Computer Networks_Class #8 Subnetting & Dynamic Routing PDF

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Basic logic and theory behind Subnetting and theory and concepts about RIPv1 and RIPv2...

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Class #8: Subnetting, VLSM - Dynamic Routing RIPv2 Subnetting Subnetting is a division of a network into smaller networks. There are several things to take into consideration for this division First there needs to be 2 IP addresses reserved for the network IP and the the broadcast address. The network IP address has all zeros in the host bits and it s the address that marks the start of a subnet. The broadcast address has all ones in the host bits and it usually marks the end of a given subnetted network. VLSM stands for Variable length Subnet mask. This means that we use a variable subnet mask to divide our networks. Example: Let s say that we have available the network 192.168.80.0/24 but we require 4 different networks. Another requirement is that we need every network to be Solution: So if we need 4 subnets, that means that we need at least 2 more bits to tell the subnets apart. Also, we need to increase the number of mask bits to /26. The subnets would be the following: 192.168.80.00000000/26 192.168.80.01000000/26 192.168.80.10000000/26 192.168.80.11000000/26 The bits in red are the bits that we are going to use to divide our network into 4. The bits in blue indicate the valid IP address However, we must remember that on each network we need to reserve an address for the network itself and for the broadcast. For the first Subnet we have: Network IP: 192.168.80.00000000 or 192.168.80.0/26 Broadcast: 192.168.80.00111111 or 192.168.80.63/26 Valid IP addresses for hosts: 192.168.80.1 to 192.168.80.62/26 For the second Subnet we have: Network IP: 192.168.80.01000000 or 192.168.80.64/26 Broadcast: 192.168.80.01111111 or 192.168.80.127/26 Valid IP addresses for hosts: 192.168.80.65 to 192.168.80.126/26 For the third Subnet we have: Network IP: 192.168.80.10000000 or 192.168.80.128/26 Broadcast: 192.168.80.10111111 or 192.168.80.191/26 Valid IP addresses for hosts: 192.168.80.129 to 192.168.80.190/26 For the fourth Subnet we have: Network IP: 192.168.80.11000000 or 192.168.80.192/26 Broadcast: 192.168.80.11111111 or 192.168.80.255/26 Valid IP addresses for hosts: 192.168.80.193 to 192.168.80.254/26

If these concepts are still puzzling to you make sure you have a solid understanding on the use of the netmask and IP addressing. Or watch this video from the New Boston. He has some real useful videos on the topic: https://www.youtube.com/watch?v=FM169QUIQco&list=PL6gx4Cwl9DGBpuvPW0aHa7mKdn_k9SPKO&index=25 RIP protocol The Routing Information Protocol(RIP), is a first gen protocol designed for IPv4. It s very easy to set up and it s best for small networks. This protocol is based on the maintenance of the routing tables according to a parameter linked to the amount of hops needed to reach a given network. This routing table is updated every 30 seconds in a process which every router sends their own routing table to a neighbor. This process is called

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The RIP protocol is an example of the Distance Vector Protocol. It s also classified as a IGP(Interior Gateway Protocol) because it s used inside of an autonomous system. There s 2 versions of this dynamic routing protocol: RIPv1 and RIPv2 Characteristics of RIPv1 the routing updates are transmitted via broadcast every 30 seconds The number of hops are used to make a decision on which route to take It s only compatible with FLSM. It doesn t support VLSM. Any route that has a hop count of more than 15 is considered infinite and will be discarded. this means that the router 0 won t communicate with router 16 Characteristics of RIPv2 It s a type-less routing protocol It allows VLSM and CIDR because it sends the Subnet mask info along with the routing table information. Routing table updates are done via multi-cast not broadcast. The 15 hop rule still stands.

if anyone has a question or would want to point out something I got wrong, feel free to send an e-mail to: [email protected] Also resting and distracting yourself from time to time can be healthy. Help a brother out and check out a video game I made: https://knowledge-monster.itch.io/demon-hunter (PC) https://play.google.com/store/apps/details?id=com.KnowledgeMonsterGames.DemonHunter(Android) Thanks for the support...