1. IS3120 Network Communications Infrastructure
Unit 4
IP Addressing Schema Designs for a Layer 2/Layer 3 IP Network Infrastructure

2. Learning Objective
Translate IPv4 and IPv6 IP addressing schemas and perform logical IP addressing schema designs.

3. Key Concepts IPv4 addressing structure IPv6 addressing structure
Alignment of subnet mask addressing to appropriate number of IP subnetworks
IP addressing schema design using IPv4 for Layer 2 and Layer 3 networking
IP addressing schema design using IPv6 for Layer 2 and Layer 3 networking

4. EXPLORE: CONCEPTS

5. IPv4: Address Structure
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IPv4: Address Structure
32-bit addresses (4 bytes)
Usually displayed in dot notation
4 separate 8-bit numbers (octets)
Octets separated by periods
Octet value is between 0 and 255
Example:
IPv4 networks can be classful or classless
RFC 791 Internet Protocol (
RFC 1166 Internet Numbers (
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6. IPv4: Classful Network Architecture
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IPv4: Classful Network Architecture
IP addresses originally organized into five classes: A, B, C, D, and E
A, B, and C used for networks
Each class restricted to a particular IP address range
Range based on number of nodes needed
Maximum number of 4,294,967,296 addresses (232)
Class D and E are not used for hosts, as is illustrated by the next slide
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7. IPv4: Classful Network Breakdown
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IPv4: Classful Network Breakdown
Class
# of
Networks
# of Nodes
Address Range
A (large)
128
16,777,216 to
B (medium)
16,384
65,536 to
C (small)
2,097,152
256 to
D (multicast)
N/A to
E (future use) to
This method of addressing was not very flexible and IP address shortage was inevitable
Because D and E were reserved for other purposes, there are a maximum of 16,843,011 available IP addresses.
This does not count reserved addresses within each class.
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8. IPv4: Networks versus Nodes
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IPv4: Networks versus Nodes
Tradeoff between number of networks and number of nodes
Class A = 1 octet to identify network, 3 to identify nodes
Class B = 2 octets to identify network, 2 to identify nodes
Class C = 3 octets to identify network, 1 to identify nodes
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9. IPv4: CIDR Replacement for classful network architecture (1993)
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IPv4: CIDR
Replacement for classful network architecture (1993)
Temporary solution for IP address shortage
Networks are split into groups of IP addresses called CIDR blocks
Flexible network allocation
Minimal IP address waste
RFC 4632 Classless Inter-Domain Routing (CIDR) (
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10. IPv4: Dot Notation to Binary
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IPv4: Dot Notation to Binary
The instructor should discuss the difference between decimal (base 10) and binary (base 2) by noting the different manner in which the common decimal values are represented in binary format. It may be helpful in a classroom environment to write on a white board the binary place values (2^0, 2^1, 2^2, etc.) to provide students with a framework. Using this slide, the Instructor should draw attention to the first decimal value, and then show the addition of the binary place values for all “1”s.
Example: For decimal 168, the Instructor should identify the highest value (by position) of 128, then locate the next “1” at 32 and add that value to the previous total of 128 to obtain =160, then locate the final “1” at 8 and add that value to the previous total of 160 to obtain 168+8=168 and draw the students’ attention back to the original matching decimal value.
Decomposition of an arbitrary decimal value provided by a student (255 and below) can be performed using a white board by first laying out eight spaces and identifying the 2’s value for each, then writing down the decimal value for reference. Decomposition begins by finding the highest 2’s position with a decimal equivalent value under or exactly equal to the arbitrary decimal value and putting a “1” above that position and subtracting the equivalent value from the original, performing the same process on the remainder until the remainder is zero. Then “0” can be placed in all of the empty spaces to fill out the full byte.
Example: For the arbitrary value of 17, the highest 2’s value below or equal is the 5th position from the right (2^4=16), leaving a remainder of 1 which matches the 1st position from the right (2^0=1). Thus, the result will appear as: ___ ___ ___ _1_ ___ ___ ___ _1_, with zeros as:
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11. IPv4: Private Addresses
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IPv4: Private Addresses
Not routable through public routers
Network Address Translation (NAT) maps internal addresses to public routable addresses
Private Address Ranges to to to
RFC 1918 Address Allocation for Private Internets (
As discussed earlier, there are a limited number of IP addresses
Organizations may find it difficult to acquire enough public addresses
The instructor should stress that organizations should never use unauthorized public addresses, even if not connected to the Internet.
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12. IPv6: Address Structure
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IPv6: Address Structure
128 bit addresses
First 64 bits identify network
Last 64 bits identify host (based on MAC address)
Maximum number of 2128 addresses (> 340 undecillion)
1 undecillion = 1,000,000,000,000,000,000,000,000,000,000,000,000
RFC 4291 IP Version 6 Addressing Architecture (
While the number of addresses is not infinite, the world is unlikely to run out of addresses in the foreseeable future.
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13. IPv6: Address Notation 8 groups of 4 hexadecimal numbers 4/11/2017
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14. IPv6: Address Compression
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IPv6: Address Compression
Drop leading 0s in each group
2001:0db8:0000:0000:0000:0053:0000:0004
becomes
2001:db8:0:0:0:53:0:4
Replace the first group of 0s with ::
2001:db8::53:0:4
Only one set of :: can exist in an address
It is important to stress that only one set of double colons can exist in an address in order to keep track of the missing groups of zeros.
Because we know there must be 8 sets of numbers, we know that in the above example 3 groups of 0s have been compressed.
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15. IPv6: Network Prefix Address block 2001:db8::/32
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IPv6: Network Prefix
Address block 2001:db8::/32
Range: 2001:db8:: to 2001:0db8:ffff:ffff:ffff:ffff:ffff:ffff
Any IP address sharing the same initial 32 bits is in the same Internet network, leaving 32 bits for further sub-netting.
Instructor should note that the CIDR notation plays the same role for IPv6 as for IPv4 and avoids the need for a subnet mask as in early IPv4 subnet specification.
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16. One-to-First-of-Many
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IPv6: Address Types
Unicast
One-to-One
Packets are delivered to a single node
Anycast
One-to-First-of-Many
Packets are delivered to one of a group of nodes
Multicast
One-to-Many
Packets are delivered to many nodes
The Instructor should call attention to the lack of a Broadcast (one-to-all in a subnet) addressing system. In order to provide greater extensibility in the much larger address space of Ipv6, Multicasting to a group of nodes subscribing to a single multicast address provides the same functionality as broadcast did in IPv4.
Anycast functions similarly, but by sending packets only to the nearest host (AAAA) address, which then forwards packets to the remaining subscribing group members. This allows for a change in packet routing during an extended transfer in case of network saturation or failure along a particular route.
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17. IPv6: Unicast Addressing
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IPv6: Unicast Addressing
Single device
Similar to IPv4 CIDR
Global or local (public or private)
Can contain embedded IPv4 addresses
Network prefix set to 0
::FFFF:
RFC 3587 IPv6 Global Unicast Address Format (
RFC 4193 Unique Local IPv6 Unicast Addresses (
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18. IPv6: Global versus Local Unicast
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IPv6: Global versus Local Unicast
Interfaces in IPv6 have at least two addresses:
Link-local
Non-routable
Inter-node identification between neighbors within the same LAN segment
May be automatically or manually assigned
Equivalent to private IPv4 address
Unicast
Globally unique
Routed communications between non-neighbor nodes
Computed using the interface MAC address
Equivalent to public IPv4 address
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19. IPv6: Unicast Host Identifier
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IPv6: Unicast Host Identifier
Calculated from interface’s 48-bit MAC address
MAC is assigned by manufacturer:
1c:6f:65:35:85:6d
EUI-64 inserts ff:fe as the middle 16 bits:
1c:6f:65:ff:fe:35:85:6d
If the host address is globally unique the 7th bit is inverted:
1e:6f:65:ff:fe:35:85:6d
Any IP address sharing the same initial 32 bits is in the same Internet network, leaving 32 bits for sub-netting.
The instructor should develop learner understanding by first noting that all interfaces in IPv6 have at least two addresses:
Link-local – Non-routable, used for inter-node identification between neighbors within the same subnet
Unicast – Globally-unique, used for routed communications between non-neighbor nodes
Each interface also has at least two multicast assignments:
Solicited-node – Used to send tentatively-unique identifier announcements to neighbors within the subnet.
All-hosts - Used to communicate with all nodes within a subnet.
Link-local addressing can be automatically assigned or directly assigned.
Unicast addresses rely on a unique identifier, calculated from the interface MAC and determined to be unique through neighbor discovery. Importance of this process should be noted in virtualized environments where multiple virtual interfaces may share the same physical network interface on the virtualization host. This slide details the process of calculating the unique identifier for an IPv6 unicast interface address.
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20. IPv6: Multicast Addressing
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IPv6: Multicast Addressing
Bits
Field
Purpose 8
Prefix
FF is reserved for multicast addressing
FF00::/8 address range 4
Flags
Flags specify whether a rendezvous address [R] or network prefix [P] is included, or whether address is “well known” (assigned) or transient (temporary use) [T]
Scope
Scope defines whether the address is:
[0x1] Interface-local: Only used for loopback multicast
[0x2] Link-local: Non-routable, unique on physical link
[0x4] Admin-local: Arbitrary Admin-assigned scope
[0x5] Site-local: Not routable beyond site, administratively assigned, including one or more unicast scopes
[0x8] Organization-local: Admin-assigned to include one or more sites within an organization
[0xE] Global: Routable, globally unique address
112
Group ID
Manually-assigned or derived address value.
RFC 3306 Unicast-Prefix-Based IPv6 Multicast Addresses (
RFC 2375 IPv6 Multicast Address Assignments (
Multicast addressing will always begin with (ff) and will be within the ff00::/8 address space in IPv6 CIDR notation. This is similar to the /4 address space for IPv4 multicast.
The Instructor should note that the first 16 bits perform the same function for all multicast addresses, with the 112 bits of the Group ID varying by use.
Site-level scope has been deprecated in future IPv6 standards, but may be found in existing solutions.
Scope should be addressed as only one scope is assigned per multicast address, so an interface requiring multiple scopes could have multiple multicast addresses – one for each scope.
It is possible to have more than one flag, such as both the P and T flags, specifying that the address is a temporarily-assigned (transient) address with network prefix included.
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21. IPv6: Multicast Assignment
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IPv6: Multicast Assignment
Interfaces in IPv6 have at least two multicast assignments:
Solicited-node
Used to validate host identifier uniqueness
Announces interface to neighbors
All-hosts
Communicate with all nodes within a LAN segment
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22. IPv6: Multicast Addressing
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IPv6: Multicast Addressing
Example:
Solicited-node addresses
Translated from a node’s unicast address
General Multicast Addressing
Field
Prefix
Flag
Scope
Group ID
Bits 8 4
112
The Instructor should drawn attention to the multicast fields from the previous (Multicast Addressing) slide in the General address illustration.
The Group ID has been segmented for a specific purpose (Solicited Node address discovery) in the second example, with the same first three fields as above. The Instructor should note that only the last 24 bits of the node’s unicast address identifier are used to verify uniqueness.
Solicited-Node Multicast Address
Field
Prefix
Flag
Scope
All 0s
All 1s
Last 24 from Unicast Address
Bits 8 4 79 9 24
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23. IPv6: Reserved Multicast Addresses
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IPv6: Reserved Multicast Addresses
ff02::1 is all nodes
ff02::2 is all routers
ff02::101 is all Network Time Protocol (NTP) servers
ff02::fb is all multicast DNS servers
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24. IPv6: Anycast Addressing
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IPv6: Anycast Addressing
New to IPv6, no IPv4 equivalent
Can be translated from unicast address
Change node identifier bits to all 0s or all 1s except the last 7 bits
Associated with a unique identifier
Each LAN segment can have 126 unique anycast IDs
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25. IPv6: Anycast Addressing
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IPv6: Anycast Addressing
Node address of all 0s
Subnet-router communications
Takes the place of a default gateway in IPv4
Node address of 1s except the last 7 bits
0x00 ( ) through 0x7d ( ) may be designated Anycast identifiers
0x7e ( ) and 0x7f ( ) are reserved
RFC 4291 IP Version 6 Addressing Architecture (
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26. EXPLORE: PROCESSES

27. Elements of an IPv4 Address Schema
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Elements of an IPv4 Address Schema
Network ID (aka network address)
First address of the block
Subnet mask
Broadcast address
Last address of the block
If multiple subnets
Each subnet has its own network ID and broadcast address
This is the traditional method of subnetting.
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28. IPv4 Schema: Determine Network
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IPv4 Schema: Determine Network
How many hosts (nodes)?
Workstations
Servers
Other
Number of nodes determines network class
Class
Networks
Nodes
Address Range
A (large)
128
16,777,216 to
B (medium)
16,384
65,536 to
C (small)
2,097,152
256 to
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29. IPv4 Schema: Subnets How many subnets are needed?
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IPv4 Schema: Subnets
How many subnets are needed?
Security
Services
Organizational structure
How many hosts for each subnet?
# of hosts per subnet determines subnet mask
Net Bits
Subnet Mask
Addresses
/20
4096
/21
2048
/22
1024
/23
512
/24
256
/25
128
/26 64
/27 32
/28 16
/29 8
/30 4
RFC 950 Internet Standard Subnetting Procedures (
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30. IPv4 Example Network ID 10.0.0.0 (Class A) Subnet Mask 255.255.255.0
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IPv4 Example
Network ID
(Class A)
Subnet Mask
Mask Bits 24
Subnet Bits 16
Total Addresses
255
IP Address (gateway)
Broadcast Address
Total Host (assignable addresses)
254
CIDR Notation
/24
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31. Elements of an IPv6 Addressing Schema
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Elements of an IPv6 Addressing Schema
Internetworking is generally automatic
Assignment of unicast host identifiers
Network and gateway mapping through Neighbor Discovery
Link-local addressing is manual or automatic
Configurable scopes
Admin Level
Site Level (deprecated)
Organization Level
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32. 4/11/2017
Types of IPv6 Addresses
Type
Address Format
Compressed
Unicast
2001:0db8:0:0:0:53:0:4
201:0db8::53:0:4
Multicast
ff01:0:0:0:0:0:0:0c32
ff01::c32
Link-local
fe80:0:0:0:0:0:0:a6fb
fe80::a6fb
Loopback (self)
0:0:0:0:0:0:0:0001
::1/128
Undefined
0:0:0:0:0:0:0:0
::/128
IPv4 Compatible
0:0:0:0:0:0:
::807c:1034
Link-local addressing defines node neighbors within the same subnet. Link-local addresses will always begin with (fe) and will be within the fe80::/10 address space in IPv6 CIDR notation.
Because IPv6 uses colons (:) to separate address groups, it is necessary to enclose IPv6 addresses in brackets [] to specify a particular port (performed using a colon in IPv4)
Enclose IPv6 addresses in brackets [] to specify a particular port
Example: telnet [201:0db8::53:0:4]:23 for port 23
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33. IPv6 Schema: Subnets Support Business Needs
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IPv6 Schema: Subnets Support Business Needs
Segmentation across routers to limit network congestion on critical subnets
Regulatory mandates requiring transport isolation of certain data categories
Logical segmentation of neighbor nodes based on disparate facility locations
Isolation for each client or function
RFC 5942 IPv6 Subnet Model (
Because the IPv6 address space is so vast, subnetting IPv6 address space follows business rules and matters of convenience rather than address control concepts as with the IPv4 address space, where governments compete for Class A assignments, and even a portion of a Class C address space is a valuable commodity.
The Instructor should address the global suitability of IPv6 compared to the earlier IPv4 addressing scheme, where an early-adopter such as a single USA university may own a larger address space than many countries elsewhere in the world.
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34. IPv6 Schema: Subnetting
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IPv6 Schema: Subnetting
Classless
Notation is similar to IPv4 CIDR addressing notation.
Example: 2001:0db8:0:0:0:53:0:4/16
Defines 2001 (the first 16 bits) as the network address
Subnets of 2112 node addresses each
Further subnetting is possible (hierarchical)
The instructor should draw attention to the sheer size of the maximum possible address space for the IPv6 system, noting that while the default 64-bit network address for IPv6 leaves 2^64 possible node addresses, the entire IPv4 Internet only allows just 2^32 total possible addresses all together.
The classless nature of IPv6 should be noted, along with brief discussion of the reason subnet broadcasts would not work if every ISP was given its own /32 IPv6 subnet (with 2^96 possible node addresses). This would amount to broadcasting packets to 2^64 copies of the entire Internet at once.
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35. IPv6: Subnet Segmentation
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IPv6: Subnet Segmentation
Each Provider assigned a /32 network (65536 /48 Subscriber subnets)
A Subscriber assigned a /48 subnet (65536 /64 LAN segments)
A single /64 LAN segment is 264 nodes
Further segmentation administratively assigned through Admin-, Site-, and Organizational-scope specification
The instructor should drawn attention to the significant capacity for subnets at the /32 and /48 level, plus the sheer size of nodes possible at the LAB segment level.
Learner engagement should be enhanced through discussion of the proliferation of personal devices, environmental sensors, and other similar emerging technologies expected to require millions of individual addresses. Discussion should include asking students to consider the number of devices needed to monitor the power consumption of all buildings in a “smart city.”
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36. EXPLORE: ROLES

37. Role of IP Addressing in Network Routing
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Role of IP Addressing in Network Routing
IP addressing is based on hosts and networks
End hosts are assigned IP addresses
Subnets of IP host addresses are divided and grouped together
IP address are used to route packets and are essential to getting information to the proper destination
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38. EXPLORE: CONTEXTS

39. IPv4 and IPv6 in Context Most devices still using IPv4
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IPv4 and IPv6 in Context
Most devices still using IPv4
Compatibility with IPv6 networking is mainly a software or firmware issue
American Registry for Internet Numbers (ARIN) suggests that all Internet servers be prepared to serve IPv6-only clients by January 2012
As of October 2010:
243 (83%) of the 294 top-level domains (TLDs) in the Internet supported IPv6 to access their domain name servers
About 1.4 million domains (1%) had IPv6 address records in their zones
Mobile telephone service transitioning from 3G systems to 4G
Voice is provisioned as Voice over Internet Protocol (VoIP); requires use of IPv6
All major PC and server operating systems support IPv6
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40. EXPLORE: RATIONALE

41. 4/11/2017
Rationale
The number of network-enabled devices has grown beyond IPv4’s address capacity.
IPv6 provides a more globally equitable distribution of network addresses than the legacy IPv4 system which provides more addresses to early-adopters (US universities) than to many governments elsewhere in the world.
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42. Summary In this presentation, the following were covered:
IPv4 addressing
Classful and classless networking (IPv4)
IPv6 addressing
IPv4 address schema design
IPv6 address schema design