© 2008 Cisco Systems, Inc. All rights reserved.Cisco PublicSCTE_IP_Basics 1 Dan Baum Systems...

© 2008 Cisco Systems, Inc. All rights reserved. Cisco PublicSCTE_IP_Basics 1

Dan Baum

Systems Engineer

Cisco

[date]

Understanding the Internet Protocol (IP) for RF Technicians

© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 2

Objectives

Better understand the Internet Protocol’s (IP) background and popularity in today’s networks

Better understand the Internet Protocol Suite; including applications

Better understand a Router’s role in IP communications

Better understand the operation of IP in cable networks

Better understand the use of IP for delivering Voice, Video, Home Networking and other services

Gain a fundamental understanding of IP version 6


Agenda

Internet Protocol (IP) background

Internet Protocol Suite

IP applications and services

Routing IP

IP in cable networks

Using IP to deliver services

Introduction to IP version 6

Q&A


Internet Protocol (IP) Background


Internet Protocol History Lesson

Work began in mid 1970s for an internet technology First packet-based switching network was ARPANET Internet Protocols in current form took shape 1977-1979 The global Internet (what we have today) began in 1980 In 1983 the Office of the Secretary of Defense mandated

that all devices connected to long haul networks use TCP/IP

In 1986 the National Science Foundation funded an effort to create a wide area backbone network called NSFNET and connected it to ARPANET

Today it is estimated there are over 1.4 Billion Internet users


IP Standards and Specifications

Based on open systems interconnection

No single vendor owns the TCP/IP technology

Publicly available

Facilitate communication between devices of diverse hardware architectures

Supported on multiple Operating Systems

Contained in Internet Request For Comments; http://www.ietf.org


Why Use the Internet Protocol?

The Internet Protocol is the de facto standard for the Internet

Applications can quickly and easily be built upon an IP foundation

The Internet Protocol suite is an open specification allowing for interoperability

Resources for information related to IP are easy to find


What is the Internet Protocol?

Officially named the TCP/IP Internet Protocol Suite Suite of protocols which define how devices communicate

with each other Facilitates communication between networks and devices

of varying underlying technologies Provides various Application Level Services

– Electronic Mail

– File Transfer

– Terminal Emulation

– Streaming Media

– World Wide Web Based Services

Isn’t unique to the Global Internet; applies to private networks as well



Application

Transport

Internet

Network Interface

FTP, TFTP, TELNET, SMTP, HTTP, DNS, BOOTP, TFTP, SNMP

TCP or UDP (BGP and RIP)

IP, ARP, ICMP, OSPF

Ethernet, Packet Over SONET,Wireless

PhysicalData link

Network

Transport

SessionPresentationApplication

OSI Layers IPS Layers Internet Protocol Suite


Network Interface Layer


Host

The Internet orPrivate Networks

TCP/IP Host

Network Interface Layer

Varying underlying technologies- Ethernet- Packet Over SONET- Frame Relay

Different geographic locations Talking Frames

Mutliple Layer 2

Technologies


Internet Layer


Internet Layer

IP Packet format

IP Address

Network Mask

Default Gateway

Private IP Addresses

Address Resolution

Internet Control Message Protocol


DataVariable LengthTCP or UDP Header

24 or 8 Bytes

IP Packet Format

IP Header20 Bytes

Up to 1500 Bytes

The process starts with Data to be transmittedThe Data is encapsulated in a Transport ProtocolThen an IP Header is appliedFCS

4 BytesEthernet Header

14 Bytes

The Packet is then packaged in a Data Link frame

IP Header20 Bytes

TCP or UDP Header24 or 8 Bytes

DataVariable Length

FCS4 Bytes

Ethernet Header14 Bytes

The Ethernet frame with IP Packet is Transmitted


IP Header Information

IP Header20 Bytes

Version = 4 bits Length = 4 bits Type of Service (TOS) = 8 bits Total Length = 16 bits Identification = 16 bits Flags = 3 bits Fragment Offset = 13 bits TTL = 8 bits Protocol = 8 bits Header Checksum = 16 bits Source IP Address = 32 bits Destination IP Address = 32 bits


IP Address


IP Address

A 32 bit number divided into octets where each octet has a value of 0-255; example 192.168.1.1

Uniquely identifies an IP enabled device on an IP network

It is common to use a dotted decimal representation of 4 octets

Addresses can be assigned Statically or Dynamically

Most servers (email, web, DNS) use a static IP address and most clients (PC’s, Laptops, Cable Modems, etc) use dynamic addresses assigned via DHCP

Example:

192.168.1.1 is the same as:

11000000.10101000.00000001.00000001 binary

IP Addresses are assigned in blocks by ARIN (American Registry of Internet Numbers)


An IP Address is 32 bits (or 4 bytes)in length

It takes the form of N.N.N.N

where N is a number from 0 to 255

e.g. 192.168.1.1

An IP Address is 32 bits (or 4 bytes)in length



e.g. 192.168.1.1

IP Address

An IP Address is a UNIQUE identifier assigned to EVERY device on a network. It is used to

allow communications between devices ona network


192 168 1

DottedDecimal

Maximum

Network Host

128 64 32 16 8 4 2 1

11000000 10101000 00000001Binary

32 Bits

1 8 9 16 17 24 25 32

128 64 32 16 8 4 2 1

128 64 32 16 8 4 2 1

128 64 32 16 8 4 2 1

IP Address

1

00000001


Class A:

Class B:

Class C:

Class D: Multicast

Class E: Research

NetworkNetwork HostHost HostHost HostHost

NetworkNetwork NetworkNetwork HostHost HostHost

NetworkNetwork NetworkNetwork NetworkNetwork HostHost

8 Bits 8 Bits 8 Bits 8 Bits

IP Address Classes


1

Class A:

Bits:

0NNNNNNN0NNNNNNN HostHost HostHost HostHost

8 9 16 17 24 25 32

Range (1-126)

1

Class B:

Bits:

10NNNNNN10NNNNNN NetworkNetwork HostHost HostHost

8 9 16 17 24 25 32

Range (128-191)1

Class C:

Bits:

110NNNNN110NNNNN NetworkNetwork NetworkNetwork HostHost

8 9 16 17 24 25 32

Range (192-223)1

Class D:

Bits:

1110MMMM1110MMMM Multicast GroupMulticast Group Multicast GroupMulticast Group Multicast GroupMulticast Group

8 9 16 17 2425 32

Range (224-239)

IP Address Classes


Network Mask


A Network Mask is 32 bits (or 4 bytes)in length



i.e. 255.255.255.0

A Network Mask is 32 bits (or 4 bytes)in length



i.e. 255.255.255.0

Network Mask

A Network Mask is associated with an IP Address and defines a boundary IP devices use to

determine whether or not packets need to be forwarded to a Gateway


Default Mask for a Class A Network is 255.0.0.0,

Default Mask for a Class B Network is 255.255.0.0,

Default Mask for a Class C Network is 255.255.255.0

The Network Mask indicates how many bits are being used for the Network Portion of an Address

Network Mask


10.0.0.0 mask 255.0.0.0 is equivalent to 10.0.0.0/8



Network Mask Notations


Default Gateway


When a IP host needs to communicate with anotherIP host on a different IP network

i.e. 170.10.0.0 to 192.1.1.0or a different sub-network

i.e. 192.168.1.64 to 192.168.1.128

Data must be forwarded through a gateway

THIS FUNCTION IS NORMALLY DONE BY AROUTER OR LAYER 3 SWITCH

Default Gateway - Default Router

A gateway forwards data from the local(sub) network to another (sub) network


Private IP Addresses


Class A Address - Network 10.0.0.0

Class B Address - Networks 172.16.0.0 to 172.31.0.0

Class C Address - Range from 192.168.1.0 to 192.168.255.0

As defined in RFC 1918

As defined in RFC 1918

If you use any of these addresses in your network,then you MUST use address translation if you want to connect

to the INTERNET

If you use any of these addresses in your network,then you MUST use address translation if you want to connect

to the INTERNET

Private IP Address Space - RFC 1918


Private IP Address Space

Private addresses can be used in any network internally, they cannot be used for the global Internet

Class A Private Addresses:

10.0.0.0 to 10.255.255.255

Class B Private Addresses:

172.16.0.0 to 172.31.255.255

Class C Private Addresses:

192.168.0.0 to 192.168.255.255


Address Resolution


Every Host has at least 2 addresses…

1. A protocol address (i.e. IP address 172.16.1.1)2. A Media address (i.e. Ethernet MACaddress of the Network Interface Card 00:00:0c:12:34:56)

When a device wants to talk,

1. It uses the PROTOCOL address to identify thedevice it wants to talk to, and..2. The MEDIA address to send the data to the target deviceor gateway on the same segment

Host Addresses


ARP works by broadcasting packets to all hosts attached to the LAN

ARP packet contains IP address in which sender is interested in communicating with

Hosts keep a list of ARP responses in an ARP table

ARP is propagated through Bridges/Switches but not through Routers

Address Resolution Protocol - ARP

Address Resolution Protocol

www.ietf.org Open Standards


I heard that broadcast. The message is for me. Here is my Ethernet address.

172.16.3.1 172.16.3.2

IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???

I need the Ethernet address of 172.16.3.2

IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111

ARP

Now the IP Address is mapped to the MAC address, yielding a table like this:

IP 172.16.3.2 : MAC 0800.0200.1111

Next time I want to talk to 172.16.3.2 I don’t have to use ARP since it’s already in my table.


Internet Control Message Protocol


Internet Control Message Protocol - ICMP

IP protocol number 1

Used for troubleshooting

Error Reporting Mechanism

Notifies Hosts and Routers of presence and type of errors


Ping

Packet InterNet Groper

Check end-to-end network connectivity

Baseline network layer performance

Depending on implementation can indicate:

Host Alive

Roundtrip Delay


Traceroute

Used to determine path through a network between two endpoints

Uses the IP Time To Live (TTL) field Initiated via Echo Request or UDP probe on high ports Narrow down connectivity issues Baseline network performance on a hop by hop basis


Time To Live


Time To Live - TTL

Mechanism to prevent loops in an IP Network

Originating host sets the initial TTL value

Intermediate hops, i.e. routers, decrement the TTL value by 1

When TTL expires:- The packet is dropped

- An ICMP report is sent back to the source


TTL = 10

Host 1

10.1.1.1

Host 2

20.1.1.1

TTL

TTL = 8 TTL = 7

TTL = 6TTL = 9


TTL = 10

Host 1

10.1.1.1

Host 2

20.1.1.1

TTL

TTL = 8 TTL = 7

TTL = 6TTL = 9TTL = 0

Introduce a loop with broken routing


Transport Layer


Transmission Control Protocol - TCP


Connection oriented

Reliable transport

Assumes very little about the underlying protocol and architecture

HTTP, Email, Telnet, FTP

TCP is a Transport Layer Protocol used to provide reliable, connection oriented communications between two devices. Each packet transmitted is acknowledged by the receiving station.


User Datagram Protocol - UDP


Connectionless

Unreliable by nature

Upper layer applications responsible for reliability

Real time applications – VoIP, Video over IP

UDP is a Transport Layer Protocol used to provide fast, connectionless communications between to devices. Each packet transmitted is not acknowledged and reliability is left up to higher layer protocols and/or applications.


Application Layer


Dynamic Host Configuration Protocol - DHCP

RFC 2131

Protocol used to supply IP Layer information to Hosts

IP Address

Subnet Mask

IP Gateway

DNS Server(s)

Often used to simplify the management of IP Address Space

Prevents undertaking laborious task of manually configuring many Hosts


DHCPOFFERDHCPDISCOVER DHCPACKDHCPREQUEST

Host DHCPServer

I need an IP Address

You can use this IP Address

I will use that IP Address

DHCP

Acknowledged


Domain Name Service - DNS

RFCs 1034 and 1035

Resolves hostname with domain to matching IP Address

Easier to remember www.cisco.com than 198.133.219.25

Utilizes TCP and UDP as underlying Transport Protocols

Alternative to Host Tables on all Hosts

Domain Name Service

www.ietf.org Open Standards


DNS - Name Resolution

I heard that request. Here is the IP Address.

www.cisco.com = 172.16.3.2

www.cisco.com = ???www.cisco.com = ???

I need the IP Address for www.cisco.com

www.cisco.com = 172.16.3.2 www.cisco.com = 172.16.3.2


IP Routing


What is Routing?

Routing is the process of forwarding a datagram from one hop to the next

Routers forward traffic to a logical destination in an internetwork

Routers perform two primary functions

Routing – share/learn network routes

Switching – take packets from the inbound interface and send them through the outbound interface

Routers are a fundamental component to the very fabric of the Internet


Why are Routers Important?

Separate internetworks into logical entities

Maintain Routing information for end stations

Dynamically update Routing information as networks become available/unavailable

Determine the best path for communication through the internetwork


Routers make internetworking possible.

Network 1

Network 2

Network 5

Network 4

Network 3

Network 6

Why are Routers Important?

As the network topology changes, all routers will update their tables using their chosen routing protocol. (e.g. OSPF)When a new link from Network 5 to Network 6 is established. The routers on Network 5 and 6 will advertise the new route to Network 3.If the link from Network 5 to Network 3 breaks, the routers will update their tables and will choose the next best path which is now through Network 6.

X

I can now get to Network 6 directly!

I can now get to Network 5 directly!

I can no longer reach Network

3 directly!


General Networking Concepts


Packet Types

Three types of Packets

Unicast

Only one end-point for the packet

Multicast

Only select endpoints (those who asked for it) should receive a copy of the packet

Broadcast

All end points should receive the packet


Unicast


Multicast


Quality of Service


TOS and DSCP

Type of Service (TOS) and Differentiated Services Code Point (DSCP) Used to differentiate traffic types Provide priority queuing to important packets Originating host or intermediate routers can set TOS value Intermediate routers can act upon (Per Hop Behavior) or modify the value TOS has been expanded to Differentiated Services Code Point (DSCP) to provide

more levels of service TOS and DSCP are important to classify and prioritize services such as:

Voice over IP

Broadcast Video

Video on Demand

This ensures our customers have a pleasant TV viewing experience and coherent phone conversations


Sample ToS/DSCP Effect

Class definition sets minimum bandwidth Queue servicing (metering) controls latency Unused capacity is shared amongst the other classes Each Class can be separately configured for QoS

10%

40%

50%

Voice

Video

Data

Step 1:Define Scheduling

Step 2:Define Bandwidth

Low Latency, High Servicing (Voice)Low Latency, High Servicing (Voice)

Broadcast VideoBroadcast Video

High Speed DataHigh Speed Data


Ethernet


Ethernet Overview

Invented by Xerox in Early 1970’s

Became IEEE Standard in 1980’s

Ethernet Version 2 Jointly Developed by Digital Equipment Corp, Intel Corp, and Xerox

Popular as a Layer 2 Protocol


Ethernet Overview

Ethernet Speeds

Ethernet - 10 Million Bits Per Second

Fast Ethernet - 100 Million Bits Per Second

Gigabit Ethernet - 1000 Million Bits Per Second or 1 Gbps

Ten Gigabit Ethernet - 10000 Million Bits Per Second or 10 Gbps


Ethernet Overview

TypeDestAddr

SrcAddr

FCSData Payload (IP) Up to 1500 Bytes

Ethernet Frame

Destination MAC Address

Source MAC Address

Frame Check Sequence (CRC)

Type field

IPv4 = x0800


Why Ethernet?

Gigabit Ethernet and Ten Gigabit Ethernet offer high throughput capabilities

Ethernet relatively inexpensive compared to other technologies offering the same throughput

Ethernet is well known and understood; resources abound


MAC Address

MAC = Media Access Control

Hardware identifier

Burned in at time of manufacturing

6 Bytes in length

Uniquely identifies devices connected to Ethernet

Organization Unit Identifier is first 3 bytes

Example: Cisco has OUI of 00-00-0c

Typical Formats

00-00-0c-12-34-56

0000.0c12.3456

00:00:0c:12:34:56


Putting it all Together


Putting It All Together…

1. Information to transmit - Node A to Node B

2. Determine which Protocol to use – TCP or UDP

3. Name Resolution – www.cisco.com to 192.168.1.1

4. Address Resolution – 192.168.100.1 to 00:00:0c:12:34:56

5. Send Information to local Router to get on the Network

6. Router determines QoS tag and queues appropriately

7. Information flows from Hop to Hop (Router to Router) until it reaches the destination


IPv6 Fundamentals


What changed from IPv4?

Expanded address space Addresses quadrupled from 32 bits to 128 bits Header Format Simplification

Fixed length, optional headers are daisy chained

IPv6 header is double that of IPv4, from 20 to 40 bytes

No checksum at the IP network layer

Relies on lower layer (POS, Ethernet, etc) or upper application layer (TCP, UDP)

No hop-by-hop segmentation/fragmentation

Path MTU discovery mandated No broadcast


Version IHL Type of Service Total Length

Identification Flags Fragment Offset

Time to Live Protocol Header Checksum

Source Address

Destination Address

Options Padding

Version Traffic Class Flow Label

Payload Length Next Header Hop Limit

Source Address

Destination Address

IPv4 HeaderIPv4 Header IPv6 Header – RFC 2460Header – RFC 2460

- field’s name kept from IPv4 to IPv6

- fields not kept in IPv6

- Name & position changed in IPv6

- New field in IPv6Leg

end

IPv4 & IPv6 Header Comparison


Larger Address Space

IPv4

32 bits

= 4,294,967,296 possible addressable devices

IPv6

128 bits

=3.4 X 1038 possible addressable devices

=340,282,366,920,938,463,463,374,607,431,768,211,456

5 x 1028 addresses per person on the planet

13 quintillion IPv4 domains per person

(a quintillion is one million trillion)


IPv6 Addressing

IPv6 addressing rules are covered by multiple RFC’sArchitecture defined by RFC 4291

3 Address types:

Unicast: One to One (Global and Link Local)

An identifier for a single interface. A packet sent to a unicast address is delivered to the interface identified by that address.

Anycast: One to Nearest (Allocated from Unicast)

An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to an anycast address is delivered to one of the interfaces identified by that address (the "nearest" one, according to the routing protocols' measure of distance).

Multicast: One to Many

An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to a multicast address is delivered to all interfaces identified by that address.

No Broadcast address, use multicast instead


All addresses are 128 bits. 16-bit fields in case insensitive colon hexadecimal

representation – Preferred form2031:0000:130F:0000:0000:09C0:876A:130B

Leading zeros in a field are optional:2031:0:130F:0:0:9C0:876A:130B

Successive fields of 0 represented as ::, but only once in an address – Compressed form

2031:0:130F::9C0:876A:130B

2031::130F::9C0:876A:130B

0:0:0:0:0:0:0:1 => ::1

0:0:0:0:0:0:0:0 => ::

IPv6 Address Representation


Address Type Identification

Localhost: 00..1 (128 bits) ::1/128

equivalent to 127.0.0.1 in IPv4

Multicast: 1111 1111 FF00::/8

Link-Local IPv6 Addresses 1111 1110 10 x xFE80::/10

(FE80, FE90, FEA0, FEB0)

Used within a network segment

Global Unicast: Everything else

All address types (except multicast) have to support EUI-64 (64 bit extended unique identifier)


IPv6 Global Unicast Addresses

IPv6 Global Unicast addresses are:

Addresses for generic use of IPv6

Structured as hierarchy to keep the aggregation

First 3 bits 001 (2000::/3) is the first allocation from IANA for IPv6 Unicast use

001Global Routing

PrefixSubnet ID Interface ID

n bitsProvider

(64-n) bitsSite

64 bitsHost


Dual Stack Approach

Dual stack node means:

Both IPv4 and IPv6 stacks enabled

Applications can talk to both

Choice of the IP version is based on name lookup and application preference

* Does not mean that all applications are dual stack aware

TCP UDP

IPv4 IPv6

IPv4 Application

Data Link (Ethernet)

0x0800 0x86dd

TCP UDP

IPv4 IPv6

IPv6-enable Application

Data Link (Ethernet)

0x0800 0x86ddFrame Protocol ID

Preferred method on

Application servers


Q and A


References

http://www.ietf.org

RFC 761 – DoD Standard Transmission Control Protocol

RFC 768 – User Datagram Protocol

RFC 791 – Internet Protocol

RFCs 1034 and 1035 – Domain names – concepts and facilities, Domain names – implementation and specification

RFC 1918 – Address Allocation for Private Internets

RFC 2131 – Dynamic Host Configuration Protocol


References cont.

RFC 2460 – Internet Protocol, Version 6 (IPv6) Specification

RFC 4291 – IP Version 6 Addressing Architecture

Internetworking with TCP/IP by Douglas E. Comer


Contact Info

Dan Baum

Cisco Systems

[email protected]

469-255-2021

© 2008 Cisco Systems, Inc. All rights reserved.Cisco PublicSCTE_IP_Basics 1 Dan Baum Systems...

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