04 Mobile+Internet+Part+1

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Chapter 8, secs 8.1,8.2

Wireless LANs, 802.11, and WiFi

Part 2

Resources Folder in Sakai:

Protocols-reading.pdfIP-reading.pdf

Outline

Network Layer

Protocols and Internetworkin

IP version 4

Address Exhaustion

IP version 6

McNair, Sp13 EEL 4930: Wireless and Mobile Networks 2


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Network Layer

1. Manages Global Connections

b) Datagram and virtual circuit networks Routing

2. Manages Global addresses

(e.g., telephone number or IP address)

a) The IP Address

b) IP Address assignment

c) Address resolution

d) Address exhaustion / Making the IP Address Las

(subnets, supernets, network address translation)

3. Manages Global Packet Delivery

a) IP v4 or v6 Packets

b) Fragmentation and Reassembly

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Protocols and Internetworking

Node D

IP addr:Router X

Node A

IP addr:

MAC addr:

Node B

IP addr:

MAC addr:

Node C

IP addr:

MAC addr:

Node E

IP addr:

MAC addr:

A a r:

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Internetworking:

Sending a Packet from Node A to Node E

Node D

IP addr:

MAC addr:Router X

Node A

IP addr:

MAC addr:Router Y

IP addr:

MAC addr:

Node C

IP addr:

MAC addr:

Node E

IP addr:

MAC addr:

Node A (Source) operation.Determine if destination

address is in the current

Router X operation.LAN headers are strippedIP address obtainedRouting decision is made.IPdata ram is ut in X.25

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.

If destination is in a

different destinationnetwork, a router is chosen

(Router X).

Put IP datagram in MAC

frame and send to Router X.

packet and sent to Router Y.

Router Y operation.X.25 headers are strippedIP address obtainedRouting decision is made.IP datagram is put in MACframe and sent to Node E

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Address Resolution

1. The source must determine the IP address of the

.

2. The source must also determine the address that

should be used to send the packet.

a) Note: the address chosen will depend on whether the

destination is on the same LAN or is outside of the LAN

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. .

Address Resolution

1. Find IP Address of Destination.

Source queries the domain name system (DNS)

to o ta n t e a ress o t e est nat on.

An application program on the source passes the

name of the destination (e.g., www.ufl.edu) as a

parameter to a DNS library procedure (the resolver).

The resolver sends the name to a local DNS server.

The DNS server looks u the name and returns the IP

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address of the destination to the resolver, which

returns the IP address to the source.


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2a. Find MAC Address of Destination

Destination is in the same LAN.

Source broadcasts and ARP acket to the LANto determine destination address

ARP -- Address Resolution Protocol

ARP packet contains the destinations IP address.

Destination recognizes its own IP address in theARP packet

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espon s w a pac e con a n ng e es na on sMAC address.

2b. Find MAC Address of Destination

Destination is outside of the LAN.

Source broadcasts and ARP packet to the LAN

o e erm ne es na on a ress ARP -- Address Resolution Protocol

ARP packet contains the destinations IP address.

Edge router recognizes that the IP address is

not on the LAN

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Proxy ARP

Source maps the edge routes MAC address to the

destinations IP address.


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3. Find IP Address of the Source.

Reverse ARP (RARP) server

A server on the LAN.

Contains a table that maps the local MAC

addresses to their IP addresses.

RARP

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own MAC address.

RARP server sends back the sources IP

address.

Address Resolution

Example

Node A

Node B

IP addr:

MAC addr:

Node C

IP addr:

MAC addr:

Node E

IP addr: 222.222.222.222

MAC addr:

Node D

IP addr:

MAC addr:Router X

MAC addr:

Router Y

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IP version 4

0 4 8 16 19 31

Identification Flags Fragment Offset

Time to Live Protocol Header Checksum

Source Address

Destination Address

IPv4

Header

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Options + Padding

Data Field

IP Addresses

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IP Address Example

IP addresses can be in binary form (32 bits) or indotted decimal notation, w.x. .z 8 bits each

Given the following binary address:

10000000111000110000001100101000

Write the dotted decimal notation.

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What is the network ID?

What is the host ID?

Global Addresses:

IP Address Assignment

The Internet Assigned Numbers Authority (IANA) is broadly

responsible for the allocation of globally-unique names and numbers

that are used in the Internet protocol.

The IANA is managed by the Internet Corporation for Ass igned

Names and Numbers (ICANN) under contract to the United States

Department of Commerce (DOC).

Regional Internet registries are used to allocate IP addresses on a

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reg ona as s: ttps: www.ar n.net

A name indicates what we seek.

An address indicates where it is.

A route indicates how we get there.

--John Postel, former administrator of the IANA


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Domain Name

IP Address Assignment

Name, Address, Route

edu com gov mil org net uk fr

IP Address: www.wam.ece.ufl.edu

ufl ucla

ciseece

wam hcs

physics

cisco yahoo nasa nsf arpa navy acm ieee

>> nslookup www.wam.ece.ufl.edu

Server: mindy.ece.ufl.edu

128.227.220.11

Name: http.ece.ufl.edu

Address: 128.227.220.98

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Address Exhaustion Example

A. How many Class B networks are possible in the

B. When a Class B IP address is purchased, oneClass B network ID is removed. How many host

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IDs are removed from allocation?


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Managing Global Addresses:

Address Exhaustion(https://www.arin.net/knowledge/statistics/)

2009 IPv4 Delegations Issued By American Registry for Internet Numbers

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Address Exhaustion Example (cont.)

C. How many network IDs are available to be

D. If a block of 20,000 network IDs were allocatedevery month, how long would the IPv4 addressspace last?

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Making IP Addresses Last:

Size of Routing Table at Internet Core

w/o CIDR, routing tables would have

reached 100,000 entries @ 1998

23Source: http://www.cidr-report.org/

Managing Global Packet Delivery

IP version 4 Packet

0 4 8 16 19 31

Identification Flags Fragment Offset

Time to Live Protocol Header Checksum

Source Address

Destination Address

IPv4

Header

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Options + Padding

Data Field


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Internet Protocol version 6 (IP v.6)

The Internet Engineering Task Force (IETF).

In 1994, the result was the IP Next GenerationProtocol (IPng or IPv.6).

IPv.6 enhancements. Expanded address space.

Im roved o tion mechanism.

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Address autoconfiguration.

Increased addressing flexibility. Support for resource allocation.

IP v.6 Mandatory Header

0 4 12 16 24 31

Payload Length Next Header Hop Limit

Source Address (128 bits)

40

octets

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Destination Address (128 bits)


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IP v.4 versus IP v.6 Structure

IP v4 IP v6

Mandatory Header

Header Options

Mandatory Header

Optional

Extension

Headers

y es

variable

40 bytes

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Payload/Data Payload/Data

IP v.6 Addresses Example

If a block of 1 million addresses is allocated

, .

address space last?

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IP v.6 Address Notation

IP v.6 uses hexadecimal notation. First every four

.

they are divided into 8 groups, separated by

colons (:).

4000:0000:0000:0000:BA5F:039A:000A:2176

= 4000:0:0:0:BA5F:39A:A:2176

= 4000::BA5F:39A:A:2176

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IP v.4 addresses can also be represented:

0000:0000:0000:0000:0000:0000:128.227.x.y

= ::128.227.x.y

IP v.6 Address Notation Example

Abbreviate the following IP v.6 address:

0000:0000:0000:AF36:7328:0000:87AA:0398

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2009 IPv6 Address Assignments and

Requests

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