Transcript ATM

Internet Technology
NETW 902
Tutorial 3
Mohamed Esam
1
Outline
1.
2.
3.
4.
5.
6.
SONET/SDH
Core Network
ATM
ISDN
Dialup
Access Network
DSL
IP Addressing
 Exercise 3.
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Main Points for Problems
1.
2.
3.
4.
5.
6.
7.
8.
9.
ALOHA
Slotted ALOHA
CSMA/CD
Token Ring, Token BUS & Ring Types. (last Tutorial)
BUS Segments
WLAN
FDDI
Spanning Tree
Performance of (Aloha, CSMA & Token Ring)
10.
11.
12.
13.
14.
15.
SONET/SDH
ATM
Virtual Connections
ISDN
Dial up
DSL
Ch’s 1&2
Till page: 200
Ex.1:
LAN-Inter working
& Spanning Tree
Ex.2:
MAC protocols
Performance
Ch’s 3
Till page: 255
Ex.3:
IP Addressing, ATM
& Access Networks
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29.
30.
Internet Arch. & IP Addressing.
ARP
MTU
Routing Functions
Forwarding
Routing Principles
Distance Vector Algor.
Link State Algor.
Path Vector Algor.
Routing in Internet.
Internet Routing Protocols
ARQ
UDP
TCP
QoS
Some of Ch’s 4&5
Till page: 554
Ex.4:
Distance Vector &
Link State Routing
Ex.5:
TCP
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IP Addressing
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IP Addressing
• IP Addressing:
– Subnetting: a network is divided into smaller subnets with each
subnet having its own subnet address.
• Classless
• Classful
– Benefits:
•
•
•
•
Faster routing
Smaller broadcast domains
Reduced network traffic
Simplified management
– Supernetting
• IP v4  4 Bytes (Dotted decimal x.x.x.x)
• IP v6  16 Bytes (128 bits)
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Classless Subnetting
• The IP address is divided into two part:
– Network Addr. (n bits)
– Host Addr. (32 – n bits  for IPv4)
– IP Address with Prefix Notation: ex. 120.112.2.1/n
• Subnet Mask:
– Example if n=26  subnet mask is:
– 11111111 11111111 11111111 1100000
– And gate is used to get the Network address using the subnetmask
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Classful Subnetting
• Special case of classless
subnetting when n has
defined values.
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Supernetting
• Opposite to subnetting
• Example:
– If A0(Network 0 Address)=
00000000.11111111.00000000.00000000/24
– & A1(Network 1 Address)=
00000000.11111111.11111111.00000000/24
 Aagg=
00000000.11111111.00000000.00000000/16
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IP Static Routing
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•
•
•
•
Assume 2 BUS topology networks connected by router. The router is the gateway for
each network to the other one.
Station (1.1) will send data to station 2.3.
Next Hop station is the first station will receive the data from the Tx.
Interface is the station in the network domain that will send to the next hop or the Rx
station.
Router knows that address (1.x) is in network 1 and (2.x) is in network 2
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Exerc.3 Prob.1
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Asynchronous Transfer Mode (ATM)
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WAN Definition
• WAN can be divided
into:
– Core Networks:
Connects cities or
countries. (ATM or
SONET)
– Access Networks:
Connects clients with
network operators by
IWU. (DSL or Dialup)
• IWU: Interworking
Unit (Bridge, Router or
gateway)
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ATM
• Is designed to integrate all
communication services with
different traffic classes:
– Constant bit rate (phones)
– Variable bit rate (video)
– Packetized traffic
• By:
– Packetization into small constant
size cells.
– Asynchronous multiplexing into high
transmission channels.
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Asynchronous Multiplexing
Voice
Data
packets
MUX
Wasted bandwidth
Images
TDM
4
3
2
1
4
3
2
1
4
ATM
Leon-Garcia & Widjaja: Communication Networks
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1
2
1
`
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Copyright ©2000 The McGraw Hill Companies
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Figure 7.37
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Virtual Path & Virtual Connections
• ATM is a Connection Oriented Technology.
• Virtual Channel (VC): the channel of ATM cell identified by VCI (VC
ID)
• Virtual Channel Connection (VCC): sequence of VC’s links to
establish a path between terminal equipments (TEs).
• Virtual Path (VP): group of VC’s identified by a (VPI)
• Virtual Path Connection (VPC): sequence of VC’s links to establish a
path between terminal equipments (TEs).
• Each cell carriers both transmission VPI and VCI
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ATM Cell
• Header details in Page
233
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Cell Switching
• Base on the
connection
establishment phase,
switching tables are
used.
• In the switching table,
each input VCI /VPI
is mapped to another
output VCI/VPI and
the corresponding
output port number.
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 Exer.3Prob. 2, Part 1
ATM based access network
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User
information
User
information
AAL
AAL
ATM
ATM
ATM
ATM
PHY
PHY
PHY
PHY
…
End system
Network
End system
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Adaptation Layer : A detailed view
Higher
layer
Ethernet Frame
Convergence
Sub-layer
CS-header
(CS)
layer
Ethernet Frame
Pad
CS-trailer
AAL
Segmentation
&
Reassembly
SAR-PDU SAR-PDU SAR-PDU
(SAR)
header
payload
trailer
layer
ATM
layer
Cell
header
Cell
payload
SAR-PDU SAR-PDU SAR-PDU
header
payload
trailer
Cell
header
Cell
payload
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AAL5
• The most Common used AAL type.
• CPCS payload: The actual information that is sent by the user.
• Pad: Padding bytes to make the entire packet (including control and CRC)
fit into a 48-byte boundary.
• UU: CPCS user-to-user indication to transparently transfer CPCS user to
user information.
• CPI: Common part indicator is a filling byte (of value 0). This field is to
be used in the future for layer management message indication.
• Length: Length of the user information without the Pad (65535).216  1
• CRC: CRC-32. Used to allow identification of corrupted transmission.
User Data
Divided into 53 bytes
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Synchronous Digital Hierarchy (SDH)
• SDH is used to integrate ATM cells in the
transmission system
• Synchronous Optical Network (SONET) is
the protocol for North America and Japan by
ANSI while SDH is the definition for Europe
by ITU-T.
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Synchronous TDM
• In Synchronous TDM, the time slots are
preassigned to sources and fixed.
– The time slots for each source are transmitted
whether or not the source has data to send
– capacity is wasted to simplify the hardware
implementation
– It is possible for a synchronous TDM device to
handle sources of different data rates.
• For example:
– the slowest input device could be assigned one slot per cycle,
– faster devices are assigned multiple slots per cycle.
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Synchronous TDM
Station A is Faster
Asynchronous (Statistical) TDM
Station B&D are idle
Normal TDM
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SDH- Standard Frame Representation
• All frames are:
– 9 rows Matrix
– 125 us
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Overhead
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Check slides
4, 7
Preamble and SFD are
not considered as given
in the problem
ATM CS layer
Given in the
problem
Encapsulation
Headers
n  (216  1),16 bits is the frame length header size
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Part 2
Ethernet based access network
• ATM technology in DSLAM is replaced by an
Gigabit Ethernet interface.
• Ethernet frames in the VLAN switch are
encapsulated using the Generic Framing Procedure
(GFP).
• GFP adds a header of 8 bytes, but does not include
the preamble and the start frame delimiter of the
Ethernet frame.
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For Encapsulation
Given in the problem
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