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Once upon a time in a Migration from Legacy to OCI Public Cloud

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In my previous experience with AWS, Alibaba, Google and PTCL Public cloud I have been working with mostly green field deployment for in house solution with all in and out clear. This time I get challenge with a brown field migration from on-prem to OCI Public cloud for a big public service company. As I always say go with the basic and build from the scratch we start a kick-off meeting with the customer and ask about their plan for this migration and what they are planning for it after discussing we get to know that whole environment need to be migrated so at that time, we bring the most tough ask on the table as plan was that customer want to perform migration in phases with more than 20 application on-boarded in current environment as i studied during my AWS exam preparation it's never suggested to use same IPs across different environments to avoid complicity and better plan for the migration we ask for the change of IPs for the instances that includes Web, Application and DB ti...
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SDN Isn’t Magic – It’s Collaboration with Core Networking at Heart

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Since 2015 when first question I asked from my NOC team are they getting MAC on particular VLAN, I learn something new about networks/IT. First time I heard about SDN from my teacher he was a Cisco TAC Engineer knowing very little the first task assigned to us was find out how ansible works and what is the use case of it. We took two weeks to understand it and then successfully used it to configure a Router in our lab environment, We were too happy you can imagine a network Engineer doing configuration without a cli is kind of magic for us. Afterwards in same training we deployed OpenStack opensource code using blue stack and use it most of services to deploy a image and then use it as router with power of Linux, anyhow training finished and we did our all lab testing and it was end of SDN for us as we didn't get any more time for RND and don't have any solution and that time which were based on SDN in our data centers.  Fast forward in 2019  first time I used SDN base solutio...
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Important concepts in ACI Physical/Access polices Concepts

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I know Cisco ACI has been around for a long time. The first time I got into it was in 2021. It was not that hard to relate the legacy concepts with ACI but doing a job via CLI and doing it via GUI have a lot of differences. In this particular blog, I will discuss the key concepts without explaining the ACI core components like leaf switches, spine switches, and APIC. Cisco ACI is a policy-driven solution in which everything has an object assigned to it, and you need to connect all those dots to make your network work. In a legacy network, we have devices like bare metal servers, L2 switches, L3 switches, routers, and firewalls. We connect the networks using different protocols to make our network work, but sometimes there are physical requirements that need to be fulfilled to get the required topology. In Cisco ACI, we have all these kinds of devices, and they are connected to our fabric. However, in ACI, we have a term called "domains," which include four different types: Ph...
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1 sec and Team work Story

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 I n the world of IT, a single second can be the difference between success and failure. Recently, I experienced this firsthand when a 1-second delay caused a critical application flow to shut down. Through intense troubleshooting, collaboration, and respect for diverse opinions, we identified and resolved the issue. This experience taught me the importance of: - Active listening among all stakeholders - Exploring all options and possibilities - Embracing the value of diverse perspectives - The power of collaboration and teamwork - The crucial role of TCP dumps in troubleshooting In IT, every problem requires a unique solution, and collaboration is key to finding it. Delay we Observe at Client end server end had no delay though Raja Shajeel Ahmad Enterprise DC Engineer Happy Learning The limit is the sky. #TeamWork#TCPDump#HappyLearning
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Flow with respect to Networks in AWS

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Flow with respect to Networks in AWS which need to be clear to expose any application on AWS and having some of services in on-premises. I will compare AWS services with on-prem technology, so it become ease to understand.                                                           Building Block of AWS Networking VPC: Consider it as a switch place in multiple Data center and all switches are connected with each other we can further have small subnets on it which can be part of all switches or only one depend upon the planning and requirements. Route Tables : Each subnet we create in VPC can have each route table or all subnets have one, Route table is used to control the routing of subnets and how traffic will be routed for any workload on the subnets. Route table can be attached to few other services of AWS as per requirements. NAT Gateway: I...
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Pipelining and multiplexing in HTTP connection.

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Yes, HTTP is that old. Same of my age.  So today we were troubleshooting an issue and found that our application was consuming new TCP connection which led to SSL handshake between client and server communication while there was already open TCP connection with server. We are using HTTP 1.1 concurrent with pool numbers in which if a sequential call is not completed you cannot have another request until that call is completed default behavior  of HTTP 1.1. So, i put my hat of research and wanted that same TCP should be used for the new call instead creating new one so i Google it and found the concept of Pipelining in HTTP 1.1,  I  thought yes i crack the thing and now we will implement it and will use same connection for all the streams but wait what HTTP 1.1 pipelining have same serious issue and one should use HTTP 2.0 instead but i then again hit by a surprise that HTTP 2.0 also have some issue and now there is a new version of H...
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Citrix as a Application Load Balancer

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We have different option available in market for the ALB (Application load balancer) one of them is Citrix. As per my experience with F5 and AVI Citrix flow is just like same mostly in interviews I say this that if one person has the understanding of the concepts and flow, he/she will be able to operate/manage the solution of any vendor. Same is the case with ALB's flow is same just name are different for each vendor. As in F5 we have a management IP to manage it in Citrix we have NetScaler IP to manage it and configure it. We do have Self IP/Floating IP to communicate with servers if we are using SNAT in Citrix we have Subnet IP serve the same purpose. For services to expose via F5 we have Virtual IP's Luckly in Citrix it also known as Virtual IP. We have different modes of deployment one Arm and Two Arm any one can be used. HA deployment is quite simple in Citrix then off F5 as we just need to add the Node its IP and username, Password to be added in HA also the Subnet IP...
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