03_cidr - CSS432 Subnetting and CIDR Textbook Ch 3.2.5 Instructor Joe McCarthy(based on Prof Fukudas slides CSS 432 Subnetting CIDR 1 Global addressing

03_cidr - CSS432 Subnetting and CIDR Textbook Ch 3.2.5...

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CSS 432: Subnetting & CIDR 1 CSS432 Subnetting and CIDR Textbook Ch 3.2.5 Instructor: Joe McCarthy (based on Prof. Fukuda’s slides)
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Global addressing CSS 432: Subnetting & CIDR 2 Properties globally unique hierarchical: network + host Dotted Decimal Notation Class A: 2 24 – 2 = 16,777,214 hosts – ( –,,, and – reserved) Class B: 2 16 – 2 = 65,534 hosts – Class C: 2 8 – 2 = 254 hosts – Network Host 7 24 0 A: Network Host 14 16 1 0 B: Network Host 21 8 1 1 0 C:
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CSS 432: Subnetting & CIDR 3 Internet Structure Autonomous System (AS): Administered independently of other AS Have a different routing protocol and metrics Classful Addressing: Do we really need to give an independent class A/B/C network number to every single AS? NSFNET backbone Stanford BARRNET regional Berkeley P ARC NCAR UA UNM Westnet regional UNL KU ISU MidNet regional
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CSS 432: Subnetting & CIDR 4 Scaling Issues in Routing Inefficient use of IP Address Space Class C with 2 hosts (2/254 = 0.78% efficient) Class B with 256 hosts (256/65534 = 0.39% efficient) IP address space gets consumed too quickly Too Many Networks Routing tables do not scale Route propagation protocols do not scale Router gets slower to scan a big forwarding table Hierarchy
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CSS 432: Subnetting & CIDR 5 Subnetting - Concept Problem: Internet identifies only classes Four networks each must receive an independent class of network number, (which exhausts IP addresses and floods network #s) Subnet: collects networks belonging to the same AS and give a single class of network number, which is then divided into subnet numbers internally. Simple IP networks A collection of subnets 40 nodes: Class C 200 nodes: Class C 256 nodes: Class B Internet IAS BBUS EDU - 30 CSS – 30 nodes: Class C 40 nodes Subnet: 200 nodes Subnet: 256 nodes Subnet: Internet IAS BBUS EDU CSS – 30 nodes Subnet: Class B:
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CSS 432: Subnetting & CIDR 6 Subnetting – How to Address Subnet masks define variable partition of host part Subnets visible only within site Network number
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  • Spring '16
  • Farag Ezziden
  • IP address, Subnetwork, Classless Inter-Domain Routing, CIDR

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