Welcome to TCP/IP Part 7

IP ADDRESSING

An IP Address is a numeric identifier assigned to each machine, or host, on an IP network.  It also happens that each IP Address is software and not a hardware address; the hardware based addresses, which are hard coded on the network interface card (NIC) and is the media access control address (or MAC Address) and is a Data Link Layer hardware address that every port or device needs in order to connect to a LAN segment.  Our primary purpose of this section is the IP Address.  IP Addresses were designed to allow hosts on one network to communicate with a host on another network.

IP Terminology

It is rather rudimentary, but you know the drill as repetition of the basics is the mother of skill. 

Bit is one digit, either a one (1) or zero (0).

Byte is 7 or 8 bits, dependent upon use of parity; always assume an 8 bit byte.

Octet is made up of 8 bits, is an ordinary 8 bit number and is interchangeable with byte for the purposes of this information.

Network address is the designation used in network routing to send packets to another network – for example 10.1.1.0, 172.16.20.200, and 192.168.1.100.

Broadcast address is the address used by applications and hosts to send information to all nodes and devices on the network – for example 10.255.255.255, 172.16.255.255, or 192.168.1.255.

IP ADDRESSING SCHEME

IP Addressing consists of 32 bits of information, which are segmented into 4 separate sections referred to as octets or bytes.  The address can be depicted in one of the following ways:

  • Dotted decimal, or 10.8.30.56
  • Binary, or 00001010.00000100.00011110.00111000
  • Hexadecimal, or 0A.08.1C.38

The 32-bit address is a structured, or hierarchical, address and is used for a specific purpose that permits larger numerical values, its maximum allotment being 4.3 billion.  Here is a handy little tool as you will be expected to determine the powers of two, check out the POWERS OF 2 TABLE – this will aid you as you learn, or relearn the multiples of two.  Also, it will be a help to some degree as you start learning the newer format IPv6; the reason being IPv4 has run out of blocks of numbers during of 2011, but we will get into IPv6 at a later time.

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Network Addressing

The network address, also referred to as the network number, uniquely identifies each network.  Every device, node, host, or machine shares part of the IP Address assigned to it. (i.e., 192.168.1.100 is the IP Address assigned by DHCP; however, as it is /24 and a Class C IP Address its network address would be 192.168.1.0. A Class B, a /16 mask, address would go like this 172.31.1.100 as the IP Address and the network address would be 172.31.0.0.  And Class A address would be, since it has a /8 mask, 10.35.172.242 as the IP Address with a network address of 10.0.0.0.)

Private Address Space

 
The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets:
 
     10.0.0.0        -   10.255.255.255  (10/8 prefix)
     172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
     192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

Reserved IPv4 addresses

CIDR

IP Range

Number of Unique Addresses

Routed on the public internet

Purpose

0.0.0.0/8

0.0.0.0 –
0.255.255.255

16777216

No

Used for broadcast messages to the current (“this”) network as specified by RFC 1700, page 4.

10.0.0.0/8

10.0.0.0 –
10.255.255.255

16777216

No

Used for local communications within a private network as specified by RFC 1918.

100.64.0.0/10

100.64.0.0 –
100.127.255.255

4194304

No

Used for communications between a Service Provider and its subscribers when using a Carrier-grade NAT, as specified by RFC 6598.

127.0.0.0/8

127.0.0.0 –
127.255.255.255

16777216

No

Used for loopback addresses to the local host, as specified by RFC 5735.

169.254.0.0/16

169.254.0.0 –
169.254.255.255

65536

No

Used for autoconfiguration between two hosts on a single link when no IP address is otherwise specified, such as would have normally been retrieved from a DHCP server, as specified by RFC 5735.

172.16.0.0/12

172.16.0.0 –
172.31.255.255

1048576

No

Used for local communications within a private network as specified by RFC 1918

192.0.0.0/29

192.0.0.0 –
192.0.0.7

8

No

Used for the DS-Lite transition mechanism as specified by RFC 6333

192.0.2.0/24

192.0.2.0 –
192.0.2.255

256

No

Assigned as “TEST-NET” in RFC 5737 for use solely in documentation and example source code and should not be used publicly.

192.88.99.0/24

192.88.99.0 –
192.88.99.255

256

Yes

Used by 6to4 anycast relays as specified by RFC 3068.

192.168.0.0/16

192.168.0.0 –
192.168.255.255

65536

No

Used for local communications within a private network as specified by RFC 1918.

198.18.0.0/15

198.18.0.0 –
198.19.255.255

131072

No

Used for testing of inter-network communications between two separate subnets as specified in RFC 2544.

198.51.100.0/24

198.51.100.0 –
198.51.100.255

256

No

Assigned as “TEST-NET-2” in RFC 5737 for use solely in documentation and example source code and should not be used publicly.

203.0.113.0/24

203.0.113.0 –
203.0.113.255

256

No

Assigned as “TEST-NET-3” in RFC 5737 for use solely in documentation and example source code and should not be used publicly.

224.0.0.0/4

224.0.0.0 –
239.255.255.255

268435456

Yes

Reserved for multicast assignments as specified in RFC 5771

240.0.0.0/4

240.0.0.0 –
255.255.255.254

268435455

 

Reserved for future use, as specified by RFC 5735.

255.255.255.255/32

255.255.255.255

1

No

Reserved for the “limited broadcast” destination address, as specified by RFC 5735.

 

See also:  Part 1, Part 2, Part 3, Part 4, Part 5, Part 6

Works Cited

Cisco Systems, Inc. (2008, January 28). Document ID: 13718. Retrieved January 08, 2013, from Cisco: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094adb.shtml

Karenberg, D., Groot, G. d., & Lear, E. (1996, February). RFC1918 Address Allocation for Private Internets. Retrieved January 19, 2013, from IETF Tools: https://tools.ietf.org/html/rfc1918

Lammle, T. (2007). CCNA Cisco Certified Network Associate Study Guide. Indianapolis: Wiley Publishing, Inc.

Odom, W. (2012). Official Cert Guide ICND1 640-822. Indianapolis, IN: Cisco Press.

Odom, W. (2011). Official Cert Guide ICND2 640-816. Indianapolis, IN: Cisco Press.

 

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Welcome to TCP/IP Part 6

To further our use and understanding of our introduction of TCP/IP, we will continue on with some necessary protocols.  More importantly, Address Resolution Protocols.

Address Resolution Protocol (ARP) is the protocol which is used to find the address host from a known IP address.  ARP sends out a broadcast to the network asking for the machine with the specific IP address.  In essence, ARP translates the IP address into a hardware address.

ARP

Reverse Address Resolution Protocol (RARP) is the protocol used to discover the identity of the IP address for diskless machines and essentially requests for the IP address of itself through other equipment by sending out its MAC address.  Recall that DHCP is the protocol used to determine who is assigned what IP address (Welcome to TCP/IP Part 2).  On a side note, most home networks set their routers up to assign the IP addresses to their equipment throughout their home.

RARP

Proxy Address Resolution Protocol (PARP) is the protocol used to help machines on a subnet reach remote subnets without configuring routing or a default gateway.  The detriment to using Proxy ARP is that it will severely increase the traffic on your network.  And you thought a slow network was bad?  Most medium to large businesses can handle the traffic, home networks not so easily.  It is configured on all Cisco routers by default.

PrARP

This is what would be shown in the ARP cache memory of Host A.

IP Address

MAC Address

172.16.20.200 00-00-0c-94-36-ab
172.16.20.100 00-00-0c-94-36-ab
172.16.10.99 00-00-0c-94-36-ab
172.16.10.200 00-00-0c-94-36-bb

Next week, we will discuss IP Addressing, until then…

See also:  Part 1, Part 2, Part 3, Part 4, Part 5

Works Cited

Cisco Systems, Inc. (2008, January 28). Document ID: 13718. Retrieved January 08, 2013, from Cisco: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094adb.shtml

Lammle, T. (2007). CCNA Cisco Certified Network Associate Study Guide. Indianapolis: Wiley Publishing, Inc.

Odom, W. (2012). Official Cert Guide ICND1 640-822. Indianapolis, IN: Cisco Press.

Odom, W. (2011). Official Cert Guide ICND2 640-816. Indianapolis, IN: Cisco Press.

Goals for 2013

goals

It is my intention to become more focused upon the task at hand, to attain a CCNA certification.  This means most of my other posts will slip to the side until this is accomplished.  If there is no value within the certification process for CCNA, I will not post it until I have completed this process.

Thank you for following my blog, I truly appreciate your support!  It is my hope to attain this goal by June of this new year.

MK Murphy

goals_target