HP LaserJet 3052 HP LaserJet 3050/3052/3055/3390/3392 All-in-One User Guide - Page 204

Subnets, Subnet mask, Gateways, Default gateway

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Subnets When an IP network address for a particular network class is assigned to an organization, no provision is made for more than one network being present at that location. Local network administrators use subnets to partition a network into several different subnetworks. Splitting a network into subnets can result in better performance and improved use of limited network address space. Subnet mask The subnet mask is a mechanism used to divide a single IP network into several different subnetworks. For a given network class, a portion of an IP address that would normally be used to identify a node is used, instead, to identify a subnetwork. A subnet mask is applied to each IP address to specify the portion used for subnetworks, and the portion used to identify the node. For example, see Table 9-9 Example: Subnet mask 255.255.0.0 applied to class A network. Table 9-9 Example: Subnet mask 255.255.0.0 applied to class A network Class A Network Address Network 15 Subnet Mask 255 IP Address fields with Subnet Mask applied Network Example of a node's IP Address 15 on Subnet 1 Example of a node's IP Address 15 on Subnet 254 xxx 255 Subnet 1 254 xxx 0 Host 25 64 xxx 0 Host 7 2 As illustrated in Table 9-9 Example: Subnet mask 255.255.0.0 applied to class A network, the Class A IP network address "15" has been assigned to company ABC. To allow additional networks at company ABC's site, the subnet mask of 255.255.0.0 is used. This subnet mask specifies that the second byte of the IP address will be used to identify up to 254 subnets. Using this designation, each device is uniquely identified on its own subnet, but company ABC can incorporate up to 254 subnetworks without violating their assigned address space. Gateways Gateways (routers) are used to connect networks together. Gateways are devices that act as translators between systems that do not use the same communication protocols, data formatting, structures, languages, or architectures. Gateways repackage the data packets and change the syntax to match that of the destination system. When networks are divided into subnets, gateways are required to connect one subnet to another. Default gateway The default gateway is the gateway or router that, if not specified, will be used to move packets between networks. It is specified by an IP address. If multiple gateways or routers exist, then the default gateway is typically the address of the first, or nearest, gateway or router. If no gateways or routers exist, then the default gateway will typically assume the IP address of the network node (such as the workstation or all-in-one). 186 Chapter 9 Networking ENWW

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Subnets
When an IP network address for a particular network class is assigned to an organization, no
provision is made for more than one network being present at that location. Local network
administrators use subnets to partition a network into several different subnetworks. Splitting a
network into subnets can result in better performance and improved use of limited network address
space.
Subnet mask
The subnet mask is a mechanism used to divide a single IP network into several different
subnetworks. For a given network class, a portion of an IP address that would normally be used to
identify a node is used, instead, to identify a subnetwork. A subnet mask is applied to each IP
address to specify the portion used for subnetworks, and the portion used to identify the node. For
example, see
Table
9-9
Example:
Subnet
mask
255.255.0.0
applied
to
class
A
network
.
Table 9-9
Example: Subnet mask 255.255.0.0 applied to class A network
Class A Network Address
Network 15
xxx
xxx
xxx
Subnet Mask
255
255
0
0
IP Address fields with Subnet
Mask applied
Network
Subnet
Host
Host
Example of a node’s IP Address
on Subnet 1
15
1
25
7
Example of a node’s IP Address
on Subnet 254
15
254
64
2
As illustrated in
Table
9-9
Example:
Subnet
mask
255.255.0.0
applied
to
class
A
network
, the Class
A IP network address “15” has been assigned to company ABC. To allow additional networks at
company ABC’s site, the subnet mask of 255.255.0.0 is used. This subnet mask specifies that the
second byte of the IP address will be used to identify up to 254 subnets. Using this designation, each
device is uniquely identified on its own subnet, but company ABC can incorporate up to 254
subnetworks without violating their assigned address space.
Gateways
Gateways (routers) are used to connect networks together. Gateways are devices that act as
translators between systems that do not use the same communication protocols, data formatting,
structures, languages, or architectures. Gateways repackage the data packets and change the
syntax to match that of the destination system. When networks are divided into subnets, gateways
are required to connect one subnet to another.
Default gateway
The default gateway is the gateway or router that, if not specified, will be used to move packets
between networks. It is specified by an IP address.
If multiple gateways or routers exist, then the default gateway is typically the address of the first, or
nearest, gateway or router. If no gateways or routers exist, then the default gateway will typically
assume the IP address of the network node (such as the workstation or all-in-one).
186
Chapter 9
Networking
ENWW