Brief history, WANs, LANs Examples Issues Cabling. Miscellaneous Network Info. WAN – Wide Area Network. Connect geographically separate networks ATM has played an important part in WAN (not LAN). LAN. LAN. WAN. LAN. LAN. WANs started with telephone (analog) lines.
Needed to send digital data over analog lines.
Wanted to use digital lines (e.g. FR, ATM) instead.
Wiring was a big problem!
36/64/128 serial ports (local or dial)
IEEE 802.3 or ethernet (DEC, Xerox, Intel)
IEEE 802.4 token bus (General Motors)
IEEE 802.5 token ring (IBM)
Random access vs. deterministic approach
Hardware and cabling
Applications and protocols
IBM started building structured cabling plants.
Devised a better copper cable so got reasonable distance for digital info.
CAT 5 was a major innovation - at every jack guaranteed to work to 300 ft (100 m).
Future is fiber optic (cost still high).
Traffic Collapses to the Core
Core is ATM (OC3)
Each floor in each building has a switch
To building floor
10BaseT – 10 Mbps
Spanning tree is in silicon.
Every port has spanning tree running on it.
Others don’t see conversation between ports.
In switched ethernet, every port is its own ethernet.
Virtual LANs, VLANs, were important in switches
Not physically connected as a LAN.
HW can be programmed so each port belongs to a VLAN
(All belong to the same collision domain)
So all on VLAN see the ethernet packet.
(e.g. ISDN lines go down if no activity so may get errant message, then need to actively send traffic on line to check). Need to avoid storms.
Found in telephone applications, ethernet. Form of wiring in which two
conductors are wound together to cancel out electromagnetic interference
from external sources and crosstalk for neighboring wires.
Category 1 Voice Only (Telephone Wire)
Category 2 Data to 4 Mbps (LocalTalk)
Category 3 Data to 10 Mbps (Ethernet)
Category 4 Data to 20 Mbps (16 Mbps
Category 5 Data to 100 Mbps (Fast
Some hubs have an uplink port. Straight through can be used between uplink port of hub and regular hub port.
If UTP port on switch is MDI/MDI-X (Medium Dependent Interface), either can be used to connect to another
Uses standard connector (FC, SC, ST, LC, MTRJ)
A 15 pin physical connector interface between a NIC and an Ethernet cable
DSU/CSU – Data Server Unit/Channel Service Unit
DSL Digital Subscriber Line (same cable as telephone)
T1 1.5 Mbps ~$800/month
T3 2nd fastest non-optical 45 Mbps ~15K/month
SONET Synchronous Optical Networking uses laser or light emitting diodes/LEDs to send digital info
OC3 155.52 Mbps Optical size of largest Internet backbone provider
OC12 fiber optic net 621.84 Mbps, smaller backbones
OC48 2488.32 Mbps/2.4 Gbps (48x basic SONET signal 51.84 Mbps)
OC192 as of 2005 only large ISPs 9953.28 Mbps
802.11b 11 Mbps
802.11g 54 Mbps
Cable 10 – 20 Mbps ~$100/month
Satellite slower than DSL or cable
Broadband intranet access > 56K dialup with cable modem and fiber optic
10 Gigabit ethernetMiscellaneous Technologies