Networking and Internetworking Devices

dingdongboomNetworking and Communications

Oct 27, 2013 (3 years and 7 months ago)

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Networking and
Internetworking
Devices


Repeaters


Bridges


Routers


Gateways


Routing Algorithms

Homework


p.641 prob 1
-
18

Connecting Devices and

the OSI Model

Repeater and OSI Model

A Repeater

Function of a Repeater

Bridge and the OSI Model

Bridges


Reduces Collision Domain / Congestion


Simple


Addresses manually entered


Multiport


Transparent


Builds routing table itself


Updates table based on source addresses

A Bridge

Function of a Bridge

Router and the OSI Model

Routers in an internet

Routing Concepts


Least cost routing


Hop count


Link
-
quality


Speed, congestion, link medium

Routing concepts

Non
-
adaptive

Adaptive

Packet Lifetime


Gateway and the OSI Model

A Gateway

Gateway


Each Side Unaware of The OTHER


Protocol Converter


SNA
-
> TCP/IP


AppleTalk
-
> TCP/IP


Novell Netware
-
> TCP/IP

Other Devices


Multi
-
Protocol Routers


IPX, TCP/IP


Brouter


Router if known protocol


Bridge otherwise

Switches


Function at Level 2


Bridging Capability


Store and Forward


Telex


Cut
-
Through


Immediate Transfer


Routing Switches


Function as routers


Faster than traditional routers


USE Level 3


Network Addresses

Distance Vector Routing


Knowledge about the entire network


Routing only to neighbors


Information Sharing with neighbors

Link State Routing


Knowledge of neighborhood


Shares with all routers


flooding


Information sharing when change

Dijkstra Algorithm


Breadth Search from root


Select lowest cost


Add node and arc

Routing Classifications


Adaptive routing (dynamic)




Non
-
adaptive routing (fixed or static)

Dynamic Routing Algorithms




Distance Vector Routing




Link state routing

Routing Algorithms


Distance Vector Routing



Each link is assigned a weight



Distance to the destination is the sum of the
weights along the path to the destination

Routing Algorithms


Distance Vector Routing


Each router sends its
entire information

about the
entire network to its neighbors.


Neighbors are other routers with direct link to it.



Information are shared periodically, even if nothing
has changed.


Eventually, every router will learn about other routers
on the network.


Slow convergence
(it takes longer for all routers
to receive all information)


Distance Vector Routing
Protocol


RIP (Routing Information Protocol)



Each router uses broadcasting to send its
entire information

to its neighbors every 30
seconds.



The best path is based on the least number
of hops.



It’s suitable for small networks



RIP is used by IPX/SPX and TCP/IP.

Distance Vector Routing Table

Routing Algorithms


Link state routing


If there is a change
, each router sends its
information
about its neighbors

to every
other router in the network using
flooding
.


A router, periodically sends a message to its
neighbors, the
response

indicates that the
device is alive and functioning.


No response, change has occurred.

Link State Routing Protocol



OSPF (Open Shortest Path First)


More efficient than RIP


Only the changes are sent


each router sends its information
about its neighbors

to
every other router in the network using
flooding
.


A router, periodically sends a message to its
neighbors, the
response

indicates that the device is
alive and functioning.


No response, change has occurred.

Concept of Link State Routing

Costs in Link State Routing

Link State Packet

Flooding of A’s LSP

Flooding of B’s LSP

Link State Database

Finding the Shortest Path


Select a node (A) and make it permanent


Examine each of the adjacent nodes to A.


Relabel each one with the distance to A.


Make the one with the smallest label
permanent. (14)


This becomes the new working node.



Costs in Dijkstra Algorithm

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Shortest Path Calculation

Link State Routing Table for A