Different types of Routing methods

Different types of Routing methods:

there are four type of routing methods are there those are:

         1 Fixed
  2 Flooding
  3 Random
  4 Adaptive

       1 Fixed Routing:

1 Single permanent route for each source to destination pair

2 Determine routes using a least cost algorithm 

3 Route fixed, at least until a change in network topology

2) Flooding:

1 No network info required Packet sent by node to every neighbor

2 Incoming packets re transmitted on every link except incoming link

3 Eventually a number of copies will arrive at destination

4 Each packet is uniquely numbered so duplicates can be discarded

5 Nodes can remember packets already forwarded to keep network load in bounds

6 Can include a hop count in packets

3 Random:

1 Node selects one outgoing path for re transmission of incoming packet

2 Selection can be random or round robin

3 Can select outgoing path based on probability calculation

4 No network info needed

5 Route is typically not least cost nor minimum hop

 4 Adaptive:

1 Used by almost all packet switching networks

2 Routing decisions change as conditions on the network change

1Failure

2 Congestion

3 Requires info about network

4 Decisions more complex

5 Tradeoff between quality of network info and overhead

6 Reacting too quickly can cause oscillation

7 Too slowly to be relevant 

Segmentation vs. Fragmentationa

Segmentation vs. Fragmentation:

         Segmentation is basically the same as fragmentation, with a few differences:

          Fragmentation (IP layer):

      only occurs when transmitting a packet whose size is larger than the MTU of the estination network

       Any router (connecting two different network types) could theoretically fragment ackets

      Fragmentation can almost be considered an emergency practice (what to do when omething goes wrong)

Segmentation (TCP layer):

      Occurs for all data streams, to divide the data into packets (above TCP layer data is ontinuous)

        Only the source host will segment packets

        Segmentation is a normal part of TCP’s job

Shortest-Job-First (SJF) Scheduling with example

Shortest-Job-First (SJF) Scheduling:

• Associate with each process the length of its next CPU burst.Use these lengths to schedule the process with the shortest time
• Two schemes:
• l nonpreemptive – once CPU given to the process it cannot be preempted until completes its CPU burst
• l preemptive – if a new process arrives with CPU burst length less than remaining time of current executing process, preempt. This scheme is know as the Shortest-Remaining-Time-First (SRTF)
• SJF is optimal – gives minimum average waiting time for a given set of processes

First-Come, First-Served (FCFS) Scheduling with Example

First-come, first-served (FCFS): – sometimes first-in, first-served and first-come, first choice – is a service policy whereby the requests of customers or clients are attended to in the order that they arrived, without other biases or preferences. The policy can be employed when processing sales orders, in determining restaurant seating, on a taxi stand, etc. In Western society, it is the standard policy for the processing of most queues in which people wait for a service that was not prearranged or pre-planned.

Example:

Suppose that the processes arrive in the order

P2 , P3 , P1

 The Gantt chart for the schedule is:

• Waiting time for P1 = 6; P2 = 0; P3 = 3
•  Average waiting time: (6 + 0 + 3)/3 = 3
•  Much better than previous case
•  Convoy effect short process behind long process

Adaptive Routing and its advantages

Adaptive Routing:

• Adaptive Routing used by almost all packet switching networks
• Routing decisions change as conditions on the network change
• Failure
• Congestion
• Requires info about network
• Decisions more complex
• Trade off between quality of network info and overhead
• Reacting too quickly can cause oscillation
• Too slowly to be relevant 

Advantages of Adaptive Routing:

1) Improved performance
2) Aid congestion control 
3) Complex system
4)May not realize theoretical benefits

What are the Properties of Flooding?

1. All possible routes are tried
2. Very robust
3. At least one packet will have taken minimum hop count route
4. Can be used to set up virtual circuit
5. All nodes are visited
6. Useful to distribute information (e.g. routing)

What is flooding?

1. No network info required
2. Packet sent by node to every neighbor
3. Incoming packets re transmitted on every link except incoming link
4. Eventually a number of copies will arrive at destination
5. Each packet is uniquely numbered so duplicates can be discarded
6. Nodes can remember packets already forwarded to keep network load in bounds
7. Can include a hop count in packets

what are the different type of networks

Different type of networks are :

• LAN
• MAN
• WAN 

Local Area Network(LAN): LAN is only limited space cover like one bulling, college,university and industry.we can send data very efficient to delivery on node to other. 

Local Area Network

Metropolitan Area Network (MAN): Metropolitan area network   is it cover only city's and big industry.

  metropolitan area network