Internet overview
end systems, clients, servers
design philosophy "keep complexity at the edges"
connectionless service eg UDP
connection-oriented service eg TCP
circuit switched network
TDM
FDM
virtual circuit vs packet switching
circuit ids
addressing at link, network
physical media
guided (ethernet), broadcast
(wireless)
Layered architecture and protocols: Application,
transport, network and link
demultiplexing to layer above
network access-- ISP, DSL, HFC (cable)
ISP's and Backbone (tier 1, tier2,
tier 3)
packet delay--processing queueing, transmission (L/R)
Application Layer
transport layer services
http-- browsers, web servers
stateless server
persistent, nonpersistent
pipelining
ascii fields
cookies
Web Cache (proxy Server)
"if
modified since" problem
FTP
clear text authentication
out of band control
E-mail
user agent, mail server
text is 7-bit ascii
MIME
protocol between servers
SMTP
protocol between user agent and
server
IMAP and
POP3, web browser
DNS
host name, domain, IP address
host aliases and cononical name
root servers
Top Level Domain (TLD)
authoritative servers
caching
iterative vs. recursive domain name
look up
P2P
how it works
central
directory (Napster)
overlay
network
sockets--TCP, UDP, port numbers
active vs. passive open
Transport Layer
possible services: reliable, full duplex, guaranteed
bandwidth, security,
network layer services upon which transport layer is built
multiplexing and demultiplexing
UDP--segments and checksum
Reliable data transfer GBN, Selective repeat
TCP
connection
protocol
segments
flow control
Congestion control
3-way handshake: syn and ack
tragedy of commons
reliable data transfer protocols (FSM diagrams)
acks, naks, sequence numbers, timers,
cummulative ack, piggyback, lost packet and or currupt packets
stop and wait
alternating bit
go back n
selective repeat
link utilization-- keep pipe full
sliding window and flow control
Set timer by estimating round trip time RTT with weighted averages,
estimating deviation
TCP congestion control:
congestion window
triple ack
fast retransmit
additive increase multiplicative
decrease
slow start, fast recovery
Network Layer
end host to end host delivery best effort
forward, routing
typically, one ip address per router (or host) interface
virtual circuits with ATM and X.25
CIDR--classless inter domain routing
subnet address
routing with max prefix match
ICANN
DHCP
NAT
Hosts are known to outside world by
router's address
problem with servers and connection
reversal
strategy for managing translation
table
router hardware
line speed procesing
content addressable memory
switching fabric, input port queueing
switching by 1 cpu, by bus, by cross
bus
IPv4 and IPv6 addressing, differences
fragmentation
checksum
address sizes
transition
problems, dual stack
tunneling
ICMP,
runs on IP
ping
traceroute
fragmentation MTU (max transmission
unit),
time to live TTL
routing algorithms
link-state
distance vector
count to
infinity
poisoned reverse
broadcast and multicast
n-way unicast
flooding
reverse path forward RPF
minimum spanning tree
IGMP
Link Layer
adapter hardware services
hardware address
media access protocol
error detection and correction
parity and checksums
2 dim parity
CRC
Mod 2
arithmetic, polynomial representation of bit pattern
polynomial
remainder
sharing channels among multiple protocols Appletalk, Decnet,
IP
framing
Slotted Aloha
efficiency
Aloha
CSMA/CD carrier sense multiple access/collision detection
token rings FDDI
link layer addressing
MAC and ARP
DHCP details
Ethernet
CSMA/CD
Hubs and switches and routers
how switches learn to forward or drop and detect cycles
cut through switches
PPP
byte stuffing
Wireless and Mobile Networks
CDMA
Wi-Fi and 802.11 and CSMA/CA (collision avoidance
and why)
access points
beacon
frames, SSID
reservations, RTS request to send and
CTS clear to send
4 MAC address fields in frame
moblility -- mobile IP
home agent, foreign agent and COA
indirect routing
direct routing and anchor agent
Security
confidentiality, authentication, integrity and nonrepudiation
denial of service
Cryptography
plain text, cypher text
public key encryption RSA
symmetric key --DES 3DES, AES
Authentication protocols that don't, and do work (with a
nonce)
playback attack
Digital Signatures
Message Digest MD5, properties of adequate message digests
Key Distribution and certification
Certification authority
KDC (Key Distribution Center)
firewalls
filters on port and Ip source and
destination
filter TCP traffic with ack bit 0
filter ICMP traffic
Application gateways--mailservers,
HTTP servers, Web Cache
Attacks
mapping with ping
port scanning
packet sniffing and detection of same
Ip spoofing, ingress filter
Denial of Service (DOS)
DDOS
Smurf attack
TCP connection hijack
Email security and PGP
SSL
IPSec
802.11 Wired Equivalent Privace (WEP)