Submitted By RASHMI SINGH 71 RATI OJHA 72 REKHA SHAKYA 74 RISHI SINHAL 75 ROHIT SINGOUR 77

Submitted to

Lect. Agya Mishra

DEFINITION PURPOSE CLASSIFICATION ROUTING ALGORITHM ADVANCED TECHNOLOGY APPLICATION CRITICAL REVIEW CONCLUSION

A router is a device that actually delivers information to its intended destination, using one of several different routing protocols. Routers have access to network layer addresses and contain software that enable them to determine which of several possible paths between those addresses is the best for particular transmission.

Routing is the process of delivering information to its intended destination.

Need of firewall features to isolate networks and provide security for private networks.

Recovery of TCP/IP protocols from the local Ethernet protocols which are routed over PPP protocols for transferring data information over GSM, GPRS and PSTN networks.

Routers are used to reduced traffic load through the network.

Internal Routers - routers with all directly connected networks belonging to the same area.

Area Border Routers - routers that are attached to multiple areas.

AS Boundary routers - routers that exchange routing information with routers belonging to other AS.

Designated Routers (DR) and Backup Designated Routers (BDR) Instead of each router exchanging

database information with every other router on the segment, every router exchanges information with the DR and BDR (foe example- OSPF)

OSPF:- stands for Open Shortest Path First

Bellman-Ford Algorithm [Distance Vector Algorithm]:-

Basic idea:- each network node (router) maintains a Distance Vector table containing the distance between Itself and ALL possible destination nodes.

Dijkstra’s Algorithm [Link State Algorithm]:-

Basic idea:-Each router constructs a link state packet (LSP) .which is transmitted to ALLALL other routers. Each router stores the most recently generated LSP from each other router.

Routing table updates occur periodically or when the topology in a distance vector protocol network changes

Routing loops can occur when inconsistent routing tables are not updated due to slow convergence in a changing network

Each router is responsible for meeting its neighbors and learning their names.

Each router constructs a link state packet (LSP) which consists of a list of neighbors’ names and the cost to reach each neighbor.

Each router uses complete information on the network topology to compute the Shortest path route to each destination node.

Correctness

Simplicity and Low Overhead

Robustness and stability

Rapid convergence

Flexibility

Larger internetworks require the use of RIP, or Routing Information Protocol, to keep track of new routes.

Why RIP is still with us today is for several reasons – first, the protocol has undergone vast improvements in Version 2, and second - it is really simple to configure and use! And, oh yes, when used in a network of appropriate size (small) – it actually works!

RIP v2 does manage to solve many issues found in the first iteration of this distance vector protocol and this article is a celebration of these new features.

RouteTableCPU Buffer

Memory

LineInterface

MAC

LineInterface

MAC

LineInterface

MAC

Typically <0.5Gb/s aggregate capacity

Shared Bus

Line Interface

CPU

Memory

Off-chip Buffer

Line card DMAs into buffer, CPU examines header, has output DMA out

RouteTableCPU

LineCard

BufferMemory

LineCard

MAC

BufferMemory

LineCard

MAC

BufferMemory

FwdingCache

FwdingCache

FwdingCache

MAC

BufferMemory

Typically <5Gb/s aggregate capacity

Bypasses memory bus with direct transfer over bus between line cards

Moves forwarding decisions local to card to reduce CPU pain

Punt to CPU for “slow” operations

Third Generation Routers

LineCard

MAC

LocalBuffer

Memory

CPUCard

LineCard

MAC

LocalBuffer

Memory

“Crossbar”: Switched Backplane

Line Interface

CPUMemory Fwding

Table

RoutingTable

FwdingTable

Typically <50Gb/s aggregate capacity

Periodic

Control

updates

It is used to create a network with remote access to private networks.

It enables Private networks to be inter-networked with other networks such as the Internet.

Companies to create their own networks in customers' premises to eliminate reliance on the end customers' network.

Routers are useful to provide security in military transmissions that require highly secure lines by using “Hop-count Algorithm”.

A small network to be created in mobile applications, where fixed line solutions aren’t possible.

There is a drawback of a router that transfers , accepts and relays packets only across networks using similar protocols.

The packet at the front of the queue experiences contention for the output queue, blocking all packets behind it.

Software can only be repaired by redesign. Software bugs can be highly contagious. Still need protection against link failure.

Output 1

Output 2

Output 3

Input 1

Input 2

Input 3

Problem: The packet at the front of the queue experiences contention for the output queue, blocking

all packets behind it.

Maximum throughput in such a switch: 2 – sqrt(2)

Modern routers are very complex hardware and software systems with demanding requirements and constraints

To achieve carrier class converged networks, router software and hardware architecture is going to have to evolve to better achieve scale and reliability

WEBSITES: www.google.com www.howstuffworks.com BOOKS REFERRED: Behrouz A . Forouzan Andrew S. Tanenbaum

Questions?