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Nexus 9K –ACI Mode – PART 1

  SDN is the Buzzword for Network Guys, How is it related to Nexus 9k in API mode. Let’s Start with SDN to understand the co–relation between SDN and Nexus 9K (ACI Mode). To understand SDN in network terms, SDN does decoupling of control plane and data Plane, thus decision making now done at centralized […]

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Learning Python: Week3 (Conditionals and For Loops) -Part 3

As discussed in post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. This post will focus on Week 3 (Conditionals and For Loops) .This post will focus on […]

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Learning Python: Week3 (Conditionals and For Loops) -Part 2

As discussed in post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. This post will focus on Week 3 (Conditionals and For Loops) .This post will focus on […]

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Learning Python: Week3 (Conditionals and For Loops) -Part 1

As discussed in post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. This post will focus on Week 3 (Conditionals and For Loops)  Exercises. As Usual , lets […]

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Learning Python: Week2 (Printing, Numbers, and Lists) -Part 5

As discussed in post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. This post will focus on Exercise 4. ################# Exercise 4 ############# IV. You have the following […]

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Learning Python: Week2 (Printing, Numbers, and Lists) -Part 4

As discussed in last post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. This post will focus on Exercise 3 ########### EXERCISE 3  ######### III. You have the […]

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Learning Python: Week2 (Printing, Numbers, and Lists) -Part 3

As discussed in last post,  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. Here we are going to discuss the Exercise 2 . Here is the Exercise 2 […]

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Learning Python: Week2 (Printing, Numbers, and Lists) -Part 2

As discussed in last post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. Now its time to go for the exercise , already shared the notes related to […]

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Learning Python: Week2 (Printing, Numbers, and Lists) -Part 1

As discussed in last post,  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. Kirk discussed about the printing ,raw_input,numbers,List and Tuple . Few of my friends asks to […]

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Learning Python: Week1 (Preliminaries and Strings)

  As discussed in last post  ( https://crazyrouters.wordpress.com/2017/02/25/learning-python-kirk-byers-python-course/  ) , i will be sharing the my learning on weekly basis as course continues. This will not only motivate me but also help others who are in phase of learning python 3. Kirk discussed about the string methods in first week ,where he also put some […]

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Learning Python -Kirk Byers Python Course

Learning is process and there is no end to it. I came across Kirk Byers free python series and subscribed to the same . The next Learning Python course starts on April 13th. I should receive the first class on that day. Reviews for this course is positive .Hopefully i will be able to follow the course as schedule and would share my […]

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Python Functions – Basic

Python Function is a block of statements that can be used multiple times in a program. Its tedious task to use same block of statements multiple times, instead we can have function which contains same block of statement and can be called wherever there is need for the same. A function in Python is defined […]

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ARP – Address Resolution Protocol

When ever Network Engineer thinks  of ARP , first thing which comes in his mind is MAC address and layer 2. MAC  Address is unique identity provided to NIC card for communication at layer 2. It’s also sometime referred as Burned-in-address or hardware Address. Every network engineer should have good understanding of ARP. ARP is […]

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Python Loops – Basics

  The if, while and for statements implement traditional control flow and provide the output depending upon the condition.   IF /ELSE   An if statement consists of a  condition followed by one or more statements.An if statement can be followed by an optional else statement. Else statments is used with for loop to give […]

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Get Trained on the AWS Cloud

Date: 6 December 2016
Time: 10am – 1.30pm IST
Location: Online

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Python Basics – Part 2 cont…

4.Tuples

A tuple is similar to a list. The difference between the two is that we cannot change the elements of a tuple once it is assigned whereas in a list, elements can be changed. A tuple is created by placing all the items (elements) inside a parentheses ()

• We generally use tuple for different datatypes and list for homogeneous similar datatypes.
• Since tuple are immutable, means value can not be changed.
• Tuples that contain immutable elements can be used as key for a dictionary. With list, this is not possible.
• If you have data that doesn’t change, implementing it as tuple will guarantee that it remains write-protected.

Empty tuples are constructed by an empty pair of parentheses; a tuple with one item is constructed by following a value with a comma (it is not sufficient to enclose a single value in parentheses)

CODE:

OUTPUT:

 

 

5 .Dictionary

Python dictionary is an unordered set of key:value pairs , with the requirement that the keys are unique (within one dictionary). A pair of braces creates an empty dictionary: {}.Dictionary have no concept of order among elements.

Keys are unique within a dictionary while values may not be.The values Continue reading

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Python Basics – Part 1

Let’s start with Python basics, with the help of program .Theory part in posts is just enough to understand the program.

Python Data Type:

• Numbers
• Strings
• List
• Tuple
• Dictionary

1. Numbers :  
   1.  Int                  1 ,10,-145, 22
   2. Float               1.1,0.9,-29.9
   3. Complex        1.4j, 4e+6j

2. Strings

Way to remember how slices work in string  is to think of the indices as pointing between characters, with the left edge of the first character numbered 0. Then the right edge of the last character of a string of n characters has index n, for example:

“Crazyouters ”  represented in indices form

0	1	2	3	4	5	6	7	8	9	10	11
C	r	a	z	y	r	o	u	t	e	r	s
-11	-10	-9	-8	-7	-6	-5	-4	-3	-2	-1	0

Program Code : Str.py

Output

 

There are special operators in strings

Program Code : str1.py

Output

 

3. List

The list is a most versatile datatype available in Python which can be written as a list of comma-separated values (items) between square brackets. Important Continue reading

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Python – Must for Network Engineer

Automation is need of Time.We as network engineers have to go with automation to simplify major chunk of the work done by us.We can not escape from automation.I will be having series of Python posts starting from basics.I  will try to put all  learning  in post in most easiest way.

Let’s start with Basics.What is Python ? As per Wiki ,Python is a widely used high-level, general-purpose, interpreted, dynamic programming language.

In layman terms , it’s one of the coding  language much simpler, easy to understand and most importantly reduces number of code lines in C++ to fewer lines.

It was created by Guido van Rossum during 1985-1990.

Installation:

Note:We will be doing coding in Python 3.

Windows:  can be installed from Site :http://www.python.org

Linux: run below mentioned  command

$ sudo apt-get install python 3.5

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Failover Mechanism Part- 3

How should Fail over need to be implemented if CPE router is common for
primary and secondary link ? Answer for the same can be found in this post.
This scenario may be refer as DPDLSC (DUAL POP DUAL LAST MILE SINGLE CPE)
Just to mention that traffic control is being done from CPE,ISP is very
much transparent and is not influencing traffic in this scenario.

 

 

Considering the above Topology.

FAILOVER MECHANISM —-
1. Outgoing Traffic from CPE is controlled using Local Preference (Higher local Preference, better path)
2. Incoming Traffic to CE is controlled using As Path Prepend ( lower as path count , better path)

 

NORMAL SCENERIO
Primary link is up ,Local preference is high for primary link than secondry and also there is no as-prepend as in secondry

OUTGOING TRAFFIC >>> LAN>CPE>PE1
INCOMING TRAFFIC >>> PE1>CPE>LAN

PRIMARY WAN LINK DOWN(PE1-CPE link down)
OUTGOING TRAFFIC  >>> LAN>CPE>PE2
INCOMING TRAFFIC >>> PE2>CPE>LAN

RELATED CPE CONFIGURATION

router bgp 64520
bgp log-neighbor-changes
network 10.0.0.0 mask 255.255.0.0
neighbor 172.10.1.1 remote-as 9730
neighbor 172.10.1.1 description PRIMARTY
neighbor 172.10.2.1 remote-as 9730
neighbor 172.10.2.1 description SECONDRY
Continue reading

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Failover Mechanism Part-2

Dual POP Dual last mile Dual CE (DPDLDC)
This is second post related to fail over Mechanism ,In first post we have configured IP SLA to track the Primary link.Here we won’t be configuring track but will be having IBGP configured between CPE-1 and CPE-2. It’s topology is also Dual POP Dual last mile Dual CE (DPDLDC).It provides redundancy both  for WAN connectivity as well as LAN connectivity.

Here we will be controlling the Traffic from CPE. ISP is very much transparent and is not influencing traffic in this scenario.

 Topology.
Here we wont’t track the WAN IP as in fail over Mechanism in last post but will have IBGP running between CPE-1 and CPE-2
Failover Mechanism —
1. Outgoing Traffic from CPE wan is controlled using Local-Preference (Higher LP preferred)
2. Incoming traffic to CPE is controlled using AS Path Prepend attribute of BGP at secondary( lower as path count , better path)
Normal Scenario
================
Primary WAN link is up .HSRP running on CPE-1 towards LAN is active state. CPE-1 has routes to other location from both EBGP and IBGP but will be preferred via PE1 (High Local Preference configured ).Whereas AS prepend is configured on CPE-2 Continue reading