© ITT Educational Services, Inc. All rights reserved. IS3120 Network Communications Infrastructure Unit 4 IP Addressing Schema Designs for a Layer 2/Layer

© 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

© ITT Educational Services, Inc. All rights reserved.Page 2IS3120 Network Communications Infrastructure

Learning Objective

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


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


EXPLORE: CONCEPTS


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


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)


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


IPv4: Networks versus Nodes


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


IPv4: Dot Notation to Binary


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


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


IPv6: Address Notation

8 groups of 4 hexadecimal numbers


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


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


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


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


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


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.


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.


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


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


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


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


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


EXPLORE: PROCESSES


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


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


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


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


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


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


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


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)


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


EXPLORE: ROLES


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


EXPLORE: CONTEXTS


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


EXPLORE: RATIONALE


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.


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

Documents

© ITT Educational Services, Inc. All rights reserved. IS3120 Network Communications Infrastructure Unit 4 IP Addressing Schema Designs for a Layer 2/Layer