IGP & EGP

Interior Gateway Protocol (IGP)

An Interior Gateway Protocol (IGP) is a routing protocol which is use to exchange routing information within an autonomous system (AS). We can understand it as exchanging routing information between gateways (hosts or routers) within an autonomous network (The Corporate LAN network is an example, where as we can implement IGP). The routing information can be used by the Internet Protocol (IP) or other network protocols to specify how to route packets.

The interior gateway protocols can be divided into two categories:

1-      Distance-vector Routing Protocol 

2-      Link-state Routing Protocol

  

Exterior Gateway Protocol (EGP)

While an Exterior Gateway Protocol (EGP) is a routing protocol which is use to determining the network reach-ability between autonomous systems and makes use of Interior Gateway Protocol to resolve routes within an AS. EGP is commonly used between hosts on the Internet to exchange routing information. EGP is based on periodic polling using Hello/I-Heard-You (I-H-U) message exchanges to monitor neighbor reach-ability and Poll commands to solicit Update responses. The routing table contains a list of known routers, the addresses they can reach, and a cost metric associated with the path to each router so that the best available route is chosen. 

BGP (Border Gateway protocol) is an example of EGP, which is used on the edge of network (Huge Network) and mostly used by ISP's Networks.

Static Routing Configuration

Static Route

If We have Network  between two Routers. Then how to configure between them with Static Routing or Static Route.

First we see on which serial interface side is DCE or DTE, 

R# show controllers serial 0/0  (whichever your interface no.)

at which side interface is DCE, we run the following command
Lets suppose This is R1 then. 

R1(config)# int serial 0/0
R1(config-if)# clock rate 64000 (whichever rate you need as per your requirement)

No we need to define the static route for the communication.
On the R1 side
R1(config)# 11.1.1.0   255.255.255.0   150.1.1.2

and 

On the R2 side
R2(config)# 10.1.1.0  255.255.255.255.0  150.1.1.1

now we can see the Routing table to run the below command.

R# Show ip route

its done and communication begin between both hosts.

MAC Address or Physical Address.

MAC is stands for Media Access Control. This is also called Physical Address or Hardware address. MAC works on layer 2 or Data link layer of OSI model. All devices on LAN must have a unique MAC address . A MAC address is a 48-bits address burned into a Network Interface Card (NIC). The first 24 bits of MAC address indicate the vendor that Manufactured the Network Interface Card (NIC). This is called the Organization Unique Identifier (OUI). The last 24 bits of the MAC Address are the unique host address. 

A MAC address is looka like the below given example.

 00-68-4a-e8-9d-da

in this example- Vendor ID --  00-68-4a

                            Host ID   --  e8-9d-da

MAC address is always in Hex a decimal format.

it use the No. 0 - 9

and use alphabets a - f

Any Computer LAN Card making Company get registration in IEEE. and IEEE provide a 24 bits ID to this company.

What is CSMA/CD

CSMA/CD is express as Carrier Sense Multiple Access Collision Detect. This is a Method to detect a collision on  Ethernet network. CSMA/CD describes the Ethernet access method, In CSMA/CD many devices can transmit on the same cable and no device has priority over any other. Before a device transmits, it listens on the wire to make sure no other device is transmitting. If no other device is transmitting, this device transmits across the wire. CSMA/CD is all about devices taking turns using the wire.

Communication Mode and Method

Communication Mode

 Half Duplex

• It uses only one wire pair with a digital signal running in both directions on the wire.
• It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur.
• If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions.
•  Half-duplex Ethernet—typically 10BaseT—is only about 30 to 40 percent efficient because a large 10BaseT network will usually only give you 3 to 4Mbps—at most.

Full Duplex
 

In a network that uses twisted-pair cabling, one pair is used to carry the transmitted signal from one node to the other node. A separate pair is used for the return or received signal. It is possible for signals to pass through both pairs simultaneously. The capability of communication in both directions at once is known as full duplex.

Full duplex means you can send and receive at the same time. This was impossible on Coax, the original Ethernet media since it had only 1 conductor and Ethernet uses base-band signaling. However, 10BaseT and 100BaseT use a cable with 4 conductors.

Simplex Duplex

This communication mode is one way only. In this mode one host has data transmitted and other all hosts receive this data for which its sent. but these hosts could not communicate back with the sender. This is like broadcasting.

Television , Radio are the example of this mode.

Communication Method

There are three type of LAN traffic as given below:-
 
Uni-casting

This is one to one communication. In this communication Uni-cast frames are the most common type of LAN traffic. A uni-cast frame is a frame intended for one host. In this communication one by one host can communicate to each one. Phone communication is example of this method.

Multicast

In Multicast communication method, A group of devices has been defined that has common interest and after that multicast frames address to this group. Audio and Video Conferencing  are example of this method.

Broadcasting

In this communication method, Broadcast frames are intended for everyone. Host or devices view broadcast frame as public service announcements. all devices receive and process broadcast frames. In the large networks Broadcast can bring the network crawl, because every computer must process them.

TCP/IP Model

Like the OSI network model we have also another Network model named TCP/IP model. The TCP/IP model is different from OSI model. OSI have seven layers standard, however TCP/IP has four layers. After taking some layers from OSI, and combine then, developers create a model, which was called TCP/IP. TCP and IP protocols have great importance in network communications that why model have name as TCP/IP. From the below figure we can understand the both model differences.

Comparison chart of Both models:-

OSI Model Layers	TCP/IP Model Layers
Application Layer	Application Layer
Presentation Layer
Session Layer
Transport Layer	Host to Host Layer/Transport Layer
Network Layer	Internet
Data Link Layer	Network Layer
Physical Layer

From the above figure, Application ,Presentation and Session layers are all together as combined called Application layer in TCP/IP Model. Also note that the Network Layer is combination of Data-link Layer and Physical Layer of OSI model. 

Layer 4. Application Layer 

Application layer is the top most upper layer of TCP/IP model. The TCP/IP Application layer protocols operate at the Session, Presentation and Application layers of the OSI model. this layer enables applications to communicate with one another and it provides access to the services of the underlying layers.There is a wide variety of Application layer protocols, all of which rely on all the TCP/IP services beneath them in the protocol stack. This layer is responsible for TCP/IP application protocols and any host or computer programs interface with layer 3 services to use the network.

Application layer includes all the higher-level protocols like DNS, HTTP, Telnet, FTP, SNMP, SMTP, DHCP, RDP etc

Layer 3. Transport Layer

The layer 3 of TCP/IP model is Transport layer sometimes its called host to host protocol also. Transport layer is responsible for data conversion at time of transferring, the working protocol on this layer divided the data in segments, after labeling them, reassembling,  flow control, error connection, and when reach data on other hand, again arrange data in the sequence in that the real data received. 

The main protocols of Transport layer are TCP and UDP.  

Layer 2. Internet Layer 

The second layer 2 of the  TCP/IP model Internet Layer. The position of Internet layer is between Network Access Layer and Transport Layer. Internet layer is responsible to pack data into data packets known as IP data-grams, which contain source and destination addresses. These information is used to forward the data-grams to the hosts or across networks. The routing of IP data-gram is one of the work of this Internet layer.

The main protocol of Internet layer are IPv4, IPv6, ICMP, IGMP, IGRP, IPX, Apple talk DDP, EIGRP etc.

 Layer 1. Network Access Layer 

This is the first layer of the four layer TCP/IP model. This layer 1 is responsible ,how data would be physically sent through the network, including how bits are electrically or optically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted pair copper wire. 

Ethernet, frame relay, DTP, CDP, L2F, SLIP, STP, etc are some protocols that’s working on this layer.

But most common model which is using in Modern time is OSI model. 

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