NFNN2, 20th-21st June 2005
National e-Science Centre, Edinburgh
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Just What is OC-192?
M
T
S
Acronym of the Day
Robin Tasker
CCLRC, Daresbury Laboratory
20 June 2005
http://gridmon.dl.ac.uk/nfnn/
http://gridmon.dl.ac.uk/nfnn/
Contents
Reading the Dictionary
A is for ADSL: asymmetric digital subscriber link
ATM: asynchronous transmission mode
B is for Bandwidth: ….
Back to Basics
Understanding bits and bytes
POTS and PANS; bit stuffing and bit robbing
DS0 et al, T-1 et al, E1 et al, STM-1 et al and OC-1 et al
A journey from syntax to semantics
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Slide: 2
“The Greatest Exploration Ever Undertaken”
So turning to Page 1
“A” is for ….
…. Oh! Gosh! you’re all asleep.
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Slide: 3
Analogue Domain
Digital Domain
So Let’s Get Back to Basics
Packet (Asynchronous)
Packet (Asynchronous)
Packet over SONET (PoS)
QSIG GFP
10GigE
Time (Synchronous)
Switched Ethernet
Resilient Packet Ring
Time (Asynchronous)
SDH/SONET
Byte Multiplexing, ADM
Time Slot Interchange Switching
SDH/SONET Protection Rings
ad hoc usage
Wave / Frequency : Coarse/Metro/Dense, Erbium Doped Fibre Amps, OADM,
Blocking switching with no wave translation, Non-blocking
switching with wave translation
Spatial : Fibre, Single Mode / Multi-Mode,
Fibre switching (remote controlled patching),
Cable diversity
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With thanks to Chris Cooper, UKERNA
Slide: 4
It’s all in the packets, or frames???
Packet/Frame (Asynchronous)
Frames and Packets are asynchronous with respect to the media
Packet or Frame? What’s the difference?
A network provides an end-to-end path constructed from point-to-point links
Packets are carried from end-to-end across the network
Frames carry the packets on the point-to-point links except...!!
Except that in the local area it’s not necessarily a point-to-point link!
Chances are that the frames equates to Ethernet and packets to TCP/IP
Ethernet? A local area network technology where between any two end
systems there is apparently a point-to-point path
TCP/IP?
Coming later today…
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Ethernet? Just what is it?
Ethernet Highlights!!
1. Early history (need to be old to remember this stuff)
2. AUI and MAU types specified:
10BASE-T, 10BASE-FL, 10BASE-FB, 10BASE-FP;
100BASE-T4, 100BASE-TX, 100BASE-FX, 100BASE-T2;
1000BASE-X, 1000BASE-SX, 1000BASE-LX,
1000BASE-CX.
3. Full duplex specifications are provided at the PHY
10BASE-T, 10BASE-FL;
100BASE-TX, 100BASE-FX, 100BASE-T2;
Gigabit Ethernet.
4. Support for Virtual Bridged Local Area Networks
(VLAN) as specified in IEEE P802.1Q
5. Specifies an optional Link Aggregation sub-layer
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Slide: 6
Yikes! it gets worse…if you let it.
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But the frame is really easy!
Preamble, which is comprised of 56 bits of alternating 0s and 1s.
The preamble provides all the nodes on the network a signal
against which to synchronize.
Start Frame delimiter, which marks the start of a frame. The start frame
delimiter is 8 bits long with the pattern10101011
Media Access Control (MAC) Address
Every Ethernet network card has, built into its hardware, a unique six-octet
(48-bit) hexadecimal number that differentiates it from all other Ethernet cards
in the universe. The DA and SA define the path across the link
Length/Type field two octets long.
If the value =< 1500 (0x05dc hex) indicates the length of data
If the value > 1500 indicates network-layer protocol : “Ethernet Types”
Data, the reason the frame exists
Frame Check Sequence to protect the frame
contents
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Slide: 8
And the Virtual Local Area Network?
VLANS are logical networks built over
the same physical cable plant.
Distinguishes Ethernet frames between
their logical networks using VLAN
header
VLAN is defined by the use of value 0x8100 in the Type field location.
The next two octets are composed of the following three fields:
User Priority field
This field is 3 bits in length and is used to define the priority of the Ethernet frame.
This is utilized to define and deliver a class of service
Canonical format indicator
This is 1 bit in length. Just **don’t** ask!!!
VLAN Identifier field
This field is 12 bits in length and contains the VLAN identifier (VID)
of this frame.
The original Length/Type field will then follow the inserted VLAN tag.
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Slide: 9
Analogue Domain
Digital Domain
So Let’s Get Back to Basics
Packet (Asynchronous)
Packet (Asynchronous)
Packet over SONET (PoS)
QSIG GFP
10GigE
Time (Synchronous)
Switched Ethernet
Resilient Packet Ring
Time (Asynchronous)
SDH/SONET
Byte Multiplexing, ADM
Time Slot Interchange Switching
SDH/SONET Protection Rings
ad hoc usage
Wave / Frequency : Coarse/Metro/Dense, Erbium Doped Fibre Amps, OADM,
Blocking switching with no wave translation, Non-blocking
switching with wave translation
Spatial : Fibre, Single Mode / Multi-Mode,
Fibre switching (remote controlled patching),
Cable diversity
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Slide: 10
Let’s start with a history lesson…
Time (Synchronous)
Long Ago, in a Galaxy Far, Far Away the Digital Signal (DS) was defined to
carry voice traffic in our telephone systems
Now read on : DS-0 : digitised voice grade telephone signal at 8000 bytes/second, i.e. 64kbits/s
and as the technology advanced a means was developed that carried multiple DS-0
channels in frames that were generated each and every 125 µs .
This multiplexing developed a hierarchy DS-0, DS-1 and DS-3 each of which being
able to carry greater and greater capacity…
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DS-1 was the start of framing…
A single DS-1 frame contains 24 DS-0 channels
A DS-1 frame contains 1 byte from each of the 24 DS-0 channels i.e. (24 x 8) bits + 1 bit
for “framing” = 193 bits :-
but remember frames are generated each and every 125 us, i.e. 8000 frames are
generated per second
Therefore the DS-1 capacity is (193 x 8000) = 1.5Mbits/s
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Slide: 12
And then there was SONET…
90 Bytes
or “Columns”
9
Rows
Frame contents = (90 x 9) bytes = (810 x 8) bits = 6480 bits / frame
but remember frames are generated each and every 125 us, i.e. 8000 frames are
generated per second
STS-1 capacity = (6480 x 8000) = 51.84Mbits/s
(base unit of SONET)
But when carried across an optical medium it’s called OC-1 (Optical Carrier)
And by extension STS-3 / OC-3 has a capacity of 155Mbits/s
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and also there’s SDH
Synchronous Digital Hierarchy (SDH)
The SDH frame (called STM or “Synchronous Transmission Module”) is the base unit
of SDH with STM-1, STM-4, STM-16 … STM-N What does this mean?
Let’s consider a single STM-1 frame, i.e. N=1
Total content of a single frame is (270 x N x 9) bytes or 19440 bits
A frame is transmitted each 125us
i.e. 8000 frames per second
STM Frame Format
Capacity = content x 8000
= (19440 x 8000)
= 155Mbits/s
Now consider an STM-64 frame
Content = (270 x 64 x 9) bytes
= 1244160 bits
Capacity = content x 8000
= 9.95Gbits/s
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Slide: 14
And to summarise…
Capacity
PDH
1 DS-0
64k
24 DS-0
1 DS-1
672 DS-0
28 DS-1
1.54M
DS-3
STS-1
OC-1
SDH / SONET
810 DS-0
2016 DS-0
45M
3 DS-3
8064 DS-0
32756 DS-0
129024 DS-0
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51.84M
STS-3
OC-3
STM-1
155M
STS-12
OC-12
STM-4
622M
STS-48
OC-48
STM-16
2.52G
STS-192
OC-192
STM-64
9.98G
Slide: 15
Analogue Domain
Digital Domain
So Let’s Get Back to Basics
Packet (Asynchronous)
Packet (Asynchronous)
Packet over SONET (PoS)
QSIG GFP
10GigE
Time (Synchronous)
Switched Ethernet
Resilient Packet Ring
Time (Asynchronous)
SDH/SONET
Byte Multiplexing, ADM
Time Slot Interchange Switching
SDH/SONET Protection Rings
ad hoc usage
Wave / Frequency : Coarse/Metro/Dense, Erbium Doped Fibre Amps, OADM,
Blocking switching with no wave translation, Non-blocking
switching with wave translation
Spatial : Fibre, Single Mode / Multi-Mode,
Fibre switching (remote controlled patching),
Cable diversity
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With thanks to Chris Cooper, UKERNA
Slide: 16
But look! All this is carried on fibres
Wave / Frequency
Dense wavelength division multiplexing (DWDM) is a technology that puts data
from different sources together on an optical fibre, with each signal carried at
the same time on its own separate light wavelength.
Using DWDM, up to 96 (and theoretically more) separate wavelengths or
channels of data can be multiplexed into a light-stream transmitted on a single
optical fibre.
Each channel carries a time division multiplexed (TDM) signal operating up to
at least 10Gbits/s. So in total 96 * 10Gbits/s = 960Gbits/s which is broadly
equivalent to transferring 14,400 3-hour movies in one second! Cool!
The “data per wavelength” channel rates will increase, i.e. to use 20Gbits/s
and even 40Gbits/s. So expect to see 100 wavelength channels @ 10Gbits/s,
i.e. a pipe that delivers 1Tbits/s
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Slide: 17
Analogue Domain
Digital Domain
So Let’s Get Back to Basics
Packet (Asynchronous)
Packet (Asynchronous)
Packet over SONET (PoS)
QSIG GFP
10GigE
Time (Synchronous)
Switched Ethernet
Resilient Packet Ring
Time (Asynchronous)
SDH/SONET
Byte Multiplexing, ADM
Time Slot Interchange Switching
SDH/SONET Protection Rings
ad hoc usage
Wave / Frequency : Coarse/Metro/Dense, Erbium Doped Fibre Amps, OADM,
Blocking switching with no wave translation, Non-blocking
switching with wave translation
Spatial : Fibre, Single Mode / Multi-Mode,
Fibre switching (remote controlled patching),
Cable diversity
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With thanks to Chris Cooper, UKERNA
Slide: 18
And here’s a brief introduction…
Spatial Stuff
Mode
A single electromagnetic field pattern, e.g. a
ray of light, that travels in fibre.
Step index
multimode
The first fibre design but too slow due to the
dispersion caused by the different path
lengths of the various modes. Step index fibre
is rare - only POF uses a step index design
today
Graded index
multimode
Variations in the composition of the glass in
the 62.5 or 50 microns core to compensate for
the different path lengths of the modes. Much
better than Step index fibre - up to about 2
gigahertz.
Single mode
Uses a 9 micron core such that the light
travels in one ray. This increases the
bandwidth to about 100,000 gigahertz
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with some specific technical detail.
Spatial Stuff
Technical Update ISO11801 2nd Edition
OM1
Aligns with today’s 62.5/125 fibre
OM2
Aligns with today’s 50/125 fibre
OM3
A ‘laser enhanced’ 50/125 fibre intended to support 10 gigabit Ethernet over 300
metres. OM3 has a very large bandwidth at the first operating window (850nm) (ten
times more than OM1 and OM2), and will have a near perfect refractive index profile
optimised for laser transmission through multimode fibres
OS1
OS1 is G652 single mode fibre
Distance
Speed
300m
500m
2000m
100Mb/s
OM1
OM1
OM1
1000Mb/s
OM1
OM2
OS1
10000Mb/s
OM3
OS1
OS1
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Slide: 20
But remember cabling matters too…
Spatial Stuff
Category 5
Cable (UTP)
(Unshielded
Twisted Pair)
A multi-pair (usually 4 pair) high performance cable that consists of twisted pair
conductors, used mainly for data transmission. Category-5 UTP cabling systems
are by far the most common. It was designed for characteristics of up to 100 MHz.
Category 5 cable is typically used for Ethernet networks running at 10 or 100
Mbps.
Category 5E
Cable
(enhanced)
Same as Category 5, except that it is made to somewhat more stringent standards
and was designed for transmission speeds of up to 1 gigabit per second (Gigabit
Ethernet).
Category 6
Same as Category 5E, except that it is made to a higher standard.
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and applying all this stuff
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Questions?
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