Bus Network with Backbone Interconnections Between Different Network Types
Token Ring Network Topology Self-healing Ring TopologyTwo rings
Star Network Topology
Network Topology
FDDIDeveloped by the American National Standards Institute (ANSI) standards committee in the mid-1980s - at a time when high-speed engineering workstations were beginning to tax the bandwidth of existing LANs based on Ethernet and Token Ring - the Fibre Distributed Data Interface (FDDI) specifies a 100 Mbit/s token-passing, dual-ring LAN using fibre-optic cable.
Token RingIn 1984, IBM introduced the 4 Mbit/s Token Ring network. Instead of the normal plug and socket arrangement of male and female gendered connectors, the IBM data connector (IDC) was a sort of hermaphrodite, designed to mate with itself. Although the IBM Cabling System is to this day regarded as a very high quality and robust data communication media, its large size and cost - coupled with the fact that with only 4 cores it was less versatile than 8-core UTP - saw Token Ring continue fall behind Ethernet in the popularity stakes. It remains IBM's primary LAN technology however and the compatible and almost identical IEEE 802.5 specification continues to shadow IBM's Token Ring development.
EthernetEthernet was developed in the mid 1970's by the Xerox Corporation, and in 1979 Digital Equipment Corporation DEC) and Intel joined forces with Xerox to standardise the system. The Institute of Electrical and Electronic Engineers (IEEE) released the official Ethernet standard in 1983 called the IEEE 802.3 after the name of the working group responsible for its development, and in 1985 version 2 (IEEE 802.3a) was released. This second version is commonly known as "Thin Ethernet" or 10Base2, in this case the maximum length is 185m even though the "2" suggest that it should be 200m.
Fast EthernetFast Ethernet was officially adopted in the summer of 1995, two years after a group of leading network companies had formed the Fast Ethernet Alliance to develop the standard. Operating at ten times the speed of regular 10Base-T Ethernet, Fast Ethernet - also known as 100BaseT - retains the same CSMA/CD protocol and Category 5 cabling support as its predecessor higher bandwidth and introduces new features such as full-duplex operation and auto-negotiation.
Client-ServerClient-server networking architectures became popular in the late 1980s and early 1990s as many applications were migrated from centralised minicomputers and mainframes to networks of personal computers. The design of applications for a distributed computing environment required that they effectively be divided into two parts: client (front end) and server (back end). The network architecture on which they were implemented mirrored this client-server model, with a user's PC (the client) typically acting as the requesting machine and a more powerful server machine - to which it was connected via either a LAN or a WAN - acting as the supplying machine.
Peer-to-peerIn a Peer-to-peer networking architecture each computer (workstation) has equivalent capabilities and responsibilities. There is no server, and computers simply connect with each other in a workgroup to share files, printers, and Internet access. It is practical for workgroups of a dozen or less computers, making it common in many SOHO environments, where each PC acts as an independent workstation that stores data on its own hard drive but which can share it with all other PCs on the network.
P2P computingBy early 2000 a revolution was underway in an entirely new form of peer-to-peer computing. Sparked by the phenomenal success of a number of highly publicised applications, "P2P computing" - as it is commonly referred to - heralded a new computing model for the Internet age and had achieved considerable traction with mainstream computer users and members of the PC industry in a very short space of time.
The Napster MP3 music file sharing application went live in September 1999, and attracted more than 20 million users by mid-2000
Gigabit EthernetThe next step in Ethernet's evolution was driven by the Gigabit Ethernet Alliance, formed in 1996. The ratification of associated Gigabit Ethernet standards was completed in the summer of 1999, specifying a physical layer that uses a mixture of proven technologies from the original Ethernet Specification and the ANSI X3T11 Fibre Channel Specification:
Use of the same variable-length (64- to 1514-byte packets) IEEE 802.3 frame format found in Ethernet and Fast Ethernet is key to the ease with which existing lower-speed Ethernet devices can be connected to Gigabit Ethernet devices, using LAN switches or routers to adapt one physical line speed to the other.
FDDI- Fibre Distributed Data Interface specifies a 100 Mbit/s token-passing, dual-ring LAN using fibre-optic cable.
Network Topology
Self Healing Net – Dual Ring
WAN Introductions
• LAN (local area network) - Network that links computers, printers and other devices located in an office, a building or even a campus
• WAN (wide area network) - System that extends for greater distances and is used to connect LANs together.
Interconnections – To link LANs into a WAN
• DSL - Speeds up to a very fast 1.54 Mbps • T1- A digital transmission link with a total signaling
speed of 1.544 Mbps • T3 - Comprised of 28 T1 lines - 45 Mbps • OC1 - 51.85 Mbps • OC3 - 155.52 Mbps • Frame Relay - A telecommunication service
designed for cost-efficient data transmission for intermittent traffic between LANs and between end-points in a WAN
Key Components of a WAN I
• Access Router - the gateway devices connected to LANs
• WAN connections - the actual connectivity between sites
Key Components of a WAN II
• DSL (Digital Subscriber Line) – 1.54 Mbps – To delivers reliable, high-speed
office-to-office connectivity over
traditional copper wires – Affordable to most small businesses
• Security - Prevent any unauthorized people from accessing communications between sites
WAN (Real-World Example)
• Large architecture firm– 4 offices
• Portland, Seattle, Los Angeles, Washington DC– Reasons for implementing a WAN
• Share Internet connection• Access email• Transfer files• Foster the sense of one firm but four offices
The Past
• Frame Relay– Past to 2002– Hub-and-spoke topology
• Portland was hub• 64 Kbps, 128 Kbps, 256 Kbps to other offices
– Issues• Expensive• Inflexible• Requires routers which needed maintenance• No way to manage• Difficult to troubleshoot
The PastFrame Relay
Portland
768K
LocalTelco
768K
Frame RelayNon-Meshed
Los AngelesSeattle Washington D.C.
LocalTelco
256KLocalTelco
T1
LocalTelco
384K
Internet
256K
256K25
6K384K
T1
T1
T1
The Recent Past
• Leased Lines– 2002 to 2003– Time Division Multiplexed Leased Lines – 50% cost savings over Frame Relay
• Increased speed to 1.544Mbp for all offices
– Issues• Still hub-and-spoke• No more flexibility, just higher speeds and lower costs
The Recent PastLeased Line
Portland
T1 (Leased Line)T1 (Internet) Local
Telco
T1 (Internet)
Los Angeles
Seattle
Washington D.C.
LocalTelco
LocalTelcoT1 (leased line)
T1 (Leased Line)
T1 (Internet)LocalTelco
Internet
T1 (Internet)
T1 (Internet)
T1 (Internet)
Telco
T1 (Leased Line)T1 (Internet)
T1 (I
nter
net)
T1 (L
ease
d Li
ne)
T1 (Leased Line)T1 (Leased Line)
T1 (Leased Line)
The Present and Future• MPLS – Multi-Protocol Label Switching
– 2003 to Future– Fully meshed - 3 Mbps– Layer 2 label switching
• A label is added to the packet– Benefits
• QOS – Quality of Service• Complete control end-to-end• No IP routing so pre-defined path, no hops• Extend Ethernet• No routers• More secure• Cost savings• Converged network (voice, data, video)
The Present
9Mbps
3Mpbs
3Mbps
3Mbps
Public Internet
Public Switched TelephoneNetwork
Local / Long Distance
Videoconferencing
Portland
Seattle
Los Angeles
D.C.
Wide Area Network Provider
Partially converged MPLS Network
Local Telco
(PacBell)
Local Telco
(Verizon)
Local Telco
(Qwest)
isdn backup
isdn backup
isdn
back
up
isdn backup
The Future
10/100
10/10010/100
10/100
backup
backup
backup
backup
Public Internet
Public Switched TelephoneNetwork
Local / Long Distance
Videoconferencing
Portland
Seattle
Los Angeles
D.C.
Wide Area Network Provider
Fully converged MPLS Network (voice/video/data)
back
up
back
up
back
up
Metro Ethernet
MetroEthernet
MetroEthernet
MetroEthernet
Why not use a VPN?
• Issues– Quality, flexibility, management and ease of
use when compared to a private WAN– Internet is stable but not a priority in downtime
• Vendors cannot guarantee Service Level Agreements (SLAs)
– Requires advanced knowledge of IP Security (IPSec)
– Required special routers with VPN accelerators
WAN enhancement• Riverbed – Steelhead appliance
– Reduces the latency of the WAN• Latency is the reason why you don’t get your full bandwidth
– For example, 1.544 Mbps is actually 900 Kbps• TCP/IP has inherent limitations
– Reduces 87% of protocol overhead and unnecessary round-trips.
• Increasing bandwidth by 2.6 times– Uses special data sequencing to cache data and only send
across changes– Transaction prediction– Examples
• Users in DC connecting to Portland like LAN• Backup warm servers across the WAN and replicate the changes
– http://www.riverbed.com/
Enabling Mobile Users• Mobile Users and Wireless Technology: The Beginning
– Started with proprietary wireless technologies – Applied to Automated Data Collection years before 802.11a/b/g– 802.11b is still most common in industry– Small, hand-held wireless computing allow workers to work
throughout an entire plant or warehouse, collecting and receiving data real-time
– Referred to as Wireless Local Area Networking (WLAN)
• Wide Area Applications of Wireless Technology– IP Tunneling– Wireless Hops– Wireless Wide Area Networking (WWAN)
IP Tunneling: Roaming Across Networks
• What if users want to work wirelessly across multiple sites?– Could use DHCP and have wireless infrastructure installed at
each site– IP Tunneling can provide static IP addressing and session
persistence– Generally uses privately owned networks
IP Tunneling: Roaming Across Networks
• What is IP Tunneling?– IP Tunneling uses encapsulation to carry entire original packets
across a router using IP– The outer IP and other header information is then stripped and
the original packet is provided on the wired network– Mobile IP is a similar method, defined by TCP/IP– Most implementations require a client and/or server to manage– Our solution uses encapsulation and spanning tree to extend the
wireless network across routers– Allows roaming across subnets seamlessly
Wireless Hops:Extending Wired Networks
• Wireless Hops can connect and extend networks – Alternative to wired options for connecting buildings that are
100s of feet or even miles apart– Saves trouble and expense – Usually 802.11b’s range is a few hundred feet, but vendors use
high power directional antennas to extend significantly– Must have LOS (Line of Sight)
Wireless WANs
But…what if users need to work across a much wider geographic area such as a whole city, or even several states???
Wireless Wide Area Networks:Helping bring your favorite stuff to a store near you!
A well-known customer…
Wireless WANs• Some WWAN Fun Facts
– This technology allows route drivers to receive and transmit real-time data wherever they are (Earlier solutions involved batched data, sent by modem)
– Latest networks are shared use, packets-as-needed rather than circuit-based, making them cheaper
– Several providers…must match standard and provider– Must subscribe to provider’s service– Some interfaces use SIM cards for activation, just like mobile
phones– Basically a cellular technology – used for mobile phones as well– Limited bandwidths, speed depending on technology and
number of channels used– Similar to modem speeds: 14.4 Kbps to 114 Kbps– Some newer technologies promising 384 Kbps (EDGE)
Wireless WANs• Some Service Types
– Code-Division Multiple Access (CDMA) – Uses multiplexing, which allows numerous signals to occupy a single transmission channel
– General Packet Radio Services (GPRS) – Packet-based…used to provide data to phone and laptops
– Global System for Mobile communication (GMS) – Most widely used worldwide and is the de facto standard in Europe
– Enhanced Data GSM Environment (EDGE) – Newer faster service available since around 2001
Wireless WANs• WWAN Enables Mobile Users to:
– Download the day’s deliveries and orders– Enter new orders– Track inventory a store has on hand– Capture signatures– Print receipts– Run reports– Close out day
• Other Customers Include:– UPS– DHL– Blue Dart (Fedex)– Camera based device allowed real estate agents and appraisers
to collect property photos
Upgrade Fast WAN, More Storage
• SEC upgrades infrastructure• Increased traffic in imaging and optical
character-recognition files• System will handle 30 to 50 terabytes of
data in first year• 2 high-speed 45-Mbps pipes at every
office
Cisco, 3Com fire up new WAN routers
• Cisco faces more competition than ever • Complete refresh of enterprise WAN
access routers for 2004• Addresses security concerns/
obsolescent technology• will combine VoIP, VPN, firewall and
intrusion-detection system (IDS) support
Start-up crams more data onto WAN
• Orbit boosts throughput on WAN connections 10 times over TCP
• TCP can lead to throttled-back connections, Orbit uses a feedback mechanism to use full network connection
• Sold in pairs with one at each end of a WAN link• Pricing ranges from $12,000 for T-I throughput to
$50,000 for 200M bit/sec throughput
VoIP for Global Companies
• Potential saving of 95%, VoIP averages 2 cents per minute
• International long distance rates average 53 cents per minute
• International teleconferencing rates average 20-35 cents per minute
• Three year window of opportunity
How some rural communities are installing high-speed Internet connections
• Cable franchises are not interested in wiring rural areas for broadband
• 70 small communities are bridging the digital divide on their own
• Kutztown PA, spent $5 million to bring residents cable TV, telephone and Internet service
• Fiber-optic lines connect the entire town to the internet; costs is less than half that of private carriers