Announcements:
Review #1: List two advantages of a T-Carrier?
Review #2: Is a T-carrier a physical medium or a service (at what layer of the OSI model does the T-carrier live?
Review #3: Compare and Contrast Channelized and Unchannelized T1 lines.
- LAN Topologies
- Star Topology
- All stations attached to one common point
- Advantages:
- Most common topology in use today
- Ring Topology
- All stations are repeaters in a closed loop (NIC)
- Unidirectional
- Disadvantages
- Used for Token Ring and FDDI LANs.
- Bus and Tree Topologies
- All workstations connected to a single length of cable
- No stations are repeaters
- Bus/backbone must be terminated
- Topology Summary
- Topologies only represent cable plant (physical vs. logical)
- Topologies are commonly intermixed
- No specific topology for any one LAN
- Wiring Systems
- Metrics:
- speed=>how fast can it transmit?
- repeaterless distance=>distance before a repeater is needed(max segment length)
- security=>can it be tapped or not?
- method of access=>device required for access
- cost=>cheap/expensive
- robustness=>durability;
- Cable Naming Conventions
- Thick Coax
- ThinNet (Thin Coax)
- Unshielded Twisted Pair (UTP)
- Fiber Optic
- The Ethernet Standard
- History
- Developed at Xerox PARC in 1972.
- Addresses only layers 1 and 2 of OSI
- =d>Multi-access, packet-switched communications system for carrying digital data among locally distributed computing system.
- Three Functions of Ethernet
- Transmit and receive packets
- Decode packets and check address validity before handing off to higher layers
- Error detection within packet
- Ethernet Defined
- Ethernet Transmission
- CRC=>
- Media Access Control
- Collision Detection
- Ethernet Reception
- Promiscuous Mode Reception
- Token Ring
- Topology is ring or star-wired ring
- Parts
- Multistation Access Unit
- Operation
- Connectors
- 4 Types:
- Universal Data Connector (UDC)=>old style; used for STP
- RJ-11 (4-pin)
- RJ-45 (8 pin)=>Used with aUTP
- DB-9=>9 pin connector shaped like a D. Only 4 pins are used. STP or UTP application.
- Cable Plant
- Shielded Twisted Pair (STP)
- Category 4 or 5 Twisted UTP
- Data Link Layer
- Responsible for:
- Frame Fields (9) for Token Ring
- Field 1: Starting Delimiter (SD)
- Field 2: Access Control (AC)
- Field 3: Packet (Frame) Control=>Tells receiving station whether or not frame contains data or maint. Controls for network
- Field 4: Destination Address (DA)=>Physical address of destination device
- Field 5: Source Address (SA)
- Field 6: Information=>payload
- Field 7: Frame Check Sequence=>runs CRC on fields: FC, DA, SA, and Information fields
- Field 8: Ending Delimiter (ED)
- Field 9: Frame Status (FS)=>status of error checking and provides some duplicate error checking
- FDDI
- Overview
- Physical Layer
- Cable Plant
- Connectors
- FDDI Port Types
- Data Link Layer
- Data Delivery
- FDDI Uptime
- FDDI Timers
- Other LAN Hardware
- Hubs
- Active
- Passive
- Bridges=>
- LAN Switch=>
- Routers
- Gateways
- LAN Internetworking
- =>networking (connecting) two or more LANs
- Via MANs and WANs
- Internetworking Protocols
- TCP
- =>transmission control protocol
- IP
- =>internet protocol
- Virtual LANs
- =>software defined LANs, via an intelligent hub or Switch