Transcript Network Architecture

Network Architecture
Layout designed and
constructed by:
Vicki Kertz
TOPOLOGIES
 Bus
 Ring
 Star
 Hybrid
 Enterprise-wide
 WAN
Bus
 a central cable that
connects all devices
on a local-area
network
Ring
 Each node is
connected to the two
nearest nodes so that
the entire network
forms a circle.
Star
 Each node (file
server, workstations,
and peripherals)
connected directly to
a central network hub
or concentrator
Hybrids
 Star-wired Ring
 Star-wired Bus
 Daisy-chained
 Hierarchical
Enterprise -wide
 Backbone Networks – cabling that connects
the hubs, switches and routers
 Serial – simplest; two or more connected by a single
cable
 Distributed – number of hubs connected to a series
of central hubs in a hierarchy
 Collapsed – a router or switch as the single central
connection point for multiple subnetworks
 Parallel – robust; more than one connection from the
central router to each network segment
 Mesh – routers interconnected with others and
at least two pathways connecting each router
WAN
 Peer-to-peer
 Ring
 Star
 Mesh
 Tiered
Network Transport Systems
 The logical topology is the way that the
signals act on the network media, or the
way that the data passes through the
network from one device to the next
without regard to the physical
interconnection of the devices.
Switching
 Circuit - A type of communications in which a dedicated channel
(or circuit) is established for the duration of a transmission.
 Message – establishes a connection between two devices,
transfers the info to the 2nd device, then breaks the connection.
 Packet - Refers to protocols in which messages are divided into
packets before they are sent. Each packet is then transmitted
individually and can even follow different routes to its destination.
Once all the packets forming a message arrive at the destination,
they are recompiled into the original message.
CSMA/CD
 Carrier Sense Multiple Access with
Collision Detection
 Set of rules determining how network
devices respond when two devices
attempt to use a data channel
simultaneously (called a collision)
 Standard Ethernet networks use
CSMA/CD
Ethernet Versions
 10Base2
 10Base5
 10BaseT
 100BaseT
 100BaseTX
 100BaseVG
 1000BaseX
10Base2
 The 10Base-2 standard (also called Thinnet) uses 50
ohm coaxial cable (RG-58 A/U) with maximum lengths of
185 meters.
 Ethernet over coaxial cable with a maximum distance of
185 meters. Also referred to as Thin Ethernet or Thinnet
or Thinwire.
10Base5
 The original cabling standard for Ethernet that
uses coaxial cables. The name derives from the
fact that the maximum data transfer speed is 10
Mbps, it uses baseband transmission, and the
maximum length of cables is 500 meters.
10BaseT
 10 Mbps baseband
100BaseT
 A networking standard that supports data
transfer rates up to 100 Mbps (100 megabits per
second). 100BASE-T is based on the older
Ethernet standard. Because it is 10 times faster
than Ethernet, it is often referred to as Fast
Ethernet. (100BaseTX & 100BaseT4)
1000BaseT
 A specification for Gigabit Ethernet over copper wire
(IEEE Std. 802.3ab). The standard defines 1 Gb/s
data transfer over distances of up to 100 meters
using four pairs of CAT-5 balanced copper cabling
and a 5-level coding scheme.
 Other 1000Base-T benefits include compatibility with
existing network protocols (i.e. IP, IPX, AppleTalk),
existing applications, Network Operating Systems,
network management platforms and applications.
Switched Ethernet
 An Ethernet LAN that uses switches to connect
individual hosts or segments. In the case of
individual hosts, the switch replaces the repeater
and effectively gives the device full 10 Mbps
bandwidth (or 100 Mbps for Fast Ethernet) to the
rest of the network.
Ethernet Frame Types
 802.2
 802.3
 Ethernet II
 Ethernet SNAP
802.2
 General standard for the data link layer in the
OSI Reference Model. The IEEE divides this
layer into two sub layers -- the logical link control
(LLC) layer and the media access control (MAC)
layer.
Preamble
8 bytes
Destination
address
Source
address
Length
2
bytes
LLC
FCS
46 – 1500 4 bytes
bytes
SSAP
1 byte
DSAP
1 byte
Control
Field
1 byte
802.3
 Defines the MAC layer for bus networks
that use CSMA/CD. This is the basis of the
Ethernet standard
Destination
address
Preamble
7 bytes
SFC
1 byte
Source
address
Length
2
bytes LLC
46 – 1500
bytes
FCS
4 bytes
Mau
 Multistation Access Unit
 a token-ring network device that physically
connects network computers in a star topology
while retaining the logical ring structure
 MAU is a special type of hub
 One of the problems with the token-ring topology
is that a single non-operating node can break
the ring. The MAU solves this problem because
it has the ability to short out non-operating
nodes and maintain the ring structure
Design Considerations for
Token Ring Networks
 Cabling
 Connectivity devices
 # of stations
 Speed
 Scalability
 Topology
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