Internet Protocol Analysis/Subnetting
Appearance
This lesson continues the Internet layer and looks at subnetworks, Classless Inter-Domain Routing (CIDR), subnetting, and supernetworks. Activities include IPv4 subnetting, and using the Cisco Subnet Game.
Readings
[edit | edit source]- Wikipedia: Subnetwork
- Wikipedia: IPv4 subnetting reference
- Wikipedia: CIDR notation
- Wikipedia: Classless Inter-Domain Routing
- Wikipedia: Supernetwork
Multimedia
[edit | edit source]- YouTube: Subnetting, Cisco CCNA, Binary Numbers - Part 1
- YouTube: Subnetting, Cisco CCNA, Binary Numbers - Part 2
- YouTube: Subnetting, Cisco CCNA, Binary Numbers - Part 3
- YouTube: Subnetting, Cisco CCNA, Binary Numbers - Part 4
- YouTube: Subnetting Cisco CCNA - Part 1 The Magic Number
- YouTube: Subnetting Cisco CCNA - Part 2 The Magic Number
- YouTube: Subnetting Cisco CCNA - Part 3 The Magic Number
- YouTube: Subnetting Cisco CCNA - Part 4 The Magic Number
- YouTube: Subnetting Cisco CCNA - Part 5 The Magic Number
- YouTube: Subnetting Cisco CCNA - Part 6 The Magic Number
Activities
[edit | edit source]- Review Cisco: IP Addressing and Subnetting for New Users.
- Review Understanding TCP/IP addressing and subnetting basics.
- Experiment with an online subnet calculator such as Online IP Subnet Calculator.
- Generate practice subnetting questions using this Subnet Calculator.
- Review EasySubnetting.com subnetting resources.
- Play the Cisco: Subnet Troubleshooting Game.
- Consider situations in which a packet analyzer might be used to troubleshoot subnetting and routing traffic.
Lesson Summary
[edit | edit source]- An IP address has two fields, a network prefix and a host identifier.[1]
- The network prefix is identified using CIDR notation.[2]
- In IPv4, the network prefix may also be identified using a 32-bit subnet mask in dotted-decimal notation.[3]
- A network is divided into two or more subnetworks by dividing the host identifier field into separate subnet number and smaller host identifier fields.[4]
- All hosts on a subnetwork have the same network prefix.[5]
- Traffic between subnets is exchanged through a router.[6]
- The first address on any given IPv4 network or subnet is reserved for the network itself.[7]
- The last address on any given IPv4 network or subnet is reserved for broadcast.[8]
- The separation of the network prefix/subnet number from the host identifier is performed by a bitwise AND operation between the IP address and the (sub)network mask.[9]
- The number of subnetworks created by subnetting can be calculated as 2n, where n is the number of bits used for subnetting.[10]
- The number of available hosts on each subnet can be calculated as 2n -2 ,where n is the number of bits available for the host identifier.[11]
- The goal of Classless Inter-Domain Routing was to slow the growth of routing tables on routers across the Internet, and to help slow the rapid exhaustion of IPv4 addresses.[12]
- Classless Inter-Domain Routing is based on variable-length subnet masking (VLSM), which allows a network to be divided into variously sized subnets, providing the opportunity to size a network more appropriately for local needs.[13]
- The benefits of supernetting are conservation of address space and efficiencies gained in routers in terms of memory storage of route information and processing overhead when matching routes.[14]
Key Terms
[edit | edit source]- bitwise AND
- A binary operation that takes two representations of equal length and performs the logical AND operation on each pair of corresponding bits. The result in each position is 1 if the first bit is 1 and the second bit is 1; otherwise, the result is 0.[15]
- CIDR notation
- A compact specification of an Internet Protocol address and its associated routing prefix.[16]
- provider-independent address space
- A block of IP addresses assigned by a regional Internet registry (RIR) directly to an end-user organization.[17]
- routing table
- A data table stored in a router or a networked computer that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes.[18]
- subnet
- A logically visible subdivision of an IP network.[19]
- subnet mask
- A bitmask that encodes the (sub)network prefix length in dotted-decimal notation, starting with a number of 1 bits equal to the prefix length, ending with 0 bits, and encoded in four-part dotted-decimal format.[20]
- subnetting
- The practice of dividing a network into two or more networks.[21]
- supernet
- An Internet Protocol (IP) network that is formed from the combination of two or more networks (or subnets) with a common Classless Inter-Domain Routing (CIDR) prefix.[22]
Review Questions
[edit | edit source]Click on a question to see the answer.
-
An IP address has two fields, _____.An IP address has two fields, a network prefix and a host identifier.
-
The network prefix is identified using _____.The network prefix is identified using CIDR notation.
-
In IPv4, in addition to using CIDR notation, the network prefix may be identified using _____.In IPv4, in addition to using CIDR notation, the network prefix may be identified using a 32-bit subnet mask in dotted-decimal notation.
-
A network is divided into two or more subnetworks by dividing _____.A network is divided into two or more subnetworks by dividing the host identifier field into separate subnet number and smaller host identifier fields.
-
All hosts on a subnetwork have the same _____.All hosts on a subnetwork have the same network prefix.
-
Traffic between subnets is exchanged through a _____.Traffic between subnets is exchanged through a router.
-
The first address on any given network or subnet is reserved for _____.The first address on any given IPv4 network or subnet is reserved for the network itself.
-
The last address on any given IPv4 network or subnet is reserved for _____.The last address on any given IPv4 network or subnet is reserved for broadcast.
-
The separation of the network prefix/subnet number from the host identifier is performed by _____.The separation of the network prefix/subnet number from the host identifier is performed by a bitwise AND operation between the IP address and the (sub)network mask.
-
The number of subnetworks created by subnetting can be calculated as _____.The number of subnetworks created by subnetting can be calculated as 2n, where n is the number of bits used for subnetting.
-
The number of available hosts on each subnet can be calculated as _____.The number of available hosts on each subnet can be calculated as 2n-2, where n is the number of bits available for the host identifier.
-
The goal of Classless Inter-Domain Routing was to _____.The goal of Classless Inter-Domain Routing was to slow the growth of routing tables on routers across the Internet, and to help slow the rapid exhaustion of IPv4 addresses.
-
Classless Inter-Domain Routing is based on _____.Classless Inter-Domain Routing is based on variable-length subnet masking (VLSM).
-
The benefits of supernetting are _____.The benefits of supernetting are conservation of address space and efficiencies gained in routers in terms of memory storage of route information and processing overhead when matching routes.
Assessments
[edit | edit source]References
[edit | edit source]- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnet mask#Network addressing and routing
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Subnetwork#Special addresses and subnets
- ↑ Wikipedia: Subnetwork#IPv4 subnetting
- ↑ Wikipedia: Subnetwork#Subnet and host counts
- ↑ Wikipedia: Subnetwork#Subnet and host counts
- ↑ Wikipedia: Classless Inter-Domain Routing
- ↑ Wikipedia: Classless Inter-Domain Routing#Background
- ↑ Wikipedia: Supernetwork
- ↑ Wikipedia: Bitwise operation#AND
- ↑ Wikipedia: CIDR notation
- ↑ Wikipedia: Provider-independent address space
- ↑ Wikipedia: Routing table
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Classless Inter-Domain Routing#Subnet masks
- ↑ Wikipedia: Subnetwork
- ↑ Wikipedia: Supernetwork