2. 2
AGENDAEthernet Webinar Courses
1. Ethernet Intro Part A
2. Ethernet Intro Part B
3. Carrier Ethernet Intro
4. Carrier Ethernet Test
5. New GbE Testers Intro
3. 3
AGENDAEthernet Webinar Courses
1. Ethernet Intro Part A
2. Ethernet Intro Part B
3. Carrier Ethernet Intro
4. Carrier Ethernet Test
5. New GbE Testers Intro
4. 4
Agenda
Introduction Ethernet
IEEE 802.3
ISO/OSI Reference Model
Layer 1 - The physical layer
Ports
Power over Ethernet PoE
Duplex
Autonegotiation
Layer 2 - The Data Link Layer
Traffic Distribution
Ethernet Frame IEEE 802.3
MAC Adress
Layer 3 - The network layer
Internet Protocol IP
IPv4
IPv6
Addresstypes
Layer 4 - The Transport Layer
UDP
TCP
5. 5
History of Data Networks
1973 Robert Metcalfe deploys Ethernet (3Mb/s) for the company XEROX
1979 Metcalfe founded 3com (Computers, Communication and Compatibility) and convinced
DEC, Intel and Xerox (DIX Consortium)
1980 Ethernet - DIX v1.0 (10Mb/s)
1982 Ethernet - DIX v2.0
1983 IEEE 802.3 - Ethernet 10Mb/s
1995 IEEE 802.3u - Fast Ethernet 100 Mb/s
1998 IEEE 802.3z - Gigabit Ethernet 1000 Mb/s
2002 IEEE 802.3ae - 10 Gigabit Ethernet
6. 6
IEEE 802.3
International Association of Electrical Engineering and computer science Engineers
Since 1963
Forms committees on standardization of technology, hardware and software
400000 Members worldwide
Design standards for Data Transmission within the Project number 802 (deducted from February 1980 )
The wrokgroup No. 3 is taking care about Ethernet
Networks can now carry Data due to a common standard
► Transmission standard IEEE 802.3
7. 7
ISO
due to different applications the type of data carried is varying
it is very imprtant to standardize the way of communication through the Data Networks
all stations across the world must be able to communicate to each other
This will then be the basis for the Internet as well
all systems must be open and interconnectable
Therefore the ISO created a model how the interaction can work
International Standards Organization
ISO / OSI
The Open System Interconnection Model
This is comparable with a book containing 7 chapters.
The 7-Layers-Reference-Model
8. 8
The ISO/OSI 7-Layer Reference Model
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
Ethernet Frame: Transport of IP-
Packets through local networks
Session Packets: To carry the
digital User Data (between the
Applications)
TCP/UDP-Packets: To carry the
Session Packets (between the
Devices)
IP Packet: To carry the TCP-
UDP Packets through different
Networks
Analogue Signal
Digital Signal
Bit stream
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
User data
layer 5
header
9. 9
The physical Layer: L1
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Bit stream
Ethernet
HTTP, FTP, HTTPS, SMTP,
LDAP, NCP, SIP, H.323, RTP
TCP, UDP, SCTP, SPX,
ICMP, IGMP, IP, IPX
Softphone, Email…
G.729, G.723, G.711,..
11. 11
Ports
Optical - SFP
Small Form-Factor Pluggable
Having Tx & Rx two ports with LC Connectors
Rate from 100Mb/s to 10Gb/s.
1000 Base SX (850 nm, Multimode)
Multimode SFPs can reach a distance of 500 m. A LED is
enough to couple the light into the broader core of a
Multimode Fiber. They are therefore much cheaper and
only seen in LANs
1000 Base LX (1310 nm, Singlemode)
Singlemode SFPs can reach a distance up to 40 km. They
are using Laser-Diodes which are required to couple the
light into the thin core of a singlemode Fiber. They are
therefore expensive and mostly used for long distance in
WANs
Other type of SFPs
1000 Base ZX (1550nm, Singlemode) for up to 70 km.
1000 Base BX10 (1490nm Tx, 1310nm Rx) or Bi-Di SFP
for up to 10Km over a single fiber. SFP+ supports up to
10Gb/s at 850nm MM or 1310nm SM.
12. 12
Ports
Optical - Connectors
LC: Lucent Connector is the most common optical connector due
to its small form factor. It therefore displaced the SC connector
as the standard in the LAN. MM and SM
SC: In 2002 the Subscriber Connector diplaced the ST-Connector as
the standard in the LAN. Easier to use as and requires less
space as ST.
ST: The Straight Tip connector is still very common in the LAN. It is
mainly used in Multimode. Secure connection due to a bajonet
mechnaism.
FC: Due to its robustness the Fiber Connector is still very common
in WAN. Mainly SM
E2000: A mechanical Laser Protection flap is automaitcally closing to
protect the Fiber. Mainly used for Singlemode in MAN and WAN
Networks
13. 13
Power over Ethernet PoE
PoE
Defined by the standard IEEE 802.1af
Enddevices are feeded via the Data Cable and doesn't need an external power supply anymore
Typically used for IP-Phones, Cameras and Wireless access points
Reduction of Installation costs
Devices are feeded by a PoE-Switch, a PoE Patch Panel or a supsequently installed PoE-Injector
Typical Values: 48V at a maximum consumption of 15 Watts
14. 14
Power over Ethernet PoE
PoE+ / PoE PLUS
The standard IEEE 802.1at defines a higher powerconsumption up to 25 Watts.
PoE / PoE+ power range
Depending on the type of devices there are typical power ranges
These Ranges are defined by 5 PoE-Classes as follows
Class Available Power in Watt
0 0.44–12.96
1 0.44–3.84
2 3.84–6.49
3 6.49–12.95
4 (Poe+) 12.95-25.50 (only 802.3at)
15. 15
Port Properties
Halfduplex HD
The port can only work unidirectional at a time meaning either transmit data (Tx) or receive data (RX)
The port never can send and receive Data at the same time
A typical Halfduplex device is a Hub.
A typical Example for halfduplex: Phonecall - one person is listening while the other person is talking
Fullduplex FD
Ports are working bidirectional
Rx and Tx can be done simultaneusly
Typical Fullduplexdevice: Switch
Example:Videoconferencing - your picture is transmitted while you are receiving the picture of others
.
17. 17
Port Properties
Autonegotiation / Autoneg
Is taking place after the link establishment
A handshake to determine the best way of transmission between two Interfaces
Automoatic detection if Transmission can be done on Fullduplex or must be done on Halfduplex
It follows the simple Principle: Question A: Can you work on fullduplex
Answer B: Yes, I can
Commitment: OK, let's then do fullduplex
It is absolutely necessary, that both interfaces have enabled Autoneg!
.
Fullduplex Fullduplex
Autoneg ONAutoneg ON Can you do Fullduplex?
Yes, I can
18. 18
Port Properties
Autonegotiation / Autoneg
Missing Autoneg Configurations will cause Network errors
Both stations need to set to Autoneg ON
Otherwise the questioning Interface is going back to halfduplex once the answer is missing
It follows a the simple Priciple: Question A: Can you work on fullduplex
Answer B: No Answer due to Autoneg is set to OFF
Interface A: is going to Halfduplex while B is set to 100 Mb/s - FD!
Gigbabit is always on Fullduplex!
.
Halfduplex Fullduplex
Autoneg OFF
Fixed to 100 Mb/s - FD
Autoneg ON Can you do Fullduplex?
No Answer
CollisionCollision
19. 19
Port Properties
Tester Switch
Auto Auto
1000 FD Auto
1000 FD 1000 FD
100 FD 1000 FD
100 FD Auto
Auto 100 FD
100 FD 100 FD
100 HD Auto
10 HD Auto
10 HD 100 HD
Auto 100 HD
Auto 10 HD
ResultTester ResultSwitch
1000 FD 1000 FD
1000 FD 1000 FD
1000 FD 1000 FD
no link no link
100 FD 100 FD
100 HD 100 FD
100 FD 100 FD
100 HD 100 HD
10 HD 10 HD
no link no link
100 HD 100 HD
10 HD 10 HD
Practice Autoneg
20. 20
Summary
We have choosen now the right cable
We decided to choose the right connector
We decided if we need PoE or not
We configured our Ports correctly.
due to a working Autoneg Scenario the Link is now established without any issue
► Let's start to transmit Data
21. 21
The Data Link Layer: L2
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Bit stream
HTTP, FTP, HTTPS, SMTP,
LDAP, NCP, SIP, H.323, RTP
TCP, UDP, SCTP, SPX,
ICMP, IGMP, IP, IPX
Softphone, Email…
G.729, G.723, G.711,..
The Core element of a Layer 2 - Network: Switch
Ethernet Frame: Transport of IP-
Packets through local networks
22. 22
Traffic Distribution
HUB
Node B
Node D
Node C
Node A
How can we send Data from A to Station B in that Local Area Network (LAN) ?
A Hub can help here as it is spreading the traffic into every span
Disadvantage: Every network element will receive the Traffic which is causing a high load in the LAN
Hubs can only work in Halfduplex mode and are internally causing network errors and collisions
CollisionsCollisions
23. 23
Traffic Distribution
SWITCH
Node B
Node D
Node C
Node A
How can we send Data from A to Station B in that Local Area Network (LAN) ?
A Switch is the perfect solution
Advantage: Only the target element will receive the Traffic - the network load is drastically reduced
A switch is a Fullduplexdevice - no errors or collisions anymore
Addressing is required
24. 24
Traffic Distribution
As we heard now that addressing is required this is the first time where we have to think about the
structrue of our Data
Somebody did that already for us: IEEE
Within their Transmission standard they defined how the Data Structure must look like.
They created a model and gave it the simple name: Frame
► IEEE 802.3 Ethernet Frame
25. 25
Ethernet Frame (IEEE 802.3)
The principal design of the Ethernet Frame
Data Structure: Thousands of alligned Bits
7 bytes 4 bytes
Preamble SFD FCSDestination Source DATA
Length /
type
1 byte 6 bytes 6 bytes 2 bytes 46 - 1500 bytes
Definitions of frame size
Smallest Ethernet Frame: 64 Byte
biggest Ethernet Frame: 1518 Bytes
Special Form: VLAN Frame 1522 bytes
Special Form VLAN (Q-in-Q) Frame: 1526 Bytes
Jumboframes up to 10000 Bytes
Frame size
26. 26
Ethernet Frame (IEEE 802.3)
Data Structure: Thousands of alligned Bits
7 bytes 4 bytes
Preamble SFD FCSDestination Source DATA
Length /
type
1 byte 6 bytes 6 bytes 2 bytes 46 - 1500 bytes
Preamble: required to get every single packet synchronized
SFD: Start Frame Delimiter indicates the beginning of the relevant data
Destination: Contains the Destination Address (MAC)
Source: Contains the source Address (MAC)
Lenght: Indicates the Lenght of the Ethernet Frame
Type: Indicates the type of packets which are coming from higher Layers
DATA: Contains the User Data / Packets of the higher Layers
FCS: Frame Check Sequency determines incorrect transmission due to faults
27. 27
MAC Address
Every Device is having a unique Hardware-Address
Every Medium can then be accessed in a controlled way
It is therefore called Media Access Control MAC
It's hexadecimal and looks like that: 00:16:06:88:01:6F
The first part is the Vendor Code
00:16:06:xx:xx:xx = Ideal Industries
Due to the MAC Addresses the Switches are now
able to determine where the Frame needs to got to within
the local network
28. 28
MAC Address
Ethernet Frames are on Layer 2 and can therefore only be transmitted
locally. They can not be transmitted in foreign networks!!
Sender
Anwendung / Prüfmuster
IP - Layer 3
Ethernet - Layer 2
Physikal. - Layer 1
IP - Layer 3
L 2
L1
Router
L 2
L 1L 1 L 1
Ethernet - Layer 2
SwitchL3
L3L2 L3L2 L3L2
LAN WAN
Layer 3
Layer 2
29. 29
Summary
Layer1
We have choosen now the right cable
We decided to choose the right connector
We decided if we need PoE or not
We configured our Ports correctly.
due to a working Autoneg Scenario the Link is now established without any issue
Layer 2
The data structure is framed by IEEE 802.3 can can be trasmitted locally
► What's to do if we need to leave the local network (Internet)?
30. 30
The Network Layer: L3
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Bit stream
HTTP, FTP, HTTPS, SMTP,
LDAP, NCP, SIP, H.323, RTP
TCP, UDP, SCTP, SPX,
Softphone, Email…
G.729, G.723, G.711,..
The Core element of a Layer 3 - Network: Router
Ethernet Frame: Transport of IP-
Packets through local networks
IP Packet: To carry the TCP-
UDP Packets through different
Networks
31. 31
7 b y t e s 4 b y t e s
P r e a m b l e S F D F C SD e s t i n a t i o n S o u r c e D A T A
L e n g t h /
t y p e
1 b y t e 6 b y t e s 6 b y t e s 2 b y t e s 4 6 - 1 5 0 0 b y t e s
E t h e r n e t F r a m e
IP
Header
TCP, UDP, ICMP
Daten
L3: Intenet Protocol IP
As Ethernet Frames are not transmitted by Routers another Packet Type is used in Layer 3
IP Packet
The IP Packed is embedded within a Ethernet Frame
The IP header contains a new Address format
IP-Packet
Ethernet Frame
32. 32
Since the early 80s the Internet Protocol has already been defined in its fourth Version
► IPv4
The plan was, that every device should have it's unique IP-Address that the devices can
communicate worldwide
32 bit are reserved in the header for an IPv4 Address, meaning 4.294.967.296 Addresses
are available
In the Local Networks there is no need of unique addresses. e.g. we can use 192.168.1.1 in
Chigaco locally as well as locally in London as long as those networks are not linked to each
other.
Two Adress types are therefore defined: Private IP Addresses
Public IP Addresses
L3: Internet Protocol version 4 - IPv4
33. 33
Format: four blocks written in decimal: e.g. 192.168.0.1
Written in binary numbers: 11000000.10101000.00000000.00000001
Private IPs can not be routed through the internet. They can only be used locally
Public IPs are basically the remaining ones e.g. 212.67.56.187
the Public IPs are owned by the service providers.
Every user gets one Public IP Adress assigned with the contract.
Addressrange Number of hosts Netclass
10.0.0.0–10.255.255.255 224
= 16.777.216 Class A: 1 private Network
172.16.0.0–172.31.255.255 220
= 1.048.576 Class B: 16 private Networks
192.168.0.0–192.168.255.255 216
= 65.536 Class C: 256 private Networks
L3: Internet Protocol version 4 - IPv4
34. 34
IP Packets are routed on Layer 3
Since the traffic is now routed on Layer 3 the communication can work worldwide
Sender
Anwendung / Prüfmuster
IP - Layer 3
Ethernet - Layer 2
Physikal. - Layer 1
IP - Layer 3
L 2
L1
Router
L 2
L 1L 1 L 1
Ethernet - Layer 2
SwitchL3
L3L2 L3L2 L3L2
LAN WAN
Layer 3
Layer 2
L3
L3L2
L3: Internet Protocol version 4 - IPv4
35. 35
L3: Internet Protocol version 4 - IPv4
LAN WAN
DSL Modem
WLAN-Router
Network Address translation
NAT
WAN Port
1 Public
IP AddressLAN Port
Copper and WiFi
multiple Private
IP Addresses
36. 36
Since the early 90s it turned out that the reccources of IPv4 addresses are coming to its end
► IPv6
128 bit are reserved in the header for an IPv6 Address, meaning 3,4 × 1038
Addresses are
available. 3,400,000,000,000,000,000,000,000,000,000,000,000,000
every device can now get a unique IP Address which is written hexadecimal
Example 2001:0db8:0000:08d3:0000:8a2e:0070:7344
If one block consists of purely zeros then it can be replaced by a single zero:
2001:db8:0:8d3:0:8a2e:70:7344 is therefore the same address as mentioned above
If there are continous blocks of zeroes, they can be left out completely:
2001:0db8:0:0:0:0:1428:57ab is the same as 2001:db8::1428:57ab
L3: Internet Protocol version 6 - IPv6
38. 38
Summary
Layer1
We have choosen now the right cable
We decided to choose the right connector
We decided if we need PoE or not
We configured our Ports correctly.
due to a working Autoneg Scenario the Link is now established without any issue
Layer 2
The data structure is framed by IEEE 802.3 can can be trasmitted locally
Layer 3
Within the Ethernet frame there are now IP Packets why we now can leave the local network because IP
Packets can be routed between different networks
. ► What if some packets are lost during the transmission. Does it make sense to retransmit them?
39. 39
The Transport Layer: L4
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Bit stream
HTTP, FTP, HTTPS, SMTP,
LDAP, NCP, SIP, H.323, RTP
TCP, UDP, SCTP, SPX,
ICMP, IGMP, IP, IPX
Softphone, Email…
G.729, G.723, G.711,..
Ethernet Frame: Transport of IP-
Packets through local networks
40. 40
L4: Transport
The Transport layer is basically to ensure that everything is transmitted completely
But Some applications are allowing to loose some data
Realtime Applications such as Video or VoIP
lost data doesn't need to be delivered subsequently.
E.g. Video streaming. When you see a pixel error then it doesn't make sense to deliver the missing
information later on. We don't need it to understand the core message.
Data Transfer
Missing informations are making the files looking like corrupted. The Data is not usable anymore
Lost informations must be delivered subsequently
E.g. backup of a laptop: such files are containig very important informations to recover the system.
If the file is not complete then the restore cannot be done.
41. 41
L4: Transport
The protocols of the Transport layer are furthermore responsible that the arrived data is directed to
the right application
The Transport Packets are therefore using Addresses again. No address to find a station (Like IP
or MAC).
These addresses are now used to find the right applications within the device.
These addresses are now called Ports
42. 42
L4: UDP
When Realtime Transmission doesn't
require and end-to-end error correction,
then
The User Datagram Protocol (UDP) is
only addressing the data to the application
UDP doesn't do an end-to-end error
correction
UDP is the Transport Protocol for
Realtime Transmission
UDP could be used for: Video, IPTV,
CCTV, VoIP
Bit stream
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Ethernet Frame: Transport of IP-
Packets through local networks
RTP: Realtime Transport
Porotocol (between the
Applications)
UDP-Packets To carry the
Session Packets (between the
Devices) No Error Correction
IP Packet: To carry the UDP
Packets through different
Networks
Analogue Speech
Digital Speech Signal
User data
layer 5
header
Example VoIP Call
43. 43
L4: TCP
For DATA Tranmission an end-to-end error
correction is essential.
The Transmission Control Protocol
(TCP) is detecting if some informations are
missing.
Every single Packet gets its own number
(TCP Sequence Number) from the Sender.
A missing number can then be dected via
TCP at the destination device
The destination is chasing the sender to
retransmit the missing packet.
PCs are basically transmitting DATA and
therefore using TCP
That's why most users are talking from
TCP/IP (TCP over IP)
User data
User data
User data
layer 2
header
layer 3
header
layer 4
header
layer 2
trailer
Bit stream
Ethernet Frame: Transport of IP-
Packets through local networks
SMTP: Simple Mesage Transfer
Protocol (between the
Applications)
TCP-Packets To carry the
Session Packets (between the
Devices) With Error Correction
IP Packet: To carry the UDP
Packets through different
Networks
Typing email on a keyboard
Convert into digital
User data
layer 5
header
Example Email
44. 44
Summary
Layer1
We have choosen now the right cable
We decided to choose the right connector
We decided if we need PoE or not
We configured our Ports correctly.
due to a working Autoneg Scenario the Link is now established without any issue
Layer 2
The data structure is framed by IEEE 802.3 can be trasmitted locally
Layer 3
Within the Ethernet frame there are now IP Packets why we now can leave the local network because IP
Packets can be routed between different networks
Layer 4
The assurance of end to end connection and flow control of specific application is made via sessions.
45. 45
The ISO/OSI 7-Layer Reference Model
7
6
5
4
3
2
1
Application
Presentation
Session
Tansport
Network
Data Link
Physical
Network process to application
Data Representation, encryption and
decryption, convert user dependent data into
machine dependent data
Interhost communication, managing
sessions between applications
End-to-end connections, reliability and
flow control
Path determination and logical addressing
Physical addressing
Media, signal and binary transmission
Ethernet Frame: Transport of IP-
Packets through local networks
Session Packets: To carry the
digital User Data (between the
Applications)
TCP/UDP-Packets: To carry the
Session Packets (between the
Devices)
IP Packet: To carry the TCP-
UDP Packets through different
Networks
Analogue Signal
Digital Signal
Bit stream
User data
layer 3
header
User datalayer 2
header
layer 2
trailer
User data
layer 5
header
User data
layer 4
header
Ethernet is just a name - not a function. Robert Metcalfe has been advised to find something that enables his company XEROX to connect some stations so that they can communicate to each other. He followed a former idea of the University of Hawaii. In the early seventies they deployed a radio link to transmit data through the ether. Metcalfe did that in a similar way and "replaced" the ether by a copper cable. The name Ethernet was born. He convinced DEC, Intel and Xerox to fund a consortium which deployed the first transmissin standard: DIX-Frame v1.0 (10 Mb/s) Later on a very big organisation (IEEE) covered the deployment of further transmission standards.
The IEEE is a worldwide organisation which is taking care about standardisations. As there are many vendors of network components around the world it is neccesary to have a common transmission standard. Otherwise the worldwide communication would not be possible. They formed a transmission standard which we know as IEEE 802.3 Ethernet.
It is not enough to have a common transmission standard as IEEE is suggesting. Today we use thousands of different applications within our datanetworks. The International Standards Organisation ISO defined a sort of reference book which contains 7 chapters. It describes how the communication has to take place worldwide. The traget of the 7 chapters is that all systems open to be able to interconnect to each other. That's why the ISO called it the Open Systems Interconnection Model. It should be a Reference for everybody. It is therefore called: ISO /OSI 7-Layer-Reference-Model
Layer 1 - Physical That is the chapter where the ISO defined the physical properties of our networks. It's about the Media like copper or fiber and its properties; The way of transmitting the signals across the medias. Ports and its physical properties, Cables and its Categories.
This is one of the common problems appearing in the field peope using 100Base cable for 1000 Base T cable.
SFP is widely used in today‘s network equipment such as switches and routers to carry Ethernet signal over the fibres. This is mainly to overcome the short distance coverage of the copper cable (<100m typically). Using fibre technology, the link length can reach as far as 120Km under single mode fibre. Today, there are lot of different type of SFPs (standard or non standard) developed by manufactures to meet different appliction demand. There are two operation mode of fibre optics used for SFP. One is call Multi Mode (MM) and the other called Single Mode (SM). In Multi Mode fiber, there are two types of core diameters 50um and 62.5um used in multi mode fibre. The most commonly used is diameter 50um fiber. The single mode fibre has only one diameter 9um. The common structure of SFP is having Tx and Rx port with LC connectors. The rate covers from 100Mb/s up to 10Gb/s. Today, two of the most commonly used SFP types are 1000 Base SX and 1000 Base LX. The 1000 Base SX is 850nm Multimode LED source and mainly used in LAN application for short distance (500m max). The 1000 Base LX is 1310nm Singlemode laser source mainly used for WAN application for the long distance up to 40Km. There are other type of SFPs to cover even longer distance such as 1000 Base ZX using 1550nm singlemode laster source for up to 70Km. For limited fiber access restriction and PON (Passive Optical Network) application, a bi-directional type SFP has been developed to support Tx and Rx over one fiber instead of two fibers on traditional SFPs. A typical example is 1000 Base BX10 (or sometime called Bi -Di SFP). It use 1490nm or 1550nm wavelength as one direction and 1310nm for other direction over just one fiber. The distance can reach 10Km or more depending the vendor specification. Recent network is demanding 10Gb/s rate with small form factor in SFP. Hence the SFP+ is developed to overcome the big form factor of XFP which can support up to 120km. It has the same SFP form factor supporting the bit rate up to 10Gb/s instead of SFP‘s 1Gb/s with relative short distance of XFP in general.
Connector surfaces of PC UPC APC Usually we hear about descriptions like" LC/UPC multi mode duplex fiber optic patch cord 3 meters", or "FC/APC single mode fiber optic pigtails"," ST/PC multi mode duplex fiber optic jumper", what do these words PC, UPC, APC mean? Here we give the explanations. As we know, fiber optic cable assemblies are mainly with connectors and cables, so the fiber cable assembly names is related to the connector names, we call it LC fiber patch cord, because it is with LC fiber connector, here the words PC, UPC, APC also are related only to the fiber optic connectors and has nothing to do with fiber optic cables. We have known that PC, UPC, APC is standard of the fiber optic connectors, PC, UPC, APC are short for: Physical Contact (PC), Ultra Physical Contact (UPC), and Angled Physical Contact (APC), they are actually the polish style of fiber optic ferrules. Unlike copper cables with copper thread in the connectors as connection media, fiber optic connectors are with these ceramic ferrules for connection, and different fiber optic connectors the ferrule size and length and polish styles are different. Such ferrules are inside the fiber optic connectors and with fiber glass from the fiber optic cable to plug into the ferrule for linking. The different polish of the fiber optic connector ferrules result in different performance of them, mainly on the back reflection (return loss),.Generally, PC type is required at least 40dB return loss or higher, UPC is 50dB or higher, APC is 60dB or higher. (As we know, the higher the return loss the better the performance). Insertion loss of them all should be less than at least 0.3dB, the lower the insertion loss the better the performance. Single mode fiber optic cables can be with PC, UPC or APC polished connectors, while multimode there is no APC ones. When you are using fiber optical cable, please make sure you are using the same type of surface connectors (same colour) to connect each other. APC is normally green and PC/UPC is blue. Mismatch connectors (colour) will cause extra loss of the fiber link and poor return loss.
The main advandage of PoE is the reduction of installation costs, as no installation of electricity is required anymore. It is already very common for CCTV cameras and IP-Phones. PoE can feed devices with a low power consumtipon. It can also increase the resiliance of the devices as these ones are secured via the switch and its untinterrrupted power supply unit. In Ethernet / Fast Ethernet Networks the feeding normally takes place via the unused Pairs 4-5 and 7-8, but can also be done via the data carrying pairs 1-2 3-6. The feeded Power is not disturbing the Data carried on the Pairs. PoE can therefore be used in GbE Networks as well. The typically feeding Voltage is 48 V, while the delivered Power may vary due to different end user devices. The maximum Power consumption is 15 Watts as per defined in the standard IEEE 802.1af. It defines also a secure-mechanism to protect non PoE devices which are connected to a PoE feeding unit. Modern devices myy need more than 15 Watts. The newer standard is IEEE 802.1at which defines a maximum power consumtpion up to 25 Watts. We call it easily PoE Plus or PoE+
We clearly can say: Only when the Duplexconfigurations are matching to each other, a correct tranmission can take place. The example in the middle shows an incorrect transmission due to a duplex mismatch The left computer can only work halfduplex, the computer on the right firced to speak fullduplex. While the Computer on the left is transmitting it has a blocked Rx-Port. We see in the example that the computer on right is sending back to the station on the left. Due to the currently blocked Rx Port of the left device, all traffic coming from the right station is lost there. Furthermor a network tester will discover the network error "Collisions"
Interfaces are sending a link pulse every 16 ms. As soon the interfaces are connected to each other, they are detecting the Link Pulse from each other. The link is becoming active. As soon this has happened the Autonegotiation handshake will begin to determine the Duplex.
Autonegotioation is very comfortable as it automatically detects the Duplex-Mode. Attention: Only when both Interfaces are configured to "AUTONEG ON " it may work correctly. If one station is set to "AUTONEG OFF" one interface is only working on halfduplex . We determine then Trafficloss and Collisions again.
While we were talking about a transmission of signals in Layer 1 we are now talking for the first time about transmitting Data: Layer 2
The easiest way to build a network in terms of distributing the traffic is simply to use a Hub. The Hub is distributing the incoming traffic to every port. Although we may get a fullduplex connection to the Hub it can only work in halfduplex mode. A Hub is therefore causing Traffic loss and Collisions. Furthermore as it is directing the incoming traffic into every span it is causing a high network load. That's why IT-Administrators are removing Hubs from the network.
The Hubs are replaced by switches as these are intelligent devices. They are directing the incoming Traffic to a destination. Addressing is therefore required. That method of "switching" is reducing the network load. Switches are able to operate in Fullduplex mode. They are eliminating the collisions which occured by the usage of Hubs. Nowadays we only see switches in modern Multimedia environments
Ethernet frames can look much more complicated. That slide should simply illustrate the priciple of the Data structure
Against a very common opinion the Ethernet transmission is always synchronized. Every single frame is containing a special Bitstructure wich is used for synchronisation ( Preamble ) A sort of "Alert Message" indicates that now the important Data is beginning ( Start Frame Delimiter SFD ) The Ethernet Frame begins after the SFD
A Swith is normally a pure Layer 2 device, meaning it can only handle MAC Addresses. Switches are not interested in the content of the User Data of a frame. They are disregarding the DATA and are only using the layer 2 informations, such as Destination MAC and Source MAC. Therefore Switches can only handle local traffic. They can not direct the traffic from locally into the outer world or in foreign networks. A new functionality is required: Routing on Layer 3. There are switches available on the market which can do Routing. These are called "L3-Switch"
IP Packets are generated by the devices. These IP packets are transmitted between the local devices by mapping them into an Ethernet Frame. Comparable with the Frame, a IP Packet is having an header as well. Within that header there are Addreses of a new format. I P-Adresses
While the switch is transmitting the Ethernet Frame locally, the Router is working on layer 3. It is removing the Ethernet Frame and uses only the IP Packet. Due to configured Routing Tables the Router can couple now different networks.
Example Internet Access via DSL: The service provider has assigned one single public IP-Address to his customer. That public IP-Address is configured on the WAN-Port of the DSL Router. On the LAN side the Router is assigning private IP-Addresses to every client via DHCP. As soon a client wants to communicate with the outer world, the Router is translating the internal private IP-Address to the public IP-Address on the WAN side. That scenario is called Network Address Translation NAT
One of the main advantages of IPv6 is that there is no NAT required anymore. This makes the transmission faster which is good for latency sensitive services.
The UDP is mainly addressing the user data to the right application. It is transmitting the data without any error correction. Meaning if data is lost within the network it is never retransmitted. UDP is therefore the right choice for Realtime Transmissions.
The TCP is addressing the user data to the right application and is doing an error correction if some data is lost. The sender is marking every single packet with a number, the TCP Sequence Number. The principle is quite simple: it is simply an ascending numbering of the packets. The destination is now able to detect, if a packet is missing. If that is the case, a messeage is sent back to the sender, who is then retransmitting the lost packet. TCP is therefore the right choice for DATA Transmissions.
As summary, the OSI model gives us a clear job description in different layers in the network to make sure the communication between two parties is error free. It is the base of the troubleshooting of the network problem in different layers and associated devices from instrument point of view. So how these different layers working together to make the network for use in today‘s IP world? Next session will give you more detailed looking on this.