Chapter 1 Section 2: Network Edge
Radio Link: Wide-Area
Cellular, 3G. Few Mbps
Frequency Division Multiplexing:
Difference Channels Transmitted in different frequency band
Coaxial Cable
Two Concentric copper conductors Bidirectional Broadband: Multiple Channels on Cable. HFC
Enterprise Access Networks (Ethernet)
Usually has a "Ethernet Switch" that is connected to the Institutional Link to ISP which is then connected to the Institutional Router and then connected to Institutional Mail & Web Servers
Access Net Home Network
Usually has a "wireless access point" that is connected a "router" that sometimes contains a firewall or NAT. (Sometimes a Wireless access point & Router are combined into one box).then the router is connected to the cable or DSL Modem, and from there the connection goes to & From Headend or Central office
Physical Link:
What lies between Transmitter & Receiver
Wireless LANs
Within Building (100ft) 802.11b/g (Wi-Fi):11,54 Mbps Transmission Rate
Q: How to Connect End Systems to Edge Router?
*Residential Access Nets *Institutional Access Networks (School,Company) *Mobile Access Networks (3G, 4G: LTE, Cellular) Also Bandwidth (bits per second) of access network? will it be shared or dedicated?
DSL Rates
< 2.5 Mbps Upstream Transmission rate (typically < 1 Mbps) < 24 Mbps Downstream Transmission Rate (typically < 10 Mbps)
(HFC) Hybrid Fiber Coax
Asymmetric: Up to 30 Mbps Downstream Transmission rate, 2 Mbps Upstream Transmission rate
Cable Headend
Cable Modem Termination System
Fiber Optic Cable
Glass Fiber carrying light pulses. each pulse a bit. High Speed Operation,Low Error Rate
Network Edge
Hosts: Clients and Servers Servers are often in Data Centers
Network Core
Interconnected Routers, Network of Networks
Radio Link: Satellite
Kbps to 45 Mbps Channels (or Multiple smaller channels) 270 msec end-end delay geosynchronous versus low altitude.
Packet Transmission Delay
L (Bits) ____________________ R (Bits/Sec
Bit
Propagates between Transmitter/Receiver Pairs
Access Networks,Physical Media
Wired, Wireless communication links
Fiber Optic Cable Low Error Rate
Repeaters spaced far apart. immune to electromagnetic noise
Category 6
10 Gbps
Enterprise Access Networks (Ethernet) Transmission Rates
10 Mbps 100 Mbps 1 Gbps 10 Gbps
Category 5:
100 Mbps, 1 Gbps Ethernet
Radio
Signal Carried in electromagnetic spectrum no physical "wire" Bidirectional propagation environment effects: Reflection Obstruction by objects Interference
Unguided Media
Signals propagate freely. Radio
Guided Media
Signals propagate in solid media. Copper, fiber, coax
Packets Length L Bits
Smaller chunks of Data all a part of an Application Message
DSLAM
DSL Access Multiplexer
DSL Phone Line
Data over it goes to Internet. Voice over it goes to Telephone net
Fiber Optic Cable High Speed Operation:
High speed point to point transmission.ex: 10's-100's Gbps transmission rate
Access Network
Is a Network which connects Subscribers to their Immediate Service Provider
Link Bandwidth
Link Transmission Rate, aka Capacity
Cable Network #2
Network of cable or Fiber that attaches to homes to ISP Router
Wide-Area Wireless Access
Provided by Telco (Cellular) Operator, 10's km Between 1 and 10 Mbps 3G, 4G:LTE
Twisted Pair (TP)
Two insulated copper wires
Radio Link: Terrestrial Microwave
Type of Radio Link that can go Up to 45 Mbps Channels
Radio Link: LAN
Type of Radio Link that is known as Wi-Fi. 11 Mbps, 54 Mbps
Enterprise Access Networks (Ethernet) #2
Typically used in companies,universities, etc. today end systems typically connect into Ethernet switch
Digital Subscriber Line (DSL) #2
Uses existing telephone to the Central Office(s) DSLAM. Has a splitter within the residence to separate frequencies to DSL Modem and Telephone
Digital Subscriber Line (DSL)
Voice and Data transmitted at different Frequencies over Dedicated line to central office
Cable Network
data, TV transmitted at different frequencies over Shared cable distribution network
Transmission Rate R
transmits packet into Access network At
