Download Define the Circuit Switching, Message Switching, and Packet

1. Describe the Circuit Switching, Message Switching, and Packet Switching methods of
network communication.
2. Describe the three communication types of Unicast, Multicast and Broadcasting.
3. What are the Key Features of a Protocol?
Set of rules or conventions to exchange blocks of formatted data
Syntax: data format
Semantics: control information (coordination, error handling)
Timing: speed matching, sequencing
4. Describe the router functions in an internetworking environment.
Routers
Provide link between networks
Accommodate network differences:
Addressing schemes
Maximum packet sizes
Hardware and software interfaces
Network reliability
Timing: speed matching, sequencing
5. What is the function of Checksum Field in a TCP header?
Applied to data segment and part of the header
Protects against bit errors in user data and addressing information
Filled in at source
Checked at destination
6. How the next generation IPv6 improves
IPv4 Options
Security
Source routing
Route recording
timestamping
IPv6
Increase IP address from 32 bits to 128
Accommodate higher network speeds, mix of data streams (graphics,
video, audio)
Fixed size 40-octet header, followed by optional extension headers
Longer header but fewer fields (8 vs 12), so routers should have less
processing
IPv6 Header
Version
Traffic class
Flow label
Payload length
Next header
Hop limit
Source address
Destination address
IPv6 Addresses
128 bits
Longer addresses can have structure that assists routing
3 types:
Unicast
Anycast
multicast
7. Briefly describe the Circuit-Switching and Packet-Switching techniques, and list the
advantages and disadvantages of Packet-Switching Networks
Circuit-Switching
Long-haul telecom network designed for voice
Network resources dedicated to one call
Shortcomings when used for data:
Inefficient (high idle time)
Constant data rate
Packet-Switching
Data transmitted in short blocks, or packets
Packet length < 1000 octets
Each packet contains user data plus control info (routing)
Store and forward
Packet-Switching Networks
Basic technology the same as in the 1970s
One of the few effective technologies for long distance data
communications
Frame relay and ATM are variants of packet-switching
Advantages:
Flexibility, resource sharing, robust, responsive
Disadvantages:
Time delays in distributed network, overhead penalties
– Need for routing and congestion control
8. How the Frame Relay Networks varies from packet-switching technique? Describe the
Frame Relay Architechure and LAPF core.
Frame Relay Networks
Designed to eliminate much of the overhead in X.25
Call control signaling on separate logical connection from user data
Multiplexing/switching of logical connections at layer 2 (not layer 3)
No hop-by-hop flow control and error control
Throughput an order of magnitude higher than X.25
Frame Relay Architecture
X.25 has 3 layers: physical, link, network
Frame Relay has 2 layers: physical and data link (or LAPF)
LAPF core: minimal data link control
Preservation of order for frames
Small probability of frame loss
LAPF control: additional data link or network layer end-to-end functions
LAPF Core
Frame delimiting, alignment and transparency
Frame multiplexing/demultiplexing
Inspection of frame for length constraints
Detection of transmission errors
Congestion control
9. Describe the ATM Protocol Architecture and list it’s three planes Protocol Model
ATM Protocol Architecture
Fixed-size packets called cells
Streamlined: minimal error and flow control
2 protocol layers relate to ATM functions:
Common layer providing packet transfers
Service dependent ATM adaptation layer (AAL)
AAL maps other protocols to ATM
Protocol Model has 3 planes
User
Control
management
10. What are the ATM’s Service Categories and VPC/VCC Characteristics?
Service Categories
Real-time service
Constant bit rate (CBR)
Real-time variable bit rate (rt-VBR)
Non-real-time service
Non-real-time variable bit rate (nrt-VBR)
Available bit rate (ABR)
Unspecified bit rate (UBR)
Guaranteed frame rate (GFR)
VPC/VCC Characteristics
Quality of Service (QoS)
Switched and semi-permanent virtual channel connections
Cell sequence integrity
Traffic parameter negotiation and usage monitoring
(VPC only) virtual channel identifier restriction within a VPC