© 2012 Cisco and/or its affiliates. All rights reserved.SPNGN1 v1.01—1-1 IP Fundamentals.

© 2012 Cisco and/or its affiliates. All rights reserved. SPNGN1 v1.01—1-1

Managing IP Addressing

IP Fundamentals


Objectives• List the different types of the IP addresses

• Describe the IPv4 addresses reserved by the IANA for special use

• Describe private and public IPv4 addresses.

• Describe the IPv6 address formats and types

• Describe the IPv6 link-local unicast address

• Describe generic IPv6 unicast addresses

• Describe unique local IPv6 unicast addresses

• Describe special-purpose IPv6 unicast addresses

• Describe multicast IPv6 addresses

• Describe anycast IPv6 addresses

• Describe the IPv4 header format

• Describe the IPv6 header format


Objectives (Cont.)• Compare the IPv4 and IPv6 header formats

• Describe IPv6 address assignment

• Describe stateless IPv6 address autoconfiguration

• Describe DHCPv6

• Describe ICMP

• Describe the ICMP types used in IPv4 and IPv6

• Describe how ICMP is used in the IPv6 neighbor discovery process

• Verify the IPv4 and IPv6 address of a host

• Describe how to enable IPv6 on a Windows PC

• Describe the ipconfig command

• Describe the basic purpose of a DNS

• Describe the supported DNS objects

• Describe the DNS hierarchy


IPv4 Address Classes: The First Octet

1 1 0 x x x x x .

Class C: The first 3 bits are fixed.

Network . Network . Host

1 0 x x x x x x .

Class B: The first 2 bits are fixed.

Network . Host . Host

0 x x x x x x x .

Class A: The first bit is fixed.

Host . Host . Host

1 1 1 1 x x x x .

Class E: The first 4 bits are fixed.

. Experimental .

1 1 1 0 x x x x .

Class D: The first 4 bits are fixed.

. Multicast .


Reserved IPv4 Address

IPv4 addresses reserved by IANA for special use:• Network address

• Directed broadcast address

• Local broadcast address

• Local loopback address

• Autoconfiguration IP addresses

• Network ID

• Host ID


Private and Public IPv4 Addresses

Class Private Address Ranges

Class A 10.0.0.0–10.255.255.255

Class B 172.16.0.0–172.31.255.255

Class C 192.168.0.0–192.168.255.255

Class Public Address Ranges

Class A 1.0.0.0–9.255.255.255

11.0.0.0–126.255.255.255

Class B 128.0.0.0–172.15.255.255

172.32.0.0–191.255.255.255

Class C 192.0.0.0–192.167.255.255

192.169.0.0–223.255.255.255


IPv6 Address Formats and Types• Unicast:

- Link-local addresses

- Global unicast addresses

- Unique local addresses

- Special-purpose unicast:

• Unspecified

• Loopback

• IPv4-mapped

• Multicast

• Anycast

• No support for broadcast addresses in IPv6


Link-Local IPv6 Unicast Addresses• Have a scope limited to the link

• Are automatically configured with the interface identifier

• When used, must be paired with outgoing interface information

Interface ID0

1111 1110 10

FE80::/10

10 bits

64 bits

128 bits


Global IPv6 Unicast Addresses• Global unicast addresses are addresses for generic use of IPv6.

• Interface identifier should be kept at 64 bits.

128-n-m bitsm bitsn bits

Interface IDGlobal Routing Prefix Subnet ID

InterfaceSiteProvider


Unique Local IPv6 Unicast Addresses• FC00::/7:

- FC00::/8 planned to be globally managed

- FD00::/8 assigned locally by network administration

• For network in which only internal IPv6 communication is required

• Not routable on the Internet

64 bits16 bits40 bits

Interface IDGlobal ID Subnet ID

InterfaceSiteRandom Identifier

FD00::/8

Prefix

8 bits


Special-Purpose IPv6 Unicast Addresses• Unspecified address:

- 0:0:0:0:0:0:0:0

- Used as a placeholder when no address is available (initial DHCP request, DAD)

• Loopback address:

- 0:0:0:0:0:0:0:1

- Same as 127.0.0.1 in IPv4

• IPv4-mapped addresses:

- Used to represent the addresses of IPv4 nodes as IPv6 addresses

- Used for next-hop representation in Cisco 6PE and 6VPE

- Used in network stacks when both address families are processed internally as IPv6

80 bits 32 bits16 bits

IPv4 AddressFFFF0

0:0:0:0:0:ffff:192.0.2.100 = ::ffff:192.0.2.100 = ::ffff:c000:0246


Multicast IPv6 Addresses• Multicast is used in the context of one-to-many.

• Explicit multicast scope is a new concept in IPv6.

Group ID

112 bits

F F x y

1111 1111

8 bits

F F

Flags Scope

8 bits

Flags: 4 Bits = “0”, “R”, “P”, “T”

Scope: 1 = Interface-local2 = Link-local3 = Subnet-local4 = Admin-local5 = Site-local8 = OrganizationE = Global


Anycast IPv6 Addresses• Used in the context of one-to-nearest

• Assigned to more than one interface

• Allocated from the unicast address space

• Indistinguishable from regular unicast addresses

• Must be explicitly configured as anycast on the node

• All nodes with the same anycast address should behave the same way

128-n bits

Prefix Interface ID

n bits


IPv4 Header FormatVersion IHL Type of Service Total Length

Identification Flags Fragment Offset

ProtocolTTL Header Checksum

Source Address

Destination Address

Options Padding

Data Portion

32 bits

20 Octets

Variable Length


IPv6 Header Format

32 bits

Version

40 Octets

Variable Length

Traffic Class Flow Label

Payload Length Next Header Hop Limit

Source Address

Destination Address

Extension Header Information

Data Portion

Next Header


IPv4 and IPv6 Header Comparison

Version IHL ToS Total Length

Identification Flags Fragment Offset

ProtocolTTL Header Checksum

Source Address

Destination Address

Options Padding

Version Traffic Class Flow Label

Payload Length Next Header Hop Limit

Source Address

Destination Address

IHL = Internet Header LengthToS = Type of Service

Field

Legend:

Field

Field

Field

Field name kept from IPv4 to IPv6

Field not kept in IPv6

Field name and position changed in IPv6

New field in IPv6

IPv4 Header IPv6 Header


Assigning IPv6 Global Unicast Addresses• Static assignment:

- Manual interface ID assignment

- EUI-64 interface ID assignment

• Dynamic assignment

- Stateless autoconfiguration:

- DHCPv6 (stateful)

Interface ID0DB82001

/23 /32 /48 /64

Registry

ISP Prefix

Site Prefix

Subnet Prefix


Stateless IPv6 Autoconfiguration• Often uses Layer 2 identifier (derived from OUI)

• Autoconfiguration with no collisions

• “Plug-and-play”

MAC Address:00:2c:04:00:fe:56

Router Solicitation (RS)request prefix

Router sends network-type information (prefix, default

route, etc.)

Host autoconfigured address:prefix received + 64-bit

interface ID

1

2

3


DHCPv6

DHCPv6 is an updated version of DHCP for IPv4:• Supports new addressing

• Enables more control than stateless autoconfiguration

• Can be used for renumbering

• Can be used for automatic domain-name registration of hosts by using DDNS


ICMP PacketThe ICMP packet is identified as 1 in the Protocol field of the IPv4 header and 58 in the Next Header field of the IPv6 header.

IP Basic Header

ICMP Packet

ICMP Type ICMP Code Checksum

ICMP Data


ICMP Type

ICMP Type IPv4 IPv6

Destination Unreachable 3 1

Packet Too Big - 2

Fragmentation Needed 3 -

Time Exceeded 11 3

Parameter Problem 12 4

Echo Request 8 128

Echo Reply 0 129


ICMP in the IPv6 Neighbor Discovery• How does IP acquire the Layer 2 address of a neighbor?

- Known network layer address, unknown data link layer address

- IPv4 uses ARP

- IPv6 uses neighbor discovery

• Neighbor discovery:

- Queries for duplicate addresses

- Determines the data link layer address of a neighbor

- Finds neighbor routers on link

- Is achieved by using ICMPv6 with IPv6 multicast


Network Connection


Enabling IPv6 on Windows


The ipconfig CommandC:\Users\username>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : PCUSER Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . :

<...part of the output omitted...>

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Intel(R) 82579LM Gigabit Network Connection Physical Address. . . . . . . . . : 00-15-58-2F-21-E6 DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IPv6 Address. . . . . . . . . . . : 2001:db8::0215:582f:21e6(Preferred) Temporary IPv6 Address. . . . . . : 2001:db8::1234:5678(Preferred) Link-local IPv6 Address . . . . . : fe80::0215:582f:21e6%10(Preferred) IPv4 Address. . . . . . . . . . . : 209.165.200.251(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.224 Lease Obtained. . . . . . . . . . : 29. August 2011 7:59:08 Lease Expires . . . . . . . . . . : 30. August 2011 7:59:07 Default Gateway . . . . . . . . . : fe80::1%10 209.165.200.226

<...rest of the output omitted...>


Domain Name System• TCP/IP suite application layer protocol

• A way to translate human-readable names into IP addresses

What is the IP address of www.cisco.com?


DNS-Supported Objects• Several types of DNS objects

exist:

- A, AAAA, PTR, MX, etc.

• Two DNS issues exist for IPv6:

- IPv6 record support

- IPv6 transport support

• DNS uses A for IPv4 and AAAA for IPv6 forward lookups

Node 1node1.example.com

192.168.201.23


2001:db8:0:1abc:cc5::55b1

node1.example.com. IN A 192.168.201.23node5.example.com. IN AAAA 2001:db8:0:1abc:cc5::55b1

Examples of A and AAAA records:


DNS-Supported Objects (Cont.)• Reverse lookups:

- IPv6 uses PTR records for reverse lookups, similar to IPv4, but with the new nibble format


2001:db8:0:1abc:cc5::25e4


2001:db8:0:1abc:cc5::55b1

$ORIGIN c.b.a.1.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.4.e.5.2.0.0.0.0.0.0.0.0.5.c.c.0 14400 IN PTR node4.example.com.1.b.5.5.0.0.0.0.0.0.0.0.5.c.c.0 14400 IN PTR node5.example.com.

Examples of Nibble-Formatted Records:


DNS Tree Structure• IPv6 needs an updated version of a DNS server and client resolver.

• The DNS tree structure in IPv6 is identical to the one in IPv4:

- Root DNS server

- Top-level domain DNS server

- Authoritative DNS server for each particular domain

• From the operational perspective, there are three types of DNS servers:

- Primary

- Secondary

- Caching

• The majority of DNS root servers are accessible by using IPv6:

- Enabled end-to-end IPv6 communication without using IPv4 for communication with the Root DNS server

- Removed the need for dual stack (from DNS perspective)


DNS Tree Structure Components• Authoritative primary and secondary DNS servers support both IPv6 and IPv4

records:

- Forward and reverse zones are rarely on the same system

- Reverse zones are often maintained by ISPs

• Caching DNS is typically provided by ISPs (for home or small business) or by large enterprises for in-house clients.

PC1node4.example.com

2001:db8:0:1abc:cc5::25e4

PC2node5.example.com

2001:db8:0:1abc:cc5::55b1

Primary DNS–ForwardSOA = example.com2001:db8:400:200c

192.168.2.20

Secondary DNS–ForwardSO A = example.com2001:db8:300:400a

192.168.2.20

Primary DNS–ReverseSOA = 2001:db8:0::/48

2001:db8:700:abcd::1000192.168.2.130

Secondary DNS–ReverseSOA = 2001:db8:0::/48

2001:db8:600:ef12::2000192.168.2.140

CacheDNS A

CacheDNS B

PC3node45.example2.com

Router

RouterRoot DNS–WIDE TokyoIPv4: 172.30.232.40IPv6: 2001:db8:f:3::35

Root DNS–ISC CA USAIPv4: 192.168.79.201IPv6: 2001:db8:e:53


Summary• There are five IPv4 address classes.

• Certain IPv4 addresses are reserved by the IANA and cannot be assigned to individual devices on a network.

• Three blocks of IPv4 addresses are designated for private, internal use.

• IPv6 supports three types of addresses: unicast, multicast, and anycast.

• Link-local IPv6 addresses are used for automatic address configuration, neighbor discovery, and router discovery.

• Global unicast IPv6 addresses are for generic use of IPv6.

• Unique IPv6 local addresses provide an IP addressing mechanism for organizations that prefer the concept of private address space for internal communications.

• An unspecified address (::) is used on a network only as a source address for special purposes.

• Multicast IPv6 addresses uses the FF/8 range.


Summary (Cont.)• An IPv6 anycast address is assigned to an interface on more than one

node.

• The IPv4 header carries crucial information for the routing of an IP packet.

• The IPv6 header has 40 octets as opposed to IPv4 which has 20 octets.

• The IPv6 header is simpler than the IPv4 header in terms of header fileds number.

• Global unicast IPv6 addresses can be assigned manually or dynamically using stateless autoconfiguration or DHCPv6.

• Autoconfiguration enables plug-and-play, which connects devices to the network without any configuration and without any stateful DHCP servers.

• DHCPv6 is an updated version of DHCP for use with IPv6.

• ICMP plays an important role in troubleshooting networks, facilitating simple tools, or determining that a packet could not reach its destination.


Summary (Cont.)• ICMP provides different types of ICMP messages.

• In IPv6, ARP was replaced by neighbor discovery which uses ICMPv6.

• Most operating systems provide a series of tools that can be used to verify the host addressing.

• An IPv6 address on the Windows host can be configured statically or acquired automatically.

• The ipconfig command can be used to display all TCP/IP network configuration values of a Windows computer.

• DNS is a distributed directory service that is used to translate between domain names and IP addresses.

• Two types of lookups are used most in DNS: forward and reverse lookups.

• On the top of the DNS hierarchy, are root DNS servers. Below the root server are top-level domain DNS servers. Beneath TLD servers are authoritative servers for each domain.


© 2012 Cisco and/or its affiliates. All rights reserved.SPNGN1 v1.01—1-1 IP Fundamentals.

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