IT Tutorials

  Theory     Load Balancing in  OpenSIPS   ·        The "load-balancing" module comes to provide traffic routing based on load. Shortly, when OpenSIPS routes call to a set of destinations, it is able to keep the load status (as number of ongoing calls) of each destination and to choose to route to the less loaded destination (at that moment)   ·        OpenSIPS is aware of the capacity of each destination - it is preconfigured with the maximum load accepted by the destinations.     ·        OpenSIPS will consider the less loaded destination not the destination with the smallest number of ongoing calls, but the destination with the largest available slot.   ·        Also, the "load-balancing" (LB) module is able to receive feedback from the destinations (if they are capable of). This mechanism is used for notifying OpenSIPS when the maximum capacity of a destination changed (like a GW with more or less E1 cards)   ·        The "load-b

  AWS VPC integrates with numerous integrated services. ·        Each AWS account can create multiple vpcs ·        A VPC defines an IP address space that is then divided by subnets. ·        Subnets are deployed within the availability zones. U can create many. Fewer is recommended to limit the network complexity. ·        You can configure route tables to the subnets. - to control the traffic between subnet and the internet. ·        By default all subnets in vpc can communicate with each other. ·        2 types of subnets. Public has direct access to the internet. Private doesn’t have direct access. ·        To make the subject public you have to attach the gateway to the vpc and update the route table. ·        EC2 instance also needs public ip to route to internet gateway. ·        Example have HA o    Private subnet is isolated from the internet.

  ·        There are 3 parts. o    Aws regions o    AWS availability Zones o    AWS Edge locations. ·        AWS Regions are geographic areas that host 2 or more availability zones, o    Organizing levels for AWS services o    Resources in one region are not automatically replicate to another region. o    Not all services are available in all-region.   ·        Availability Zones o    Availability zones are the collections of data centers in a specific region. o    Each AZ in physically isolated from the others but connected together by a fast low-latency network. o    Network through Tier 1 transit providers. o    Ensures High availability and data redundancy within the region. o    If one zone goes down others can handle requests.   ·        Edge Locations. o    Edge locations host a content delivery network Or CDN called amazon cloud front. o    Cloud front used to deliver content to the customers. o    Request for the content are automatical

  ·        Provide simple API for storing and retrieving data. ·        Data in s3 isn’t associated with any particular server. ·        Can put many objects. ·        Objects can be any data file – Images, videos, or server logs. ·        Even large database snapshots as objects. ·        Give access from HTTP or HTTPS. ·        Can access privately through virtual private cloud endpoint. ·        Can encrypt your data in transit. ·        Can create a bucket to hold the data. ·        Key can be a string “media /welcome.mp4” to retrieve data later. ·        |Data storage grow as your application needs     ·        Additionally, you can handle the data from the bucket directly from the rest endpoints ·        These supports HTTP or HTTPS access ·        S3 bucket name must be globally unique and DNS compliant. ·        Supports cross-region replication – data put in s3 bucket in one region can be automatic

  ·        You can choose EBS volumes between HDD and SSD types. ·        Pay as you go ·        Backup using snapshots. ·        Block-level replication – much more durable because of that. ·       The right  tool for the right job. – choose magnetic for the logs. ·        For DR protection (Disaster recovery) protection you can copy snapshots to different AWS Region. ·        Can change to HDD to SSD or increase capacity ·        Can to this on fly. Without needing to stop the instances. ·        If you want to attach new volume to existing instances u have to create the EBS volume should be created on the same availability zone as the instance resides. ·        how to attach volume to an instance o    Go to action and click attach volume. o    Select the instance o    Select device - /dev/sdb o    Go to the instance tab and click connect. o    Go to the terminal and connect with the instance o    “lsblk” use to find out what are the blocks within the

  Ø   Elastic Compute Service. Ø   You can increase or decrease the number of servers that required by the application automatically. Ø   Servers = Amazon EC2 instances. Ø   How to build and configure EC2 instance. ü   Log in to AWS console ü   Choose a region ü   Launch EC2 wizard ü   Select AMI ( Amazon Machine Image)( software ) ü   Select instance type (HW) ü   Configure network ü   Configure storage ü   Configure key pairs – Allow us to connect to the instance. ü   Launch & connect. Ø   DHCP – Dynamic Host configuration service ü   Network management protocol used to automate the process of configuring devices on IP networks. ü   Dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks. ü   IN AWS auto-assign public IP will give the DHCP address. Ø   In order to connect with SSH need to create a key pair. Ø   Default user – ec2@user{copy the public