Comtech EF Data SLM-5650A Vipersat Parameter Editor - Manual (Page 45)

Chapter 2 - Using Parameter Editor 2-29
Routing
Routing
Routing in a Vipersat Network
SLM-5650A Modem Routers operating in Vipersat mode do not use the Multi-
point, Point to Point, or Bridge network modes described in the SLM-5650A
Installation and Operation Manual. There is no HDLC address in a Vipersat
network; instead, the SLM-5650A role designation — Hub or Remote, Expan-
sion unit or not — determines routing rules that prevent multicast loops. This
simplifies the configuration of a Vipersat network.
Because satellite networks are often used as extensions for access to services
such as the Internet or the PSTN, they lend themselves quite readily to private
addressing. For example, to provide Internet access to the satellite network, only
the Hub requires a public IP address in order for the entire satellite network that
is controlled by the Hub to have access to the Internet backbone. Utilizing
Network Address Translation (NAT), the administrator can effectively address
the network using a minimum number of static route statements.
Example:
The IP address 172.16.0.0 is the private address network number for class B
networks. If there is a router at the Hub with a connection to the Internet, the
operator can define the local network as a class B. If the operator splits the
Class B in half and points the upper half toward the satellite there will be
over 16,000 usable addresses at the Hub as well as at the Remotes.
By putting the one route statement “Remotes 172.16.128.0/17 WAN to
LAN” in the TDM Hub modem, and by using the route statement “GW
0.0.0.0/0 LAN to WAN” at each of the Remote modems, the network will
successfully route packets. The Remotes can then be subnetted as class C
networks or below. Additional routers at the Remotes can be added for
unusually large sites, allowing an additional layer of NAT without requiring
any more explicit routing within the Vipersat Modem Routers.
Refer to the SLM-5650A Installation and Operation Manual for additional
information on entering routes.
Creating the Static Routes
The following procedure outlines the basic route structure that the target
SLM-5650A will require for its role in the network. One of the key routes that
must be created is a default gateway address for routing the data traffic that is
received by the unit.