Chapter 7: IP Addressing - Intro to Networks v6

RFC 790

In 1981, *Internet* IPv4 addresses were assigned using *classful addressing* in RFC 970, Assigned Numbers. It divides *unicast ranges* into 3 classes: A, B, or C

What were some problems with the Classul IPv4 Addressing system?

It *wasted* a lot of addresses & *exhausted* the availability of IPv4 Addresses. Ex: network of 260 hosts needed to be given a Class B address / more than 65,000 addresses |\| wasting 64,740 addresses (65,000 - 260 = 64,740) This is why it was abandoned in the late 1990's for...??

What is used to translate between private IPv4 addresses and public IPv4 addresses?

Network Address Translation (*NAT*) Usually done on the router that connects the internal network of an org. to the ISP's network. Home routers have the same capability.

Unicast Transmission

One-to-One. Used for host-to-host comms. in both client/server & peer-to-peer networks. Source = IPv4 of originating device Dest. = IPv4 of destination device Include the address range of: *0.0.0.0 to 223.255.255.255* (w/some reserved for special purposes) The *source address* of *any packet*, regardless of destination address (uni-, broad, multi-), is always the *unicast address*.

Broadcast Transmission

One-to-all. Used to send packets to all hosts in a network. Routers do not forward broadcasts by default. Used by many network protocols (DHCP clients, ARP).Broadcast traffic *should be limited* so as not to adversely affect network/device performance. *Sub-dividing* networks can improve network performance by eliminating excessive broadcast traffic. There are *2 types* of broadcast transmissions.

Multicast Transmission

One-to-some. A host sends a single packet to a selected set of hosts that subscribe to a multicast group (multicast clients). Each group is represented by a *single* IPv4 multicast dest. address. Reserved local network multicast addresses are often used in routing protocols to exchange routing info. Routers do not forward by default.

Experimental Addresses

Reserved for future use (RFC 3300). 240.0.0.0 to 255.255.255.254

Binary to Decimal & Decimal to Binary Conversions

See handouts & pgs. 331-337

What does *preferred format* mean when referring to IPv6 addresses?

That it is written using all 32 hexadecimal digits. Essential for when you compress/apply IPv6 address shortcut/abbreviation rules later.

The most common global routing prefix

The */48* prefix

AND-ing

The comparison of 2 bits that produce the following: 1 AND 1 = 1 0 AND 1 = 0 0 AND 0 = 0 1 AND 0 = 0 |\| Anything with a 0 is equal to 0.

First Host Address

The first available host IP address in a network. The *host* portion *always* has *all 0's and ends with a 1*

Last Host Address

The last available host IP address in a network. The *host* portion *always* has *all 1's and ends with a 0*

Radix

The number base of a numbering system. Decimal's radix = 10 Binary = 2 Hexadecimal = 16

Purpose of a *loopback address*

Used by a host to direct traffic to itself. Often used to test if the TCP/IP configuration is operational.

Private IPv4 Addresses

Used by most orgs. to assign IPv4 addresses to *internal hosts*. They are *not unique*, *not allowed* on the Internet, and must |\| be filtered/discarded by Internet routers. Were introduced in the mid-1990's to address IPv4 address depletion.

CIDR

(*Classless Inter-Domain Routing*) - The standard created by the IETF in 1993 that *replaced Classful IPv4 Addressing* - Allows service providers to allocate IPv4 Addresses on any *prefix length/bit boundary* instead of only classes A, B, or C. - Still *only a temporary solution* to the exhaustion of IPv4 Addresses.

EUI-64 Process

(*Extended Unique Identifier*) Process reqd when RA message either SLAAC or SLAAC w/stateless DHCPv6 that use's a client's 48 bit Ethernet MAC address, and inserts another 16 bits in the middle of the 48 bit MAC address to create a 64 bit *Interface ID* (b/c the prefix is already known from RA message)

Some advantages of ICMPv6 over ICMP for IPv4

(*I*nternet *C*ontrol *M*essage *P*rotocol) - includes address resolution - ...& address auto-configuration

How many RIRs have run out of IPv4 addresses?

(*R*egional *I*nternet *R*egistries) - 4 out of 5 (AfriNIC's projected exhaustion date is in 2019)

Link-Local Address Range

(first 10 bits are 1111 1110 10xx xxxx) FE80::/10 (first hextet = 1111 1110 1000 0000 to FEBF::10 ("" = 1111 1110 1011 1111)

What an *octet* is to an IPv4 address, a (blank) is to an IPv6 address.

(unofficially) *hextet* = a segment of *16 bits* OR *4 hexadecimal values*

The actual process used to ID the network and host portions

*AND-ing*

Method ensuring the uniqueness of a randomly generated Interface ID

*DAD* (Duplicate Address Detection) - Similar to an ARP request for devices own address. If no reply, then address is unique.

Class E

*Experimental Address Block* 240.0.0.0 to 255.0.0.0

Which type of IPv6 addresses are currently being assigned to RIRs by the IANA?

*GUAs* with the *first 3 bits* of *001* |\|...

Class D

*Multicast Address Block* 224.0.0.0 to 239.0.0.0

stateless

*NO central server* allocating GUAs & keeping a list of devices and their addresses

Assigned Multicast addresses

*Reserved* multicast addresses for *predefined* groups of devices. A single address used to reach a group of devices running a common protocol or service.

RA & RS

*Router Advertisement & Router Solicitation* - ICMPv6 messages used in SLAAC for devices to obtain routing info. - RA is sent (every ~200 seconds) in response to a RS

The name of the bit that's flipped in the EUI-64 process

*U/L* (Universally/Locally) bit = 7th bit in OUI is *reversed* <-- reason why discussed in RFC 5342

Command to configure an IPv6 GUA & prefix length

*ipv6 address* {ipv6 address/prefix-length}

Command to configure a *link-local* address

*ipv6 address* {link-local-address} *link-local* Remember link-local 1st hextet range: *FE80 to FEBF*

Command to enable a router as an IPv6 router

*ipv6 unicast-routing* GLOBAL CONFIG. command

Command to display the MAC addresses of the Ethernet interfaces

*show interface*

Command to display abbreviated IPv6 interface configurations

*show ipv6 interface brief* Output Ex: up/up means the layer1/layer2 interface state

Command to display specific IPv6 interface addresses installed in the IPv6 routing table

*show ipv6 route* - *C* means the route is a *directly connected network* - *L* indicates a 'Local Route'/specific IPv6 address assigned to interface - NOT a Link-local address (b/c Link-locals NOT included router's routing table b/c they're NOT routable)

What are the private IPv4 address blocks?

- *10*.0.0.0 /8 or 10.0.0.0 to 10.255.255.255 - *172.16*.0.0 /12 or 172.16.0.0 to *172.31*.255.255 - *192.168*.0.0 /16 or "" to 192.168.255.255

The 2 ways that a device can obtain an IPv6 GUA automatically

1. *SLAAC* (*Stateless* Address Autoconfiguration) (SLAAC & SLAAC w/Stateless DHCPv6) 2. *Stateful* DHCPv6 NOTE: In either case, the local *router's link-local* address will auto. be the *default gateway* address

The 3 options for RA messages

1. *SLAAC* - "everything you need" 2. SLAAC w/*stateless DHCPv6* server - "some from IPv6 router & some from DHCPv6 server" 3. *Stateful DHCPv6* - "default gateway address from IPV6 router & everything else from DHCPv6 server"

What are the 3 basic binary operations used in digital logic?

1. AND-ing 2. OR 3. NOT

What are the 3 categories of IPv6 *migration techniques*?

1. Dual Stack 2. Tunneling 3. Translation

The 3 ways a host that is successfully connected to a network can communicate with other devices

1. Unicast 2. Broadcast 3. Multicast

The 3 types of IPv6 addresses

1. Unicast 2. Multicast 3. *Anycast* (like a phone-tree, Bunge) - any IPv6 unicast address that can be assigned to multiple devices. (*Beyond the scope of this course*) *No broadcast* - There's an all-nodes multicast IPv6 address that gives the same result though.

With IPv6, the default gateway can be either...

1. the *GUA* for the network interface of the same network 2. the *link-local* address for the network interface of the same network

IPv4 address range for *loopback addresses*

127.0.0.0 /8 or 127.0.0.1 to 127.255.255.254 *Any* address within this range will loop back to the local host.

Class B IPv4 Address Range

128.0.0.0 /16 to 191.255.0.0 /16

APIPA Address Range

169.254.0.0 /16 or 169.254.0.1 to 169.254.255.254

Class C IPv4 Address Range

192.0.0.0 /24 to 223.255.255.0 /24

TEST-Net IPv4 Address Range

192.0.2.0 /24 or 192.0.2.0 to 192.0.2.255

The IPv4 *multicast* address range reserved for the *local network* only

224.0.0.0 to 224.0.0.255

The IPv4 *multicast* address range

224.0.0.0 to 239.255.255.255

What is required to put an IPv6 address into *compressed format*? (Rule 2)

A double colon (*::*) can replace any *single, contiguous* string of one or more 16-bit segments (hextets) consisting of all 0's. That double colon can *only* be used once in an IPv6 address otherwise there'd be more than one possible resulting address.

Broadcast Address

A special address that communicates with all hosts in a network and is the *highest address in the network range*. The *host* portion is *all 1's*.

TEST-Net IPv4 Addresses

Addresses set aside for teaching & learning purposes & can be used in documentation & network examples.

Public IPv4 Addresses

Addresses that are *globally routed* between ISP routers // are able to be used on the internet.

Why can you *only* omit the *leading 0's* in a hextet of an IPv6 address? (Rule 1)

Because if you also omitted trailing 0's the address would be ambiguous. Ex: 'ABC' could be either '0ABC' or 'ABC0' which represent *2 different values*

RA Option 1: SLAAC only

Client device uses the info in the RA message to create is own GUA & all other information. Services of DHCPv6 server are NOT reqd.

Class A (IPv4 Addressing)

Designed to support *extremely large* networks. - More than *16 million* host addresses. - Uses fixed /8 prefix |\| *last 3 octets* for hosts - Most significant bit of *high-order octet* be a 0(zero) |\| *128* possible Class A Networks

Class B (IPv4 Addressing)

Designed to support *moderate to large* networks. - *~65,000* Host addresses - Uses fixed /16 prefix |\| last 2 octets for hosts - Most significant *2 bits* of the *high-order octet* must = (Bin.) 10xx xxxx |\| over *16,000* possible networks

Class C (IPv4 Addressing)

Designed to support *small* networks. - MAX of *254* Hosts - Uses fixed /24 prefix |\| *last octet* for hosts - Most significant 3 bits of *high-order octet* must = (Bin.) 110x xxxx |\| over *2 million* possible networks.

How & when does a client generate its own Interface ID?

Either the EUI-64 process or Randomly generated. If the RA is either option 1 (SLAAC) or 2 (SLAAC w/stateless DHCPv6)

Slash Notation

a '/' followed by the number of bits set to 1

Translation

aka *NAT64* - allows IPv6-enabled devices to communicate w/IPv4-enabled devices via translation technology (IPv4 to IPv6 & vice versa)

stateful

allocates & maintains a list of which device receives which IPv6 or IPv4 address.

Both IPv4 & IPv6 provide *(blank)* addressing for packets that carry data.

hierarchical

Easy way to ID that an IPv6 address was likely created using EUI-64

if *FFFE* is located in the middle of the Interface ID

How do hosts know which portion of the 32-bit IPv4 address is the network portion and which is host portion?

the *subnet mask*. Is a sequence of 1 bits followed by a sequence of 0 bits. The 1's ID the network portion & the 0's ID the host portion.

APIPA

(*Automatic Private IP Addressing*) Used by Windows DHCP client to self-configure when *no DHCP server available*. Only useful in a peer-to-peer connection.

The IPv4 multicast address used by RIPv2

(*Routing Information Protocol version 2*) 224.0.0.9

The general "chain of command" for both IPv4 & IPv6 management & allocation

- *IANA* (Internet Assigned Number Authority) - *RIR* (Regional Internet Registries) - *ARIN* (American Registry for Internet Numbers) - *RIPE* (Reseaux IP Europeans) - *APNIC* (Asia Pacific Network Information Centre) - *AfriNIC* (African Network Information Centre) - *LACNIC* (Regional Latin-American and Caribbean IP Address Registry) *** Orgs. *CAN* get their addresses directly from an RIR subject to the RIR's policies.

IPv4 Address Structure

- Consists of 32-bits - divided into 4 sections / *octets* - each section contains *8 bits / 1 byte* - Computers see *binary*, Humans see *dotted decimal notation*

IPv6 address space (in bits) and rough estimation of total number of addresses it can provide.

- IPv6 addresses are *128-bit addresses* written as a string of *hexadecimal values*. - Can provide *~340 Undecillion // 340 followed by 36 zero's Undecillion = 1 billion billion billion billions (Bunge)

ICMPv6 RA message includes..

- Network Prefix & Prefix Length - Default gateway address - DNS addresses & domain name

Issues with NAT

- breaks many applications - has limitations that impede P2P comms

The (blank blank) is the number of bits set to 1 in the subnet mask and it is written in (blank blank)

...*prefix length*.......*slash notation*(/CIDR Notation(?))

Bits within the *network portion* of an IPv4 address must be (blank). Bits within the *host portion* of an IPv4 address must be (blank).

...identical for all devices within the *same* network. ...unique to identify a specific host within the network.

The prefix length can range from....

0 to 128 bits - typically though it's 64

Class A IPv4 Address Range

0.0.0.0 /8 to 127.0.0.0 /8

The 2 types of IPv6 multicast addresses

1. *Assigned* multicast 2. *Solicited node* multicast

The 2 types of Broadcast Transmissions

1. *Directed Broadcast*: HOST portion of dest. address = *all 1's* / *255* (but not always 255, VLSM) - Can be a message sent to *all* hosts on a *remote* network 2. *Limited Broadcast*: dest. address = 255.255.255.255 / network & host portions are *all 1's*

The 2 most common types of IPv6 *unicast* addresses

1. *GUA* (Global Unicast Addresses) - globally unique & internet-routable 2. *Link-Local* Addresses - used to comm. w/other devices on same local *link*/subnet. Routers won't forward packets w/a link-local source or destination address. Typically the *link-local* address of a *router* is used as the *default gateway*.

The 3 parts of a GUA

1. *Global Routing Prefix* - network portion of address *assigned by the provider* (like an ISP) 2. *Subnet ID* - Used by orgs. to ID subnets 3. *Interface ID* - equivalent to *host portion of an IPv4* address

The 2 parts of a MAC address

1. *OUI* (Organizationally Unique Identifier*) - 24-bit/6 Hex digits vendor code assigned by IEEE 2. *Device Identifier* - unique identifier w/24-bit/6 hex digits

Theoretical maximum number of hosts for IPv4

4.3 Billion

Positional Notation

A digit represents different values depending on the position the digit occupies in the sequence of numbers.

Tunneling

A method of transporting an IPv6 packet over an IPv4 network. The IPv6 packet is encapsulated inside an IPv4 packet.

Dual Stack

Allows IPv4 & IPv6 to coexist on the same network segment.

The number of *binary bits* represented by a single *hexadecimal digit*

Every *4 bits* is represented by a single hexadecimal digit for a total of *32 hexadecimal* values in the 128-bit IPv6 address. 4 bits x 32 hex digits = 128 bits 4 hex digits = 16 bits

Unique Local Address range

FC00::/7 to FDFF::/7

The prefix for IPv6 multicast addresses

FF00::/8

Which org. is the operator for IANA and what do they do?

ICANN (Internet Committee for Assigned Names & Numbers) allocates IPv6 address blocks to the five RIRs.

RA Option 3: Stateful DHCPv6

Option most similar to DHCP for IPv4. RA requires the client obtain all info. from a DHCPv6 server *except* the default gateway address (which is ONLY obtained dynamically from the RA message)

Unique Local

Type of *unicast* address. Similar to RFC 1918 (Private Addresses). Used for local addressing w/in a site or b/t limited # of sites or for devices that will never need/have access from another network