Network is the method to share hardware resources and software ...

chinchillatidyΔίκτυα και Επικοινωνίες

26 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

75 εμφανίσεις


1

Network is the method to share hardware resources and software resources. We can share
the resources with the help of operating system like windows, Linux, UNIX etc. To
connect multiple networks we have to use internetworking devices like router, bridge,
l
ayer 3, switches etc.



Administrator model for networking

Server software:
-

which software are used to giving services that are server software.

Client software:
-

which gets services.





Apache,






Internet Explore
r,


IIS,






Outlook Express,




Exchange 2003,





Yahoo messenger,




FTP Server,





Cute FTP




Send Mail













TCP/IP,





IPX/SPX,




AppleTalk,




N
etbeui















If NIC are different then use bridge. If media is different then use Trans
-
Receive devices.




Server
Software

Client
Software

P
R
O
T

O
C
O
L
Stack

P
R
O
T
O
C
O
L
Stack


NIC

NIC


Media


Media


2


OSI (Open Systems Interconnection) Model


OSI model is the layer approach to design, develop and implement network. OSI
provides follo
wing advantages:
-

(i)

Designing of network will be standard base.

(ii)

Development of new technology will be faster.

(iii)

Devices from multiple vendors can communicate with each other.

(iv)

Implementation and troubleshooting of network will be easy.


























Protocol Stack



















NIC

























































Media























Software






Application Layer














Presentation Layer














Session Layer















Tr
ansport Layer














Network Layer














Data Link Layer














Physical Layer


3













(1)

Application Layer:
-

Application layer accepts data and forward into the protocol stack. It creates us
er
interface between application software and protocol stack.


2). Presentation Layer:
-

This layer decides presentation format of the data. It also able to performs other
function like compression/decompression and encryption/decryption.


3.)Session Layer
:
-

This layer initiate, maintain and terminate sessions between different applications.
Due to this layer multiple application software can be executed at the same time.


4.)Transport Layer:
-

Transport layer is responsible for connection oriented and con
nection less
communication. Transport layer also performs other functions like

(i)

Error checking

(ii)

Flow Control

Buffering

Windowing

Multiplexing

(iii)

Sequencing

(iv)

Positive Acknowledgement

(v)

Response






Connection Oriented Communication












4

























Connection
less Communication






Send



(i)

Error checking

Transport layer generates cyclic redundancy check (CRC) and forward the
CRC value to destination along with data. The other end will generate
CRC according to data and match the CRC value with received value
. If
both are same, then data is accepted otherwise discard.




(ii)

Flow Control

Flow control is used to control the flow of data during communication.
For this purpose following methods are used:
-

(a)

Buffer

Buffer is the temporary storage area. All the data is

stored in the buffer
memory and when communication ability is available the data is
forward to another.




(b)

Windowing

Windowing is the maximum amounts of the data that can be send to
destination without receiving Acknowledgement. It is limit for buffer
to
send data without getting Acknowledgement.






Sender

Receiver


5
















































6








(c)

Multiplexing

Multiplexing means combining small data segment, which has same
destination IP and same destination service.



(iii)

Sequencing

Transport layer

add sequence number to data, so that out of sequence data
can be detected and rearranged in proper manner.















(iv)

Positive Acknowledgement and Response

When data is send to destination, the destination will reply with
Acknowledgement to indicate th
e positive reception of data. If
Acknowledgement is not received within a specified time then the data is
resend from buffer memory.















7


























5.)

Network Layer

This layer performs function like logical addressing and path determin
ation. Each
networking device has a physical address that is MAC address. But logical
addressing is easier to communicate on large size network.


Logical addressing

defines network address and host address. This type of
addressing is used to simplify imple
mentation of large network. Some examples
of logical addressing are:
-

IP addresses, IPX addresses etc.




Path determination

Network layer has different routing protocols like RIP, EIGRP, BGP, and ARP
etc. to perform the path determination for different ro
uting protocol.


Network layer also perform other responsibilities like defining quality of service,
fragmentation and protocol identification.








8










6.)

Data Link Layer


The functions of Data Link layer are divided into two sub layers

a.

Logical Link C
ontrol

b.

Media Access Control


(i)

Logical Link Control defines the encapsulation that will be used by the
NIC to delivered data to destination. Some examples of Logical Link
Control are ARPA (Ethernet), 802.11 wi
-
fi.

(ii)

Media Access Control defines methods to acce
ss the shared media and
establish the identity with the help of MAC address. Some examples of
Media Access Control are CSMA/CD, Token Passing.



7.)

Physical Layer

Physical Layer is responsible to communicate bits over the media this layer deals
with the stand
ard defined for media and signals. This layer may also perform
modulation and demodulation as required.



Data Encapsulation




Data






Application Layer Data*

Presentation Layer Data**

Session Layer


Data***

Transport Layer

Transport Header |

Data

= Segment

Network Layer

Network Header | Segment

= Packet

Data Link Layer

Header | Packet | Trailer

= Frame

Physical Layer


1 0




= Bits


Data => Segment => Packet => Frames => Bits



DATA FLOW THROUGH A NETWORK




9

















Devices at differe
nt Layers





Physical Layer Devices

Hub, Modem, Media, DCE (Data comm. Equipment), CSU/DSU, Repeater, Media
converter













DCE








CSU | DSU



DTE







Channel Service Unit


Data Service Unit



Data Terminal Equipment




Data Li
nk Layer

NIC, Switch, Bridge



Network Layer Device

Router, Layer 3 Switch



All Layers Device

PC, Firewall


R


1
0


DCE:
-

DCE convert the bits into signal & send them on media.

FDDI


Fiber Distributed Data Interface

Switch

forwards frames on the base of MAC addre
ss.

Router

forwards packets on the base of IP address.












LAN Technologies









10


10000 mbps


4


16 mbps


4


16 mbps


1


108 mbps


100 m



100m


up to 2 km


up to 40 km


Ethernet

Ethernet is the most popular LAN technology. It ca
n support verity of media like copper
(UTP, Coaxial, fiber optic). This technology supports wide range of speed from 10mbps
to 10000 mbps.


Ethernet at Logical Link Control

To create logical link control Ethernet uses ARPA protocol also called IEEE802.3.
E
thernet adds source MAC, destination MAC, error checking information and some other
information to data. Ethernet encapsulation explain as follows



















1010101010..10 10101011



Ethernet at Media Access Control

Ethernet at

Media Access Control layer uses CSMA/CD protocol to access the shared
media.


LAN

Ethernet

Token Ring

FDDI

Wi
-
Fi

Preamble start frame Destination Source MAC Length Data u
p to Frame



64

Delimiter 8


MAC




48



16


1500 bytes Check

48

Sequence


16






















1
1

In these days, we use Ethernet with switches and in switches the technology is made
CSMA/CA (Collision Avoidance). So this reason Ethernet is best compare with Token
Ring, FDDI &

Wi
-
Fi.





















Yes










No












No










Yes






Back off Algorithm

This algorithm runs when a collision created.












Sense the carrier

Is
carri
er
busy
?

Do we have
any data to
communicat
e?

Send data over
media

Receive data

Detect the Collision

Stop transmitting receiving data


1
2














Ethernet Family


Speed



Base band


10



Base 2



200
-
meter


Coaxial c
able

10



Base 5



500
-
meter


Thick Coaxial cable

10



Base T



100 meter


Twisted Pair (UTP)

10/100(present)

Base TX


100 meter


UTP

100



Base T4


r100 mete


UTP 4 Pairs used

100



Base FX


up to 4 kms


Fiber Optic

1000(Server)


Base TX


100 meter


UTP

1
000



Base FX


up to 10 kms


Fiber Optic

10000



Base FX





Fiber Optic

















Ethernet frame

Preamble

An alternating 1,0 pattern provides a 5MHz clock at the start of each packet,
which allows the receiving devices to lock the incoming bit strea
m.


Start Frame Delimiter (SFD)/Synch

The preamble is seven octets and the SFD is one
octet (synch). The SFD is 10101011, where the last pair of 1s allows the receiver to come
into the alternating 1,0 pattern somewhere in the middle and still sync up and d
etect the
beginning of the data.


Generate a
random Number

Try to communicate after delay
X r.no.


1
3

Length or type

802.3 uses a length field, but the Ethernet frame uses a type field to
identify the network layer protocol. 802.3 cannot identify the upper
-
layer protocol and
must be used with a proprietary LAN
-
IPX, for exa
mple









Ethernet Cabling



Coaxial cabling

Requirement:
-

T connector, Terminator, BNC connector, Coaxial cable, 10 base2 lan cards




T Connector BNC









Terminator Lan card


This is used by BUS topology wit
h 10 mbs Base 2 and Base 5. it is not used currently.



UTP Cabling

In the UTP, we have used different topology to create the network.


(1)












PC PC


In any Ethernet UTP topology we have to use one of the two types of cables

(1)

Strai
ght cable

(2)

Cross cable



Hub / Switch


1
4

TX

RX


Structure Cabling

Requirement:
-

Rack, patch panel, Switch/ Hub( Rack Mounable), patch cord, I/O connector, I/O box,
UTP cable

Tool:
-

Punching tool



Problems of Ethernet technology


(3)

In Ethernet only one pc is able to send d
ata at a time, due to this the bandwidth of
Ethernet will be shared.

(4)

Not an equal access technology.

(5)

One pc will send data, which will be received by the all devices of network. Due
to this data communication will not be secured.

(6)

Collision will occur in th
e network and collision will lead to other problems like
latency, delay and reduce throughput.



Latency


time duration to send packet from start to end.



Throughput


speed to send data (output)

(7)

All PCs will have single broadcast domain. Due to this the

bandwidth will be
reduced.

EMI


Electro Magnetic Indication



LAN Segmentation of Ethernet Network

There are three methods to perform LAN segmentation

(1)

LAN segmentation using bridge.

(2)

LAN segmentation using switches.

(3)

LAN segmentation using Routers.

LAN seg
mentation using bridge.


Existing








New








1
5















Working of Bridge:
-


Working of Bridge explains in following steps:
-

(i)

Bridge can receives a frame in the buffer memory.

(ii)

The source MAC address of frame this stored to the bridging table.

Port number


MAC address

1

2

3

(iii)

According to the destination MAC address the frame will be forwarded or
drop

(a)

If destination MAC address of the frame is known then frame is
forwarded to the particular port.

(b)

If destination MAC address is unknown by bridging t
able then frame
is forwarded to the all port except receiving port.

(c)

If destination MAC address is broadcast MAC address ff.ff.ff.ff.ff.ff.

(d)

If destination MAC address exist on the same port from which port
received then frame is dropped.


Collision domain

A

group of pc, in which collision can occur, is called a collision domain.


Broadcast domain

A group of pc in which broadcast message is delivered is called broadcast domain.



LAN segmentation using Switches

Due to perform Lan segmentation using switches. W
e have to remove hubs from the
network and replace hub with switches the working of switches. The working of switch is
exactly like a bridge. A multiport bridge can be used as a bridge.











1
6











1 broadcast domain





Collision domain = micro segmentation

























Switch’s working is same like bridge

Advantages:
-

(1)

Bandwidth will not be shared and overall throughput will depend on wire
speed of the switch. Wire speed is also
called switching capacity measured
in mbps or gbps.

Minimum port on switches = 4

Maximum port on switches = 48

(2)

Any time access technology.

(3)

One to one communication so that network will be more secures.

(4)

Switches will perform micro segmentation and no collis
ion will occur in
network.



Lan segmentation using router

If we are facing high concession in the n/w due to the large number of broadcast then we
can divide broadcast domain of network. So that number of broadcast message will be
reduced.


1
7


Exist:
-





New:
-














1
st

Broadcast Domain

2
nd

Broadcast Domain




Router is unicast.

We have to install router between multiple switches to divide the broadcast domain. Each
broadcast domain has to used diff
erent network address and router will provide inter
network communication between them.



Router operation

When a pc has to send data to a different network address, then data will be forwarded to
the router. It will analysis IP address of the data and obt
ain a route from the routing table.
According to the route data will be dropped, If route not available.











Switch | Hub

Switch | Hub

Switch | Hub


1
8


Pc Architecture






















Router Architecture
















Incomplete


IOS






IOS



Startup Configuration




Non
-
Volatile


RAM




(1)

Processor

Speed:
-

20 MHz to 1GHz

I/O

Controller

K/B

Controller

Keyboard

Display

Card

V.D.U

Serial

Parallel

USB

Sound

Card

Processor

RAM

Memory controller

BIOS

RO
M

CMOS

RAM

HDD

FD

CD
D

Processor

Memory
Controller

BIOS
ROM

NVRAM

RAM

Flash
RAM
O/S

I/O
Controller

LAN

WAN

Ports


1
9


Architecture:
-

RISC




Reduce Instruction set computer


Manufacturers:
-

Motorola, IBM, Power PC, Texas, Dallis, Intel.


(2)

Flash RAM

Flash Ram is the
permanent read/write memory. This memory is used to store one
or more copies of router o/s. Router o/s is also called IOS (Internetwork Operating
System).



Flash Ram stores the only o/s.

The size of flash ram in the router is 4mb to 128mb. The flash ram may

be
available in one of the following three packages:
-

SLMM Flash:
-

Single Line Memory Module

PCMCIA Flash:
-

Personal Computer Memory Card Interface Architecture

Compact Flash:
-

(Small Memory)




(3)

NVRAM

NVRAM is a “Non Volatile Random Access Memory”. It

is used to store the
configuration of the Router. The size of NVRAM is 8 KB to 512 KB.


(4)

RAM

Ram of the router is divided into two logical parts.

(i)

Primary RAM

(ii)

Shared RAM



Primary RAM

Primary RAM is used for:
-

(a)

Running copy of IOS.

(b)

Running configuration

(c)

Rout
ing table

(d)

ARP table (IP address to MAC address)

(e)

Processor & other data structure



Shared RAM

Shared RAM is used as a buffer memory to shared the data received from
different interfaces. Size of ram in a router may vary from 2 mb to 512 mb. The
types of mem
ory that may be present in a ram are:
-

(a)

DRAM
-
> Dynamic RAM

(b)

EDORAM
-
> Extended Data Out Ram

(c)

SDRAM
-
> Synchronous Dynamic Ram


(5)

BIOS ROM

The BIOS ROM is the permanent ROM. This memory is used to store following
program & Routines:
-

(i)

Boot strap loader (doing
booting)


2
0

(ii)

Power on self test routines

(iii)

Incomplete IOS

(iv)

ROM Monitor (ROM
-
MON)




Booting difference between router & Pc


Router







PC

ROM
-
MON






CMOS Setup

Incomplete IOS





Bootable Floppy/CD

FLASH






O/S From HDD















2
1
















Router Inte
rfaces & Ports


Interface is used to connect LAN networks or wan networks to the router.
Interface will use protocol stacks to send/receive data. Ports are used for the
configuration of routers. Ports are not used to connect different n/ws. The primary
purp
ose of port is the management of router.


Router Interfaces

Interface Connector color Speed Use

Ethernet RJ45 yellow 10 mbps to connect Ethernet LAN










Using UTP media

AUI DB15 yellow 10 mbps to connect Ethernet LAN










Using Trans
-
Receiver

Fast Ethernet RJ45 yellow 100 mbps to connect Ethernet

LAN

Serial DB60 blue E1
-
2 mbps to connect WAN

T1
-
1.5 mbps Technology like Leased


Lines, Radio link, Frame


Relay, X.25, ATM

Smart S
erial SS blue “ “

BRI ISDN RJ45 orange 192 kbps to connect ISDN Basic







Rat
e Interface



VOIP RJ11 white
-

to connect Phones, Fax,










EPABX



AUI


Attachment Unit Interface

EPABX


Electronic Private Automatic Branch

PSTN


Public Switched Telephon
e Network


Router Ports

Port Connector Color Speed Details

Console RJ45 sky blue 9600bps used for configuration




Using PC

Auxiliary RJ45 black depend on to connect remote


2
2


Modem router using P
STN line

Virtual terminal
-

-

-

to connect remote router

Vty with telnet protocol via



interface



Types of routers:
-


(1) Fixed configuration router


(2) Modular router

(3) Chassis based router





Other interfaces:
-


(1) Token Ring RJ45

Violet 4/16 mbps


To connect Token Ring network.

(2) E1/T1 controller RJ45 White E1
-
2048 kbps






T1
-
1544 kbps

(3) ADSL RJ11

-




up
-
640 kbps


(Asynchronous Digital Subscriber Line)



Down
-
8 mbps




Router Access Modes

When we access router command prompt the router will display different modes.
According to the modes, privileges and rights are assigned to the u
ser.




















2
3



User mode

In this mode, we can display basic parameter and status of the router we can test
connectivity and perform telnet to other devices. In this mode we are not enable to
manage & configure router.



Privileged mode

In this mod
e, we can display all information, configuration, perform administration task,
debugging, testing and connectivity with other devices. We are not able to perform here
configuration editing of the router.



The command to enter in this mode is ‘enable’. We
have to enter enable
password or enable secret password to enter in this mode. Enable secret has more priority
than enable password. If both passwords are configured then only enable secret will
work.



Global configuration

This mode is used for the configu
ration of global parameters in the router. Global
parameters applied to the entire router.

For e.g:
-

router hostname or access list of router

The command enter in this mode is ‘configure terminal’.



Line configuration mode

This mode is used to configure l
ines like console, vty and auxiliary. There are main types
of line that are configured.

(i) Console


router(config)#line console 0


(ii) Auxiliary


router(config)#line aux 0


(iii) Telnet or vty


router(config)#line vty 0 4




Interface configur
ation mode

This mode is used to configure router interfaces. For e.g:
-

Ethernet, Serial, BRI etc.



Router(config)#interface <type> <number>


Router(config)#interface serial 1



Routing configuration mode

This mode is used to configure routing protocol like

RIP, EIGRP, OSPF etc.


Router(config)#router <protocol> [<option>]



2
4

Router(config)#router rip

Router(config)#router eigrp 10



Configuring Password

There are five types of password available in a router


(1) Console Password


router#configure terminal


router(config)#line console 0


router(config
-
line)#password <word>


router(config
-
line)#login


router(config
-
line)#exit


to erase password do all steps with no command.


(2) Vty Password

router>enable

router#configure terminal

router(
config)#line vty 0 4

router(config
-
line)#password <word>

router(config
-
line)#login

router(config
-
line)#exit


(3) Auxiliary Password

router#configure terminal

router(config)#line Aux 0

router(config
-
line)#password <word>

router(config
-
line)#login

router(con
fig
-
line)#exit


(4) Enable Password

router>enable

router#configure terminal

router(config)#enable password <word>

router(config)#exit


(5) Enable Secret Password

Enable Password is the clear text password. It is stored as clear text in configuration
where
as enable secret password is the encrypted password with MD5 (Media Digest 5)
algorithm.


Router>enable

Router#configure terminal

Router(config)#enable secret <word>

Router(config)#exit



2
5


Encryption all passwords

All passwords other than enable secret passw
ord are clear text password. We can encrypt
all passwords using level 7 algorithm. The command to encrypt all password are


Router#configure terminal

Router(config)#service password
-
encryption



Managing Configuration

There are two types of configuration pr
esent in a router

(1) Startup Configuration

(2) Running Configuration


(1) Startup configuration is stored in the NVRAM. Startup configuration is used to save
settings in a router. Startup configuration is loaded at the time of booting in to the
Primary RA
M.


(2) Running Configuration is present in the Primary RAM wherever we run a command
for configuration, this command is written in the running configuration.



To save configuration

Router#copy running
-
configuration startup
-
configuration


Or

Router#write



To abort configuration

Router#copy startup
-
configuration running
-
configuration



To display running
-
configuration

Router#show running
-
configuration



To display startup configuration

Router#show startup
-
configuration




To erase old configuration

Router#erase

startup
-
configuration

Router#reload


Save[y/n]:n



Access Router using console




Com/Port
--------
DB9
------------------------
Console




Cisco Console RJ45 Router



In windows


2
6

Click start=> program=>

accessories=> comm.(communication)=> hyperterminal

Type any name

Select com port

Set settings


Speed 9600 stop bit 1


Data bits 8


Parity no

Click ok


Press shift+home to default prompt



CISCO command line shortcuts

Tab


to auto complete
command

?


To take help

Ctrl+P


to recall previous command

Ctrl+N


next command

Ctrl+Z


alternate to ‘end’ command

Ctrl+C


to abort

Q


to quit

Ctrl+Shift+6


to break connection



Command line editing shortcuts

Ctrl+A


to move cursor at start of line

Ctrl+E


to move cursor at end of line

Ctrl+ B


to move cursor one character back

Ctrl+F


to move cursor one character forward

Ctrl+W


to delete word one by one word back

Ctrl+D


to delete one character

Ctrl+U


to delete one line

Esc+B


to take curs
or one word back

Esc+F


to take cursor one word forward





Configuring HostName

Router#configure terminal

Router#hostname <name>

<name>#exit or end or /
\
z



Configuration Interfaces

Interfaces configuration is one of the most important part of the router c
onfiguration. By
default, all interfaces of Cisco router are in disabled mode. We have to use different
commands as our requirement to enable and configure the interface.



Configuring IP, Mask and Enabling the Interface

Router#configure terminal


2
7

Router(con
fig)#interface <type> <no>

Router(config
-
if)#ip address <ip> <mask>

Router(config
-
if)#no shutdown

Router(config
-
if)#exit



Interface Numbers

Interface numbers start from 0 for each type of interface some routers will directly used
interface number while oth
er router will use slot no/port no addressing technique.


Eth 0




Slot 1



Slot 0

Serial 0




Serial 1/0


Serial 0/0

Serial 1




Serial 1/1



To configure Interface description

Router#configure terminal

Router(config)#interface <type> <no>

Router(config
-
if)#description <line>



Configuring optional parameter on LAN interface

Router#configure terminal

Router(config)#interface <type> <no>

Router(config
-
if)#duplex <half|full|auto>

Router(config
-
if)#speed <10|100|auto>

Router(config
-
if)#end



Con
figuring optional parameter on WAN interface

Router#configure terminal

Router(config)#interfac <type> <no>

Router(config
-
if)#encapsulation <protocol>

Router(config
-
if)#clock rate <value>

Router(config
-
if)#end







To display interface status

Router#show inte
rfaces (to show all interfaces)

Router#show interface <type> <no>


This command will display following parameters about an interface

1)

Status

2)

Mac address

3)

IP address

4)

Subnet mask

5)

Hardware type / manufacturer

6)

Bandwidth

7)

Reliability


2
8

8)

Delay

9)

Load ( Tx load



Rx load)

10)

Encapsulation

11)

ARP type (if applicable)

12)

Keep alive

13)

Queuing strategy

14)

Input queue details

Output queue details


15) Traffic rate


(In packet per second,



bit per second)


16) Input packet details


17) Output packet details



18) Modem signals (wan interface only)


19) M.T.U maximum transmission rate (mostly 1500 bytes)




Configuring sub interface

Sub interface are required in different scenario. For e.g:
-

in Ethernet we need sub
interface for Vlan communication and in
frame relay we need sub interface for multipoint
connectivity. Sub interface means creating a logical interface from physical interface.


Router#config ter

Router(config)#interface <type> <no> <subint no>

Router(config
-
subif)#

Router(config
-
subif)#end


Rou
ter(config)#interface serial 0.2



Configuring secondary IP

Router#config terminal

Router(config)#interface <type> <no>

Router(config
-
if)#IP address 192.168.10.5 255.255.255.0

Router(config
-
if)#IP address 192.168.10.18 255.255.255.0 secondary

Router(config
-
if)#no shutdown (to enable the interface because they always shutdown)

Router(config
-
if)#exit


Router#show run (to display secondary IP)



Managing Command Line History

We can use CTRL+P & CTRL+N shortcuts to display command history. By default
router will
up to 10 commands. In the command line history, we can use following
commands to edit this setting



To display commands present in history

Router#show history


2
9



To display history size

Router#show terminal



To change history size

Router#config terminal

Rout
er(config)#line console 0

Router(config
-
if)#history size <value(0
-
256)>

Router(config
-
if)#exit



Configuring Banners

Banners are just a message that can appear at different prompts according to the type.
Different banners are:
-


Message of the day (motd)

T
his banner appear at every access method



Login

Appear before login prompt



Exec

Appear after we enter to the execution mode



Incoming

Appear for incoming connections



Syntax:
-

Router#config terminal

Router(config)#banner <type> <delimation char>

Text Mass
age

<delimation char>

Router(config)#


Example:
-

Router#config terminal

Router(config)#banner motd $

This router is distribution 3600 router connected to Reliance

$

Router(config)#



To configure synchronous logging on console

Router#config terminal

Router(c
onfig)#line console 0

Router(config)#logging synchronous

Router(config)#exit



3
0


Configuring Router Clock

We can configure router clock with the help of two methods.

(1) Configure clock locally

(2) Configure clock on NTP server (Network Time Protocol)


Router

does not have battery to save the clock setting. So that clock will reset to the
default on reboot.



To display clock

Router#show clock



To configure clock

Router#clock set hh:mm:ss day month year


00
-
23: 00
-
59:00
-
59 1
-
31 JAN
-
DEC 1993
-
2035



To

configure clock from NTP server

Router#config terminal

Router(config)#ntp server <IP address>

Router(config)#exit


C:
\
>ping pool.ntp.org

To get ntp server ip from internet


C:
\
>route print