Class01

as slideshow

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

Networks

Network Definition

wikipedia

A network is a set that can share information.

Node or end station, cable, network equipment.

Network Types

Connection-oriented

circuit-switched (PSTN, ISDN, ATM)

Connectionless

packet-switched

fractal, bursty

Network Topology

mesh
bus
ring
double ring
tree (graph) ... star ... snowflake ... spaghetti

The Seven-Layer Model

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

repeater / hub
- wikipedia on 5/4/3 rule ...

a hub is a "multi-port repeater"

max of 2 repeaters between any pair of nodes following the 5/4/3 rule

bridge / switch

keeps SAT (source address table of MACs seen in last 5 minutes)

drops any oops

router

aka gateway

definitions in RFC 1242

Network devices: hubs vs switches

shared or switched?

divide, multiply

which one scales to a large network?

Network Domains

collision

collision domain: bounded by bridge/switch/router (each switch port has its own)

Layer 2

broadcast

broadcast domain: bounded by router (?)

Layer 3: LAN, VLAN, WAN

Data Elements

packet

a fundamental data unit (like an atom in chemistry) is a packet

frame

over Ethernet or modem, a frame

cell

over ATM, a cell of 53 bytes (committee)

datagram (RFC 1594)

datagram is self-contained

segment

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

latency: fixed (speed of light), procedural (nodes), processing (network devices), queuing, routers

jitter

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 盜 for 10 Mbps and 0.96 盜 for 100 Mbps, original ran at 2.94 MHz

Charles Spurgeon's Ethernet Site

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

Homework

Yes, really!
Please fill in this form.
Skim 12 Internet Myths, a fun read, to get you thinking about the right issues.