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Network models (Benefit of using layer model (Less complex, break into…
Network models
Benefit of using layer model
Less complex, break into smaller parts
Standard interfaces, allow vendors create products/multifunction products
Easier ro learn/discuss
Easier to develop
Multivendors interoperability
Modular engineering, write software independently
provide
language to discribe networks
Mental tools
Use RFC: Request For Comments
to avoid duplicate work
searchable in online searching engine
TCP/IP: Transmition Control Protocol/ Internet Protocol
4-5 Layers
1 Link (old-RFC 1122)
Data link (new)
Protocols
Ethernet
Format: [Ethernet header + IP header + TCP header + HTTP header (if SEQ = 1) + data + Ethernet trailer]
called frame
trailer: [FCS 4 bytes]
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data 46-1500Bytes
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header: [Preamble 7Bytes + SFD 1Byte + Destination (MAC) 6 Bytes + Sourse (MAC) 6Bytes + type 2Bytes]
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LAN: Local Area Network
coonect with WAN throw
Typical LANs
SOHO: Small Office/Home Office
Enterprise Network
2 more items...
Define wired LAN technology only
Devices required
3 more items...
Standards begin with 802.3
Nowaday
can build one LAN use both technology
Wirelss LAN connections
2 more items...
Sending logic
Full Duplex
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Half Duplex
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Config by engineer not by Hub itself
between any connections to Hub
WAN: Wide Area Network
Devices required
Router
Leasing
CPE: Custom Premises Equipmenst
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from telco's router to customer's router
1 more item...
Routing logic
PC encapsulate packet into Ethernet frame then send to Router
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SP: Service Providers
provide
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Internet
Way to access
4 more items...
is a large/global WAN
contain many LANs
Internet Protocol is core layer
Internet Core is LANs + WANs own by Internet SP (ISP)
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Standards
Define
Way to send data throw aa particular type of cabling/particular speed
Protocols
Rules
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Cabling
Glass fiber
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Copper
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Types
Gigabit Ethernet
1000BASE-T
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1000BASE-LX
3 more items...
1000Mbps
1000BASE-ZX
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Ethernet
10BASE-T
2 more items...
10Mbps
Fast Ethernet
100BASE-T
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100Mbps
10 Gig Ethernet
10GBASE-T
1 more item...
PPP: Point to Point Protocol
Physical (new)
#
transmit bits over electrical circuits
also call
network access
network interface
2 Network (old-RFC 1122)
Internet (new)
Protocols
IP: Internet Protocol
#
forward packets
version
IPv4
IPv6
routing by compare destination vs near by IP then forward packets
Format: [IP header (sourse + destination) + TCP header + HTTP header (if SEQ = 1) + data]
called Packet
3 Transport
Protocols
TCP
Error recover
use SEQuences number to mark order of file
check missing sequences
request for missing sequences
more common than UDP
Format: [TCP header (SEQ) + HTTP header OK (if SEQ = 1) + data]
called Segment
UDP: User Datagram Protocol
4 Application
protocols
HTTP: HyperText Transfer Protocol
pull contents from a web server
sent request and receive files corresponding
send GET xyz.htm
receive header OK + Data xyz.htm
return code 200
not found
return code 404
web address
real web address in IP
http - mean HTTP is used
http://0.0.0.0
or
http://website.abc
people see
URL: Uniform Resource Locators
URI: Universal Resource Identifiers
Format: [HTTP header + data]
POP: Post Office Protocol
SMTP: Simple Mail Transfer Protocol
so on ...
Provide services apps need
Interactions
Same-Layer
same layer between computers
to communicate
use header
Adjacent-Layer
Layers in a same computer
work together
lower layer provide services to above layers
Encapsulation + addressing
encapsulate app's data with required App Layer header
then encapsulate with Transport Layer header
then encapsulate with Network Layer header
then encapsulate with Data Link Layer header + trailer
transmit bits and decapsulate
repeat again
called
TCP: Segment
Network: Packet
Data Link: Frame
OSI: Open System Interconection
7 layers
1 Physicsal
#
Devices
Cables
UTP <duplicate>
LAN hub
LAN repeater
Define (by IEEE)
Devices/characters
Hub
Switch
Pin
use of pins
Light modulation
Connectors
so on...
everything else to create an Ethernet LAN
Method of moving data between systems/computers
Protocols
#
RJ-45
2 Data link
#
NIC: Network Interface Card
ROM on this card
MAC: Media Access Control address (MAC-48)
48 bits
never share same MAC address
company makes NICs contact to Institute Electrical n Electronic Engineers (IEEE) to request blocks of MAC
display in 12 hexcaracter (4 bits each)
first 6 digits represent for manufacture
last 6 digits is
device ID
check by type: ipconfig/all in cmd
also call: EUI-48: Extended Unique Identifier
Data flow
NICs on the same network must use same frame type
hub copy frame from network and send to all NICs is connecting to it, right NIC will keep, else delete that frame
Frame <duplicate>
ask for other MAC
send
broadcast
frame: to FF-FF-FF-FF-FF-FF + data contain request for MAC
receive by all NICs connected
requesting computer use IP to pick the target
Define
Protocols
Ethernet <duplicate>
to delivering data over physical network
HDLC <duplicate>
Devices
LAN switch
Wireless access point
Cable modem
DSL modem <duplicate>
3 Network
#
Define
Logical addressing
Routing (forwarding)
Protocols
IP <duplicate>
4 Transport
#
Error recovery
Define
Protocols
TCP <duplicate>
UDP <duplicate>
Devices
Router
5 Session
#
Method
Group multiple bidirectional messages into workflow
Backout if work flow fails
Define
#
6 Presentation
#
#
Negotiate data formats
ASCII texts
JPEG images
so on...
Define
#
7 Application
#
Provide interface from app to network
Define
Protocols
Telnet
HTTP <duplicate>
FTP
SMTP <duplicate>
POP3 <duplicate>
VoIP
SNMP
Devices
Hosts
Firewalls
Encapsulation
Encapsule data with App Layer header
then encapsulate with Presentation Layer header
then encapsulte with Session Layer header
then encapsulate with Transport Layer header
then encapsulate with Network Layer header
then encapsulate with Data Link Layer header
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called
LxPDU: Layer x Protocol Data Unit