http://beginnersforum.net/blog Beginner's Forum - Here to help the beginners Thu, 16 May 2019 10:27:48 +0000 en-US hourly 1 https://wordpress.org/?v=5.1.1 http://beginnersforum.net/blog/wp-content/uploads/2019/01/cropped-BForum-Logoo-oo-32x32.jpg http://beginnersforum.net/blog 32 32 78092692 Top 50 CISCO ACI interview questions & answers http://beginnersforum.net/blog/2019/04/20/top-50-cisco-aci-interview-questions-answers/ http://beginnersforum.net/blog/2019/04/20/top-50-cisco-aci-interview-questions-answers/#respond Sat, 20 Apr 2019 12:09:52 +0000 http://beginnersforum.net/blog/?p=1261 Cisco ACI is a part of Software Defined Network (SDN) product portfolio from Cisco . Cisco ACI is an emerging technology on DC build up and disruptive technology for traditional networking .This Question and Answers guide will help you to understand Cisco ACI from basics to advanced level and give confidence to tackling the interviews with positive result . You

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Cisco ACI is a part of Software Defined Network (SDN) product portfolio from Cisco . Cisco ACI is an emerging technology on DC build up and disruptive technology for traditional networking .This Question and Answers guide will help you to understand Cisco ACI from basics to advanced level and give confidence to tackling the interviews with positive result . You can download PDF of 50 Q&A from here by contributing small amount of money for our effort.

1.What is Cisco ACI.?
Cisco ACI, the industry-leading software-defined networking solution, facilitates application agility and data center automation with two important concepts from SDN solution, overlays and centralized control. ACI is a is a well defined architecture with centralised automation and policy-driven application profiles. ACI uses a centralised controller called the Application Policy Infrastructure Controller (APIC),It is the controller that creates application policies for the data center infrastructure.

2. What are the three components of ACI architecture .?
Application Network Profile (ANP)– a collection of end-point groups (EPG), their connections, and the policies that define those connections
Application Policy Infrastructure Controller (APIC)– a centralized software controller that manages downstream switches and act as management plane.
ACI fabric : This is connection of Spine and Leaf switches. In the ACI world Spine and Leaf are the Cisco Nexus 9000 Series Switches (N9k) , and they are act as Control and the Data plane of the ACI. It is running re written version of NX-OS in ACI mode.


3. Describe about ACI Fabric connection terminology.?
• You should use One or more spine switches to be connected to each Leaf, Models supported are Cisco Nexus 9336PQ, 9504, 9508, or 9516 switches
• You should use One or more leaf switches to be connected to End Points and APIC cluster , Models supported are Cisco Nexus 93128TX, 9332PQ, 9372PX, 9372PX-E, 9372TX, 9396PX, or 9396TX etc switches
• Spin switches can be connected to leaf switches but not each other.
• Leaf switches can be connected only to spine switches and endpoint devices including APIC devices , so this means APIC will be connected only to Leaf switches
• ACI Switches are not running spanning tree.
• Minimum 3 APIC controller should require in ACI fabric
• Max APIC can be used are 5
• Max Spine switches can be used are 6
• Max Leaf switches can be used are 200

4. What is the use of Application Policy Infrastructure Controller (APIC) on ACI Fabric.?
This is the network controller is responsible for provisioning policies to physical and virtual devices that belong to an ACI fabric. Minimum a cluster of three controllers is used. Following are the main APIC features.

  • Application and topology monitoring and troubleshooting
  • APIC shows Physical and logical topology (who is connected to whome)
  • Third-party integration (Layer 4 through Layer 7 [L4-L7] services & VMware vCenter/ vShield)
  • Image management (spine and leaf)
  • Cisco ACI inventory and configuration
  • Implementation on a distributed framework across a cluster of appliances
  • Health scores for critical managed objects (tenants, application profiles, switches, etc.)
  • Fault, event, and performance management
  • Cisco Application Virtual Switch (AVS), which can be used as a virtual leaf switch

5. How Cisco ACI differs from other SDN controllers.?
Open SDN architecture separates control plane and data plane . Control plane resides on the central controller and data plane resides on switches. If the switches lost connection to controller, it won’t function for new connections and applying traffic policies. In CIsco ACI architecture , the APIC is not control plane, rather switches still hold control plane and data plane and can function properly if the controller down.

6. What are the different object model implementation in ACI.?
Within the ACI object model, there are essentially three stages of implementation of the model, the Logical Model, the Resolved Model, and the Concrete Model.
Logical Model: The logical model is the interface for the system. Administrators are interacting with the logical model through the API, CLI, or GUI. This is a Policy layer which include endpoint configuration on the controller .Changes to the logical model are then pushed down to the concrete model, which becomes the hardware and software configuration.
Resolved Model : The Resolved Model is the abstract model expression that the APIC resolves from the logical model. This is essentially the elemental configuration components that would be delivered to the physical infrastructure when the policy must be executed (such as when an endpoint connects to a leaf)
Concrete Model : The Concrete Model is the actual in-state configuration delivered to each individual fabric member based on the resolved model and the Endpoints attached to the fabric.This is include actual configuration of device and resides on fabric (spines and leafes )

7.What is Policy layer and Concrete Layer in ACI model.?
Concrete layer is the ACI fabric and policy layer is controllers

8.What you mean by Tenant .?
Basically a Tenant (fvTenant) is logical container for application policies to isolate switching and routing function. A tenant represents a unit of isolation from a policy perspective, but it does not represent a private network. Tenants can represent a customer in a service provider setting, an organisation or domain in an enterprise setting, or just a convenient grouping of policies.
Four types of Tenant available

  1. User
  2. Common
  3. Management
  4. Infra

9 . Difference between management tenant and infrastructure tenant.?
Management Tenant : Used for infrastructure discovery and also used for all communication/integration with virtual machine controllers. It has separate Out Of Band (OOB) address space for APIC to Fabric communication, it is using to connect all fabric management interfaces
Infrastructure Tenant : It governs operation of fabric resources like allocating VXLAN overlays and allows fabric administrator to deploy selective shared services to tenants

10.What you mean by Context/VRF on ACI .?
The top level network construct within an ACI tenant is the VRF or Context . It is called as tenant network and available as ‘private network’ in the ACI GUI .Following are the important point about VRF’s
• A VRF defines Layer 3 address domain
• One or more bridge domain can associated with VRF
• All of the endpoints within the Layer 3 domain (VRF) must have unique IP addresses because it is possible to forward packets directly between these devices if the policy allows it.
• A tenant can contain multiple VRFs How ARP handled by ACI.?

Below are some of the additional questions available on PDF

  • How ARP and broadcast handled by ACI.?
  • Why and when you require contract in ACI Fabric.?
  • How to perform unicast routing on ACI.?
  • In Fabric, which switch will act as default gateway for pertucler subnet.?
  • How Cisco ACI differentiate Layer 2 traffic and Layer 3 traffic.?
  • How VLAN working in Cisco ACI.?
  • How can you configure trunk and access port on ACI.?
  • What is micro segmentation and how to configure.?
  • How to configure inter-VRF and Inter-tenant communication.?
  • How can you integrate Cisco ACI with VmWare.?
  • Explain about ACI fabric discovery process .?
  • Explain about traffic flow lookup on ACI fabric.?

Interested to know about the detailed answers of above questions along with other exclusive commonly asked 30 interview questions.? You can download PDF copy of 50 interview Q&A from here by contributing small perks to support our efforts. Please send email to ‘beginnersforum@gmail.com‘ for PayPal payment option.


Hope you have enjoyed reading. Kindly share your feedback/suggestions in the comments section. For Q&A posts on other topics, please click here.

Ref:
https://www.sdxcentral.com/data-center/definitions/what-is-cisco-aci/

https://www.cisco.com/c/en_in/solutions/data-center-virtualization/application-centric-infrastructure/index.html

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Introducing Beginner’s Forum TV http://beginnersforum.net/blog/2019/01/19/introducing-beginners-forum-tv/ http://beginnersforum.net/blog/2019/01/19/introducing-beginners-forum-tv/#respond Sat, 19 Jan 2019 16:13:12 +0000 http://beginnersforum.net/blog/?p=1168 Introducing our YouTube channel – Beginner’s Forum TV. A new platform from the team as promised, to share more of our contents from the technology world.  We have been posting contents here in the blog in different categories around the Data Center including Networking, Servers, Storage, Cloud and a bit of programming stuff. Our channel will have contents from all these areas

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Introducing our YouTube channel – Beginner’s Forum TV. A new platform from the team as promised, to share more of our contents from the technology world. 

We have been posting contents here in the blog in different categories around the Data Center including Networking, Servers, Storage, Cloud and a bit of programming stuff. Our channel will have contents from all these areas but will not be limited to these. We will be adding more tech stuff – on electronics and gadgets, Application and Web development and anything technical of your interest.

Subscribe (by clicking the above button) to Beginner’s Forum TV so that you will not be missing any updates on our latest contents. 

 
Thank You for all your support and keep doing the same. Follow/Subscribe us, share our contents and keep sharing feedback (comments) as you always did. 

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HAPPY nEW YEAR http://beginnersforum.net/blog/2019/01/01/happy-new-year/ http://beginnersforum.net/blog/2019/01/01/happy-new-year/#respond Tue, 01 Jan 2019 05:05:34 +0000 http://beginnersforum.net/blog/?p=1090 We wish all our readers, a very happy New Year 2019..!! We had a wonderful year 2018, a year we achieved many milestones and were able to do some amazing stuff on and off our page here. Now we are into this New Year and we hope to cover even further this year. We assure you excellent and innovative content

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We wish all our readers, a very happy New Year 2019..!!

We had a wonderful year 2018, a year we achieved many milestones and were able to do some amazing stuff on and off our page here.

Now we are into this New Year and we hope to cover even further this year. We assure you excellent and innovative content and we have ‘things’ planned for this New Year. 🙂

Once again we wish all our readers a Happy New Year, 2019..!

Keep reading..!

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Vembu BDR Suite v4.0 is now GA http://beginnersforum.net/blog/2018/12/12/vembu-bdr-suite-v4-0-is-now-ga/ http://beginnersforum.net/blog/2018/12/12/vembu-bdr-suite-v4-0-is-now-ga/#respond Wed, 12 Dec 2018 13:59:56 +0000 http://beginnersforum.net/blog/?p=1060 Vembu’s BDR Suite v4.0 is now GA. Vembu announced the latest version – 4.0 – recently and is now Generally Available for customers. Vembu BDR 4.0 is only available now for fresh installations. An upgrade package will soon be available for existing customers to upgrade their environment to 4.0. There are a lot of exciting new features available with 4.0

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Vembu’s BDR Suite v4.0 is now GA.

Vembu announced the latest version – 4.0 – recently and is now Generally Available for customers. Vembu BDR 4.0 is only available now for fresh installations. An upgrade package will soon be available for existing customers to upgrade their environment to 4.0.

There are a lot of exciting new features available with 4.0 including backup of VM’s running on Hyper-V cluster etc… You can click here to read more about the new features in Vembu BDR 4.0. 

You can download the installer here for your environment today.

Also, Vembu is giving away up to 40% discount on their products till the 24th of December. Hurry and enjoy the Thanksgiving-Christmas discount from Vembu and grab your your piece of software. Please refer to the Vembu blog here for more details.

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IT Blog Awards by Cisco – Vote now..! http://beginnersforum.net/blog/2018/12/12/it-blog-awards-by-cisco-vote-now/ http://beginnersforum.net/blog/2018/12/12/it-blog-awards-by-cisco-vote-now/#respond Wed, 12 Dec 2018 13:21:29 +0000 http://beginnersforum.net/blog/?p=1058 Hurry, vote now for the best IT Blogs in the IT Blogs awards hosted by Cisco..! About the program: This is the first ever IT Blogs awards from Cisco for recognizing the contribution by the blogger community, in various categories. (about the program) from the Cisco website : The first-ever IT Blog Awards, hosted by Cisco, is our way of

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Hurry, vote now for the best IT Blogs in the IT Blogs awards hosted by Cisco..!

About the program:

This is the first ever IT Blogs awards from Cisco for recognizing the contribution by the blogger community, in various categories.

(about the program) from the Cisco website :

The first-ever IT Blog Awards, hosted by Cisco, is our way of recognizing the great community of independent tech bloggers for the passion, creativity, and expertise shared throughout the year. We appreciate your impact on the tech community.
Voting is now open through January 4, 2019.  Winners will receive a Cisco Live US pass.

You can vote for the blogs in different categories and the voting ends on 4th Jan, 2019. Make sure to consider the value, credibility and the consistency of the content while you select a blog as the best in that category.

It is your opportunity now to recognize the bloggers/blogs who are helping the community by providing excellent contents. Do not wait, Vote Now.

We are proud to announce that, we have been chosen as one of the finalists in the Best Group Effort Category. If you feel our contents were of quality, helping the community and at the same time meeting the program guidelines, you can select our blog in best group effort category.

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Azure cloud provisioning using Ansible http://beginnersforum.net/blog/2018/11/19/azure-cloud-provisioning-using-ansible/ http://beginnersforum.net/blog/2018/11/19/azure-cloud-provisioning-using-ansible/#comments Mon, 19 Nov 2018 06:46:31 +0000 http://beginnersforum.net/blog/?p=994                 Automating the IT Infrastructure is today’s one of major focus of all organizations. This reduces the cost and human workloads. When you make a plan to automating your infrastructure, it should start with provisioning of the resources, this makes managing the resources very easy. Many businesses have adopted cloud computing in their

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                Automating the IT Infrastructure is today’s one of major focus of all organizations. This reduces the cost and human workloads. When you make a plan to automating your infrastructure, it should start with provisioning of the resources, this makes managing the resources very easy. Many businesses have adopted cloud computing in their operations in the past years because of its flexibility and high sociability features. When you integrate the cloud infrastructure with today’s open source DevOps tools available in the market, this makes your daily life easier to handling huge environments.

I would rather suggest to go with Ansible as the configuration management tool because of its simplicity and straight forward operation features. This came in market late, but gained solid footing and adopted by many DevOps professionals because of its unique features. Ansible offers huge number of modules for managing the cloud operations for all major cloud providers like Azure AWS and GCP.

The Ansible playbooks which I refer below will help you to provisioning cloud resources in Azure environment, which create a Window VM and configure the VM to connect with Ansible host for any post provision activities, The playbook will perform the following tasks.

  1. Create the resource groups and Network infrastructure
  2. Provisioning of windows VMs
  3. Adding the new host to dynamic inventory for any post provision activities
  4. Enabling the PowerShell execution policy to connect to WinRM
  5. Installing a Firefox package using ansible on the newly created VM
The playbook contains 3 roles which will create Network infrastructure, provision a windows VMs and install the Firefox package on it.
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Let’s go through the main playbook first which includes 3 roles First 2 will run against the localhost which creates the Network infrastructure and Virtual machine respectively. As you can see the third role which install the Firefox package is running against a host group azure_vms which will be created dynamically after provisioning the server

Now let’s go through the first role common which creates the resource group and network infrastructure.

 

- name: Create a resource group
   azure_rm_resourcegroup:      
     name: "{{ rg_name }}"      
     location: "{{ location }}"      
     state: present 

- name: Create a virtual network   
  azure_rm_virtualnetwork:      
    name: "{{ vitual_network }}"      
    resource_group: "{{ rg_name }}"      
    address_prefixes_cidr:         
      - "{{ CIDR }}" 
- name: Create network windows base_security groups   
  azure_rm_securitygroup:     
    resource_group: "{{ rg_name }}"     
    name: windows_base     
    purge_rules: yes     
    rules:        
     - name: 'AllowRDP'          
       protocol: Tcp          
       source_address_prefix: 0.0.0.0/0          
       destination_port_range: 3389          
       access: Allow          
       priority: 100          
       direction: Inbound        
     - name: 'AllowWinRM'          
       protocol: Tcp          
       source_address_prefix: 0.0.0.0/0          
       destination_port_range: 5986          
       priority: 102          
       direction: Inbound        
     - name: 'DenyAll'          
       protocol: Tcp          
       source_address_prefix: 0.0.0.0/0          
       destination_port_range: 0-65535          
       priority: 103          
       direction: Inbound

- name: Create a Subnet and adding the windows_base security group in to it
  azure_rm_subnet:
    name: "{{ subnet }}"
    virtual_network_name: "{{ vitual_network }}"
    resource_group: "{{ rg_name }}"
    address_prefix_cidr: "{{ subnet_CIDR }}"
    security_group_name: windows_base 

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Here it’s creating a Resource group, virtual network and a security group which allow incoming RDP and WinRM traffics. You can either add the security group to the NIC card or to the subnet where we create the Virtual machine. Azure will create a NIC card and allocate to the VM in default if you are not giving any custom NIC cards while provisioning. Here I am not creating any custom NIC cards for the server instead attaching the security group with the subnet.

Let’s go through the second role which creates the Virtual machine.


- name: Create a VM    
  azure_rm_virtualmachine:      
    os_type: Windows      
    resource_group: "{{ rg_name }}"      
    virtual_network_name: "{{ virtual_network_name }}"      
    name: "{{ vm_name }}"      
    admin_username: "{{ admin_user }}"      
    admin_password: "{{ admin_passwd }}"      
    vm_size: Standard_F2s_v2      
    image:         
      offer: WindowsServer         
      publisher: MicrosoftWindowsServer         
      sku: '2016-Datacenter'         
      version: latest    
  register: output  

- name: Add new instance to the host group    
  add_host:       
    hostname: "{{ vm_name }}"       
    ansible_host: "{{ azure_vm.properties.networkProfile.networkInterfaces[0].properties.ipConfigurations[0]. properties.publicIPAddress.properties.ipAddress }}"       
    ansible_user: "{{ admin_user }}"       
    ansible_password: "{{ admin_passwd }}"       
    ansible_connection: winrm       
    ansible_port: 5986       
    ansible_winrm_server_cert_validation: ignore       
    ansible_winrm_transport: ssl 
    groupname: azure_vms    
  with_items: output.instances   

- name: create Azure vm extension to enable HTTPS WinRM listener     
  azure_rm_virtualmachine_extension:        
    name: winrm-extension        
    resource_group: "{{ rg_name }}"        
    virtual_machine_name: "{{ vm_name }}"        
    publisher: Microsoft.Compute        
    virtual_machine_extension_type: CustomScriptExtension        
    type_handler_version: 1.9        
    settings: '{"commandToExecute": "powershell.exe -ExecutionPolicy ByPass -   EncodedCommand {{winrm_enable_script}}"}'        
    auto_upgrade_minor_version: true     
  with_items: output.instances   

- name: wait for the WinRM port to come online     
  wait_for:        
    port: 5986        
    host: '{{azure_vm.properties.networkProfile.networkInterfaces[0].properties.ipConfigurations[ 0].properties.publicIPAddress.properties.ipAddress}}'        
    timeout: 600     
  with_items: output.instances
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As you can see in the second task in the role, the newly created server will be added to a host group azure_vms using the ansible add_host module. The third and 4 th task will enable HTTPS WinRM listener for ansible communication.

The third and final role in the playbook will install a Firefox browser in the newly provisioned VM using the ansible win_chocolatey module.

 - name: Install Firefox 
   win_chocolatey:
     name: firefox
     state: present

Here is the main playbook which calls all the 3 roles

---
- hosts: localhost
  gather_facts: yes
  roles:
   - common
   - vm

- hosts: azure_vms
  gather_facts: no
  roles:
   - install_firefox

Hope this post helped you. Please share your feedback/suggestions in the comments below.

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Update service-now ticket using a Python script http://beginnersforum.net/blog/2018/10/16/update-service-now-incident-using-python/ http://beginnersforum.net/blog/2018/10/16/update-service-now-incident-using-python/#comments Tue, 16 Oct 2018 03:49:34 +0000 http://beginnersforum.net/blog/?p=957 How cool it will be if you can upload the output of your script in to Service now incident notes or task notes automatically. This python script helps you to run set of command against the Cisco switches and routers and the output of command will upload to service now incident automatically. This will help you to increase the response

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How cool it will be if you can upload the output of your script in to Service now incident notes or task notes automatically. This python script helps you to run set of command against the Cisco switches and routers and the output of command will upload to service now incident automatically. This will help you to increase the response time of NOC L1  team in troubleshooting task.

Service-now a IT Service management (ITSM) tool based on cloud platform provides end to end transformation of IT services. Service Now provides REST API to communicate with SNOW instance. We will use REST API in our program to interact with service now instance.

We are explaining step by step procedure to achieve this

Following are the components required:

  1. Service now developer account
    2. Service now instance
    3. Python with Service now API installed

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Create service now developer account and instance

Please refer our post ‘Create service now developer account and instance’ and create new user for API calls.

Setup environment

We would  require ‘netmiko’ package to take ssh of devices. Please read part 1 and part 2  of our post for details about installing python and running your first program. Please read part 4 if you want to know how to take SSH of a switch.

Install python service-now API package

We also require ‘pysnow’ package which is using to interact with service now using REST API call. Please click here if you would like to know more about ‘pysnow’ package.

Install ‘psysnow’ using following command

‘pip install psynow’

please click here if you did not know how to install a package on python using pip

Script Definition:

The script will get service-now information and device credential initially. Then it will continuously run on server so user can update multiple incident by running the commands against multiple devices. All the required commands have to be saved on ‘command.txt’ file.

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It is using class ‘inc_update’ to gather information and update service-now.  Inside the class, the function ‘collectdata’ using to SSH to device and taking the out put of commands.  The function ‘inc_update’ using to update service now instance with the output.

Following are the script. It is easy to understand, and we have put inline comments for making it easy.

import pysnow
import getpass
from netmiko import ConnectHandler

print “=============================\n”
print “Program to update service now incident notes\n”
print “\n=============================\n”

##class to connect device
class cls_incident:
#initialising variables
def __init__(self,uname,password):
#initialising variables
self.uname = uname
self.password = password
self.secret=password
self.dev_type=’cisco_ios’
self.ip=”
self.output=”

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#creating dictionery for netmiko
self.dict_device = {
‘device_type’: self.dev_type,
‘ip’: self.ip,
‘username’: self.uname,
‘password’: self.password,
‘secret’: self.secret,
‘global_delay_factor’:1,

}

#function to login to device and collect output of command
def collectdata(self,ipaddress):
self.dict_device[‘ip’]=ipaddress
self.net_connect = ConnectHandler(**self.dict_device)
#opening command file
cmd_file=open(‘command.txt’)
self.output=”
#loop for reading command one by one
for line in cmd_file:
cmd=line.lstrip()
self.output+=”\nOutput of command “+cmd+” \n”
self.output+=self.net_connect.send_command(cmd)
cmd_file.close()

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print self.output
print “\nCommand Output collected”

#function to update service now
def inc_update(self,inc_number,s_uname,s_password,s_instance):
#connecting with service now
snow = pysnow.Client(instance=s_instance, user=s_uname, password=s_password)
incident = snow.resource(api_path=’/table/incident’)
#payload=self.output
update = {‘work_notes’:self.output, ‘state’: 5}
#updating incident record
updated_record = incident.update(query={‘number’:inc_number}, payload=update)
print “Incident note updated ”

def main():

#Collecting service now details
instance=raw_input(“Enter service now instant name in format of ‘company.service-now.com’ :”)

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instance=instance.rstrip(‘.service-now.com’)
s_uname=raw_input(“Enter service now user name:”)
s_password=getpass.getpass(“Password:”)

##Collecting device credential
dev_uname=raw_input(“\nEnter Device user name :”)
dev_passwd=getpass.getpass(“Password:”)

objDev=cls_incident(dev_uname,dev_passwd)

while True:
try:
inc_number=raw_input(“Enter incident number :”)
ip_address=raw_input(“Enter IP address of device:”)
print “Connecting device and collecting data ”
#creating class object
objDev.collectdata(ip_address)

print (“Updating service now”)
#updaing service nw
objDev.inc_update(inc_number,s_uname,s_password,instance)
print “\nThis program will keep on running, press ctrl C to exit”
print “Enter details for next incident \n”
except Exception,e:
print “Error on execution :”,e
if __name__== “__main__”:
main()

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How to run :

Download the ‘command.txt‘ and ‘incident-update.txt‘ in to same folder of your system. rename ‘incident-update.txt’ in to ‘incident-update.py’. Open the file ‘command.txt’ and add your required commands which need to be run on networking device.. Run the program from command prompt using ‘ python incident-update.py’ . Please provide your input and test . Please ensure you have the reach-ability to service-now instance and network devices from your machine.

Program screen shot

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Service-now screen shot

You could see service now incident notes updated with command output automatically

Hope this will ease your life a bit.. 🙂

Please comment below if you would require customized script based on your requirement which will support multiple device model like Cisco ASA, Juniper, Palo Alto, Checkpoint etc.

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Create service-now developer account and REST API user http://beginnersforum.net/blog/2018/10/16/create-service-now-dev-account-api-user/ http://beginnersforum.net/blog/2018/10/16/create-service-now-dev-account-api-user/#comments Tue, 16 Oct 2018 02:51:16 +0000 http://beginnersforum.net/blog/?p=941 Here we are explaining how to create service-now developer account and a new user with REST-API privilege which is required to update your service now task or notes using API Call.  Please refer our post ‘Updating serivice-now incident using python‘ to see the sample usage. Create Service now Developer account : We are using demo service now instance available on

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Here we are explaining how to create service-now developer account and a new user with REST-API privilege which is required to update your service now task or notes using API Call.  Please refer our post ‘Updating serivice-now incident using python‘ to see the sample usage.

Create Service now Developer account :

We are using demo service now instance available on service now developer account.Here we will explain you how to create service now developer account and make ready for REST API call. Login to service now here (https://developer.servicenow.com) and register for developer account by clicking REGISTER tab available on right side

Launch Instance:

Service Now will provide a demo instance with all functionalities. This will act as service-now platform of your company and where you can create, delete and update incidents and all other service now options.

Once you logged in to developer account, click on Manage->Instance->Request Instance to launch instance

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Click London from next window as this is the latest version.

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Service now will give you new instance .Login to new instance by using the URL showing below. You could see default user name and password on same page. Copy the URL and open using your favorite web browser. Login using user name admin and password as shown in the picture below. It will prompt for a password reset.

Once you are authenticated , we have to create new user account which is having privilege to update service now incident notes using REST API. We are assigning privilege using the ‘role assignment’.

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Create a new user with name ‘apiuser’ and give password for the user. To create new user account, type ‘user’ on search box available on left hand side. It will list Users and Groups under ‘System Security’ category. Click users and add ‘New’

Give the user details on the new window and click submit.

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Next, we have to assign roles. Navigate to ‘Roles’ tab on same page which will be available after your ‘submit’. Click ‘edit’ available under the ‘Roles’ tab

Type ‘web’ on  search box and select ‘web_service_admin’ and click ‘add’

 

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Now we have created user with required Roles. You can use same user name for REST API call from external scripts.

This user can be used for updating the Service-Now tickets or notes using API call. Hope this helps. Please add your suggestions and queries in the comments section.

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Linux Swap Space Creation and Monitoring http://beginnersforum.net/blog/2018/07/09/linux-swap-space-creation-and-monitoring/ http://beginnersforum.net/blog/2018/07/09/linux-swap-space-creation-and-monitoring/#respond Mon, 09 Jul 2018 05:10:39 +0000 http://beginnersforum.net/blog/?p=884 Overview This Post is intended to understand the swap creation, monitoring and extending in Redhat Linux. Swap space is a restricted amount of physical memory that is allocated for use by the operating system when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are

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Overview

This Post is intended to understand the swap creation, monitoring and extending in Redhat Linux.

Swap space is a restricted amount of physical memory that is allocated for use by the operating system when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.

Recommended System Swap Space
In years past, the recommended amount of swap space increased linearly with the amount of RAM in the system. But because the amount of memory in modern systems has increased into the hundreds of gigabytes, it is now recognized that the amount of swap space that a system needs is a function of the memory workload running on that system. However, given that swap space is usually designated at install time, and that it can be difficult to determine beforehand the memory workload of a system, Redhat recommend determining system swap using the following table.

Amount of RAM in the System Recommended Amount of Swap Space
4GB of RAM or less a minimum of 2GB of swap space
4GB to 16GB of RAM a minimum of 4GB of swap space
16GB to 64GB of RAM a minimum of 8GB of swap space
64GB to 256GB of RAM a minimum of 16GB of swap space
256GB to 512GB of RAM a minimum of 32GB of swap space

Note : On most distributions of Linux, it is recommended that you set swap space while installing the operating system

 

How to Monitor Swap Space

We shall look at different commands and tools that can help you to monitor your swap space usage in your Linux systems as follows

Using the swapon Command

To view all devices marked as swap in the /etc/fstab file you can use the –all option. Though devices that are already working as swap space are skipped

If you want to view a summary of swap space usage by device, use the – summary (swapon –s) option.

[root@nfsserver ~]# swapon –summary
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       2097148 0       -1
[root@nfsserver ~]#
[root@nfsserver ~]# swapon -s
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       2097148 0       -1
Note :- Use –help option to view more options and information.
Using /proc/swaps

The /proc filesystem is a process information pseudo-file system. It actually does not contain ‘real’ files but runtime system information, for example system memory, devices mounted, hardware configuration and many more.

[root@nfsserver ~]# cat /proc/swaps

Filename                                Type            Size    Used    Priority

/dev/dm-1                               partition       2097148 0       -1

[root@nfsserver ~]#

Using ‘free’ Command
The free command is used to display the amount of free and used system memory. Using the free command with -h option, which displays output in a human readable format.
[root@nfsserver ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:           7.6G        674M        6.5G        9.8M        507M        6.7G
Swap:          2.0G          0B        2.0G
[root@nfsserver ~]#
 Using top Command
To check swap space usage with the help of ‘top’ command
Using the vmstat Command
This command is used to display information about virtual memory statistics
[root@nfsserver ~]# vmstat
procs ———–memory———- —swap– —–io—- -system– ——cpu—–
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 6791708   2784 516484    0    0     7     0   24   23  0  0 100  0  0
[root@nfsserver ~]#
ADDING SWAP SPACE
Sometimes it is necessary to add more swap space after installation
You have three options: create a new swap partition, create a new swap file, or extend swap on an existing LVM2 logical volume. It is recommended that you extend an existing logical volume
Extending Swap on an LVM2 Logical Volume
To extend an LVM2 swap logical volume(suppose /dev/mapper/centos-swap is our swap volume)
1. Disable swapping for the associated logical volume:
[root@nfsserver ~]# swapoff -v /dev/mapper/centos-swap
swapoff /dev/mapper/centos-swap
[root@nfsserver ~]# swapon -s
[root@nfsserver ~]#
2. Resize the LVM2 logical volume by 256 MB
 [root@nfsserver ~]# lvresize /dev/mapper/centos-swap -L +256M
  Size of logical volume centos/swap changed from 2.00 GiB (512 extents) to 2.25 GiB (576 extents).
  Logical volume centos/swap successfully resized.
 [root@nfsserver ~]#
3. Format the new swap space
[root@nfsserver ~]# mkswap /dev/centos/swap
mkswap: /dev/centos/swap: warning: wiping old swap signature.
Setting up swapspace version 1, size = 2359292 KiB
no label, UUID=5e487401-9ae0-4e1d-adff-2346edfc6244
[root@nfsserver ~]#
4. Enable the extended logical volume
[root@nfsserver ~]# swapon -va
swapon /dev/mapper/centos-swap
swapon: /dev/mapper/centos-swap: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/mapper/centos-swap: pagesize=4096, swapsize=2415919104, devsize=2415919104
[root@nfsserver ~]#
5. Test that the logical volume has been extended properly
[root@nfsserver ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:           7.6G        677M        6.5G        9.8M        507M        6.7G
Swap:          2.2G          0B        2.2G
[root@nfsserver ~]# swapon -s
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       2359292 0       -1
[root@nfsserver ~]#
Creating an LVM2 Logical Volume for Swap
To add a swap volume group (suppose /dev/centos/swap2 is the new volume)
1. Create the LVM2 logical volume of size 256 MB
[root@nfsserver ~]# lvcreate centos -n swap2 -L 256M
  Logical volume “swap2” created.
[root@nfsserver ~]#
2. Format the new swap space
[root@nfsserver ~]# mkswap /dev/centos/swap2
Setting up swapspace version 1, size = 262140 KiB
no label, UUID=6ea40455-47a0-46bf-844e-ec0ebd4a4e6a
[root@nfsserver ~]#
3. Add the following entry to the /etc/fstab file
/dev/mapper/centos-swap2 swap                    swap    defaults        0 0
4. Enable the extended logical volume
[root@nfsserver ~]# swapon –va
swapon /dev/mapper/centos-swap2
swapon: /dev/mapper/centos-swap2: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/mapper/centos-swap2: pagesize=4096, swapsize=268435456, devsize=268435456
[root@nfsserver ~]#
5. Verify the swap space
[root@nfsserver ~]# swapon -s
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       2097148 0       -1
/dev/dm-3                               partition       262140  0       -2
Creating a Swap File
To Add a swap file
1. Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. For example, the block size of a 64 MB swap file is 65536.
2. At a shell prompt as root, type the following command with count being equal to the desired block size:
[root@nfsserver ~]# dd if=/dev/zero of=/swapfile bs=1024 count=65536
65536+0 records in
65536+0 records out
67108864 bytes (67 MB) copied, 0.0893063 s, 751 MB/s
[root@nfsserver ~]#
[root@nfsserver ~]# ls -ld /swapfile
-rw-r–r–. 1 root root 67108864 May 17 16:38 /swapfile
[root@nfsserver ~]# du -sh /swapfile
64M     /swapfile
[root@nfsserver ~]#
3. Change the permissions of the newly created file
[root@nfsserver ~]# chmod 0600 /swapfile
[root@nfsserver ~]#
4. Setup the swap file with the command
[root@nfsserver ~]# mkswap /swapfile
Setting up swapspace version 1, size = 65532 KiB
no label, UUID=8a404550-e8a3-4f2b-9daf-137fc34f7b6d
[root@nfsserver ~]#
5. Edit /etc/fstab and enable the newly added swap space
/swapfile          swap            swap    defaults        0 0
[root@nfsserver ~]# swapon -va
swapon /swapfile
swapon: /swapfile: found swap signature: version 1, page-size 4, same byte order
swapon: /swapfile: pagesize=4096, swapsize=67108864, devsize=67108864
[root@nfsserver ~]#
6. Verify the swap space created.
[root@nfsserver ~]# swapon -s
Filename                                Type            Size    Used    Priority
/dev/dm-1                               partition       2097148 0       -1
/dev/dm-3                               partition       262140  0       -2
/swapfile                               file    65532   0       -3
[root@nfsserver ~]#
Hope this has helped you ..
Thanks!!!!

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EMC ISILON Interview questions http://beginnersforum.net/blog/2018/02/15/emc-isilon-interview-questions/ http://beginnersforum.net/blog/2018/02/15/emc-isilon-interview-questions/#respond Thu, 15 Feb 2018 11:05:35 +0000 http://beginnersforum.net/blog/?p=846 Adding one more post to our interview questions post category, this time for ISILON. We are trying to cover some of the frequently asked questions from the ISILON architecture and configuration areas.  Node and drive types supported :  ISILON supported 3 different types of nodes S-Series, X-Series and NL-Series. S-Series (S210) is high performance node type supports SSD drives. X-Series

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Adding one more post to our interview questions post category, this time for ISILON. We are trying to cover some of the frequently asked questions from the ISILON architecture and configuration areas.

  •  Node and drive types supported :  ISILON supported 3 different types of nodes S-Series, X-Series and NL-Series. S-Series (S210) is high performance node type supports SSD drives. X-Series nodes (X210 and X410) supports upto 6 SSDs and can have remaining slots with HDDs in them. NL-Series (NL-410) nodes supports only one SSD in the system and SATA drives in the remaining slots. This node type is intended for the archiving requirements.

The system with the recent OneFS versions, also supports All-Flash nodes, Hybrid nodes, Archive nodes and IsilonSD nodes. ISILON All-Flash nodes (F800) can have upto 924 TB in a single 4U node and can grow upto 33PB in one cluster. One node can house upto 60 drives. Hybrid nodes (H400, H500 and H600) supports a mix of SSDs and HDDs. H400 and H500 can have SATA drives and SSDs and H600 supports SSDs and SAS drives. Archive nodes (A200 and A2000) are intended for archiving solutions. A2000 nodes can have 80 slots with 10TB drives only supported. This node is for high-density archiving. A200 is for near-primary archiving storage solutions which supports 2 TB, 4 TB or 8 TB SATA HDDs- a maximum of 60 drives.

IsilonSD is the software only node type which can be installed in customer hardware.

  •  Scale-Out and Scale-Up architecture : The first thing comes with ISILON is the architecture, Scale-Out. With Scale-Out architecture, the processing and capacity will be increased in parallel. As we add a node, both capacity and processing power will be increased for the system. Let’s take the example of VNX for Scale-Up architecture. Here, the processing power (i.e. Storage processors) can not be increased as the system limit is 2 SPs, but we can grow the overall system capacity by adding more DAEs (and disks) to the system supported limit.

  •  Infiniband Switches and types : ISILON makes use of IB switches for the internal communication between the nodes. ISILON now supports 40 GbE switches also with the Gen-6 hardware in addition to the 10GbE IB switches.
  •  SmartConnect and SSIP : [definition from ISILON SmartConnect whitepaper] SmartConnect is a licensable software module of the EMC ISILON OneFS Operating System that optimizes performance and availability by enabling intelligent client connection load balancing and failover support. Through a single host name, SmartConnect enables client connection load balancing and dynamic NFS failover  and failback of client connections across storage nodes to provide optimal utilization of the cluster resources. SmartConnect eliminates the need to install client side drivers, enabling the IT administrator to easily manage large numbers of client with confidence. And in the event of a system failure, file system stability and availability are maintained.

For every SmartConnect zone there will be one SSIP (SmarConnect Service IP), which wil be used for the client connections. SSIP and associated hostname will have the DNS entry and the client requests will come to the cluster/zone via SSIP. The zone redirects the request to the nodes for completion.

  •  SmartPool : SmartPool enables effective tiering of storage nodes within the filesystem. Data – based on the utilization – will be moved across the tiers within the filesystem automatically with seamless application and end user access. Customers can define policies for the data movement for different workflows and node types.

  •  Protection types in ISILON : ISILON cluster can have protection types N+M (where N is the number of data blocks and M is the number of nodes/drives failures the system can tolerate) or N+M:B (where N is the number of data blocks M is the number of drives failures the system can tolerate and B is the number of node failures can be tolerated ), where N>M. In case of a 3-node system, it can have +1 (i.e. 2+1) protection type. Here the system can tolerate 1 drive/node failure without any data loss.
  •  Steps to create an NFS export : Here we have listed the commands to create and list/view the NFS export.

To create the NFS export :
isi nfs exports create –clients=10.20.10.31,10.20.10.32 –root-clients=10.20.10.33,10.20.10.34 –description=”Beginnersforum Test NFS Share” –paths=/ifs/BForum/Test –security-flavors=unix

To list the NFS exports :
isi nfs exports list

To view the NFS export :
isi nfs exports view <export_number>

You can create the NFS export alias and quotas also for the NFS export.

Hope this helped you in learning some ISILON stuff. We will have more questions and details in upcoming posts. For more interview questions posts please click here. Please add any queries and suggestions in comments.

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