Transcript Ethernet basics

Ethernet Basics -10
Hubs & Switches
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.
Hubs & Switches
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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.
2.
3.
Unicast
Multicast
Broadcast
Traffic Types - Unicast
• Unicast = 1 to 1 communication. Traffic generated by one device meant
specifically for another.
Traffic Types - Multicast
• Multicast = 1 to many nodes communication. Traffic generated by one
device meant for multiple nodes but not necessarily all nodes
Traffic Types - Broadcast
• Broadcast = 1 to all nodes communication. Traffic generated by one device
and sent to all other devices.
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 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
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”)
Operating mode of a Hub
From
I/O 1
To
PLC 1
From
I/O 1
I/O 1
From
I/O 1
PLC1
To
PLC 1
To
PLC 1
From
I/O 1
To
PLC 1
Data Storage server
Operating mode of a Hub
From
PLC 1
To
I/O 1
From
PLC 1
I/O 1
From
PLC 1
PLC 1
To
I/O 1
To
I/O 1
From
PLC 1
To
I/O 1
Data Storage server
Operating method of a Hub
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
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.)
Operating mode of a Switch
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•
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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
From
PC 12
To
PLC B
From
PC 12
PC 12
To
PLC B
PLC B
PLC A
Operating mode of a Switch
• How does a switch direct Unicast traffic efficiently?
Address table
Port 1 Port 2 Port 3 Port 4 Port 5
PC 1 RC 11 PLC C PLC B PLC A
RC 12
RC 13
P3
P1
PC 1
P5
P4
P2
PLC A
PLC C
PLC B
RC 11
RC 12
RC 13
Operating mode of a switch
Address table
Port 1 Port 2 Port 3 Port 4 Port 5
From
PC 1
PC 1 RC 11 PLC C PLC B PLC A
RC 12
RC 13
To
PLC C
P3
P1
PC 1
P5 P4
P2
From
PC 1
PLC A
To
PLC C
PLC C
PLC B
RC 11
RC 12
RC 13
Operating mode of a Switch
Address table
Port 1 Port 2 Port 3 Port 4 Port 5
From
PC 1
P3
To
PLC C
P1
PC 1
From
PLC A
PLC 1 RC 11 PLC C PLC C PLC B
RC 12
RC 13
P5 P4
P2
From
PLC 1
To
RC 11
From
PC 1
To
PLC C
To
RC 11
PLC A
PLC C
PLC B
RC 11
RC 12
RC 13
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
• Multiple versions for variety of RJ45/Fiber port configurations
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
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.
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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.
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Spanning Tree Protocol facilitates redundant back bone connections and loop
free networks.
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Prioritization support, ensures that frames tagged with higher priority will be
handled quickly and efficiently.
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Broadcast Limiters which allow the administrator to filter the amount of
broadcast traffic on a packets per second per port basis.
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
Managed Vs Non-Managed
Features
Managed
 Prevent collisions
 Auto-polarity, -sensing
 Auto-negotiation, -MDI/MDIX
 Web interface
 Port security
 Port mirroring
 Multicast Filtering/IGMP
 Remote monitoring
 Redundancy
 SNMP
 Broadcast Limiter
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Unmanaged
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Thank You
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