User Manual for the NETGEAR PS121 Mini Print Server

Understanding IP Addresses

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The following table lists the additional subnet mask bits in dotted-decimal notation. To use the

table, write down the original class netmask and replace the 0 value octets with the dotted-decimal

value of the additional subnet bits. For example, to partition your Class C network with subnet

mask 255.255.255.0 into 16 subnets (4 bits), the new subnet mask becomes 255.255.255.240.

The following table displays several common netmask values in both the dotted-decimal and the

masklength formats.

Note:

The number 192.68.135.127 is not assigned because it is the broadcast address

of the first subnet. The number 192.68.135.128 is not assigned because it is the network

address of the second subnet.

Table 4-1.

Netmask Notation Translation Table for One Octet

Number of Bits

Dotted-Decimal Value

1

128

2

192

3

224

4

240

5

248

6

252

7

254

8

255

Table 4-2.

Netmask Formats

Dotted-Decimal

Masklength

255.0.0.0

/8

255.255.0.0

/16

255.255.255.0

/24

255.255.255.128

/25

255.255.255.192

/26

255.255.255.224

/27

255.255.255.240

/28

255.255.255.248

/29

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Understanding IP Addresses

NETGEAR strongly recommends that you configure all hosts on a LAN segment to use the same

netmask for the following reasons:

•

So that hosts recognize local IP broadcast packets.

When a device broadcasts to its segment neighbors, it uses a destination address of the local

network address with all ones for the host address. In order for this scheme to work, all devices

on the segment must agree on which bits comprise the host address.

•

So that a local router or bridge recognizes which addresses are local and which are remote.

Private IP Addresses

If your networks are isolated from the Internet (for example, only between your two branch

offices), you can assign any IP addresses to the hosts without problems. However, the IANA has

reserved the following three blocks of IP addresses specifically for private networks:

10.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255

NETGEAR recommends that you choose your private network number from this range.

NETGEAR products default to 192.168.0.xxx.

Regardless of your particular situation, do not create an arbitrary IP address; always follow the

guidelines explained here. For more information about address assignment, refer to RFC 1597,

Address Allocation for Private Internets,

and RFC 1466,

Guidelines for Management of IP

Address Space

. The Internet Engineering Task Force (IETF) publishes RFCs on its Web site at

www.ietf.org

.

255.255.255.252

/30

255.255.255.254

/31

255.255.255.255

/32

Table 4-2.

Netmask Formats

User Manual for the NETGEAR PS121 Mini Print Server

Understanding IP Addresses

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Address Resolution Protocol

An IP address alone cannot be used to deliver data from one device to another on a LAN. In order

for data to be sent from one device on the LAN to another, you must convert the IP address of the

destination device to its media access control (MAC) address. Each device on an Ethernet network

has a unique Ethernet MAC address, which is a 48-bit number assigned to each device by the

manufacturer. The technique that associates the IP address with a MAC address is known as

address resolution, and IP uses the Address Resolution Protocol (ARP) to do this.

If a device needs to send data to another station on the network and it does not already have the

destination MAC address recorded, ARP is used. An ARP request is broadcast onto the network,

and all stations receive and read the request. The destination IP address is included as part of the

message so that only the station with the correct IP address responds to the ARP request and all

other nodes discard it.

The node with the right IP address responds with its own MAC address directly to the sender,

providing the transmitting station with the destination MAC address needed for it to send the data.

The IP address data and MAC address data for each node are held in an ARP table, so that the next

time data needs to be sent, the address can be obtained from the address information in the table.

IP Configuration by DHCP

When an IP-based local area network is installed, each workstation must be configured with an IP

address. If the workstations need to access the Internet, they should also be configured with a

gateway address and one or more DNS server addresses. As an alternative to manual

configuration, there is a method by which each device on the network can obtain this configuration

information automatically. A device on the network may act as a Dynamic Host Configuration

Protocol (DHCP) server. The DHCP server stores a list or pool of IP addresses, along with other

information (such as gateway and DNS addresses) that it may assign to the other devices on the

network. The most of NETGEAR routers have the capacity to act as a DHCP server.

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Understanding IP Addresses

Glossary

1

Glossary

List of Glossary Terms

Use the list below to find definitions for technical terms used in this manual.

10BASE-T

IEEE 802.3 specification for 10 Mbps Ethernet over Category 3, 4, or 5 twisted pair wiring.

100BASE-Tx

IEEE 802.3 specification for 100 Mbps Fast Ethernet over Category 5 twisted pair wiring.

1000BASE-T

IEEE 802.3 specification for 1000 Mbps Gigabit Ethernet over Category 5 twisted pair wiring.

802.1Q

IEEE specification for the operation of Virtual LAN (VLAN) Bridges that permit the definition, operation

and administration of Virtual LAN topologies within a Bridged LAN infrastructure.

802.3

The IEEE standard defining the hardware layer and transport layer of (a varient of) Ethernet. The maximum

segment length is 500m and the maximum total length is 2.5km. The maximum number of hosts is 1024.

The maximum packet size is 1518 bytes.

802.3ab

Gigabit ethernet over Copper (also known as 1000BaseT) is an extension of the existing Fast Ethernet

standard. It specifies Gigabit Ethernet operation over the Category 5e/6 cabling systems already installed,

making it a highly cost effective solution.

802.3u

The IEEE committee working on standards for Fast Ethernet.

ADSL

Short for asymmetric digital subscriber line, a technology that allows data to be sent over existing copper

telephone lines at data rates of from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and

from 16 to 640 Kbps when sending data (known as the upstream rate).