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Glossary
160 Glossary User’s Manual
MIB
Management Information Base is a database in the shape of a tree of objects. Each
object is in fact a parameter which has specific settings or grouping of other
subheadings. For instance under an object heading of ethernet interface may be
information for the IP address of that interface, the netmask, or if DHCP is on or
off.
The MIB in your router is where you will be making changes to the way your
router works. You can enter your changes with the Configurator software or with
line commands via a telnet connection directly to your router.
Modem
The acronym fro modulator-demodulator device that converts digital data from
your computer to analog data that can be transmitted over your telephone line.
This analog data is in turn converted back into digital data at the other end of the
phone line.
MTU
The maximum transmission unit (MTU) is the largest size packet (or frame) that
can be sent through a connected network. Ethernet networks can use up to 1500
MTU while interfaces configured to use PPPoE can have a maximum MTU of
1492.
NAT
Network Address Translation is done on a device resting between 2 or more
networks (for instance between the WAN and the LAN). IP packets arriving or
leaving can have their source or destination changed to a different IP address.
For example, incoming NAT allows you to store a publicly registered IP
addresses at the router and link it (or them) to other IP addresses in the LAN.
Outgoing NAT changes the source address of packets leaving the device (from
the LAN to the Internet) so that the responses to the packets can find there way
back. This allows more than one computer to share a single IP address on the
Internet.
The added benefit of NAT is that it keeps a list of who asked for what information
to the Internet and when data is trying to enter your own network it is compared
against the list to be sure that someone has asked for it. If no one has the data is
rejected and a report is sent to the Syslog server.
See RFC1631