1. Physical & Data-link
ISQS 6343 #2
John R. Durrett

2. Media Access Methods Most important choice is MAC Drives:
cable installed
performance, cost, reliability
IEEE 802 series standards
Frame layout:
Mac head | LLC head | IP | TCP | data | CRC
ARCnet (obsolete)

3. Token Ring Pros: Cons: Details: fast, reliable well supported by IBM
expensive, not widely accepted
Details:
token-based
physical: star or bus, logical: bus
IEEE 802.5
STP, Coax, Optic fiber, UTP

4. Ethernet Bob Metcalfe CSMA/CD Carrier Sense - used/idle
Multiple Access - equal right to access
baseband - one transmission at a time
Collision Detection
Physical: star, Logical: bus

5. High-Speed Ethernet Full Duplex 100BaseT 100VG new hubs, etc.
UTP, STP, Fiber
Round Trip delay == limits cable length
100VG
demand priority
four pairs Cat 3

6. High-Speed Ethernet

7. Other High-Speed MAC
FDDI
Fiber
Backbone
CDDI
ATM

8. Network Cabling Circulatory system of network
Documentation (BA slides)
Installation very labor intensive
ANSI/TIA/EIA 568 & 569
generic voice & data standards
multi-vendor
performance & technical criteria
Media, Topology, Distances, Interfaces, Hardware, Performance

9. Topologies Physical - way components are connected
Electrical - how functions as a circuit
Logical - way system functions as a whole
Bus
ends terminated
simple to run, hard to fix
Star
hub=based, main choice
Ring
like bus but no termination

10. Cabling Coaxial Thick net (Ethernet 10B5) Thin net (Ethernet 10B2) STP
UTP (dominates LANs)
10BT, IEEE 802.3
4 pair up / cable
Cat 3, 4, 5
distance & signaling rate
100m total/client
Electrical interference
Fiber

11. Network Interface Cards
Maintain consistency
in every network device
physical: electrical connection
data-link: assembles frames
media dependent
MAC dependent
Protocol independent
Bus type, configuration, remote boot, client Vs. server

12. Repeaters Clean-up, amplify, rebroadcast physical layer
media dependent
protocol independent
all other active network components contain repeater functionality

13. Hubs Concentrators Multi-port repeaters Standalone Vs. stackable
Manageability

14. Bridge Data-link layer frame-based media dependent
higher protocol independent
physical address of source & destination part of frame header
Listens for “outbound” address

15. Router Media independent higher protocol independent
packet headers used for logical addresses
More complex decisions than hubs
Network layer
routable upper-level protocol

16. Gateways Translation at 1 or more layers
Most common at upper three layers
Ex: SMTP to MHS

17. Switch Broadcast Vs. virtual circuit Store-and-forward cut-through
error checking
filtering
security
cut-through
speed
Virtual LANs