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© ITT Educational Services, Inc. All rights reserved.
IS3120 Network Communications Infrastructure
Unit 4
IP Addressing Schema Designs for a Layer 2/Layer 3 IP Network Infrastructure
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Learning Objective
Translate IPv4 and IPv6 IP addressing schemas and perform logical IP addressing schema designs.
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Key Concepts
IPv4 addressing structure IPv6 addressing structureAlignment 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
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EXPLORE: CONCEPTS
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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: 192.168.0.1
IPv4 networks can be classful or classless
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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 networksEach class restricted to a particular IP
address rangeRange based on number of nodes neededMaximum number of 4,294,967,296
addresses (232)
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IPv4: Classful Network Breakdown
Class # of
Networks# of Nodes Address Range
A (large) 128 16,777,216 0.0.0.0 to 127.255.255.255
B (medium) 16,384 65,536 128.0.0.0 to 191.255.255.255
C (small) 2,097,152 256 192.0.0.0 to 223.255.255.255
D (multicast) N/A N/A 224.0.0.0 to 239.255.255.255
E (future use) N/A N/A 240.0.0.0 to 255.255.255.255
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IPv4: Networks versus Nodes
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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
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IPv4: Dot Notation to Binary
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IPv4: Private Addresses
Not routable through public routersNetwork Address Translation (NAT) maps
internal addresses to public routable addresses
Private Address Ranges
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
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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
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IPv6: Address Notation
8 groups of 4 hexadecimal numbers
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IPv6: Address Compression
Drop leading 0s in each group2001:0db8:0000:0000:0000:0053:0000:0004
becomes
2001:db8:0:0:0:53:0:4
Replace the first group of 0s with ::2001:0db8:0000:0000:0000:0053:0000:0004
becomes
2001:db8::53:0:4
Only one set of :: can exist in an address
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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.
2001:0db8:0001:0000:0000:0000:0000:0000
Subnet
Network (64 bits) Host (64 bits)
Internet Routing
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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
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IPv6: Unicast Addressing
Single deviceSimilar to IPv4 CIDRGlobal or local (public or private)Can contain embedded IPv4 addresses• Network prefix set to 0• ::FFFF:192.168.0.4
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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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IPv6: Unicast Host Identifier
Calculated from interface’s 48-bit MAC address MAC is assigned by manufacturer:
1c:6f:65:35:85:6d
00011100 01101111 01100101 00110101 10000101 01101101
EUI-64 inserts ff:fe as the middle 16 bits:1c:6f:65:ff:fe:35:85:6d
00011100 01101111 01100101 11111111 11111110 00110101 10000101 01101101
If the host address is globally unique the 7th bit is inverted:
1e:6f:65:ff:fe:35:85:6d00011110 01101111 01100101 11111111 11111110 00110101 10000101 01101101
Any IP address sharing the same initial 32 bits is in the same Internet network, leaving 32 bits for sub-netting.
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IPv6: Multicast AddressingBits Field Purpose
8 Prefix FF is reserved for multicast addressingFF00::/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]
4 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.
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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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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 4 112
Solicited-Node Multicast Address
Field Prefix Flag Scope All 0s All 1s Last 24 from Unicast Address
Bits 8 4 4 79 9 24
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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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IPv6: Anycast Addressing
New to IPv6, no IPv4 equivalentCan be translated from unicast address• Change node identifier bits to all 0s or all
1s except the last 7 bitsAssociated with a unique identifierEach LAN segment can have 126 unique
anycast IDs
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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 (0000000) through 0x7d (0111101) may
be designated Anycast identifiers• 0x7e (0111110) and 0x7f (0111111) are
reserved
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EXPLORE: PROCESSES
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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
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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 0.0.0.0 to 127.255.255.255
B (medium) 16,384 65,536 128.0.0.0 to 191.255.255.255
C (small) 2,097,152 256 192.0.0.0 to 223.255.255.255
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IPv4 Schema: Subnets
How many subnets are needed?• Security• Services• Organizational structure
How many hosts for eachsubnet?
# of hosts per subnetdetermines subnet mask
Net Bits
Subnet Mask Addresses
/20 255.255.240.0 4096
/21 255.255.248.0 2048
/22 255.255.252.0 1024
/23 255.255.254.0 512
/24 255.255.255.0 256
/25 255.255.255.128 128
/26 255.255.255.192 64
/27 255.255.255.224 32
/28 255.255.255.240 16
/29 255.255.255.248 8
/30 255.255.255.252 4
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IPv4 Example
Network ID 10.0.0.0 (Class A)
Subnet Mask 255.255.255.0
Mask Bits 24
Subnet Bits 16
Total Addresses 255
IP Address (gateway) 10.0.0.1
Broadcast Address 10.0.0.255
Total Host (assignable addresses) 254
CIDR Notation 10.0.0.0/24
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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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Types of IPv6 Addresses
Enclose IPv6 addresses in brackets [] to specify a particular port
Example: telnet [201:0db8::53:0:4]:23 for port 23
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 0:0:0:0:0:0:128.124.16.52 ::807c:1034
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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
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IPv6 Schema: Subnetting
ClasslessNotation 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)
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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
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EXPLORE: ROLES
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Role of IP Addressing in Network Routing
IP addressing is based on hosts and networksEnd 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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EXPLORE: CONTEXTS
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IPv4 and IPv6 in Context
Most devices still using IPv4Compatibility with IPv6 networking is mainly
a software or firmware issueAmerican Registry for Internet Numbers
(ARIN) suggests that all Internet servers be prepared to serve IPv6-only clients by January 2012
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EXPLORE: RATIONALE
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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.