Day 23 #Hybrid_Multi_Cloud_Training:
1. We came to know about Network that is if we have multiple instance running and we need these instances to be connected means A send data or singals to B. So we need a network between A and B.
2. For the connection between two devices we need to understand these 6 things: i) physical connection which may be wired or wireless between devices. ii) LAN Card or Network Interface Card(NIC) which provide IP address. In AWS we have ENI and for Openstack VNIC iii) IP Address (IPv4) 4bytes ip iv) Network Name and Physical Devices if devices are in same network then we use Switch of if devices are in different network then we use Routers for communication. v) Public Ip can only connect to Public IP and Private Ip can only connect to Private IP vi) Routing Tables If all these 6 requirements are fulfilled then we are able to connect or ping to the outside world.
3. Netmask decides the network name of IP Addrees and if the IP is in same network then we require switch to connect two devices A and B. IP is in different network then we require router to connect two devices
4. one setup in which we have one VM which has a NIC attached with some wire virtually and it has some IPAddress provided by DHCP server. In AWS we have no want to go inside DHCP server but openstack provide the facility to view this thing. So here we have have first 3 requirement complete now another VM is able to connect if Netmask is same.
5. The diagram of switch and also understand that we can create a switch using some software and this switch is called bridge. Similarly we can create router using software this is also called bridge. 6. Any device that work on layer 2 is called DataLinkLayer device and switch is DataLinkLayer device. Any device that work on layer 3 is called NetworkLayer device and router is NetworkLayer device. Layer 2 device does not work on IP but Layer 3 does.
7. Mobile Hotspot is a layer 3 bridge so that two device on different network can able to ping here work as switch and we can also go to internet with the same hotspot so it is work as router .
8. SDN or Software Defined Network is a network that is created by software and we can create Switch and router using SDN software. This software usually found in Linux and we can create Linux bridge and it is also available in OpenStack as "OpenVSwitch"..