Filter
Top Products
System Mode Encapsulation
88 Megabit Modem 400F, 500L, 600F, and 700F User Manual
NAPT does not have the limitation of using only the IP address in the translation. It also uses
TCP/UDP ports. It is a method that allows multiple IP addresses and their TCP/UDP ports to be
translated into one IP address and its ports. A good candidate for NAPT is a small office with
multiple hosts but one public IP address. In this case, NAPT allows the entire office to use the
public IP address to communicate out of the private network.
An example of NAPT in this small office envionment is the RealPlayer™ application. The
RealPlayer (client at the office) initiates a TCP connection to the RealServer™ on the Internet,
which then initiates a UDP connection back to RealPlayer. RealPlayer can then tell the server
to use a specific UDP port for the UDP connection. The user should set up a static NAT entry
for the UDP connection for RealPlayer to work properly through NAPT.
Bridging
You can configure the Megabit Modem 400F and 700F as a bridge to forward Ethernet data
based on MAC addresses.
MAC Layer Bridging
A bridge moves information across a network from a source to a destination at the data link layer
(of an OSI reference model). The information is sent to a physical address known as a Media
Access Control (MAC) address. The Megabit Modem 400F and 700F provide transparent
Ethernet MAC-layer bridging.
The bridge learns up to 1024 addresses. Additionally, when you configure the modem, you can
add 32 static addresses through the static MAC address configuration page.
Spanning Tree Protocol
The Megabit Modem 400F and 700F support 802.1d Spanning Tree protocol which eliminates
loops in a LAN topology by partitioning out redundant links between LAN segments. This
ensures that there is only one path, or link, between any two nodes on the network. If this link
goes down, Spanning Tree re-enables partitioned links to create a new loop-free topology if
possible.
An example of the active topology is shown on page 89. In the example, the spanning tree
algorithm partitions out the bridge from LAN A to LAN B, and creates the link from ENET2
to Bridge 5.