Networks and IP Networking
1/14/2009
Hello Class!
Protocols and Network Management, INLS 578
- Me
- PhD, Internet Service Management (network management)
- Associate Director, UNC Networking
- You
- What do you want to learn in this class?
- UNC Basketball for Spring 2009
- 1/21 Clemson 9pm
- 1/28 at Florida State 9pm
- 2/11 at Duke 9pm
- 2/18 NC State 8pm ... ticker?
- 3/4 at Va Tech 7pm
Routine
- Homework
- about every other class until project really kicks in
- Project
- SNMP + packet capture + analysis
- Final Exam
- Break
- Questions
- Guest Lectures
- "Office Hours"
- send me email (
hope)
- dinner before class, kids after
Network Definition
A network is a set that can share information.
Node or end station, cable, network equipment.
Network Types
circuit-switched (PSTN, ISDN, ATM)
packet-switched
fractal, bursty
Network Topology
mesh
bus
ring
double ring
tree (graph) ... 
star ... 
snowflake ... 
spaghetti
- Physical
- Data Link
- Network
- Transport
- Session
- Presentation
- Application
Layer Model
- each layer n can put a wrapper, an envelope, on the message from layer n+1
- wikipedia has different examples
- more layers
Network Devices
a hub is a "multi-port repeater"
max of 2 repeaters between any pair of nodes following the 5/4/3 rule
keeps SAT (source address table of MACs seen in last 5 minutes)
drops any oops
aka gateway
Network devices: hubs vs switches
divide, multiply
which one scales to a large network?
Network Domains
collision domain: bounded by bridge/switch/router (each switch port has its own)
broadcast domain: bounded by router (?)
Data Elements
a fundamental data unit (like an atom in chemistry) is a packet
over Ethernet or modem, a frame
over ATM, a cell of 53 bytes (committee)
datagram is self-contained
over TCP, a segment
Vocabulary Groups
- in-band managment vs out-of-band management
- bit, nybble/4 bits, byte/octet/8 bits, word/2 octets
- unicast, multicast, broadcast
- full duplex, half duplex, simplex
Network Performance
latency: fixed (speed of light), procedural (nodes), processing (network devices), queuing, routers
jitter (path, packet complexity, queues), buffer
time-centric: latency, jitter
- bandwidth
- throughput
- packet loss
packet-centric: bandwidth, throughput, packet loss
all measures are dependent on others because of device queues
don't measure latency when there's packet loss (just measuring queue depth)
can't optimize latency without impacting packet loss
queuing schemes: FIFO, round robin (SFQ, CBQ)
queuing schemes: tail drop, drop preference/eligible, random early drop
Why Ethernet and IP?
98%
98% of all networks run IP over Ethernet, that's why
IP Networking
- History
- ARPA, Fall 1968, expensive computers
- first transmission October 29, 1969
- ARPANET decommissioned 1990
- Cost-Effective Ethos
- best-effort
- decentralized
- distributed (*-mesh) vs centralized (single root) vs decentralized (in-between)
- dumb core, smart edge
Ethernet
- IEEE 802.3
- CSMA/CD - Carrier Sense Multiple Access with Collision Detection
round-trip time, inter-frame gap 9.6 µs for 10 Mbps and 0.96 µs for 100 Mbps, original ran at 2.94 MHz
10BaseT - speed in Mbps, baseband, twisted pair 100 m distance limit
Wireless is NOT Ethernet
- CSMA/CA - Collision Avoidance
- wireless vs wired
20% overhead to shared-medium, and half-duplex ...
...so 802.11b wireless at 11 Mbps actually compares as 4.4 Mbps to 100 Mbps Ethernet
