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Switched network

Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

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Page 1: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Switched network

Page 2: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Taxonomy of switched networks

Page 3: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

CIRCUIT-SWITCHED NETWORKS

A circuit-switched network consists of a set of switches connected by physical links. A connection between two stations is a dedicated path made of one or more links. However, each connection uses only one dedicated channel on each link. Each link is normally divided into n channels by using FDM or TDM.

Page 4: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

A trivial circuit-switched network

Page 5: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

In circuit switching, the resources need to be reserved during the setup phase;

the resources remain dedicated for the entire duration of data transfer until the teardown phase.

• Circuit switching takes place in Physical layer.• Data transfer between the two nodes is a continuous flow.• No addressing is involved during data transfer.

Page 6: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

As a trivial example, let us use a circuit-switched network to connect eight telephones in a small area. Communication is through 4-kHz voice channels. We assume that each link uses FDM to connect a maximum of two voice channels. The bandwidth of each link is then 8 kHz. Figure 8.4 shows the situation. Telephone 1 is connected to telephone 7; 2 to 5; 3 to 8; and 4 to 6. Of course the situation may change when new connections are made. The switch controls the connections.

Example

Page 7: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Circuit-switched network used in Example

Page 8: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

As another example, consider a circuit-switched network that connects computers in two remote offices of a private company. The offices are connected using a T-1 line leased from a communication service provider. There are two 4 × 8 (4 inputs and 8 outputs) switches in this network. For each switch, four output ports are folded into the input ports to allow communication between computers in the same office. Four other output ports allow communication between the two offices.

Example

Page 9: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Circuit-switched network used in Example 2

Page 10: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

DATAGRAM NETWORKS

In data communications, we need to send messages from one end system to another. If the message is going to pass through a packet-switched network, it needs to be divided into packets of fixed or variable size. The size of the packet is determined by the network and the governing protocol.

In a packet-switched network, there is no resource reservation;resources are allocated on demand.

Page 11: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

A datagram network with four switches (routers)

Page 12: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Routing table in a datagram network

A switch in a datagram network uses a routing table that is based on the destination address.

The destination address in the header of a packet in a datagram network

remains the same during the entire journey of the packet.

Switching in the Internet is done by using the datagram approach to packet

switching at the network layer.

Page 13: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

VIRTUAL-CIRCUIT NETWORKS

A virtual-circuit network is a cross between a circuit-switched network and a datagram network. It has some characteristics of both.

Page 14: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Virtual-circuit identifier

Page 15: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Switch and tables in a virtual-circuit network

Page 16: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Source-to-destination data transfer in a virtual-circuit network

Page 17: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Setup request in a virtual-circuit network

Page 18: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Setup acknowledgment in a virtual-circuit network

Page 19: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

In virtual-circuit switching, all packets belonging to the same source and destination travel the same path;

but the packets may arrive at the destination with different delays if resource allocation is on demand.

Switching at the data link layer in a switched WAN is normally implemented by using virtual-circuit techniques.

Page 20: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Message Switching

• A store-and-forward network where the block of transfer is a complete message.

• Since messages can be quite large, this can cause:– buffering problems– high mean delay times

Page 21: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

– Repeater– Hub– Bridge– Router– Gateway

Network Devices

Page 22: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Connecting Devices

Networking Devices

Repeaters Bridges

InternetworkingDevices

Routers Gateways

Page 23: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Connecting Devices

Hub

Page 24: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Repeater

• Extend the physical length• No network function has been changed• Location is matter

Page 25: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Function of repeater

Repeater is not same as Amplifier

Page 26: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Hub

• Actually is a multiport repeater• Star / Tree Topology

Page 27: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Bridge

Page 28: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Bridge

• Divide a large network into smaller segment• Isolating and controlling the link problems

(e.g. congestion)• Regenerate signal + Checking Physical

Address and forward only to the specified segment

Page 29: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Function of a bridge

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Multiport bridge

Page 31: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Routers

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Routers in an internet

Page 33: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Routers

• Act like stations on a network• Multi-home• Definition (Goal)

– “Learning how to get from here to there." – “Process of discovering, selecting, and

employing paths from one place to another (or to many others) in a network”

Page 34: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Routing Principle

• Goal: Arriving at the destination• Considerations:

– Direct route (shortest)– Reliable route– Cheap route– Safe route– Scenic route

Page 35: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Gateways (protocol converter)

Page 36: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

A gateway

SNA network (IBM)Netware network (Novell)

Page 37: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Other devices

• Multiprotocol routers• Brouters• Switches• Routing switches

Page 38: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Single VS. Multiprotocol router

Page 39: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Brouter

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Backbone Network

Bus Backbone

Star Backbone

Page 41: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Connecting Remote LAN

A point-to-point link acts as a LAN in a remote backbone connected by remote bridges

Page 42: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

Virtual LAN (VLAN)

VLANs create broadcast domains

Page 43: Switched network. Taxonomy of switched networks CIRCUIT-SWITCHED NETWORKS CIRCUIT-SWITCHED NETWORKS A circuit-switched network consists of a set of switches

VLAN with backbone switch