hubs & switches ethernet basics -10. there is only so much available bandwidth, in some...

Hubs & Switches

Ethernet Basics -10

• There is only so much available bandwidth, in some instances it can be dynamic

• An overabundance of data on the network, not only affects the infrastructure equipment tasked with its distribution, but also the end devices or nodes meant to receive it.

• Once a node has been overwhelmed, it needs to recuperate or recover and so called “time outs” can occur.

Hubs & Switches

Hubs & Switches

• To understand the differences between Hubs, Switches, and Managed switches, the 3 types of traffic must be understood

• There are 3 types of ‘traffic’

1. Unicast2. Multicast3. Broadcast

Traffic Types - Unicast

• Unicast = 1 to 1 communication. Traffic generated by one device meant specifically for another.

• Multicast = 1 to many nodes communication. Traffic generated by one device meant for multiple nodes but not necessarily all nodes

Traffic Types - Multicast

• Broadcast = 1 to all nodes communication. Traffic generated by one device and sent to all other devices.

Traffic Types - Broadcast

• The type of traffic directly effects the amount of traffic on a Network or "Networking" device

• The amount of traffic directly effects the bandwidth utilization of that device.

• The bandwidth utilized on the device effects the device’s ability to transmit and receive data in an efficient manner.

• Network performance will degrade if too much bandwidth is used because of too much of the wrong kind of traffic

Traffic Types – Unicast, Multicast and Broadcast

• Devices which regenerate incoming signals (frames) and distribute them to all other ports. (Broadcast)

• Considered to be “dumb” devices (indiscriminately send data everyone with no means to filter it)

• Do not support 10/100 auto-sensing (either 10BASE OR 100BASE)

• Subject to rules of Propagation Equivalent and Variability Value (Calculations necessary for a “collision domain”)

Hubs

ToPLC 1

From I/O 1

I/O 1

PLC1ToPLC 1

From I/O 1

ToPLC 1

From I/O 1

ToPLC 1

From I/O 1

Operating mode of a Hub

Data Storage server

I/O 1

PLC 1ToI/O 1

From PLC 1

ToI/O 1

From PLC 1

ToI/O 1

From PLC 1

ToI/O 1

From PLC 1

Operating mode of a Hub

Data Storage server

Operating method of a Hub

• A Device which delivers a received Unicast data packet only to that port on which the destination station is connected.

• ALL switches on the network instantly recognize newly attached devices, read MAC address and records that into its address table

• RJ45 ports are typically 10/100 auto-negotiation/crossing

• Multiple versions for variety of RJ45/Fiber port configurations

• It is a good practice to keep extra ports for expansion, laptop access and networking to rest of network

Unmanaged Switches

• Managed switches can operate on a network without any set up programming as do Unmanaged switches

• Managed switches can be given their own IP address, permitting custom configuration of ports and overall control of switch

• SNMP software as well as other methods allow for the monitoring and configuration of (alarming, bandwidth utilization, security, etc.)

Managed Switches

ToPLC B

From PC 12

PC 12

PLC B

PLC A

ToPLC B

From PC 12

• On a switch, each port is a Collision Domain• Can communicate @ 10/100mbps Half or Full Duplex• Unicast traffic is sent only to the port it is destined to go

Operating mode of a Switch

• How does a switch direct Unicast traffic efficiently?

PLC APLC C

PLC BRC 13

RC 12RC 11

P1P4

P3

P2P5PC 1

Address tablePort 1 Port 2 Port 4 Port 5

PC 1 RC 11RC 12RC 13

PLC B PLC A

Port 3

PLC C


Address table

PC 1

PLC C

ToPLC C

From PC 1

Port 1 Port 2 Port 4 Port 5

ToPLC C

From PC 1

PLC A

PLC BRC 13

RC 12RC 11

PC 1 RC 11RC 12RC 13

PLC B

P1P4

P3

P2P5

PLC A

Port 3

PLC C

Port 3

PLC C

Operating mode of a switch

Address tablePort 1 Port 4 Port 5

PLC 1

Port 2

RC 11RC 12RC 13

PLC C

P3

PC 1

RC 13RC 12

RC 11

P1P4

P2P5

PLC B

Port 3

PLC C

ToPLC C

From PC 1

ToRC 11

From PLC A

Port 3

PLC C

Port 2

RC 11

ToRC 11

From PC 1

ToPLC C

From PLC 1

PLC CPLC A

PLC B


Managed vs. Unmanaged Switches

Switches – unmanaged

• Device which delivers a received Uni-Cast data packet only to that port on which the destination station is connected.

• ALL switches on the network instantly recognize newly attached devices, read MAC address and records that into its address table (no manual configuration needed)

• RJ45 ports are typically 10/100 auto-sensing


Switches – Managed

• Device which delivers a received Uni-Cast data packet only to that port on which the destination station is connected.

• ALL switches on the network instantly recognize newly attached devices, read MAC address and records that into its address table (no manual configuration needed)

• RJ45 ports are typically 10/100 auto-sensing


• Can be programmed using Serial, Web interface, or SNMP software

• Port security - Security functionality is important in terms of awareness and prevention of unwanted access to devices as well as the network as a whole.

• Port mirroring - necessary for accurate network diagnostic monitoring and troubleshooting by allowing you to copy the Unicasts traffic from one port to another.

• Multicast Filtering - provides for the proper management of IP multicast traffic. It ensures that not only Unicasts but multicast traffic is properly directed only where it is meant to go.

• Remote monitoring – Allows for the capability of remotely monitoring conditions and criteria of the "goings on" of the switch.

• Spanning Tree Protocol facilitates redundant back bone connections and loop free networks.

• Prioritization support, ensures that frames tagged with higher priority will be handled quickly and efficiently.

• Broadcast Limiters which allow the administrator to filter the amount of broadcast traffic on a packets per second per port basis.

Managed Vs Non-Managed

• Unicast traffic, through a hub, is like broadcast traffic• Multicast traffic through a hub or “unmanaged Switch”

is like broadcast traffic• Broadcast traffic when not controlled, can affect overall

network performance as well as your network nodes ability to perform its primary process causing “time outs” which lead to communication failures and ultimately process failure

Remember the traffic?

Features

Prevent collisions

Auto-polarity, -sensing

Auto-negotiation, -MDI/MDIX

Web interface

Port security

Port mirroring

Multicast Filtering/IGMP

Remote monitoring

Redundancy

SNMP

Broadcast Limiter

Managed Unmanaged

Managed Vs Non-Managed

If you have any questions or comments about this presentation, email us at [email protected]

Or Skype us at Ethernet Direct1

Thank You

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