CCNA NOTES FULL

NETWORK ESSENTIALS

1. Introduction

2. Cables, Connectors

3. Standards – Ethernet – Token Ring – FDDI

4. OSI Reference Model

5. Types of Service

II. TCP/IP Basics

III. TCP/IP Addressing and Subnetting

IV. CISCO Router Hardware Basics

V. CISCO Router IOS Basics

VI. CISCO Router IOS Management

VII. ROUTING

VIII. WAN Technologies

IX. ACCESS LIST

X. SWITCH Basics

XI. VLAN Concepts and Configuration

XII. INTER-VLAN Concepts

XIII. VTP/STP Concepts

XIV. NAT

NETWORK ESSENTIALS

Types of Network

1. LAN

2. WAN

3. INTERNET

Types of LAN

1. Client/Server

2. Peer to Peer

Network Components

1. Network Hardware

2. Network Software

Network Hardware

1. Network Interface Card ( NIC )

2. Transmission Media

3. Two or more Computers

4. Network Devices

Network Software

1. Network Operating System ( NOS)

Transmission Media

1. Twisted Pair Cable

2. Coaxial Cable

3. Fiber Optic Cable

4. Wireless LAN

TIA Standard (Telecommunication Information Association)

Twisted Pair Cable

1. Unshielded twisted pair ( UTP)

2. Shielded twisted pair ( STP)

UTP categories

a. CAT 1 used for telephone (1 pair)

b. CAT 2 4 MbPS for token ring (2 pairs)

c. CAT 3 10 MbPS for Ethernet (4 pairs)

d. CAT 4 16 MbPS for Fast Token Ring (4 pairs)

e. CAT 5 100 MbPS for Fast Ethernet (4 pairs)

e. CAT 5e 1 GbPS for Gigabit Ethernet

f. CAT 6 1 Gbps for Multi Gigabit

CABLE SPECIFICATIONS

Gigabit 1000 BASE T 1000MbPS

Fast 10 BASE T 10 MbPS Baseband Twisted Pair (100 mts)

Ethernet 100 BASE T 100 MbPS Baseband Twisted Pair (100 mts)

100 BASE TX 100 MbPS Baseband (220 mts)

Connector RJ 45

STP Connector

RJ 45, RJ 11, RS- 232, RS -449

155 MbPS

Connections

1. STRAIGHT THROUGH ( T568A – T568 A )

2. CROSS OVER ( T568A – T568 B)

STRAIGHT THROUGH

T 568 A T 568 A

1. Green White (T_X +) Green White

2. Green (TX-) Green

3. Orange White (RX +) Orange White

4. Blue Blue

5. Blue White Blue White

6. Orange (RX-) Orange

7. Brown White Brown White

8. Brown Brown

[1-3, 2-6 ]

CROSS OVER

T 568A T 568 B

1. Green White [TX +] Orange White

2. Green [TX -] Orange

3. Orange White [RX +] Green White

4. Blue Blue

5. Blue White Blue White

6. Orange [RX -] Green

7. Brown White Brown White

8. Brown Brown

COAXIAL CABLE [RG /68]

1. THIN NET [ 0.25 “]

2. THICK NET [0.4 “]

CABLE SPECIFICATION

10 Base 2 Thin net 200 mts [6 mm]

10 Base 5 Thick net 500 mts [13 mm]

Connectors

BNC [BAYONET- NEILL-CONCELMAN]

It includes T-connector

Parallel connector

Terminator

VAM PIRE TAP Standard Ethernet [thick net]

BNC Thin Ethernet

FIBER OPTIC

SPECIFICATION

1000 Base LX Long wavelength, Multimode [3 km] or Single Mode [100 km]

1000 Base SX Short wavelength,

10 Base F 2000 mts

FIBER OPTIC

Multi Mode used LED used in LAN’s

Single Mode used LASER used in telephone network

Connectors

* SC

* ST

NETWORK TECHNOLOGIES

1. ETHERNET

2. TOKEN RING

3. FDDI [Fiber Distributed Data Interface ]

ETHERNET

10 MbPS
Revisions

Fast Ethernet [ IEEE 802.3U ] 100 MbPS
Gigabit Ethernet [ IEEE 802.5 ] 100 MbPS or 1 GbPS

CSMA/CD [Carrier Sense Multiple Access / Collision Detection]

Ethernet` at Data Link layer is responsible for Ethernet addressing, commonly referred to as hardware addressing or MAC addressing
Ethernet is also responsible for framing packets received from the network layer and preparing them for transmission on the local network through Ethernet CONTENTION Media Access Method

ETHERNET FRAME FORMAT IEEE 802.3

PRE

SFD

LENGTH/TYPE

DATA/PAD

FCS

PRE – Preamble – 7 bytes in alternating 1’s, 0’s – indicating the receiver stations that frame is coming

SFD – Start Frame Delimiter / synch – 1 byte

1,0,1,0,1,0,10,1 1,1,1,1,1,1,1,1

Alternations all 1’s

1, 0

PRE uses either SFD or synch

DA – Destination Address – 6 bytes

LSB is 0 – Individual Address

1 – Group Address

TOKEN RING [IEEE 802.5]

No collisions
Ideal for applications [factory automation]
4 or 16 MbPS

Logically a ring but physically a star configuration to MAU relays

Token ring LANs continuously pass a token or a Token Ring frame
MAU [ Outstation Access Unit]

FDDI [Fiber Distributed Data Interface]

100 MbPS Token passing network
Fiber optic cable with mass length of 2 km
Dual-ring architecture for redundancy
Used for corporate and carrier backbones

CDDI [Copper Distributed Data Interface]

implements FDDI over STP and UTP cable

Dual Ring Architecture

Primary ring for data transmissions
Secondary ring for reliability and robustness

Components

Single attachment station ( SAS ) for PC’s
Dual attachment stations ( DAS ) for servers
Concentrator

FDDI concentrator

also called as Dual- attached concentrator (DAC)
Building block of an FDDI network
Attaches directly to both rings and ensures that any SAS failure or power-down does not bring down the ring

NETWORK TOPOLOGIES

Defines Network Device Organization

Four common types

BUS Topology
TREE Topology
STAR Topology
RING Topology

Topologies are logical Architecture

Actual devices need not be physically organized in these configurations

BUS and TREE Topology

TREE Topology branch with multiple nodes.

STAR Topology

used in Ethernet and Token Ring
5 to 100+ devices

OSI Reference Model

Application layer, Presentation layer, Session layer, Transport layer [segment]

Network layer [packets], Data link layer [frame], Physical layer [bits]

APPLICATION LAYER

Provides network services to application processes like e-mail, File Transfer, and Terminal Emulation.

PRESENTATION LAYER

Data representation
Ensures data is readable by receiving system
Format of data
Data structure
Negotiates data transfer syntax for application layer
Compression, decompression, encryption and decryption

SESSION LAYER

Inter-host communication
Establishes, manages, and terminates sessions between applications

TRANSPORT LAYER

End-to-end connection reliability
Concerned with data transport issues between hosts
Data transport reliability
Establishes, maintains, and terminates virtual circuits
Fault detection and recovery
Information flow control

NETWORK LAYER

Addresses the best path
Provides connectivity and path selection between two end systems
Domain of routing

DATA LINK LAYER

Access to media
Provides reliable transfer of data across media
Physical addressing, network topology, error notification and flow control

PHYSICAL LAYER

Binary transmission
Through wires, connectors, voltages, data rates

TCP/ IP

A suite of protocols

TCP

Rules that dictate how packets of information are sent across multiple networks
Addressing
Error checking

Determines where packets are routed based on their destination addresses
Breaks packets into smaller packets and reassembles them.

DOD model OSI model

Application / process Application

Presentation

Session

Host-to-host Transport

Internet Network

Network Access Data link

Physical

TCP/IP PROTOCOL SUIT

PROTOCOLS

The Process / Application layer protocols

Telnet – Terminal Emulation

allows a user on a remote client machine called the Telnet client, to access the resources of another machine, the Telnet Server [ virtual terminal ]

[Port no. 23]

File Transfer Protocol

FTP is a program operating as protocol
Used for file transfer between two systems
Can access both directories and files and can accomplish certain types of directory operations.
FTP uses Telnet to transparently log on to FTP server.
Uses authentication secured with user names and passwords.

** Directory Manipulation

Typing file contents
Copying file between hosts
It can’t execute remote files as programs. [ port no. 21]

TFTP – Trivial File Transfer Protocol

Stock version of FTP
Fast
No directory-browsing abilities
Sends or receive much smaller blocks of data than FTP
No authentication, so its insecure [port no. 69]

NFS – Network File System

protocol specializing in file sharing
allows two different types of file system to interoperate port no

SMTP – Simple Mail Transfer Protocol

Used to send mail or e-mail
POP 3 used to receive mail [ port no. 110]
Port no. 25

LPD – Line Printer Daemon

designed for printer sharing
LPD along with LPR [ Link Printer Program]
Allows print jobs to be spooled and sent to network printers using TCP/IP
Port no.

X WINDOWS

* Designed for client-server operations on a GUI

* Port no.

SNMP – Simple Network Management Protocol

collects and manipulate valuable network information
it receives BASELINE – a report delimiting the operation traits of a healthy network
this protocol stands as watch dog [ AGENTS ]
Agents send an alert called a TRAP to the management
Port no. 161 / 162

DNS – Domain Name Service

it resolves host name alternative to IP address
port no. 53

DHCP – Dynamic Host Configuration Protocol

it assigns IP address to hosts
can provide following information

* IP, subnet mask, domain name, default gateway, DNS, WINS

BOOTP – Boot strap protocol

port no. 67,68

NETWORK PROTOCOLS

1. IPX / SPX–

Inter Network Packet Exchange / Sequenced Packet Exchange

Netware Core Protocol developed by Novell.

2. NETBIOS / NETBEUI

Network Basic Input Output System / NETBIOS Enhanced User Interface

Developed by IBM refined by Microsoft

Used by Windows NT for LAN management

For file and printer sharing

3. TCP / IP

Set of protocols used in Internet

4. APPLETALK

Used by MACINTOSH computers

5. DLC / Data Link Control – developed by IBM

To connect Token- ring based workstations to IBM mainframe.

Also used by printer manufacturers to connect remote printers to network print servers.

Host-To-Host Layer Protocols

TCP – Transmission Control Protocol

Connection-oriented
Sequenced
Full- duplex
Reliable and accurate
Error checking
Segment ( 20 to 24 bytes )
Windowing Flow control

UDP – User Datagram Protocol

Connection-less
Fast
No acknowledgement
Un sequenced
No windowing or flow control

Internet Layer Protocols

1. IP – Internet Protocol

2. ICMP – Internet Control Message Protocol

It is a management protocol and messaging service provider for IP

3. ARP- Address Resolution Protocol

finds the MAC address of the host from a known IP address

4. RARP – Reverse Address Resolution Protocol

Requests for IP address with help of MAC address in diskless machines

IP HEADER

Source IP address 131.107.7.29

Destination IP address 131.107.3.44

Protocol TCP or UDP

Checksum 4 DF 5

Time to Live [TTL] 60

TTL – value which determines how long the packet lives on the wire before it’s discarded

IP on the router

Decrements the TTL
Calculates new checksum
Obtains hardware address
Forwards the packet

In IP layer, the packet is defragmenter into three parts. Each part has the following information (header)

Eg. FLAG

Indicates other fragment follows

Flag is not added to the last packet because no other fragments follow it

FRAGMENT ID

Identify all fragments that belong together

FRAGMENT OFFSET

IP ADDRESS [32 bit – 4 octets] IPV 4

IPV 4 – 32 bits

IPV 6 – 128 bits

Subnet mask

Class A – 255.0.0.0

Class B - 255.255.0.0

Class C - 255.255.255.0

Subnetting

Reduce network traffic
Optimized network performance
Simplified management
Facilitates spanning of large geographical distances

0741CISCO LAYERS

1. Core Layer:

Responsible for transporting large amounts of traffic both reliably and quickly to switch traffic as fast as possible

2. Distribution layer (workgroup layer):

Routing

Implementation of tools such as access lists, packet filtering, address translation, firewall

Redistribution between routing protocols, including static routing

Routing between VLANs, and other workgroup support functions

Definitions of broadcast and multicast functions

3. Access layer (desktop layer)

Static routing, demand dynamic routing and Ethernet switching

CISCO HARDWARE BASICS

ROUTER

1. Microprocessor ( MOTOROLA 68030 series OR Orion/R4600 series

2. Motherboard / Chipsets

3. Memory

Dynamic RAM (volatile) – current configuration file [Running – config]

NVRAM [Non Volatile] – shared configuration file [Starter – config]

SRAM(STATIC DYNAMIC RANDOM ACCESS MEMORY)

FLASH - IOS resides

ROM [BIOS]

§ POST

§ BSL – Boots from : FLASH / TFTP / MINI IOS

§ MINI IOS

4. Interfaces

Console [con 0]

Asynchronous serial port [RS 232]

Connects to Com port of the system

Auxiliary port [Aux 0]

For remote configuration

Supports modem

5. LAN Interface

AUI [Attachment User Interface]

Ethernet E 0

Others - Fast Ethernet, Gigabit Ethernet, Token Ring, FDDI

6. WAN Interface

i. Serial 0

ii. Serial 1

iii. Others: ISDN, Frame Relay, ATM, DSL, VOIP

7. I / O Slots

EDITING TOOLS

Ctrl A – move cursor to beginning of the line

Ctrl E - move cursor to end of the line

Esc B - move cursor back one word

Esc F - move cursor forward by one word

Ctrl B - move cursor back by one character

Ctrl F – move cursor forward by one character

Ctrl D or Backspace – deletes a single character

Ctrl U – Erase a line

Ctrl R – redisplays a line

Ctrl W – erase a word

Ctrl Z – ends the configuration mode and returns to Exec mode

Tab – finishing typing a command

Ctrl P – shows last command typed

Ctrl N – shows previous command entered

IOS BASIC COMMANDS

Router >? Help

Router > show? Lists all the commands in Show

Router > s? Lists all the commands starting with ‘S’

Router > show terminal shows terminal configuration and history buffer size

Router > show version shows the version

Router > show flash shows details of ‘flash’

Router > enable to enter privilege exec mode

Router # show history show last ten commands

Router # terminal history size 20 to set history size to 20

Router # show running-configuration to display contents of Dynamic RAM

SETTING PASSWORDS

1. To set console password

Router>enable

Router# config t

Router (config) # line console 0

Router (config-line) # login

Router (config-line) # password <pw>

Router (config-line) # Ctrl Z

Router# wr – to save the settings

2. To set privilege password

Router>enable

Router# config t

Router (config) # enable secret <pw>

Router (config) # Ctrl Z

Router# wr

3. To set telnet password

Router>enable

Router# config t

Router (config) # line vty 0 4

Router (config-line) # login

Router (config-line) # password <pw>

Router (config-line) # Ctrl Z

Router# wr

4. To set auxiliary password

Router>enable

Router# config t

Router (config) # line aux 0

Router (config-line) # login

Router (config-line) # password <pw>

Router (config-line) # Ctrl Z

Router# wr

Encrypting password

Router>enable

Router# config t

Router (config) # service password-encryption

Router (config) # Ctrl Z

Router# wr

To recover passwords

o The default configuration register value is 0 * 2102

o To ignore NVRAM content register value is 0 * 2142

Step 1. Press Ctrl + Break when router boots

Step 2 types 0 after creating break

>o/r 0 * 2142

> I

Want to go to setup mode [Y/N]: N

NAT – NETWORK ADDRESS TRANSLATION

NAT allows a host that does not have a valid registered IP address communicate with other hosts through the internet

NAT uses a valid registered IP address to represent the non-registered IP address

PRIVATE ADDRESS

o Non-registered IP address used inside a network

RANGE IP ADDRESS

CLASS A – 10.X.X.X (10.0.0.0 to 10.255.255.255)

CLASS B - 172.16.X.X (172.16.0.0 to 172.31.255.255)

CLASS C - 192.168.X.X (192.168.0.0 to 192.168.255.255)

NAT - Static

Dynamic

Overloading

Static NAT

1 private address: 1 public address

Eg: private public

10.1.1.1 200.1.1.1

10.1.1.2 200.1.1.2

10.1.1.3

Router (config) # IP nat inside source static

192.168.10.1. 200.1.1.1

Router (config) # int e 0

Router (config # ip nat inside

Router (config) # int s 0

Router (config) # ip nat outside

Router# show ip nat translation

Static NAT

Dynamic NAT

· Sets up a pool of possible inside Global address and defines criteria for the set of inside local IP addresses whose traffic should be translated with NAT

· Address is dynamically assigned

Dynamic NAT

SERVER

Dynamic NAT

Router (config) # access-list 1 permit 192.168.10.0 0.0.0.255

Router (config) # ip nat inside source list 1 pool hcl

Router (config) # ip nat pool hcl 200.0.0.1 200.0.0.5 netmask 255.255.255.0

Router (config)#int e 0

Router (config)# ip nat inside

Router (config) #int s 0

Router (config) #ip nat outside

Router (config) #debug ip nat [*ping from source]

Router (config) #show ip nat translation

PAT

Router (config) #ip nat inside source list 1 pool hcl overload

Router (config) #ip nat pool hcl 200.1.0.1 200.0.0.2 netmask 255.255.255.0

Router (config)#int e 0

Router (config)#ip nat inside

Router (config) #int s 0

Router (config)#ip nat outside

Router (config) #debug ip nat [*telnet from source]

Router (config) #show ip nat translation

Overloading NAT with PAT

PAT – Port Address Translation

to support lots of inside local IP addresses with only a few inside Global, publicly registered IP address, NAT overload uses PAT. Instead of just translating the IP address, it also translates the port number.

IP ROUTING

1. Static

2. Default

3. Dynamic

Static Routing

Administrator manually adds routes in each router’s routing table.

Command

Ip route < destination network > < mask > < next hop add or exit interface > < administrative distance > < permanent

Eg. Ip route 192.168.10.0 255.255.255.0 192.168.20.1

To show routing table

# Show ip route

Default Routing

Used in stub network where there is only one way

Ip route 0.0.0.0 0.0.0.0 192.168.20.1

Administrative distances

Rate the trust worthiness of routing information received on a router from a neighbour router.

Default administrative distance

Connected interface 0

Static route 1

EIGRP 90

IGRP 100

OSPF 110

RIP 120

External EIGRP 170

Unknown 255 (this route will never be used)

DYNAMIC ROUTING

Protocols are used to find networks and update routing tables on routers

Routing protocols

Used to determine the path. Eg. RIP, IGRP, EIGRP,OSPF etc

Routed protocols

That carries the packets, e.g. IP, IPX, and AppleTalk.

Routing protocols

* Interior Gateway Protocols- used to exchange information inside the same autonomous system.

* Exterior Gateway Protocols - to communicate between autonomous systems. Eg. BGP

IGP à Distance vector à RIP, IGRP

à Link State à OSPF, NLSP

à Hybrid à IS-IS, EIGRP

RIP à Routing information protocol

IGRP à Interior Gateway Protocol (Cisco proprietary)

OSPF à Open Shortest Path First

NLSP à Network Link Service Protocol

IS-IS à Intermediate System- Intermediate System

EIGRP à Enhanced IGRP (Cisco proprietary)

RIP IGRP

1. Max. Hop is 15 Max. Is 255, default is 100

2. Metric is hop Composite metric (Bandwidth and

Delay) default

Also Reliability, load and MTU

(Maximum Transmission unit)

3. No asynchronous uses autonomous system no.

4. Full route table update every 30 sec 90 sec

5. Administrative Distance 120 100

6. Route by ‘R’ Route specified by ‘I’

RIP V1 OSPF

1. Maintains one table. Maintains 3 tables

A. routing table

B. topology table

C. neighboring table

2. Maintains one path to destination maintains multiple path

3. Advertise / update every 30 sec every 30 mins

4. Advertise are broadcast packets. Multicast packets

5. Entire routing table advertised. Only changed entries

6. High traffic, bandwidth consumption less traffic, no bandwidth consumption

And full in performance.

7. The metric is hop. Bandwidth, time delay, cost, traffic.

8. Max. Hop is 15, 16th unreachable. Unlimited.

9. Doesn’t support classless routing. Support classless routing.

10. The route specified by ‘R’. Route specified by ‘O’.

11. Administrative distance is 120. AD is 110.

12. Delay in convergence. No delay in convergence.

13. Bellman ford Algorithm. Dijkshetra Algorithm.

EIGRP

Multiple paths to destination.
Classless routing.
Cisco proprietary protocol.
Supports IP, IPX, Appletalk.
DUAL Algorithm ( Diffusion Update Algorithm)
Reliable Transport protocol (RTP) for advertise.
Multiple autonomous systems in same router.
AD is 90.
Route is ‘D’.
Metric – Bandwidth, time delay, cost, traffic.

Extra commands to verify the configuration

# Show protocols àdisplays all the routed protocols and the interfaces upon which is enabled

# Show ip protocols à shows only ip protocols

# debug ip rip

# Debug ip igrp events à source destination updates and no. of routers

# Debug ip igrp transactions à show transactions

# undebug all à to turn off debugging

# UN all

Configuration of RIP

Router (config) # router rips

Router (config-router) # network 192.168.10.0 (e 0)

Router (config-router) # network 192.168.20.0 (s 0)

Router (config-router) # exit

Router # show ip route

OSPF used LSO (Link State Update) – to indicate the other router to update with the new link status, when the old fails.

RIP propagations

Router (config-router) # passive-interfaces s 0

Allows receiving rip updates but does not send out any updates

Configuring IGRP

# Router igrp 10

# Network 192.168.10.0

# Network 192.168.20.0

EIGRP

classless , distance vector protocol
communicates with other routers via, RTP ( Reliable Transport Protocol )
selects the best path via Diffusing update algorithm ( DUAL )
Supports IP, IPX, Appletalk
Supports multiple autonomous system on a single router
Supports VLSM and summarization
Metric – bandwidth, delay ,load and reliability

Configuration EIGRP

Router # config t

Router (config) # router eigrp 20

Router (config-router) # network 192.168.10.0

Router (config-router) # network 10.0.0.0

To prohibit the interface from sending or receiving hello packets

Router (config) # router eigrp 20

Router (config-router) # passive-interface s 0

Verifying EIGRP

# show ip route eigrp

# show ip eigrp neighbors

# show ip eigrp topology

Trace route command

Router # trace route 192.168.10.2

Open Shortest Path First [OSPF]

OSPF calculates the best/shortest path to every network in the same area based upon the information collected in Topology database and algorithm called SPF (shortest path first)

Configuration

Router (config) # router Ospf 20

# Network 10.0.0.0 0.255.255.255 area 0

Very configuration

# Show ospf interface

# show ip ospf neighbour

# Show ip protocols

# show ip ospf database

ACCESS CONTROL LISTS

Standard [ 1-99 ] [ 1300- 1999]
Extended [100-199] [2000-2699]
Named access list

Standard – all decisions are made based on source IP address

Router (config) # access-list < number > [deny/ permit] [host any]

Router (config) # access-list 10 deny host 172.16.30.2 (to deny a single host)

Router (config) # access-list 10 deny 172.16.30.0 0.0.0.255

Router (config) # access-list 10 permits any

Router (config) # int e 0

Router (config-if) # ip access-group 10 in

Router (config-if) # int s 0

Router (config-if) # ip access-group 10 out

# Show ip interface

# Show access-list [access-list no/ access-list name]

# Show ip access-lists [access-list no/ access-list name]

# show running-config

Extended Access list

Checks source address and as well as destination address. It can block depending upon port no.

# ip access-list 101 permit tcp 12.0.0.0 0.0.0.0 10.0.0.1 0.0.0.0 eq 21

# ip access-list 101 permit tcp 12.0.0.3 0.0.0.0 eq 23

# ip access-list 101 deny tcp host 12.0.0.5

# ip access-list 101 permit ip any any

Standard access list

# Ip access-list standard Siva

Std- nacl # deny 12.0.0.0

# permits any

# Exit

# Int e 0

# Ip access-group Siva out

WAN TECHNOLOGIES

Types of WAN connections

1. Leased line connections

2. Circuit switched connections

3. Packet switched connections

Leased-line connections

can be called a point-to-point ( dedicated connection )
Provides a single, pre-established WAN communication path.
Synchronous
Speed T3 ( 45 Mbps )
Synchronous communications involve digital signals that are transmitted with precise clocking
Very expensive.

Circuit-switching

Provides a dedicated physical circuit, which stays in place between the sender and the receiver for the duration of the communication session.
Telephone company network uses the system to provide basic telephone services or ( ISDN – Integrated Services Digital Network )
Basic telephone services are asynchronous serial communication.

Packet-switching

Packet-switching method involves network devices sharing a single point-to-point link.
Point-to-point link is used to transport packets from source to destination over a telecommunication carrier network.
Statistically programmed switching devices provide physical connections
Packet headers are used to identify the destination
Less expensive
Synchronous serial lines
Speed 56 Kbps ( T3 )

Physical items needed for WAN link

1. Customer Premises Equipment ( CPE )

2. A Demarcation ( DEMARC )

3. A Local loop ( last mile ) – copper wire

4. a central office ( CO ) switch

5. a full network

Types of serial cable supported by CISCO devices

Serial cables can support leased-lines and packet-switched connections.

1. EIA / TIA – 232

2. EIA / TIA – 449

3. EIA / TIA – 530

4. X.25

5. V.35

DTE – Data Terminal Equipment is your CPE.

DCE – Data Communication Equipment – to convert the user data from DTE into a form that’s acceptable to the WAN service provider

The synchronous serial ports can be configured a either DTE or DCE, depending on the attached cable.

EIA / TIA – 530 serial ports can be configured as DTE only.

External clocking from the channel service unit/ data service unit ( CSU/DSU ) or other DIC device is needed when the port is configured as DTE.
When traffic is crossing the WAN link, each WAN connection uses a protocol to encapsulate it.
WAN encapsulation protocols operate at layer 2 of the OSI model.
The choice of encapsulation protocol depends on the WAN technology and the communication equipment.

WAN protocols

1. HDLC –High-level Data Link Control

2. PPP – Point-to-point protocol

3. SLIP – Serial Line Interface protocol

4. X.25

5. Frame Relay

6. ATM – Asynchronous Transfer Mode

HDLC – frame format

HDLC

The default encapsulation type on point-to-point, dedicated link is HDLC.
It’s typically used for communication between two Cisco devices and is a bit-oriented synchronous protocol.

SLIP

SLIP predates PPP.
It uses a variation of TCP/IP and is a standard protocol for point-to-point serial connections

PPP

PPP provides router-to-router and host-to-network connections over synchronous and asynchronous circuits.
Can work with IP and IPX.
Security mechanisms such as PAP (Password Authentication Protocol) and CHAP (Challenge Handshake Authentication protocol) are built into PPP.

Configuring PPP

Router (config) # int s 0

Router (config-if) # encapsulation PPP

Router (config-if) # exit

Configuration PPP authentication

Step 1. Setting username, password for remote router connecting to your router

Router (config) # hostname Router A

Router A (config) # username Router B password Cisco

Router A (config) # # exit

Step 2. Configuring PAP or CHAP

Router A (config) # int s 0

Router A (config-if) # PPP authentication chap pap

Router A (config-if) # exit

Verifying PPP encapsulation

Router A # show int s 0

PAP contains four main components

1. A physical layer International Standard for serial communication. I.e. EIA/TIA 232 C, V.24, V.35, and ISDN.

2. A method for encapsulating datagram over serial links. i.e. HDLC.

3. A method of establishing, configuring, maintaining and terminating the point-to-point connection. LCP – Line Control Protocol

4. NCP – Network Control Protocol – to allow communications of multiple network layer protocols.

PPP Session Establishment

1. Link-Establishment Phase – uses LCP.

2. Authentication Phase

a. CHAP ( Challenge Handshake Authentication protocol )

b. PAP ( Password Authentication Protocol )

3. Network Layer protocol phase – NCP

X.25

* It is a ITU-T standard (International Telecommunication Union – Telecommunication Standardization sector.

* It is an International body that develops world wide standards for telecommunication technologies.

* It defines how connections between DTE and the DCE are maintained.

* These connections are used for remote terminal access and computer communication in public network.

* X.25 is a precursor of frame relay, and it specifies Link Access Procedure Balanced ( LAPB ), which is a data-link layer protocol.

Frame Relay

It is an Industry Standard Protocol.
It can handle multiple virtual circuits, and is streamlined to cut out some of the lengthy processes that X.25 employs.

ATM

It is an International Standard for cell relay.
Cell relay is a network technology based on the use of small, fixed-size packets or cells.
It allows data, voice, and video to be conveyed in fixed-length cells of 53 bytes.
Fixed-length cells reduce transportation delays by allowing processing to occur in hardware.
ATM used high speed transmission media such as

E3 ( 45 Mbps)
T3 ( 56 Kbps)
SONET ( Synchronous Optical Network )

Configuring 1900 Series Switch

User(s) how active on management console
User interface menu

[m] Menus

[k] Command line

[i] ip configuration

Enter selection: k

Switch > enable

Switch # config t

Switch (config) # enables password level 1 Cisco

(Setting password for user mode)

Switch (config) # enables password level 15 Cisco

(Setting password for enable mode)

Switch (config) # enables secret Cisco

(Setting secret password for enable mode)

Switch (config) # hostname 1900switch

(Setting hostname)

# Ip address 192.168.10.1 255.255.255.0

# Ip default-gateway 192.168.10.2

To show VLAN information

Switch # show vlan brief

To show information about VLAN 2

Switch # show vlan id 2

To view the Spanning Tree information for a VLAN

Switch # show spanning-tree vlan 2

Assigning IP address to a switch

Reason - * for using Telnet

To connect to router for inter-vlan

* IP address should be given to default vlan i.e. vlan 1

Switch > enable

Switch # config t

Switch (config) # int vlan 1

Switch (config –if) # ip address 172.16.10.3 255.255.255.0

Switch (config –if) # no shutdown

Switch (config –if) # exit

Switch (config) # ip default-gateway 172.16.10.1

Switch (config) # exit

ISDN – Integrated Services Digital Network

ISDN Switch types

Type Keyword

1. AT/T basic rate switch basic-5 ess

2. Nortel DMS – 100 basic rate switch basic-dms 100

3. National ISDN-1 switch basic-ni

4. AT & T 4 ess (ISDN Pri only) Primary- 4 ess

5. AT & T 5 ess (ISDN Pri only) Primary-5 ess

6. Nortel DMS -100 (ISDN pri) Primary- dms 100

Dial-on Demand Routing ( DDR)

Router A (config) # ip route 172.16.60.2 255.255.255.255 bri 0

DDR with Access-lists

Router (config) # dialer-list 1 protocol ip list 110

# access-list 110 permits tcp any any eq SMTP

# access-list 110 permits tcp any any eq telnet

# Int bri 0

# dialer-group 1

Configuring the Dialer information

Router (config) # int bri 0

# Ip address 172.16.60.1 255.255.255.0

# no shut

# Encapsulation PPP

# dialer-group 1

# Dialer string 8350661

# Dialer map ip 172.16.60.2 name Router B 8350661

Basic Rate ISDN (BRI)

2 B + D = 16 Kbps
2 B = 64 Kbps
Q 921 & Q 931 for D channel signaling
SS 7 to set up the path

Configuring ISDN

Router A > enable

Router A (config) # isdn switch-type basic-dms 100

Router A (config) # int bri 0

Router A (config-if) # encapsulation ppp

# Isdn sped 1

# Isdn sped 2

SPID –Service provider identification

Verifying ISDN connections

# Show dialer

# Show isdn status

# Show ip route

Frame-Relay configuration

Router (config) # int s 0

Router (config-if) # encapsulation frame-relay ( cisco or ietf)

# Ip address 192.168.10.1 255.255.255.0

# frame-relay lmi-type ansi

# frame-relay interface-dlci 101

# Exit

Monitoring frame relay

# Show frame lmi

# Show frame PVC

# show int s 0

LMI – Local Management Interface

signaling standard used between the router and first frame relay switch
Standards are * CISCO

ANSI
Q.933A

DLCI – Data Link Connection Identifier ( !6-1007 )

Given by the service provider to identify the PVC ( Permanent Virtual Circuit )
IETF – Internet Engineering Task Force

Resolving hostnames

1. Building host table

2. using DNS

Building host table

IP host < hostname > < tcp port no > < ip address >

Eg. Router (config) # ip host iiht 192.168.10.1

To see the host table

Router # show hosts

Using DNS

Router (config) # ip domain-lookup

# Ip name-server 192.168.10.1

# Ip domain-name iiht.com

# Exit

SWITCHING

· Ethernet switches operate at layer 2 of the OSI model and function in a similar way to bridges.

· Ethernet switches and bridge forward and filter traffic based on MAC address.

· Switches and bridges identify host locations through a process known as Address learning.

· Switches and bridges provide Loop avoidance function in a network.

· When a switch is first initialized, its MAC data base is empty. So it forwards the received message to all its port. This is known as Flooding.

· IEEE 802.1 Specifications defines a time limit of 300 seconds for MAC database entries to remain in the database.

· When the frame reaches the switch, the destination MAC address is compared to the entries in the MAC database. The switch then transmits the frame only to the port which matches the MAC address. This is known as FRAME FILTERING.

· Bridged and Switched networks are often designed with redundant devices and links in order to prevent a single point of failure in a network.

· Redundant systems can cause bridge loops. Ie problems caused due to bridge loops.

a. Broadcast storms

b. Multiple frame copies

c. Instability in the MAC database.

· Some layer-3 protocols use Time to line (TTL) mechanism which eliminates looping packets.

· TTL – Field in IP header to indicate how long a packet can travel before it is returned or discarded.

· Layer-2 protocols like Ethernet are unable to prevent packets from endlessly looping.

· To prevent broadcast storms, multiple frame copies and MAC database instability, a loop avoidance mechanism is used. i.e. SPANNING – TREE PROTOCOL ( STP )

· STP is a link – management protocol that allows redundant systems to exist in the network but prevents undesired bridge loops.

· STP is a part of IEEE 802.LD standard, so it can function with Complaint Bridge and switches from other vendors.

· STP works by forcing certain redundant data paths into a standby or blocked state.

· When the topology of the network changes, STP reconfigures bridge ports to prevent the creation of new loops or loss of connectivity.

· Each port on a bridge or switch is included in STP support.

· All switches in a LAN participating in STP gather information on other switches in the network through an exchange of data messages. This is known as BRIDGE PROTOCOL DATA UNITS ( BPDU )

ROOT BRIDGE ELECTION

Default priority of the bridges is 32,678

Root Bridge will be a bridge with less Bridge ID. If the bridge ID is same for all the bridge, then the MAC address is considered. A bridge with less MAC address will be the rest bridge.

Root path cost

Path cost = 1000 / speed in Mbps

Port Speed STP Cost

1 Gbps 1000/1000 = 1

100 Mbps 1000/10 = 10

10 Mbps 1000/10 = 100

56 Kbps 1000/56 = 17857

Root path will be path with less cost.

BPDU- BRIDGE PROTOCOL DATA UNITS

Information Length

Protocol 10 2 bytes

Version 1

Type 1

Flags 1

Root B ID 8

Root path cost 4

Sending B ID 8

Port ID 2

Message age 2

Max. Age 2

Hello time 2

Forward delay 2

Bridge ID

Bridge priority + MAC address

16 bytes + 48 bytes

Root Path Cost

Cost of the path from the Root Bridge, identified by the bandwidth.

Root Port

Port connected to the root bridge.

Designated port

Port coming out of a root bridge towards the destination

Difference between Bridge and Switch

Bridge Switch

1. Software based Hardware based, it operate with ASIC.

2. Uses software based STP process Application-specific Integrated Circuits and

a high-capacity switching bus.

3. Slower faster

4. One spanning tree instance per port many spanning tree instance per port

5. Less number of ports (max. 16) more number of ports (>100)

6. Used to separate LAN traffic into segments used to connect directly to end-users and other switches.

7. Cannot offer dedicated bandwidth to each segment can offer dedicated

Bandwidth to end users

Two ways of transmitting frame through a switch

1. Store- and – Forward

a. Forwarding does not take place until the entire frame has been received by switch.

b. Switch reads the destination and source address and performs CRC to ensure the frame is not damaged.

c. If damaged, the frame is discarded.

d. Latency time is high since it has to check the frame and also varies with regard to size of the frame.

Latency time is the delay between receiving a frame and forwarding

2. Cut-through

a. Forwards the frame just by seeing the destination address only.

b. Latency time is constant and less.

VLAN

Static - Administrator creates VLAN.
Dynamic – uses VMP3 (VLAN management policy server) to create VLANs.

Creating VLANs

1900 (config) # vlan 2 name sales

# Vlan 3 name mark

# Exit

# Show vlan

Assigning switch ports

1900 (config) # int e 0/2

# vlan-membership static 2

# int e 0/3

# vlan-membership static 3

Configuring trunk port

1900 (config) # int f 0/2l

# Trunk on

· 1900 switch only runs on DISK (Dynamic ISC) encapsulation.

VTP – VLAN Trunk Protocol

1. Messaging protocol that is used to distribute VLAN Configuration information.

2. Supports mixed-media backbones.

3. Takes control of addition, detection, and name changes on the network.

A VTP management domain can be either one switch or multiple interconnected switching sharing the same VTP server.

VLANs are not propagated over the network until 2 VTP domain name is specified or discovered.

VTP operates in three modes.

Server ( default )
Client
Transparent

Server mode

· Switch acting at this mode can create, delete and modify VLAN’s for the entire VTP domain.

· Advertise its VLAN configuration

· Synchronize its VLAN configuration with information received from other devices in the domain.

· Forward VTP advertisements received from other switches in the domain.

· It saves VLAN configuration into NVRAM and recreates VLAN whenever the switch is booting.

Client mode

· create VTP advertisements

· synchronize its VLAN configuration

· Forward VTP messages.

· VTP transparent switch can create and modify VLANs. But it is confined to the local switch only. It is not transmitted to other switches in the domain.

· Does not participate in domain.

** VTP advertisements are automatically sent every five minutes or whenever a change occurs in a VLAN configuration. Advertisement includes 1. Configuration-Version number

*** VTP PRUNING- technique that uses VLAN advertisements to determine when a trunk connection is flooding messages unnecessarily.

Configuring VTP

1900 (config) # vtp server

# Vtp domain iiht

# Vtp password cisco

To see domain status, use

# show vtp (statistics)

To configure VLAN

Step 1. Configure VTP (optional)

Step 2. Enable trunking

Step 3. Create VLAN’s

Step 4. Assign switch ports to one or more VLAN’s

Step 5. Configure a router for inter-VLAN communications (optional)

Step 1. Configure VTP

Switch > enable

Switch # vlan database

Switch (vlan) # vtp domain iiht

Switch (vlan) # vtp server

Switch (vlan) # exit

Switch (vlan)

To show the VTP details

Switch # show vtp status

Step 2. To enable Trunking

Switch # config t

Switch (config) # int fa 0/24

Switch (config) # switch port mode trunk

Step 3. Configuring VLAN

Switch > enable

Switch # vlan database

Switch (vlan) # vlan 2 names Siva

Switch (vlan) # vlan 3 name kumar

……….

………..

Switch (vlan) # exit

Step 4. Configuring ports

Switch > enable

Switch # config t

Switch (config) # int fast Ethernet 0/2

Switch (config-if) # switch port mode access

Switch (config-if) # switch port access vlan 2

Switch (config-if) # int fast Ethernet 0/3

Switch (config-if) # switch port mode access

Switch (config-if) # switch port access vlan 3

……………..

…………………

# Exit

Step 5. Configuring router for Inter-VLAN

Router > enable

Router # config t

Router (config) # int fa 0/0

Router (config-if) # no ip address

Router (config-if) # no shutdown

Router (config-if) # int fa 0/0.1

Router (config-subif) # ip address 172.16.0.1 255.255.0.0

Router (config-subif) # encapsulation dot1q 1

Router (config-subif) # int fa 0/0.2

Router (config-subif) # encapsulation dot1q 2

Router (config-subif) # ip address ……………

………………

Router (config-subif) # exit

CDP – Cisco Discovery Protocol

to collect information about both locally attached and remote devices
can gather hardware and protocol information about neighbour devices

CDP timers and hold time information

Router # sh cdp

Sending packets every 60 sec

Sending hold time value of 180 sec

To configure cdp timer and hold time

Router (config) # cdp timer 90

Router (config) # cdp hold time 24

Router (config) exit

To turn off cdp completely

Router (config) # no cdp run

To turn off cdp for an interface

# No cdp enable

To turn on cdp for an interface

# Cdp enables

Gathering cdp information

# sh cdp neighbour
# sh cdp neighbor detail
# sh cdp traffic

STP

Definition – allows link redundancy and prevents layer two loops
Port states
BPDO
Root election
Root path cost
Root and designated ports
Convergence

Port States

Turn on the switch à Blocking à Enabled

à STP Disabled

Listening – the port listens for any message regarding the blocking state. This listening time is known as Forward Delay Timer ( default is 15 sec)
Learning (default 15 sec) – if no message is received regarding the blocking state till 15 secs the ports moves to the learning state. In learning state, the switch identifies where it is located in the topology and maintains a database for forwarding. ie. Is known as Forwarding database
Forwarding state – forwards the data

NAT – Network Address Translation

allows a host that does not have a valid registered IP address communicate with other hosts through the internet
NAT used a valid registered IP address to represent the non-registered IP address.

Private Address

non-registered IP address used inside a network

Range

Class C – 10.X.X.X (10.0.0.0 to 10.255.255.255)

Class B - 172.16.X.X (172.16.0.0 to 172.31.255.255)

Class C - 192.168.X.X (192.168.0.0 to 192.168.255.255)

NAT

Static
Dynamic
Overloading

Static NAT

1 private address: 1 public address

E.g. Private public

10.1.1.1 200.1.1.1

10.1.1.2 200.1.1.2

Static NAT

Router (config) # ip nat inside source static 192.168.10.1 200.1.1.1

Router (config) # int e 0

Router (config) # ip nat inside

Router (config) # int s 0

Router (config) # ip nat outside

Router # show ip nat translation

Overloading NAT with PAT

PAT – Port Address Translation

To support lots of inside local IP addresses with only a few inside global, publically registered IP address. NAT overload uses PAT. Instead of just translating the IP address, it also translates the port number.

PAT

Router (config) # ip nat inside source list 1 pool hcl overload

# Ip nat pool hcl 200.0.0.1 200.0.0.2 netmask 255.255.255.0

# Int e 0

# Ip nat inside

# Int s 0

# Ip nat outside

# Debug ip nat (* telnet from source)

# show ip nat translations

Dynamic NAT

Sets up a pool of possible inside global address and defines criteria for the set of inside local IP addresses whose traffic should be translated with NAT.
Address is dynamically assigned.

Router (config) # access-list 1 permit192.168.10.0 0.0.0.255

Router (config) # ip nat inside source list 1 pool hcl

Router (config) # ip nat pool hcl 200.0.0.1 200.0.0.5 netmask 255.255.255.0

Router (config) # int e 0

Router (config) # ip nat inside

Router (config) # int s 0

Router (config) # ip nat outside

# Debug ip nat (* ping from source)

Password recovery

Enable - go to privilege mode

Router # copy startup-config running –config

Router # config t

Router (config) # enable secret < pw > à change pw

Router (config) # exit

Router (config) # config-register 0*2102 à to reset original configuration

Router # copy running-config startup-config

https://learningnetwork.cisco.com/docs/DOC-32200

https://learningnetwork.cisco.com/docs/DOC-31080

Hacking

CCNA NOTES FULL

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