Ethernet basics

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Ethernet Basics -10
Hubs Switches
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Hubs Switches

• 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.

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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
• Unicast
• Multicast
• Broadcast

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Traffic Types - Unicast

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

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Traffic Types - Multicast

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

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Traffic Types - Broadcast

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

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Traffic Types Unicast, Multicast and 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
  devices 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

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Hubs

• 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)

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Operating mode of a Hub
I/O 1
PLC1
Data Storage server
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Operating mode of a Hub
I/O 1
PLC 1
Data Storage server
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Operating method of a Hub
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Unmanaged Switches

• 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

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Managed 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.)

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Operating mode of a Switch

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

PC 12
PLC B
PLC A
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Operating mode of a Switch

• How does a switch direct Unicast traffic
  efficiently?

Address table
Port 2
Port 4
Port 5
Port 1
Port 3
PC 1
RC 11
PLC B
PLC A
PLC C
RC 12
RC 13
P3
P1
P2
P4
P5
PC 1
PLC A
PLC C
PLC B
RC 13
RC 11
RC 12
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Operating mode of a switch
Address table
Port 2
Port 4
Port 5
Port 1
PC 1
RC 11
PLC B
PLC A
RC 12
RC 13
P3
P1
P2
P4
P5
PC 1
PLC A
PLC C
PLC B
RC 13
RC 11
RC 12
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Operating mode of a Switch
Address table
Port 4
Port 5
Port 2
Port 1
Port 3
PLC 1
RC 11
PLC C
PLC B
PLC C
RC 12
P3
RC 13
P1
P2
P4
P5
PC 1
PLC A
PLC C
RC 13
RC 11
RC 12
PLC B
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Managed vs. Unmanaged Switches
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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
• Multiple versions for variety of RJ45/Fiber port
  configurations

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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
• Multiple versions for variety of RJ45/Fiber port
  configurations

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Managed Vs Non-Managed

• 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.

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Remember the traffic?

• 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

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Managed Vs Non-Managed

• 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
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Thank You
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