Internet Protocol Addressing; Network Address To Name Translation; Network Address To Hardware Address Translation - Bay Networks 5390 Administering

Network Protocols

Internet Protocol Addressing

The Model 5390 server is a host on the Internet. For the network layer (IP) to route packets to the
Model 5390 server, it requires a unique Internet address. Typically, an Internet address is a 32-bit
address divided into four 8-bit fields, with each field separated by periods, and specified as a decimal
number (from 0 to 255), a hexadecimal number, or a combination of both. All entries in the next
example specify the same address in decimal dot notation: 192.9.200.100, 0xC0.0x9.0xC8.0x64,
and 192.9.200.0x64.

Network Address to Name Translation

The Model 5390 server supports the use of host names, which permits users to enter a symbolic
name rather than the Internet address when requesting a connection to, or information about, a
specific host. The Model 5390 server can translate a host name to an Internet address. The Model
5390 server provides this translation using a host table. The host table maintains host names and
Internet addresses for known hosts on the network. These names and addresses are provided by
name servers. A name server is a host on the network that supplies Internet addresses for host names
and names for addresses.
The Model 5390 server supports two widely-used name servers: IEN-116 and Domain Name System
(DNS). You can implement one or both of these name servers for the Model 5390 server.
The Model 5390 server also monitors RWHO broadcasts. The Model 5390 server stores information
in the host table from these broadcasts. RWHO is a BSD protocol for passing host information
around the network.

Network Address to Hardware Address Translation

To transmit an IP packet on the local area network, the Model 5390 server maps an Internet address
to a hardware address, using the Address Resolution Protocol (ARP). This protocol dynamically
maps between these addresses. As mappings are acquired, they are stored in an ARP table. The
information in this table can be displayed and modified.
When the Model 5390 server has data to send to an Internet address, and it does not have a hardware
address in its ARP table for that Internet address, it broadcasts an ARP request for a hardware address
for the Internet address associated with the data to be sent. If a response to the ARP request is
received, the new mapping is stored in the ARP table and the data is sent to the appropriate
destination.
893-741-B C5-3