Remote Procedure Call (RPC) - Session Layer protocol

Remote Procedure Call (RPC) is a protocol which works in session layer of OSI model and in the Application Layer of TCP/IP model. It is useful in developing network applications which need services from a remote computer in the network. With the help of Remote Procedure Call the programmer need not worry about the complex structure of OSI layer.


Working of Remote Procedure Call




1. RPC is working as a client server model

2. RPC uses different Authentication methods to validate the client request.

3. RPC protocol is independent of transport layer protocols.

4. RPC reuests can use both UDP and TCP but prefer UDP format


In RPC the client issues requests for certain services from server through the network.A client is a computer or process that accesses the services or resources of another process or computer on the network. A server is a computer that provides services and resources, and that implements network services.In short the requesting program is a client and the service-providing program is the server. According to the results of RPC authentication server may reject or accept the request.


Remote Procedure Call(RPC) Authentications



The major Remote Procedure Call (RPC) authentication methods are provided below.


1 Null Authentication

Often calls must be made where the caller does not know who he is or
the server does not care who the caller is.


2 UNIX Authentication

The caller of a remote procedure may wish to identify himself as he
is identified on a UNIX(tm) system.

3 DES Authentication

DES Authentication is the advance form of UNIX Authentication.


UNIX command to display the RPC programs that are registered on a specified computer.

rpcinfo -p


Reference:
http://www.faqs.org/rfcs/rfc1050.html

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Network Layer - Functions and Main Protocols

Network Layer is the third layer in OSI Reference model. It is responsible for providing logical topology for a network by assigning IP addresses to every hosts. Providing logical addresses to networking devices is the duty of Network Layer. It also responds to service requests from Transport Layer and issues service requests to Data Link Layer. In network layer, data is passing in the form of packets.It is responsible for establishing paths for data transfer between different networks while Transport layer provides host to host communication. Router is the most important network layer device.



Functions of Network layer

Important functions of network layer are given below.
  1. Network routing

  2. Logical Addressing

  3. Network segmentation and De-segmentation

  4. Error handling

Network layer is responsible for assigning IP addresses and maintaining routing tables (Router does this function). Internet Protocol is responsible for assigning IP addresses to each and every networking devices in the network. It is also doing the function of adding control information to the data segments coming from Transport layer and sending it to Data-link Layer. It is also responsible for maintaining error free network structure by assigning unique IP address to each host.

Major Network Layer Protocols
  1. IPv4 (Internet Protocol version 4)

  2. IPv6 (Internet Protocol version 6)

  3. Datagram Delivery Protocol

  4. Internet Control Message Protocol (ICMP)

  5. Internet Group Management Protocol

  6. IPsec

  7. AppleTalk

  8. IPX

  9. XNS

OSI Structure
  1. Physical

  2. Data-link

  3. Network

  4. Transport

  5. Session

  6. Presentation

  7. Application

Major Network Layer Devices

Important network layer devices are:
  1. Router

  2. Layer 3 Switch

These two devices are in third layer because both of them uses packets to communicate. These devices perform packet forwarding and routing based on routing protocols. Logical addressing is one of the most important features of 3rd layer of OSI Reference model. Since every devices are getting unique IP address, communication goes well without any issues.

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Fiber Distributed Data Interface (FDDI) - Tutorial

Fiber Distributed Data Interface (FDDI) is a Local Area Network standard. Thought it is a LAN standard, theoretically it can span up to 200 kilometers. It is developed by the American National Standards Institute (ANSI). Fiber Distributed Data Interface is used as the high-speed backbone technology on ISPs because it supports high bandwidth. Communication through this standard is very secure due to its dual rings structure. Second token ring is for possible backup, in case of the failure of primary ring. If the second ring is also used to carry data, the total speed will increase up to 200 Mbps otherwise the speed is limited to 100Mbps. Now let us check the different versions of this data communication standard.

Different versions of FDDI
  1. FDDI-II

    If you want to transmit video with voice over a network, we can use this standard. FDDI-2, supports the transmission of voice and video information as well as data. This version adds the capability to add circuit-switched service to the network.

  2. FDDI Full Duplex Technology (FFDT)

    It uses the same network infrastructure but can potentially support data rates up to 200 Mbps. That means, this standard can offer the data transfer rate of a normal FDDI network where both token rings are used to transfer data.

Working of FDDI

FDDI uses dual-ring architecture with traffic on each ring flowing in opposite directions. If the data is transferred on ring 1 is on clockwise direction, the second ring sends data on anticlockwise direction. Fiber Distributed Data Interface is treated as highly secure because of its dual ring character. FDDI uses optical fiber as the primary transmission medium, but it also can run over copper cabling.


FDDI is a collection of four separate specifications, each with a specific function. The function of multi specification is to provide high-speed connectivity between upper-layer protocols.

FDDI Specifications

It has four specifications. They are:
  1. Physical Layer Protocol (PHY)

  2. Physical-Medium Dependent (PMD)

  3. Media Access Control (MAC)

  4. Station Management (SMT)

Further Readings
  1. Access Control List

  2. Dynamic Host Configuration Protocol

  3. How to Check Whether NAT is Failed

  4. Difference Between PPPoE Mode and Bridge Mode

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