to relieve network congestion and increase bandwidth. Segmentation is often necessary to satisfy the bandwidth requirements of a new application or a type of information the network needs to be able to support, such as multimedia or graphical design applications. Other times, you may need to segment the network due to the increased traffic on the segment or subnet.Be careful not to over segment. Placing each port in an individual VLAN is like placing a router to stop broadcasts between each individual VLAN. Routers are like bug poisonthey kill broadcasts dead. Broadcasts cant escape through routers and they cant escape a VLAN, either. Each VLAN becomes its own individual broadcast domain. When a network node or workstation sends out an advertisement or broadcast to the other nodes on a segment, only the nodes assigned to the VLAN to which the node sending the broadcast is assigned will receive that broadcast.Another definition of a VLAN is a logical grouping of network users and resources connected administratively to defined ports on a switch. By creating VLANs, you are able to create smaller broadcast domains within a switch by assigning different ports on the switch to different sub networks. Ports assigned to a VLAN are treated like their own subnet or broadcast domain. As a result, frames broadcast are only switched between ports in the same VLAN at Layer 2. Using virtual LANs, youre no longer confined to physical locations. VLANs can be organized by location, function, department, or even the application or protocol used, regardless of where the resources or users are located. In a flat network topology, your broadcast domain consists of all the interfaces in your segment or subnet. If no devicessuch as switches or routersdivide your network, you have only one broadcast domain. On some switches, an almost limitless number of broadcast domains or VLANs can be configured.

ROUTING

The term routing is used for taking a packet from one device and sending it through the network to another device on a different network. Routers dont really care about the hosts-they only care about networks and the best path to each network. The logical network address of the destination host is used to get packets to a network through routed network and then hardware address of the host is used to deliver the packet from a router to correct destination host.If your network has no routers then it should be apparent that you are not routing. Routers route traffic to all the networks in your internetwork. To be able to route packets a router must know the following: Destination address Neighbor routers from which it can learn about remote networks Possible routes to all remote networks. The best route to each remote network How to maintain and verify routing information.The router learns about remote networks from neighbor routers or from an administrator. The router then builds a routing table that describes how to find the remote networks.There are three types of routing:1) Static Routing2) Default routing3) Dynamic RoutingIf your network has no routers then it should be apparent that you are not routing. Routers route traffic to all networks in your internetwork. To be able to route packets, a router must know, at a minimum, the following: Destination address Neighbor routers from which it can learn about remote networks Possible routes to all remote networks The best route to each remote network How to maintain and verify routing informationThe router learns about remote networks from neighbor routers or from an administrator. The router then builds a routing table that describes how to find remote networks. If a network is directly connected, then router already knows how to get to it.Static Routing:Static Routing occurs when you manually add routes in each routers routing table. There are pros and cons to static routing but that is true for all routing process.Static routing has following benefits: There is no overhead on the router CPU which means one could possibly buy a cheaper router than one would use if one is using dynamic routing. It adds security because the administrator can choose to allow routing access to certain networks only. There is no bandwidth usage between routers which means we can save money on WAN links.

Disadvantages are: The administrator must really understand the internetwork and how each router is connected in order to configure routes correctly. It is not feasible in large networks because maintaining it would be a full time job in itself.

Default Routing:We use default routing to send packets with a remote destination network not in the routing table to the next hop router. One should use default routing on stub networks-those with only one exit path out of the network.A default route of a computer that is participating in computer networking is the packet forwarding rule taking effect when no other route can be determined for a given Internet Protocol(IP) destination address. All packets for destinations not established in routing table are sent via default route.

Dynamic Routing:Dynamic Routing is when protocols are used to find networks and update routing tables on routers. True, this is easier than static or default routing but it will cost you in terms of router CPU processes and bandwidth on network links. A routing protocol defines the set of rules used by a router when it communicates routing information between neighbor routers. ROUTING PROTOCOLS

There are three classes of routing protocols: Distance vector:

They find the best path to a remote network by judging distance. Each time packet goes through a router thats called a hop. The route with least number of hops to the network is determined to be the best route. The vector indicates the direction to the remote network.RIP is a distance vector routing protocol. They send the direct routing table to directly connected neighbors. Link State:

In link state protocol also called shortest path first protocol, the routers each create three separate tables. One of these tables keeps track of directly attached neighbors, one determines the topology of entire internetwork, and one is used as the routing table. Link state routers know more about the internetwork than any distance vector routing protocol. OSPF is a routing protocol that is completely link state. Link state protocol send updates containing state of their links to all other routers on the network. Hybrid:

Hybrid protocols use aspects of both distance vector and link state. Example-EIGRPThere is no set way of configuring routing protocols for use with every business. This is something we really have to do on case by case basis.

BORDER GATEWAY PROTOCOL

BGP is a standardized exterior gateway protocol (EGP), as opposed to RIP, OSPF, and EIGRP which are interior gateway protocols (IGPs). BGP Version 4 (BGPv4) is the current standard deployment.BGP is considered a Path Vector routing protocol. BGP was not built to route within an Autonomous System (AS), but rather to route between ASs. BGP maintains a separate routing table based on shortest AS Path and various other attributes, as opposed to IGP metrics like distance or cost.BGP is the routing protocol of choice on the Internet. Essentially, the Internet is a collection of interconnected Autonomous Systems.BGP Autonomous Systems are assigned an Autonomous System Number (ASN), which is a 16-bit number ranging from 1 - 65535. A specific subset of this range, 64512 - 65535, has been reserved for private (or internal) use.

BGP should be used under the following circumstances:Multiple connections exist to external ASs (such as the Internet) via different providers.Multiple connections exist to external ASs through the same provider, but connect via a separate CO or routing policy.The existing routing equipment can handle the additional demands.BGPs true benefit is in controlling how traffic enters the local AS, rather than how traffic exits it.

BGP Peers (Neighbours)For BGP to function, BGP routers (called speakers) must form neighbor relationships (called peers).There are two types of BGP neighbor relationships:iBGP Peers - BGP neighbors within the same autonomous system.eBGP Peers - BGP neighbors connecting separate autonomous systems.BGP (Best Path determination)If BGP contains multiple routes to the same destination, it compares the routes in pairs, starting with the newest entries (listed higher in the routing table), and working towards the oldest entries (listed lower in the table).BGP determines the best path by successively comparing the attributes of each route pair. The attributes are compared in a specific order: Weight - Which route has the highest weight? Local Preference - Which route has the highest local preference? Locally Originated - Did the local router originate this route? In other words, is the next hop to the destination 0.0.0.0? AS-Path - Which route has the shortest AS-Path? Origin Code - Where did the route originate? The following origin codes are listed in order of preference:o IGP (originated from an interior gateway protocol) o EGP (originated from an exterior gateway protocol) o ? (Unknown origin) MED - Which path has the lowest MED? BGP Route Type - Is this an eBGP or iBGP route? (eBGP routes are preferred) Age - Which route is the oldest? (oldest is preferred) Router ID - Which route originated from the router with the lowest BGP router ID? Peer IP Address - Which route originated from the router with the lowest IP?

OSPF

Open shortest Path First is an open standard routing protocol that has been implemented by a wide variety of network venders including Cisco. It is efficient for large networks. OSPF is first link state routing protocol. OSPF works by Dijkstra algorithm. First a shortest path tree is constructed and then routing table is populated with resulting best paths. OSPF converges quickly and it supports multiple equal cost routes to the same destination. It does support both IP and IPv6 routed protocols.OSPF provides the following features: Consists of areas and autonomous systems Minimizes routing update traffic Allows scalability Supports VLSM/CIDR Has unlimited hop count Allows multi-vendor deploymentOSPF is supposed to be designed in a hierarchical fashion, which basically means that you can separate larger internetwork into smaller internetworks called areas. This is the best design for OSPF.The following are reasons for creating OSPF in a hierarchical design: To decrease routing overhead To speed up convergence To confine network instability to single areas of the networkSome of OSPF terms are:Link: It is a network or route interface assigned to any given network.Router ID: It is an IP address used to identify the router.Neighbor: They are two or more routers that have an interface on common network such as two routers connected on a point to point serial link.Adjacency: It is a relationship between two OSPF routers that permits the direct exchange of route updates.Hello Protocol: The OSPF hello protocol provides dynamic neighbor discovery and maintain neighbor relationships.Neighborship database: It is a list of all OSPF routers for which hello packets have been seen.Topological database: It contains information from all of Link State advertisement packets that have been received for an area. The router uses information from topology database as input into Dijkstra algorithm that computes shortest path to every network.Link Sate advertisement: A LSA is an OSPF data packet containing link state and routing information that is shared among OSPF routers. An OSPF router will exchange LSA packets only with routers to which it has established adjacencies.

SPF CalculationWithin an area each router calculates shortest path to every network in that same area. This calculation is based upon the information collected in topology database and an algorithm called shortest path first. Picture each router in an area constructing a tree-much like a family tree-where router is root and all other networks are arranged along branches and leaves. This is the shortest path tree used by router to insert routes into the routing table.OSPF uses a metric referred to as cost. A cost is associated with every outgoing interface included in an SPF tree. The cost of the entire path is sum of costs of outgoing interfaces along the path.

IS-IS Fundamentals

IS-IS (Intermediate System -to- Intermediate System) is a standardized link-state protocol that was developed to be the definitive routing protocol for the OSI (Open Systems Interconnect) Model, which was developed by ISO (International Standards Organization). IS-IS shares many similarities to OSPF. Though it was designed as an interior gateway protocol (IGP), IS-IS is predominantly used by ISPs, due to its scalability.IS-IS adheres to the following Link State characteristics: IS-IS allows for a hierarchical network design using Areas.IS-IS will form neighbor relationships with adjacent routers of the same IS-IS type.Instead of advertising the distance to connected networks, IS-IS advertises the status of directly connected links in the form of Link-State Packets (LSPs). IS-IS will only send out updates when there is a change to one of its links, and will only send the change in the update.IS-IS uses the Dijkstra Shortest Path First algorithm to determine the shortest path.IS-IS is a classless protocol, and thus supports VLSMs.Other characteristics of IS-IS includes:IS-IS was originally developed to route the ISO address space, and thus is not limited to IP routing.IS-IS routes have an administrative distance is 115.IS-IS uses an arbitrary cost for its metric.IS-IS additionally has three optional metrics: delay, expense, and error. Cisco does not support these optional metrics.IS-IS has no hop-count limit.The IS-IS process builds and maintains three separate tables: A neighbor table - contains a list of all neighboring routers. A topology table - contains a list of all possible routes to all known networks within an area. A routing table - contains the best route for each known network.IS-IS is only available on enterprise versions of the Cisco IOS.

The IS-IS Hierarchy

IS-IS defines three types of IS-IS routers: Level-1 Router - contained within a single area, with a topology table limited to only its local area (called the Level-1 Database) Level-2 Router - a backbone router that routes between areas, and builds a Level-2 Database. Level-1-2 Router - similar to an area border router. Interfaces between a local area and the backbone area, and builds both a Level-1 and a Level-2 database.Each type of IS-IS router will form only specific adjacencies: Level-1 routers form Level-1 adjacencies with other Level-1 routers and Level-1-2 routers. Level-2 routers form Level-2 adjacencies with other Level-2 routers and Level-1-2 routers. Level-1-2 routers form both Level-1 and Level-2 adjacencies with other Level-1-2 routers. Level-1 routers will never form adjacencies with Level-2 routers.The IS-IS backbone consists of multiple contiguous Level-2 routers, each of which can exist in a separate area. If a Level-1 router has a packet destined for a remote area, it forwards it to the nearest Level-1-2 router. Level-1-2 routers set an Attach (ATT) bit in their Level-1 LSPs, informing other Level-1 routers that they are attached to another area.Level-2 routers share Level-2 LSPs, and will build a Level-2 topology table, which contains a list of reachable areas across the IS-IS domain.Level-1-2 routers will share both Level-1 and Level-2 LSPs with its appropriate adjacencies. Level-1-2 routers maintain separate Level-1 and Level-2 topology tables.

IS-IS vs. OSPF

IS-IS is often compared and contrasted to OSPF. Both protocols share several similarities, including: Both are Link-State routing protocols. Both use the Dijkstra algorithm to determine the shortest path. Both are classless and support VLSMs. Both use a cost metric. Both use areas to minimize the size of topology and routing tables. Both elect a designated router on broadcast links to contain link-state update traffic.Despite these similarities, there are a multitude of crucial differences between IS-IS and OSPF, including: OSPF supports only IP, IS-IS supports both IP and CLNS. IS-IS does not require IP connectivity between routers to share routing information. Updates are sent via CLNS instead of IP. In OSPF, interfaces belong to areas. In IS-IS, the entire router belongs to an area. An IS-IS router belongs to only one Level-2 area, which results in less LSP traffic. IS-IS is thus more efficient and scalable than OSPF, and supports more routers per area. There is no Area 0 backbone area for IS-IS. The IS-IS backbone is a contiguous group of Level 1-2 and Level 2 routers. IS-IS does not elect a backup DIS. Additionally, DIS election is preemptive. On broadcast networks, even with an elected DIS, IS-IS routers still form adjacencies with all other routers. In OSPF, routers will only form adjacencies with the DR and BDR on broadcast links. IS-IS uses an arbitrary cost metric. OSPFs cost metric is based on the bandwidth of the link. IS-IS provides far more granular control of link-state and SPF timers than OSPF.

RIP

Routing Information Protocol(RIP) is a true distance vector routing protocol.RIP sends the complete routing table out to all active interfaces every 30 seconds.RIP only uses hop count to determine the best way to a remote network but it has maximum allowable hop count of 15 by default meaning that 16 is deemed unreachable.RIP works well in small networks.It is not efficient on large networks with slow WAN links or on networks with a large number of routers installed.RIP version 1 uses only classful routing, which means that all devices in network must use the same subnet mask. This is because RIP version 1 does not send updates with subnet mask information in tow.RIP version 2 provides something called prefix routing and does send subnet mask information with route updates. This is called classless routing.RIP Timers

RIP uses four different kinds of timers to regulate its performance:1) Route update timerSets the interval between periodic routing updates in which router sends a complete copy of its routing table out to all neighbours. 2) Router invalid timerDetermines the length of time that must elapse before a router determines that a route become invalid.3) Hold down timerThis sets the amount of time during which routing information is suppressed. Router will enter into hold down state when an update packet is received that indicated the route is unreachable. This continues either until an update packet is received with a better metric or until the hold down timer expires. The default is 180 seconds.4) Route flush timerSets the time between a route becoming invalid and its removal from the routing table(240 seconds) .Before it is removed from the table the router notify its neighbor of that routes impending demise. The value of the route invalid timer must be less than that of route flush timer.

Multiprotocol Label Switching (MPLS)Multiprotocol label switching (MPLS) is a versatile solution to address the problems faced by present-day networksspeed, scalability, quality-of-service (QoS) management, and traffic engineering. MPLS has emerged as an elegant solution to meet the bandwidth-management and service requirements for next-generation Internet protocol (IP)-based backbone networks. MPLS addresses issues related to scalability and routing (based on QoS and service quality metrics) and can exist over existing asynchronous transfer mode (ATM) and frame-relay networks.MPLS is an Internet Engineering Task Force (IETF)-specified framework that provides for the efficient designation, routing, forwarding, and switching of traffic flows through the network.MPLS performs the following functions: specifies mechanisms to manage traffic flows of various granularities, such as flows between different hardware, machines, or even flows between different applications Remains independent of the Layer-2 and Layer-3 protocols Provides a means to map IP addresses to simple, fixed-length labels used by different packet-forwarding and packet-switching technologies Interfaces to existing routing protocols such as resource reservation protocol (RSVP) and open shortest path first (OSPF) Supports the IP, ATM, and frame-relay Layer-2 protocolsIn MPLS, data transmission occurs on label-switched paths (LSPs). LSPs are a sequence of labels at each and every node along the path from the source to the destination. LSPs are established either prior to data transmission (control-driven) or upon detection of a certain flow of data (data-driven). The labels, which are underlying protocol-specific identifiers, are distributed using label distribution protocol (LDP) or RSVP or piggybacked on routing protocols like border gateway protocol (BGP) and OSPF. Each data packet encapsulates and carries the labels during their journey from source to destination. High-speed switching of data is possible because the fixed-length labels are inserted at the very beginning of the packet or cell and can be used by hardware to switch packets quickly between links.

LSR and LER

The devices that participate in the MPLS protocol mechanisms can be classified into label edge routers (LERs) and label switching routers (LSRs).An LSR is a high-speed router device in the core of an MPLS network that participates in the establishment of LSPs using the appropriate label signaling protocol and high-speed switching of the data traffic based on the established paths. An LER is a device that operates at the edge of the access network and MPLS network. LERs support multiple ports connected to dissimilar networks (such as frame relay, ATM, and Ethernet) and forwards this traffic on to the MPLS network after establishing LSPs, using the label signaling protocol at the ingress and distributing the traffic back to the access networks at the egress. The LER plays a very important role in the assignment and removal of labels, as traffic enters or exits an MPLS network.Label-Switched Paths (LSPs)

A collection of MPLS-enabled devices represents an MPLS domain. Within an MPLS domain, a path is set up for a given packet to travel based on an FEC. The LSP is set up prior to data transmission. MPLS provides the following two options to set up an LSP. Hop-by-Hop routingEach LSR independently selects the next hop for a given FEC. This methodology is similar to that currently used in IP networks. The LSR uses any available routing protocols, such as OSPF, ATM private network-to-network interface (PNNI), etc. Explicit routingExplicit routing is similar to source routing. The ingress LSR (i.e., the LSR where the data flow to the network first starts) specifies the list of nodes through which the ER-LSP traverses. The path specified could be non-optimal, as well. Along the path, the resources may be reserved to ensure QoS to the data traffic. This eases traffic engineering throughout the network, and differentiated services can be provided using flows based on policies or network management methods. The LSP setup for an FEC is unidirectional in nature. The return traffic must take another LSP.MPLS addresses today's network backbone requirements effectively by providing a standards-based solution that accomplishes the following:o MPLS enhances and simplifies packet forwarding through routers using Layer-2 switching paradigms.o Improves packet-forwarding performance in the network.o MPLS increases network performance because it enables routing by witching at wire line speeds and supports network scalabilityCISCO THREE LAYER HIERARCHIAL MODEL

Hierarchy has many benefits in network design. When used properly it makes network more predictable. It helps us define which areas should perform certain functions.Large networks can be extremely complicated with multiple protocols, detailed configurations and diverse technologies. Hierarchy helps us summarize a collection of details into an understandable model. The Cisco hierarchical model can help one design, implement and maintain a scalable, cost-effective hierarchical network. Cisco defines three layers of hierarchy as shown with specific functions:

Following are the three layers: The Core layer: Backbone The Distribution layer: Routing The Access layer: SwitchingDistribution layer:

It is sometimes referred to as the workgroup layer and is the communication point between access layer and the core. The primary functions of distribution layer are to provide routing filtering and WAN access and to determine how packets can access the core. The distribution layer must find the fastest way that network that network service requests are handled.There are several actions that are generally should be done at distribution layer: Routing Implementing security and network policies Redistributing between routing protocols, including static routing Implementing tools, packet filtering and queuing Defining broadcast and multicast domains Routing between VLAN and other workgroup support functionsAccess Layer:

The access layer controls user and workgroup access to internetwork resources. The access layer is sometimes referred to as desktop layer. Some of its functions are: Creation of separate collision domains Continued use of access control and policies Workgroup connectivity into distribution layerCore Layer:

It is literally the core of the network. At the top of the hierarchy the core layer is responsible for transporting large amount of traffic both reliably and quickly. The only purpose of networks core layer is to switch traffic as soon as possible. The traffic transported across the core is common to the majority of users. If there is a failure in core every single user can be affected. Therefore fault tolerance at this layer is an issue. The core is likely to see large volumes of traffic, so speed and latency are driving issue here.

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