Trends K N A

Simple step-by-step guide to change your Wi-Fi password

2025-10-24T05:26:00.000-07:00

how to setup change password wifi

🔹 Step 1: Connect to Your Wi-Fi

Make sure your device (laptop, phone, or PC) is connected to the Wi-Fi network you want to change.

🔹 Step 2: Open the Router Settings Page

Open your web browser (like Chrome or Edge).
In the address bar, type your router’s IP address, usually one of these:
- 192.168.0.1
- 192.168.1.1
- 192.168.100.1
- 10.0.0.1
(If unsure, you can find it by checking your network details — see below for help.)

🔹 Step 3: Log In to Your Router

You’ll be asked for a username and password.
Default login info is often:
- Username: admin
- Password: admin or password
If you changed it before, enter your custom credentials.

(If you don’t know it, look for a sticker on the back or bottom of your router.)

🔹 Step 4: Go to Wireless Settings

Once logged in:

Look for Wireless, Wi-Fi Settings, or Wireless Security.
Choose your Wi-Fi network name (SSID) if there are two bands (2.4GHz / 5GHz).

🔹 Step 5: Change the Password

Find the field labeled Password, Passphrase, or Pre-Shared Key.
Enter your new Wi-Fi password.
- Use at least 8 characters.
- Mix letters, numbers, and symbols for better security.

🔹 Step 6: Save and Reconnect

Click Save or Apply.
Your router will restart or disconnect briefly.
Reconnect your devices using the new password.

💡 Optional: Find Your Router’s IP Address

If you’re not sure of your router’s IP:

On Windows:

Press Windows + R, type cmd, then press Enter.
Type ipconfig and press Enter.
Look for Default Gateway — that’s your router’s IP.

On Android/iPhone:

Go to Wi-Fi settings, tap the connected network → look for Gateway or Router IP.

Query advance SQL database employee

2020-05-12T00:54:00.001-07:00

--------------------------------------------------
-------- 01. Calculation --------
--------------------------------------------------

/*
Select * From Employee
Select * From EmployeeAttendance
*/

-- Maximum, Minimum, Total
-- You can put an Alias Name for the Field
-- Example: Field Sum(HourlyWage) will be Field Total_HourlyWage
Select
Max(HourlyWage) as Max_HourlyWage,
Min(HourlyWage) as Min_HourlyWage,
Sum(HourlyWage) as Total_HourlyWage
From Employee

-- Count record
-- Syntax 'Group By' is used for grouping
Select JobTitle, Count(EmployeeId) as Count_Record From Employee Group By JobTitle

----------------------------------------------------------------------------------------------------
-- Declare Variable
Declare @a int, @b int, @x money, @y money

-- Set Value
Set @a = 5
Set @b = 3
Set @x = 5
Set @y = 3

-- Add, Substract, Multiply
Select
@a + @b as Result_Add,
@a - @b as Result_Substract,
@a * @b as Result_Multiply

-- Divide
-- Data type Integer will have no decimal point
-- Data type Money will have decimal point
Select
@a / @b as Divide_Integer,
@x / @y as Divide_Money

-- Modulo adalah sisa bagi
-- 5 dibagi 3 menghasilkan bilangan bulat 1
-- Kemudian sisa baginya adalah 5 - 3 = 2
Select @a % @b as Result_Modulo

-- Round some digit after comma
Select Round(@x / @y, 2) as Round_Money

-- Floor is to round down until no decimal point
Select Floor(@x / @y) as Round_Money
----------------------------------------------------------------------------------------------------

--------------------------------------------------
-------- 02. String --------
--------------------------------------------------

-- Left take some character from the left string
-- Example: 3 characters from the left string
-- Right take some character from the right string
-- Example: 5 characters from the right string
Select Left(Address, 3) + ' ' + Right(Address, 5) as Alamat From Employee

-- Substring take some character from the starting point to the ending point
-- Len is to count the length of a string
-- Example: The starting point is 5, the ending point is depending on the length of Field Address
Select Substring(Address, 5, Len(Address)) as Alamat From Employee

-- Replace character
Select Replace(JobTitle, 'g', 'j') as Jabatan From Employee

-- Lower & Upper case
Select Lower(FirstName) as FirstName, Upper(LastName) as LastName From Employee

--------------------------------------------------
-------- 03. Date --------
--------------------------------------------------

-- Convert data type Datetime to a specific format string
-- Format 103 = dd/MM/yyyy
-- Format 108 = HH:mm:ss
-- For complete format string: www.sqlusa.com/bestpractices2005/centurydateformat
Select FirstName, Convert(varchar(10), DOB, 103) as DOB From Employee
Select EmployeeId, Convert(varchar(8), SignInDate, 108) as SignInTime From EmployeeAttendance Where Convert(varchar(10), SignInDate, 103) = '12/05/2020'

-- Date Basic Syntax
Select
GetDate() as Current_DateTime,
DatePart(year, GetDate()) as Current_Year,
DatePart(month, GetDate()) as Current_Month,
DatePart(day, GetDate()) as Current_Day,
DatePart(weekday, GetDate()) as Current_DayOfTheWeek,
DateName(month, GetDate()) as Current_MonthName,
DateName(weekday, GetDate()) as Current_DayName,
DateAdd(day, 7, GetDate()) as Next_Week

-- DateDiff is to count the difference between starting date and ending date
Select FirstName, DateDiff(year, DOB, GetDate()) as Age From Employee

Query Basic SQL database employee

2020-05-12T00:50:00.000-07:00

--------------------------------------------------
-------- 01. Add Record --------
--------------------------------------------------

-- Recommended
-- Tell the Field Name
INSERT INTO Department (DepartmentNo, DepartmentName)
VALUES (1, 'Restaurant')

INSERT INTO Department (DepartmentNo, DepartmentName)
VALUES (2, 'Bar')

INSERT INTO Department (DepartmentNo, DepartmentName)
VALUES (3, 'Lounge')

-- Not recommended
-- Not telling the Field Name
-- This will be considered as you tell all the Field Name
INSERT INTO ShiftDetail
VALUES (1, 'Lunch', '08:00:00', '15:59:59')

INSERT INTO ShiftDetail
VALUES (2, 'Dinner', '16:00:00', '22:00:00')

INSERT INTO ShiftDetail
VALUES (3, 'Midnite', '00:00:00', '03:59:59')

-- Another way, using Query Select
-- When you want to put some condition
-- Example: Increase number by 1 for EmployeeId when adding
-- Syntax 'Max' is to get the maximum value
-- Syntax 'Coalesce' is to handle null (no value) and you put the replacement for it
-- Query Select below only get the EmployeeId value from Table Employee, the rest value is manually written
INSERT INTO Employee (EmployeeId, FirstName, LastName, DOB, Sex, Address, Phone, JoinDate, HourlyWage, Active, JobTitle, DepartmentNo, ShiftNo)
Select Coalesce(Max(EmployeeId), 0)+1, 'Agatha', 'Christie', '1976-01-12', 'F', 'New Jersey 50891', '5554961', '2010-01-01', 62500, '1', 'Manager', 1, 1
From Employee

INSERT INTO Employee (EmployeeId, FirstName, LastName, DOB, Sex, Address, Phone, JoinDate, HourlyWage, Active, JobTitle, DepartmentNo, ShiftNo)
Select Coalesce(Max(EmployeeId), 0)+1, 'Ben', 'Hecht', '1984-02-28', 'M', 'New York 50793', '5557373', '2015-10-01', 31250, '1', 'Staff', 1, 1
From Employee

INSERT INTO Employee (EmployeeId, FirstName, LastName, DOB, Sex, Address, Phone, JoinDate, HourlyWage, Active, JobTitle, DepartmentNo, ShiftNo)
Select Coalesce(Max(EmployeeId), 0)+1, 'Clive', 'Lewis', '1983-11-22', 'M', 'Los Angeles 50246', '5559449', '2013-06-01', 50000, '1', 'Supervisor', 2, 2
From Employee

INSERT INTO Employee (EmployeeId, FirstName, LastName, DOB, Sex, Address, Phone, JoinDate, HourlyWage, Active, JobTitle, DepartmentNo, ShiftNo)
Select Coalesce(Max(EmployeeId), 0)+1, 'Debra', 'Granik', '1985-05-05', 'F', 'Las Vegas 50246', '5551234', '2015-06-01', 31250, '1', 'Staff', 2, 2
From Employee

-- When meet field with IDENTITY type, do not tell the Field Name
-- That IDENTITY field will be automatically increased by SQL
-- Example: IDENTITY field for this Table is LogId, so do not tell Field LogId
INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (1, '2020-05-11 08:00:00', '2020-05-11 16:00:00', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (2, '2020-05-11 08:45:00', '2020-05-11 16:30:00', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (3, '2020-05-11 16:15:00', '2020-05-12 00:15:00', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (1, '2020-05-12 08:00:00', '2020-05-12 16:00:00', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (2, '2020-05-12 07:45:00', '2020-05-12 16:00:00', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (3, '2020-05-12 16:15:00', '', '')

INSERT INTO EmployeeAttendance (EmployeeId, SignInDate, SignOutDate, Remark)
VALUES (4, '2020-05-12 16:00:00', '', '')

--------------------------------------------------
-------- 02. Update Record --------
--------------------------------------------------

UPDATE ShiftDetail
SET EndTime='23:59:59'
WHERE ShiftNo=2

--------------------------------------------------
-------- 03. Delete Record --------
--------------------------------------------------

DELETE FROM ShiftDetail
WHERE ShiftNo=3

--------------------------------------------------
-------- 04. Get Data --------
--------------------------------------------------

Select * From ShiftDetail
Select * From Department
Select * From Employee
Select * From EmployeeAttendance

-- Distinct record
Select Distinct Sex From Employee

-- Sort by a field
Select LastName, FirstName From Employee Order By LastName

-- Sort descending, get 1 biggest record
Select Top 1 * From Employee Order By HourlyWage desc

-- Condition '>=' (Greater Than Or Equal)
-- Condition 'And'
-- Condition 'Or'
Select * From Employee Where HourlyWage>=50000 And (DepartmentNo=1 Or ShiftNo=2)

-- Condition '<>' (Not Equal)
-- Condition 'Like'
Select * From Employee Where JobTitle<>'Staff' And FirstName Like '%Aga%'

-- Condition 'Between x And y' (Value Range)
-- Condition 'In' specified values
Select * From Employee Where HourlyWage Between 10000 And 50000 And FirstName In ('Ben', 'Clive')

-- Condition 'Exists' is to check the existence from another table
-- Inside the condition 'Exists', on Query Select, the Field DepartmentName is only a formality, you can tell whatever Field Name you want, it will not be used later
-- Inside the condition 'Exists', on Query Select, at condition 'Where', must have a 'bridge' between Query Select inside the 'Exists' and the main Query Select, the 'bridge' is Field DepartmentNo
-- Syntax 'Case' is like an 'IF-THEN' logic
Select
EmployeeId, FirstName,
Case
When Sex='F' Then 'Female'
When Sex='M' Then 'Male'
Else 'Transgender'
End as Gender
From Employee
Where Exists (Select DepartmentName From Department Where Department.DepartmentNo=Employee.DepartmentNo And DepartmentName='Bar')

SQL Create Table Database Employee

2020-05-12T00:48:00.000-07:00

CREATE TABLE Department
(
DepartmentNo int not null default 0,
DepartmentName varchar(20) not null default ''
)

CREATE TABLE ShiftDetail
(
ShiftNo int not null default 0,
ShiftName varchar(20) not null default '',
StartTime varchar(8) not null default '08:00:00',
EndTime varchar(8) not null default '16:00:00'
)

CREATE TABLE Employee
(
EmployeeId int not null default 0,
FirstName varchar(20) not null default '',
LastName varchar(20) not null default '',
DOB datetime not null default '1900-01-01',
Sex varchar(1) not null default 'M',
Address varchar(50) not null default '',
Phone varchar(20) not null default '',
JoinDate datetime not null default '1900-01-01',
HourlyWage money not null default 0,
Active bit not null default '1',
JobTitle varchar(20) not null default '',
DepartmentNo int not null default 0
)

CREATE TABLE EmployeeAttendance
(
LogId int identity(1,1) not null,
EmployeeId int not null default 0,
SignInDate datetime not null default '1900-01-01',
SignOutDate datetime not null default '1900-01-01',
Remark varchar(50) not null default ''
)

CREATE TABLE EmployeeReport
(
ReportNo int not null default 0,
ReportDate datetime not null default '1900-01-01',
EmployeeId int not null default 0,
StartDate datetime not null default '1900-01-01',
EndDate datetime not null default '1900-01-01',
WorkingHour varchar(20) not null default '',
LateMinute int not null default 0
)

--------------------------------------------------
-------- 03. Add Field On Table --------
--------------------------------------------------

ALTER TABLE Employee
ADD ShiftNo int not null default 0

--------------------------------------------------
-------- 04. Change Data Type On Field --------
--------------------------------------------------

ALTER TABLE EmployeeAttendance
ALTER COLUMN Remark varchar(100)

oracle database work

2020-05-12T00:41:00.000-07:00

Oracle database is a collection of physical operating system files or disks (in the simplest terms). Oracle instance is set of Oracle background processes or threads and a shared memory area, which is memory that is shared across those threads or processes running on a single computer. There are basically 9 Processes but in a general system we need to mention the first five background processes.They do the housekeeping activities for the Oracle and are common in any system.

The various background processes in oracle.

1) Database Writer(DBWR) :

Database Writer Writes Modified blocks from Database buffer cache to Data Files.This is required since the data is not written whenever a transaction is committed.
2)LogWriter(LGWR) :

Log Writer writes the redo log entries to disk. Redo Log data is generated in redo log buffer of SGA. As transaction commits and log buffer fills, LGWR writes log entries into a online redo log file.
3) System Monitor(SMON) :

The System Monitor performs instance recovery at instance startup. This is useful for recovery from system failure
4)Process Monitor(PMON) :

The Process Monitor performs process recovery when user Process fails. Pmon Clears and Frees resources that process was using.
5) CheckPoint(CKPT) :

At Specified times, all modified database buffers in SGA are written to data files by DBWR at Checkpoints and Updating all data files and control files of database to indicate the most recent checkpoint
6)Archives(ARCH) :

The Archiver copies online redo log files to archival storage when they are busy.
7) Recoverer(RECO) :

The Recoverer is used to resolve the distributed transaction in network
8) Dispatcher (Dnnn) :

The Dispatcher is useful in Multi Threaded Architecture
9) Lckn :

We can have up to 10 lock processes for inter instance locking in parallel sql

How dangerous is the coronavirus 2020

2020-05-11T00:21:00.000-07:00

The coronavirus is extremely dangerous, and I suspect that the danger is currently being underplayed by the world medical community to minimize panic as we prepare for the worst.
Covid-19 is deadly, although fatality rates skyrocket for the elderly and those with compromised immune systems.

First and foremost, it is really important to know that as of today (February 17, 2020), there is still much we do not know about SARS-CoV-2 (i.e. the official name of the novel coronavirus) and COVID-19 (i.e. the official name of the disease caused by SARS-CoV-2). This uncertainty makes this question difficult to answer with a short or simple response.

However, epidemiologists and scientists from around the world are making rapid and significant real-time progress in understanding the nature of this novel coronavirus. Earlier today, a comprehensive report from the China CDC was released on over 70,000 individual cases in China, which included data for 99% of confirmed cases globally as of February 11th, 2020.

As I stated at the very beginning, there are still many unknowns out there. That is why there is no simple answer to the question of how dangerous this thing really is. Among others:

There is no vaccine against COVID-19 (one that can be deployed safely at scale)
We are still unsure about how contagious this is in people that are infected but asymptomatic
We do not know how many people are infected, because (very likely) many people are infected and not yet identified for a variety of reasons
We do not know exactly why infection and/or mortality rates for young people are so much lower
We do not know how countries with less-developed healthcare systems will be able to cope with potential outbreaks
SARS-CoV-2 will continue to mutate and evolve (although scientists aren’t that worried about this)
It’s hard to predict the second-order effects (e.g. policy under/over-reaction, economic disruption, etc.)

What is the difference between DBMS and SQL

2020-05-11T00:09:00.000-07:00

DBMS is a system and SQL is a language

DBMS (Database Management System)
A DBMS is a software for creating and managing databases. The DBMS provides users with a systematic way to create, retrieve, update and manage data. It is a middleware between the database which store all the data and the users or applications which need to interact with that stored database. A DBMS can limit what data the end user sees, as well as how that end user can view the data, providing many views of a single database schema

SQL (Structured Query Language)
SQL is the programming language which is used to access this DBMS and the database. It is the language in which you write the command regarding how and what to access in the database. In the figure above, API is what is SQL. The APP or the USER writes SQL commands which are processed by the DBMS

We use the DBMS system along with SQL for querying data in the database.

Now, for knowing the difference, you must understand one thing that is - in SQL we can see the data we want by asking a query, while DBMS optimizes the query and show us the data.

Let’s understand it with the example -

Suppose, you have a table that contains details of different persons such as name, age, gender, mobile number, address etc.

Now, if you want to see the mobile number of a person, you simply gave a query to DBMS, DBMS here starts working, catches query and finally, it will show you the mobile number of that person.

A DBMS (database management system) is a software system that allows you to store and retrieve data in an efficient and organized manner.

SQL is a formal language that allows you to communicate with many DBMS to insert, query, update, delete the content.

A large subset of the DBMS uses SQL, most notably almost all so-called "relational" DBMS. However, there are non-relational DBMS that use SQL (e.g. IDMS), and relational DBMS that don't use SQL (in particular the early versions of Ingres and Postgres)

Spiderman : Homeless Recent Buzz about the Exit of Spiderman Franchise from MCU

2019-08-21T04:03:00.000-07:00

In a Sony statement to USA TODAY Tuesday night, the studio said the outstanding issue remained over the future involvement of Marvel President, and comic movie mastermind, Kevin Feige as producer in future Spider-man films.

So when the two companies agreed to share his rights in 2015, it felt like a homecoming -- Spider-Man was finally able to appear in films in the Marvel Universe.

Now played by Tom Holland, the character has appeared in five Marvel movies since that deal -- most recently this year's "Spider-Man: Far From Home."

If Sony and Disney can't come to a deal, Spidey might not be in Marvel movies in the near future – but he probably wouldn't be anyway, unless for some reason he was supposed to be in "Black Widow" or "The Eternals," the MCU's next two films (which is highly doubtful). There's plenty of time to work stuff out.

Pulo Cinta Resort is an Indonesian Maldives

2019-08-21T03:47:00.000-07:00

Pulo Cinta has a very unique historical story. Once upon a time during the Dutch colonial era, this island became a place of escape between the Prince of Gorontalo and the daughter of one of the Dutch traders. When that war broke out and was expelled from the local community. As a result their love is not condoned. They finally chose to break away and isolate the Pulo Cinta.

The Pulo Cinta natural tourism destination is perfect as a honeymoon spot for a new friend to get married, this Gorontalo island is located in Tomini Bay, Patoameme Village, Botumoito District, Boalemo Regency, Gorontalo Province, North Sulawesi. The distance is indeed quite far, if calculated travel from the city of Gorontalo which is about 115 kilometers or takes about 3 hours by road or any bay.

To visit Pulo Cinta, you have to take a flight to Jalaluddin Airport and continue the journey to Bolihutuo Beach. Only then will you board the ship for approximately 15 minutes to reach this Pulo Cinta.

Mini Africa Savanna in Wonderful Indonesia "Baluran National Park"

2019-08-21T01:55:00.000-07:00

Baluran National Park protects pasture animals such as buffalo, buffalo, deer, long-tailed monkey and long-tailed bird, peacock. You can see where they are grazing in the middle of the savanna. Every now and then, a herd of deer will cross your vehicle that is passing the road. This scene is often found in pastures like this. It is as if you will be taken far to jump to Africa with such a situation.

The area of Baluran National Park is 25 thousand hectares. The location of Baluran National Park is included in Wonorejo village, Banyuputih sub-district, Situbondo district, East Java. Actually, this Baluran area is located on the border of Situbondo and Banyuwangi districts. Many people call the Baluran Situbondo National Park, others also call the Baluran Banyuwangi National Park. It's simple, because the location of this park is closer to Banyuwangi than Situbondo district.

For ticket prices on domestic weekdays, Rp. 15,000 per day and abroad Rp. 150,000 per day, groups of students or students Rp. 8,000 per day, 2 wheels Rp. 5,000 per day, 4 wheels Rp. 10,000 per day, minbus or trucks Rp. 50,000 per day.

On domestic holidays Rp. 17,500 per day, foreign countries Rp. 225,000 per day, student groups or students Rp. 9,500 per day. 2 wheel Rp 7,500 per day, car Rp 15,000 per day, minibus or truck Rp 75,000 per day.

Most Romantic married Dwayne Johnson and Lauren Hashian

2019-08-20T00:05:00.003-07:00

Dwayne Johnson was born in Hayward, California, United States, May 2, 1972.

47 years old is an American actor and professional wrestler at WWE known

as "The Rock". recently conducted a romantic marriage with an actress

named Lauren Hashian. He announced the news in an Instagram post,

featuring the couple with their arms above their heads and giant smiles

plastered on their faces.Pink and blue clouds are scattered above an

ocean backdrop, and the caption is simple: "We do. August 18th, 2019.

Hawaii. Pmamaʻi (blessed)."Johnson and Hashian, 34, first met in 2006

while the actor was filming The Game Plan and started dating in 2007.

They share daughters Jasmine, 3, and Tiana, 16 months.

Configure IP address on router using the Setup command

2013-10-16T21:44:00.000-07:00

[admin@MikroTik] > setup
Setup uses Safe Mode. It means that all changes that are made during setup
are reverted in case of error, or if [Ctrl]+[C] is used to abort setup. To keep
changes exit setup using the [X] key.

[Safe Mode taken]
Choose options by pressing one of the letters in the left column, before
dash. Pressing [X] will exit current menu, pressing Enter key will select the
entry that is marked by an '*'. You can abort setup at any time by pressing
[Ctrl]+[C].
Entries marked by '+' are already configured.
Entries marked by '-' cannot be used yet.
Entries marked by 'X' cannot be used without installing additional packages.
r - reset all router configuration
+ l - load interface driver
* a - configure ip address and gateway
d - setup dhcp client
s - setup dhcp server
p - setup pppoe client
t - setup pptp client
x - exit menu
your choice [press Enter to configure ip address and gateway]: a

To configure IP address and gateway, press a or [Enter], if the a choice is marked with an asterisk symbol ('*').

* a - add ip address
- g - setup default gateway
x - exit menu
your choice [press Enter to add ip address]: a

Choose a to add an IP address. At first, setup will ask you for an interface to which the address will be assigned. If the setup offers you an undesirable interface, erase this choice, and press the [Tab] key twice to see all available interfaces. After the interface is chosen, assign IP address and network mask on it:

your choice: a
enable interface:
ether1 ether2 wlan1
enable interface: ether1
ip address/netmask: 10.1.0.66/24
#Enabling interface
/interface enable ether1
#Adding IP address
/ip address add address=10.1.0.66/24 interface=ether1 comment="added by setup"
+ a - add ip address
* g - setup default gateway
x - exit menu
your choice: x

basic configuration the Mikrotik

2013-10-16T21:34:00.000-07:00

Before configuring the IP addresses and routes please check the /interface menu to see the list of available interfaces. If you have Plug-and-Play cards installed in the router, it is most likely that the device drivers have been loaded for them automatically, and the relevant interfaces appear on the /interface print

[admin@MikroTik] interface> print
Flags: X - disabled, D - dynamic, R - running
 #    NAME                         TYPE             RX-RATE    TX-RATE    MTU
 0  R ether1                       ether            0          0          1500
 1  R ether2                       ether            0          0          1500
 2 X  wavelan1                     wavelan          0          0          1500
 3 X  prism1                       wlan             0          0          1500
[admin@MikroTik] interface>

The interfaces need to be enabled, if you want to use them for communications. Use the /interface enable name command to enable the interface with a given name or number, for example:

[admin@MikroTik] interface> print
Flags: X - disabled, D - dynamic, R - running
 #    NAME                         TYPE             RX-RATE    TX-RATE    MTU
 0 X  ether1                       ether            0          0          1500
 1 X  ether2                       ether            0          0          1500
[admin@MikroTik] interface> enable 0
[admin@MikroTik] interface> enable ether2
[admin@MikroTik] interface> print
Flags: X - disabled, D - dynamic, R - running
 #    NAME                         TYPE             RX-RATE    TX-RATE    MTU
 0  R ether1                       ether            0          0          1500
 1  R ether2                       ether            0          0          1500
[admin@MikroTik] interface>

Basics proxy setup for beginners

2013-10-16T21:21:00.000-07:00



Normally you connect to the router by IP addresses with any telnet or SSH

client software (a simple text-mode telnet client is usually called telnet and

is distributed together with almost any OS). You can also use graphical

configuration tool for Windows (also can be run in Linux using Wine) called

Winbox. To get Winbox, connect to the router's IP address with a web

browser, and follow the link to download winbox.exe from the router.







MAC-telnet is used to connect to a router when there is no other way to

connect to it remotely if the router has no IP address or in case of

misconfigured firewall. MAC-telnet can only be used from the same

broadcast domain (so there should be no routers in between) as any of the

router's enabled interfaces (you can not connect to a disabled interface).

MAC-telnet program is a part of the Neighbor Viewer. Download it from

www.mikrotik.com, unpack both files contained in the archive to the same

directory, and run NeighborViewer.exe. A list of MikroTik routers working in

the same broadcast domain will be showed double-click the one you need to

connect to. Note that Winbox is also able to connect to routers by their MAC

addresses, and has the discovery tool built-in.





You can also connect to the router using a standard DB9 serial null-modem

cable from any PC. Default settings of the router's serial port are 9600 bits/s

(for RouterBOARD 500 series - 115200 bits/s), 8 data bits, 1 stop bit, no

parity, hardware (RTS/CTS) flow control. Use terminal emulation program

(like HyperTerminal or SecureCRT in Windows, or minicom in UNIX/Linux) to

connect to the router. The router will beep twice when booted up, and you

should see the login prompt shortly before that (check cabling and serial

port settings if you do not see anything in the terminal window).




log/ -- System logs

quit -- Quit console

radius/ -- Radius client settings

certificate/ -- Certificate management

special-login/ -- Special login users

redo -- Redo previously undone action

driver/ -- Driver management

ping -- Send ICMP Echo packets

setup -- Do basic setup of system

interface/ -- Interface configuration

password -- Change password

undo -- Undo previous action

port/ -- Serial ports

import -- Run exported configuration script

snmp/ -- SNMP settings

user/ -- User management

file/ -- Local router file storage.

system/ -- System information and utilities

queue/ -- Bandwidth management

ip/ -- IP options

tool/ -- Diagnostics tools

ppp/ -- Point to Point Protocol

routing/ -- Various routing protocol settings

export  --

[admin@MikroTik] ip>

 

.. -- go up to root

service/ -- IP services

socks/ -- SOCKS version 4 proxy

arp/ -- ARP entries management

upnp/ -- Universal Plug and Play

dns/ -- DNS settings

address/ -- Address management

accounting/ -- Traffic accounting

the-proxy/ --

vrrp/ -- Virtual Router Redundancy Protocol

pool/ -- IP address pools

packing/ -- Packet packing settings

neighbor/ -- Neighbors

route/ -- Route management

firewall/ -- Firewall management

dhcp-client/ -- DHCP client settings

dhcp-relay/ -- DHCP relay settings

dhcp-server/ -- DHCP server settings

hotspot/ -- HotSpot management

ipsec/ -- IP security

web-proxy/ -- HTTP proxy

export --

[admin@MikroTik] ip>





MAC-telnet is used to connect to a router when there is no other way to


connect to it remotely if the router has no IP address or in case of

misconfigured firewall. MAC-telnet can only be used from the same

broadcast domain (so there should be no routers in between) as any of the

router's enabled interfaces (you can not connect to a disabled interface).

MAC-telnet program is a part of the Neighbor Viewer. Download it from

www.mikrotik.com, unpack both files contained in the archive to the same

directory, and run NeighborViewer.exe. A list of MikroTik routers working in

the same broadcast domain will be showed double-click the one you need to

connect to. Note that Winbox is also able to connect to routers by their MAC

addresses, and has the discovery tool built-in.

You can also connect to the router using a standard DB9 serial null-modem

cable from any PC. Default settings of the router's serial port are 9600 bits/s

(for RouterBOARD 500 series - 115200 bits/s), 8 data bits, 1 stop bit, no

parity, hardware (RTS/CTS) flow control. Use terminal emulation program

(like HyperTerminal or SecureCRT in Windows, or minicom in UNIX/Linux) to

connect to the router. The router will beep twice when booted up, and you

should see the login prompt shortly before that (check cabling and serial port settings if you do not see anything in the terminal window).

The purpose programming language design

2013-09-18T00:44:00.000-07:00

A good language should be easy to compile.

Not complicate the compilation process.

Complexity can arise because of the symbol

have different meanings.

Example signs parenthesis (brackets open / close):

Grouping sub-expression Restricted arguments in the function / procedureIndex on the arrays (in VB) Expression of mathematics and logic Examples of simple but powerful scheme are passing parameters by value and by reference.

What Role Did She Play in Miley-Liam Split? : January Jones

2013-09-18T00:43:00.000-07:00

At least one tabloid has said Hemsworth was caught cheating with Eiza Gonzalez over the weekend, a Mexican singer/actress with whom he hooked up in Las Vegas.

But other reports have claimed tension between Liam and Miley for weeks, dating back to the latter's lewd Video Music Awards performance and continuing when Cyrus went naked for her "Wrecking Ball" video.

Then there's January Jones.

Rumors first surfaced in February that Liam swapped spit with the Mad Men actress at a Vanity Fair party, while an insider alleges the two have kept in contact ever since... especially dirty contact, that is!

More than one source says Hemsworth texted Jones that he wants to "f-ck" her, while Us Weekly quotes a friend of the star's who backs up this allegation and adds that "January thinks Liam is so sexy."

Liam Hemsworth was reportedly pursuing Mad Men’s January Jones, while his relationship with his 20-year-old fiancee crumbled in recent months.

A source told Us magazine that Jones thinks that The Hunger Games actor is very sexy.

Earlier this summer, Hemsworth had also sent the 35-year-old single mum, a graphic sexual message, which read the he wants to “**** her”.

The Mad Men star was earlier linked to Miley Cyrus’ former fiancee in February, when the two of them were spotted leaving West Hollywood hotspot, ‘Chateau Marmont,’ together.

A source had then revealed that Jones and Hemsworth were “all over each other” at a house party that night, though the 23-year-old actor denied the rumours.

Though a rep had recently hit out at claims Liam had been pursing the actress, insisting to GossipCop the rumours were "tabloid fiction," sources recently told Us Weekly the actor had once again been after her. "January thinks Liam is so sexy," a source told Us Weekly, claiming the couple were "all over each other," on the infamous night out at the Chateau Marmont.

Hamming code

2013-09-18T00:30:00.003-07:00

Hamming code
Richard Hamming invented at Bell Labs in 1950
Error detection mechanisms by adding a data word (D) with a code, usually a parity check bit (C).
The data stored in length D + C.
Known errors by analyzing the data and parity bits

# Data Bits	# Bit Paritas SEC	# Bit Paritas DEC
8	4	5
16	5	6
32	6	7
64	7	8
128	8	9
512	9	10

Parity check bits are placed with 2N formulation where
Each check bit (C) operates in every bit position data position number 1 in the column contains numbers
Data enter: 00111001 then change the data bits to 3 from 0 to 1 as its error.

how to get the data bits to 3 bits as there are errors?

N = 0,1,2, ……, while the remaining bits of the data is. Then the exclusive-OR sum::

C1 = D1 Å D2 Å D4 Å D5 Å D7

C2 = D1 Å D3 Å D4 Å D6 Å D7

C4 = D2 Å D3 Å D4 Å D8

C8 = D5 Å D6 Å D7 Å D8

answer:

Enter data into the formulation of the parity check bits :

C1 = 1 Å 0 Å 1 Å 1 Å 0 = 1

C2 = 1 Å 0 Å 1 Å 1 Å 0 = 1

C4 = 0 Å 0 Å 1 Å 0 = 1

C8 = 1 Å 1 Å 0 Å 0 = 0

Now bit 3 having a data error : 00111101

C1 = 1 Å 0 Å 1 Å 1 Å 0 = 1

C2 = 1 Å 1 Å 1 Å 1 Å 0 = 0

C4 = 0 Å 1 Å 1 Å 0 = 0

C8 = 1 Å 1 Å 0 Å 0 = 0

Query for checking

2013-09-18T00:02:00.000-07:00

/*before running this script run the report from backoffice first to store the data to table itemsales*/
/*this query will find out variance between sales after tax/gross sales and collected*/

--1.run this script to group all item per salesno
SELECT salesno,splitno,
Sum(([ItemSales].[Quantity]*[ItemSales].[ItemAmount])*case when
([ItemSales].[TransMode]='REG') then 1 else -1 end *case when ((FunctionID)=26)
then 1 else 0 end ) AS ItemSales,
Sum(((Discount)+(PromotionSaving))*case when
((FunctionID)=26) then 1 else 0 end *case when ((DiscountType)<>'FOC Item') then
1 else 0 end *case when ((TransMode)='REG') then 1 else -1 end ) AS ItemDisc,
Sum((ItemAmount)*case when ((FunctionID)=25) then 1 else 0 end *case when
((TransMode)='REG') then 1 else -1 end ) AS BillDisc,
(
Sum(([ItemAmount]*[Quantity])*case when (([FOCType])='FOC Item') then 1 else 0
end *case when ((FunctionID)=26) then 1 else 0 end *case when
(([TransMode])='REG') then 1 else -1 end )) AS TFOC,
Sum(([ItemAmount])*case
when ((FunctionID)=7) then 1 else 0 end *case when (([TransMode])='REG') then 1
else -1 end ) AS BFOC, Sum((Tax0)*case when ((TransMode)='REG') then 1 else -1
end ) AS TTax0,
Sum((Tax1)*case when ((TransMode)='REG') then 1 else -1 end
*case when FunctionID=1 or FunctionID=2 or FunctionID=3 or FunctionID=4 or
FunctionID=5 or FunctionID=6 or FunctionID=8 or FunctionID=9 then 1 else 0
end ) AS TTax1,
Sum((Gratuity)*case when ((TransMode)='REG') then 1 else -1 end
) AS TGratuity,
Sum((RndingAdjustments)*case when ((TransMode)='REG') then 1
else -1 end ) AS TRndAdj,
Sum(([ItemAmount]+[Gratuity])*case when FunctionID=1
or FunctionID=2 or FunctionID=3 or FunctionID=4 or FunctionID=5 or
FunctionID=6 or FunctionID=8 or FunctionID=9 then 1 else 0 end *case when
(([TransMode])='REG') then 1 else -1 end ) AS Collected,
Sum(([ItemSales].[Covers])*case when ([ItemSales].[TransMode]='REG') then 1 else
-1 end *case when ([ItemSales].[TransStatus]='S') then 1 else 0 end ) AS
TCovers, Sum(([ItemSales].[Quantity])*case when ([ItemSales].[TransMode]='REG')
then 1 else -1 end *case when ([ItemSales].[TransStatus]='S') then 1 else 0 end
) AS TBills
, Sum(RndingAdjustments) as RndingAdjustments
into #tot
FROM ItemSales WHERE ((ItemSales.TransStatus)=' ') OR
((ItemSales.TransStatus)='S') or ((Itemsales.TransStatus)='E')
group by salesno,splitno

--2.run this script to get netsales and tax
select salesno,itemsales,itemsales-itemdisc-billdisc-tfoc-bfoc as netsales,collected-RndingAdjustments as collected,tgratuity,ttax0,ttax1
into #tot2
from #tot

--3.a run this script for exclusive tax
select salesno,itemsales,netsales+ttax0+ttax1+tgratuity as NetAndTax,collected
into #tot3
from #tot2

--3.b run this script for inclusive tax
select salesno,itemsales,netsales+tgratuity as NetAndTip,collected
into #tot3
from #tot2

--4.run this script to find out the variance
select * from #tot3
where netandtax<>collected

/*after you find out wrong salesno,go to salesitemstemp and anlyze the data to find out the wrong record*/

Duplex Settings

2010-08-24T07:05:00.000-07:00

There are two types of duplex settings used for communications on an Ethernet network: half duplex and full duplex. The figure shows the two duplex settings available on modern network equipment.

Half Duplex: Half-duplex communication relies on unidirectional data flow where sending and receiving data are not performed at the same time. This is similar to how walkie-talkies or two-way radios function in that only one person can talk at any one time. If someone talks while someone else is already speaking, a collision occurs. As a result, half-duplex communication implements CSMA/CD to help reduce the potential for collisions and detect them when they do happen. Half-duplex communications have performance issues due to the constant waiting, because data can only flow in one direction at a time. Half-duplex connections are typically seen in older hardware, such as hubs. Nodes that are attached to hubs that share their connection to a switch port must operate in half-duplex mode because the end computers must be able to detect collisions. Nodes can operate in a half-duplex mode if the NIC card cannot be configured for full duplex operations. In this case the port on the switch defaults to a half-duplex mode as well. Because of these limitations, full-duplex communication has replaced half duplex in more current hardware.

Full Duplex: In full-duplex communication, data flow is bidirectional, so data can be sent and received at the same time. The bidirectional support enhances performance by reducing the wait time between transmissions. Most Ethernet, Fast Ethernet, and Gigabit Ethernet NICs sold today offer full-duplex capability. In full-duplex mode, the collision detect circuit is disabled. Frames sent by the two connected end nodes cannot collide because the end nodes use two separate circuits in the network cable. Each full-duplex connection uses only one port. Full-duplex connections require a switch that supports full duplex or a direct connection between two nodes that each support full duplex. Nodes that are directly attached to a dedicated switch port with NICs that support full duplex should be connected to switch ports that are configured to operate in full-duplex mode.

Standard, shared hub-based Ethernet configuration efficiency is typically rated at 50 to 60 percent of the 10-Mb/s bandwidth. Full-duplex Fast Ethernet, compared to 10-Mb/s bandwidth, offers 100 percent efficiency in both directions (100-Mb/s transmit and 100-Mb/s receive).

key elements ethernet 802.3 networks

2010-08-24T04:21:00.000-07:00

In this topic, you will learn about key components of the Ethernet standard that play a significant role in the design and implementation of switched networks. You will explore how Ethernet communications function and how switches play a role in the communication process.

CSMA/CD

Ethernet signals are transmitted to every host connected to the LAN using a special set of rules to determine which station can access the network. The set of rules that Ethernet uses is based on the IEEE carrier sense multiple access/collision detect (CSMA/CD) technology. You may recall from CCNA Exploration: Networking Fundamentals that CSMA/CD is only used with half-duplex communication typically found in hubs. Full-duplex switches do not use CSMA/CD.

Carrier Sense

In the CSMA/CD access method, all network devices that have messages to send must listen before transmitting.

If a device detects a signal from another device, it waits for a specified amount of time before attempting to transmit.

When there is no traffic detected, a device transmits its message. While this transmission is occurring, the device continues to listen for traffic or collisions on the LAN. After the message is sent, the device returns to its default listening mode.

Multi-access

If the distance between devices is such that the latency of the signals of one device means that signals are not detected by a second device, the second device may also start to transmit. The media now has two devices transmitting signals at the same time. The messages propagate across the media until they encounter each other. At that point, the signals mix and the messages are destroyed, a collision. Although the messages are corrupted, the jumble of remaining signals continues to propagate across the media.

Collision Detection

When a device is in listening mode, it can detect when a collision occurs on the shared media, because all devices can detect an increase in the amplitude of the signal above the normal level.

When a collision occurs, the other devices in listening mode, as well as all the transmitting devices, detect the increase in the signal amplitude. Every device that is transmitting continues to transmit to ensure that all devices on the network detect the collision.

Jam Signal and Random Backoff

When a collision is detected, the transmitting devices send out a jamming signal. The jamming signal notifies the other devices of a collision, so that they invoke a backoff algorithm. This backoff algorithm causes all devices to stop transmitting for a random amount of time, which allows the collision signals to subside.

After the delay has expired on a device, the device goes back into the "listening before transmit" mode. A random backoff period ensures that the devices that were involved in the collision do not try to send traffic again at the same time, which would cause the whole process to repeat. However, during the backoff period, a third device may transmit before either of the two involved in the collision have a chance to re-transmit.

Ethernet Communications

Reference the selected Ethernet Communications area in the figure.

Communications in a switched LAN network occur in three ways: unicast, broadcast, and multicast:

Unicast: Communication in which a frame is sent from one host and addressed to one specific destination. In unicast transmission, there is just one sender and one receiver. Unicast transmission is the predominant form of transmission on LANs and within the Internet. Examples of unicast transmissions include HTTP, SMTP, FTP, and Telnet.

Broadcast: Communication in which a frame is sent from one address to all other addresses. In this case, there is just one sender, but the information is sent to all connected receivers. Broadcast transmission is essential when sending the same message to all devices on the LAN. An example of a broadcast transmission is the address resolution query that the address resolution protocol (ARP) sends to all computers on a LAN.

Multicast: Communication in which a frame is sent to a specific group of devices or clients. Multicast transmission clients must be members of a logical multicast group to receive the information. An example of multicast transmission is the video and voice transmissions associated with a network-based, collaborative business meeting.

Ethernet Frame

The first course in our series, CCNA Exploration: Networking Fundamentals, described the structure of the Ethernet frame in detail. To briefly review, the Ethernet frame structure adds headers and trailers around the Layer 3 PDU to encapsulate the message being sent. Both the Ethernet header and trailer have several sections (or fields) of information that are used by the Ethernet protocol. The figure shows the structure of the current Ethernet frame standard, the revised IEEE 802.3 (Ethernet).

Roll over each field name to see its description.

Preamble and Start Frame Delimiter Fields

The Preamble (7 bytes) and Start Frame Delimiter (SFD) (1 byte) fields are used for synchronization between the sending and receiving devices. These first 8 bytes of the frame are used to get the attention of the receiving nodes. Essentially, the first few bytes tell the receivers to get ready to receive a new frame.

Destination MAC Address Field

The Destination MAC Address field (6 bytes) is the identifier for the intended recipient. This address is used by Layer 2 to assist a device in determining if a frame is addressed to it. The address in the frame is compared to the MAC address in the device. If there is a match, the device accepts the frame.

Source MAC Address Field

The Source MAC Address field (6 bytes) identifies the frame's originating NIC or interface. Switches use this address to add to their lookup tables.

Length/Type Field

The Length/Type field (2 bytes) defines the exact length of the frame's data field. This field is used later as part of the Frame Check Sequence (FCS) to ensure that the message was received properly. Only a frame length or a frame type can be entered here. If the purpose of the field is to designate a type, the Type field describes which protocol is implemented. When a node receives a frame and the Length/Type field designates a type, the node determines which higher layer protocol is present. If the two-octet value is equal to or greater than 0x0600 hexadecimal or 1536 decimal, the contents of the Data Field are decoded according to the protocol indicated; if the two-byte value is less than 0x0600 then the value represents the length of the data in the frame.

Data and Pad Fields

The Data and Pad fields (46 to 1500 bytes) contain the encapsulated data from a higher layer, which is a generic Layer 3 PDU, or more commonly, an IPv4 packet. All frames must be at least 64 bytes long (minimum length aides the detection of collisions). If a small packet is encapsulated, the Pad field is used to increase the size of the frame to the minimum size.

Frame Check Sequence Field

The FCS field (4 bytes) detects errors in a frame. It uses a cyclic redundancy check (CRC). The sending device includes the results of a CRC in the FCS field of the frame. The receiving device receives the frame and generates a CRC to look for errors. If the calculations match, no error has occurred. If the calculations do not match, the frame is dropped.

MAC Address

In CCNA Exploration: Networking Fundamentals, you learned about the MAC address. An Ethernet MAC address is a two-part 48-bit binary value expressed as 12 hexadecimal digits. The address formats might be similar to 00-05-9A-3C-78-00, 00:05:9A:3C:78:00, or 0005.9A3C.7800.

All devices connected to an Ethernet LAN have MAC-addressed interfaces. The NIC uses the MAC address to determine if a message should be passed to the upper layers for processing. The MAC address is permanently encoded into a ROM chip on a NIC. This type of MAC address is referred to as a burned in address (BIA). Some vendors allow local modification of the MAC address. The MAC address is made up of OUI numbers. Within the OUI, there are 2 bits that have meaning only when used in the destination address, as follows:

Broadcast or multicast bit: Indicates to the receiving interface that the frame is destined for all or a group of end stations on the LAN segment.

Locally administered address bit: If the vendor-assigned MAC address can be modified locally, this bit should be set.

Vendor Assignment Number

The vendor-assigned part of the MAC address is 24 bits long and uniquely identifies the Ethernet hardware. It can be a BIA or modified by software indicated by the local bit.

LOGIC GATE

2010-08-05T21:27:00.000-07:00

Computer system architecture is composed of a series of logic 1 (true) and 0 (false) combined with a number of logic gates are AND, OR, NOT, NOR, XOR, NAND.

The computer program running on the basic structure of good reasoning from a solution to the problems with the help of the program component that is if-then, if - then-else and other

Access Layer Switch Features

2010-07-23T22:48:00.000-07:00

Now that you know which factors to consider when choosing a switch, let us examine which features are required at each layer in a hierarchical network. You will then be able to match the switch specification with its ability to function as an access, distribution, or core layer switch.

Access layer switches facilitate the connection of end node devices to the network. For this reason, they need to support features such as port security, VLANs, Fast Ethernet/Gigabit Ethernet, PoE, and link aggregation.

Port security allows the switch to decide how many or what specific devices are allowed to connect to the switch. All Cisco switches support port layer security. Port security is applied at the access. Consequently, it is an important first line of defense for a network. You will learn about port security in Chapter 2.

VLANs are an important component of a converged network. Voice traffic is typically given a separate VLAN. In this way, voice traffic can be supported with more bandwidth, more redundant connections, and improved security. Access layer switches allow you to set the VLANs for the end node devices on your network.

Port speed is also a characteristic you need to consider for your access ayer switches. Depending on the performance requirements for your network, you must choose between Fast Ethernet and Gigabit Ethernet switch ports. Fast Ethernet allows up to 100 Mb/s of traffic per switch port. Fast Ethernet is adequate for IP telephony and data traffic on most business networks, however, performance is slower than Gigabit Ethernet ports. Gigabit Ethernet allows up to 1000 Mb/s of traffic per switch port. Most modern devices, such as workstations, notebooks, and IP phones, support Gigabit Ethernet. This allows for much more efficient data transfers, enabling users to be more productive. Gigabit Ethernet does have a drawback-switches supporting Gigabit Ethernet are more expensive.

Another feature requirement for some access layer switches is PoE. PoE dramatically increases the overall price of the switch across all Cisco Catalyst switch product lines, so it should only be considered when voice convergence is required or wireless access points are being implemented, and power is difficult or expensive to run to the desired location.

Link aggregation is another feature that is common to most access layer switches. Link aggregation allows the switch to use multiple links simultaneously. Access layer switches take advantage of link aggregation when aggregating bandwidth up to distribution layer switches.
Because the uplink connection between the access layer switch and the distribution layer switch is typically the bottleneck in communication, the internal forwarding rate of access layer switches does not need to be as high as the link between the distribution and access layer switches. Characteristics such as the internal forwarding rate are less of a concern for access layer switches because they only handle traffic from the end devices and forward it to the distribution layer switches.

In a converged network supporting voice, video and data network traffic, access layer switches need to support QoS to maintain the prioritization of traffic. Cisco IP phones are types of equipment that are found at the access layer. When a Cisco IP phone is plugged into an access layer switch port configured to support voice traffic, that switch port tells the IP phone how to send its voice traffic. QoS needs to be enabled on access layer switches so that voice traffic the IP phone has priority over, for example, data traffic.

Switch Features

2010-07-23T22:32:00.000-07:00

Switch Form Factors

What are the key features of switches that are used in hierarchical networks? When you look up the specifications for a switch, what do all of the acronyms and word phrases mean? What does "PoE" mean and what is "forwarding rate"? In this topic, you will learn about these features.

When you are selecting a switch, you need to decide between fixed configuration or modular configuration, and stackable or non-stackable. Another consideration is the thickness of the switch expressed in number of rack units. For example, the Fixed Configuration Switches shown in the figure are all 1 rack unit (1U). These options are sometimes referred to as switch form factors.

Fixed Configuration Switches

Fixed configuration switches are just as you might expect, fixed in their configuration. What that means is that you cannot add features or options to the switch beyond those that originally came with the switch. The particular model you purchase determines the features and options available. For example, if you purchase a 24-port gigabit fixed switch, you cannot add additional ports when you need them. There are typically different configuration choices that vary in how many and what types of ports are included.

Modular Switches

Modular switches offer more flexibility in their configuration. Modular switches typically come with different sized chassis that allow for the installation of different numbers of modular line cards. The line cards actually contain the ports. The line card fits into the switch chassis like expansion cards fit into a PC. The larger the chassis, the more modules it can support. As you can see in the figure, there can be many different chassis sizes to choose from. If you bought a modular switch with a 24-port line card, you could easily add an additional 24 port line card, to bring the total number of ports up to 48.

Stackable Switches

Stackable switches can be interconnected using a special backplane cable that provides high-bandwidth throughput between the switches. Cisco introduced StackWise technology in one of its switch product lines. StackWise allows you to interconnect up to nine switches using fully redundant backplane connections. As you can see in the figure, switches are stacked one atop of the other, and cables connect the switches in daisy chain fashion. The stacked switches effectively operate as a single larger switch. Stackable switches are desirable where fault tolerance and bandwidth availability are critical and a modular switch is too costly to implement. Using cross-connected connections, the network can recover quickly if a single switch fails. Stackable switches use a special port for interconnections and do not use line ports for inter-switch connections. The speeds are also typically faster than using line ports for connection switches.

Considerations for Hierarchical Network Switches

2010-07-18T23:07:00.000-07:00

Traffic Flow Analysis

To select the appropriate switch for a layer in a hierarchical network, you need to have specifications that detail the target traffic flows, user communities, data servers, and data storage servers.

Companies need a network that can meet evolving requirements. A business may start with a few PCs interconnected so that they can share data. As the business adds more employees, devices, such as PCs, printers, and servers, are added to the network. Accompanying the new devices is an increase in network traffic. Some companies are replacing their existing telephone systems with converged VoIP phone systems, which adds additional traffic.

When selecting switch hardware, determine which switches are needed in the core, distribution, and access layers to accommodate the bandwidth requirements of your network. Your plan should take into account future bandwidth requirements. Purchase the appropriate Cisco switch hardware to accommodate both current needs as well as future needs. To help you more accurately choose appropriate switches, perform and record traffic flow analyses on a regular basis.

Traffic Flow Analysis

Traffic flow analysis is the process of measuring the bandwidth usage on a network and analyzing the data for the purpose of performance tuning, capacity planning, and making hardware improvement decisions. Traffic low analysis is done using traffic flow analysis software. Although there is no precise definition of network traffic flow, for the purposes of traffic flow analysis we can say that network traffic is the amount of data sent through a network for a given period of time. All network data contributes to the traffic, regardless of its purpose or source. Analyzing the various traffic sources and their impact on the network, allows you to more accurately tune and upgrade the network to achieve the best possible performance.

Traffic flow data can be used to help determine just how long you can continue using existing network hardware before it makes sense to upgrade to accommodate additional bandwidth requirements. When you are making your decisions about which hardware to purchase, you should consider port densities and switch forwarding rates to ensure adequate growth capability. Port density and forwarding rates are explained later in this chapter.

There are many ways to monitor traffic flow on a network. You can manually monitor individual switch ports to get the bandwidth utilization over time. When analyzing the traffic flow data, you want to determine future traffic flow requirements based on the capacity at certain times of the day and where most of the data is generated and sent. However, to obtain accurate results, you need to record enough data. Manual recording of traffic data is a tedious process that requires a lot of time and diligence. Fortunately, there are some automated solutions.

Analysis Tools

Many traffic flow analysis tools that automatically record traffic flow data to a database and perform a trend analysis are available. In larger networks, software collection solutions are the only effective method for performing traffic flow analysis. The figure displays sample output from Solarwinds Orion 8.1 NetFlow Analysis, which monitors traffic flow on a network. While the software is collecting data, you can see just how every interface is performing at any given point in time on the network. Using the included charts, you can identify traffic flow problems visually. This is much easier than having to interpret the numbers in a column of traffic flow data.

User Communities Analysis

User community analysis is the process of identifying various groupings of users and their impact on network performance. The way users are grouped affects issues related to port density and traffic flow, which, in turn, influences the selection of network switches. Port density is explained later in this chapter.

In a typical office building, end users are grouped according to their job function, because they require similar access to resources and applications. You may find the Human Resource (HR) department located on one floor of an office building, while Finance is located on another floor. Each department has a different number of users and application needs, and requires access to different data resources available through the network. For example, when selecting switches for the wiring closets of the HR and Finance departments, you would choose a switch that had enough ports to meet the department needs and was powerful enough to accommodate the traffic requirements for all the devices on that floor. Additionally, a good network design plan factors in the growth of each department to ensure that there are enough open switch ports that can utilized before the next planned upgrade to the network.

As shown in the figure, the HR department requires 20 workstations for its 20 users. That translates to 20 switch ports needed to connect the workstations to the network. If you were to select an appropriate access layer switch to accommodate the HR department, you would probably choose a 24 port switch, which has enough ports to accommodate the 20 workstations and the uplinks to the distribution layer switches.

Future Growth
But this plan does not account for future growth. Consider what will happen if the HR department grows by five employees. A solid network plan includes the rate of personnel growth over the past five years to be able to anticipate the future growth. With that in mind, you would want to purchase a switch that can accommodate more than 24 ports, such as stackable or modular switches that can scale.

As well as looking at the number of devices on a given switch in a network, you should investigate the network traffic generated by end-user applications. Some user communities use applications that generate a lot of network traffic, while other user communities do not. By measuring the network traffic generated for all applications in use by different user communities, and determining the location of the data source, you can identify the effect of adding more users to that community.

A workgroup-sized user community in a small business is supported by a couple of switches and typically connected to the same switch as the server. In medium-sized businesses or enterprises, user communities are supported by many switches. The resources that medium-sized business or enterprise user communities need could be located in geographically separate areas. Consequently, the location of the user communities influences where data stores and server farms are located.

If the Finance users are using a network-intensive application that exchanges data with a specific server on the network, it may make sense to locate the Finance user community close to that server. By locating users close to their servers and data stores, you can reduce the network diameter for their communications, thereby reducing the impact of their traffic across the rest of the network.

One complication of analyzing application usage by user communities is that usage is not always bound by department or physical location. You may have to analyze the impact of the application across many network switches to determine its overall impact.

what is converged network

2010-07-18T22:58:00.000-07:00

Small and medium-sized businesses are embracing the idea of running voice and video services on their data networks. Let us look at how voice and video over IP (VoIP) affect a hierarchical network.

Legacy Equipment

Convergence is the process of combining voice and video communications on a data network. Converged networks have existed for a while now, but were only feasible in large enterprise organizations because of the network infrastructure requirements and complex management that was involved to make them work seamlessly. There were high network costs associated with convergence because more expensive switch hardware was required to support the additional bandwidth requirements. Converged networks also required extensive management in relation to Quality of Service (QoS), because voice and video data traffic needed to be classified and prioritized on the network. Few individuals had the expertise in voice, video, and data networks to make convergence feasible and functional. In addition, legacy equipment hinders the process. The figure shows a legacy telephone company switch. Most telephone companies today have made the transition to digital-based switches. However, there are many offices that still use analog phones, so they still have existing analog telephone wiring closets. Because analog phones have not yet been replaced, you will also see equipment that has to support both legacy PBX telephone systems and IP-based phones. This sort of equipment will slowly be migrated to modern IP-based phone switches.

Advanced Technology

Converging voice, video, and data networks has become more popular recently in the small to medium-sized business market because of advancements in technology. Convergence is now easier to implement and manage, and less expensive to purchase. The figure shows a high-end VoIP phone and switch combination suitable for a medium-sized business of 250-400 employees. The figure also shows a Cisco Catalyst Express 500 switch and a Cisco 7906G phone suitable for small to medium-sized businesses. This VoIP technology used to be affordable only to enterprises and governments.

Moving to a converged network can be a difficult decision if the business already invested in separate voice, video, and data networks. It is difficult to abandon an investment that still works, but there are several advantages to converging voice, video, and data on a single network infrastructure.

One benefit of a converged network is that there is just one network to manage. With separate voice, video, and data networks, changes to the network have to be coordinated across networks. There are also additional costs resulting from using three sets of network cabling. Using a single network means you just have to manage one wired infrastructure.

Another benefit is lower implementation and management costs. It is less expensive to implement a single network infrastructure than three distinct network infrastructures. Managing a single network is also less expensive. Traditionally, if a business has a separate voice and data network, they have one group of people managing the voice network and another group managing the data network. With a converged network, you have one group managing both the voice and data networks.

New Options

Converged networks give you options that had not existed previously. You can now tie voice and video communications directly into an employee's personal computer system, as shown in the figure. There is no need for an expensive handset phone or videoconferencing equipment. You can accomplish the same function using special software integrated with a personal computer. Softphones, such as the Cisco IP Communicator, offer a lot of flexibility for businesses. The person in the top left of the figure is using a softphone on the computer. When software is used in place of a physical phone, a business can quickly convert to converged networks, because there is no capital expense in purchasing IP phones and the switches needed to power the phones. With the addition of inexpensive webcams, videoconferencing can be added to a softphone. These are just a few examples provided by a broader communications solution portfolio that redefine business processes today.

Separate Voice, Video and Data Networks

As you see in the figure, a voice network contains isolated phone lines running to a PBX switch to allow phone connectivity to the Public Switched Telephone Network (PSTN). When a new phone is added, a new line has to be run back to the PBX. The PBX switch is typically located in a Telco wiring closet, separate from the data and video wiring closets. The wiring closets are usually separated because different support personnel require access to each system. However, using a properly designed hierarchical network, and implementing QoS policies that prioritize the audio data, voice data can be converged onto an existing data network with little to no impact on audio quality.

In this figure, videoconferencing equipment is wired separately from the voice and data networks. Videoconferencing data can consume significant bandwidth on a network. As a result, video networks were maintained separately to allow the videoconferencing equipment to operate at full speed without competing for bandwidth with voice and data streams. Using a properly designed hierarchical network, and implementing QoS policies that prioritize the video data, video can be converged onto an existing data network with little to no impact on video quality.

The data network interconnects the workstations and servers on a network to facilitate resource sharing. Data networks can consume significant data bandwidth, which is why voice, video, and data networks were kept separated for such a long time. Now that properly designed hierarchical networks can accommodate the bandwidth requirements of voice, video, and data communications at the same time, it makes sense to converge them all onto a single hierarchical network.