Reliant Octel 200 and Octel 300 Message Servers PB6001401 Bedienungsanleitung PDF herunterladen (Seite 531)

100

101

Internet

Addressing 1

1A-3

Octel Overture 200/300 Serenade 3.0

PB60014–01

all 0s

* Allowed only at system startup and is never a valid destination address.

** Never a valid source address.

*** Should never appear on a network.

This host*

all 0s host

Host on this net*

ident.

class

all 1s Limited broadcast (local net)**

net all 1s

Directed broadcast for net**

127 anything (often 1)

Loopback***

Note: The length of the net portion depends on its class.

Special

Forms of IP Addresses

Subnet

Addressing

The

netid portion of an IP address is assigned to an organization by a central agency called IANA.



The

individual or

ganization is free to divide its hostid portion into multiple smaller physical networks called

subnets.

Suppose a site has a class B address. It has 16 bits of the address to use for its local portion. Suppose

there are eight physical networks at the site. For purposes of addressing ef

ficiency

, the or

ganization could

take the top 3 bits from its local portion and assign one value to each of its eight physical networks. This

particular combination gives eight physical networks (subnets) with up to 8,192 hosts per subnetwork.

Another site may choose to assign 8 bits to the subnet, giving 256 subnets each with up to 256 hosts.

Refer to the following figure.

o allow maximum autonomy

, the TCP/IP subnet standard allows the subnet partition to be selected on a

per

-network basis. Once a partition has been selected for a particular network, machines attached to that

network are expected to use it.

The subnet mask is usually given to you by your LAN administrator along with your system’

s IP address.

If your network doesn’

t use a subnetting scheme, you should still set up the subnet mask to cover your

network portion. Refer to Example 3 in this chapter



For information on how to get your own assigned IP address, contact Joyce K. Reynolds, (213) 882-151

1 JKREY @

ISI.EDU Internet Assigned Numbers. Authority

, USC-Information Sciences Institute, 4676 Admiralty W

, Marina

del Rey

, California 90292-6695.

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Reliant Octel 200 and Octel 300 Message Servers PB6001401 Bedienungsanleitung Seite 531

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