User Manual

Basic Remote Networking IP Routing
4-7
Local routes The network that is directly attached. This route is automatically determined
from the SCS IP address and network mask, and is never deleted.
Static routes Routes that were manually entered in the routing table by a system
administrator. These routes are used when the dynamic routes cannot be.
Dynamic routes Routes learned through the receipt of RIP (Routing Information Protocol)
packets. RIP is discussed in more detail on page 4-8.
Each routing entry can point to another router on the Ethernet or to a site configured for LAN to LAN
connections.
4.4.1 Routes for Outgoing LAN to LAN
Generally, the SCS has static routes configured for each remote LAN that it will connect to. These routes
point to sites that are configured for outgoing LAN to LAN connections. The first time that the SCS needs
to send a packet destined for a network on a remote LAN, the site will be activated and the SCS will attempt
to call the remote router. Once the connection has been formed, subsequent packets for the remote LAN will
be forwarded over that link.
While the SCS is connected to the remote router, it may learn additional dynamic routes from that remote
router. Once these additional routes are entered into the routing table, packets may be routed to these new
networks as well. Once the connection is dropped, the SCS can be configured to maintain these routes.
Subsequent traffic to these dynamically learned networks or to the pre-existing static route networks will
cause the site to form a new connection.
If the SCS is a stub router (or you’re using the SCS to connect to the Internet), default routes can be used
to reduce configuration time. A stub router connects a LAN without any routers to a larger LAN. For
example, in a remote office with no other outside connections, an SCS that connects to exactly one other
(larger) location is a stub router. All traffic generated on the remote office’s LAN that is destined for the
remote location must pass through the SCS. A default route pointing to the larger site may be entered on the
SCS.
Note: Default routes should be used with caution. See Chapter 6, IP for complete
details.
4.4.2 Routes for Incoming LAN to LAN
If RIP (Routing Information Protocol) is being used, no static routing entries need to be configured on the
SCS. Routes to networks on the remote LAN will be learned automatically. For more information on RIP,
see Configuring RIP for Sites on page 4-8.
Note: RIP is enabled by default.
If RIP is not being used, the SCS must have a specific site configured for this incoming connection. The
remote router must use this site when it connects to the SCS. The site may be started in one of two ways:
through the authentication sequence (which requires that authentication be appropriately configured), or
with the Set PPP sitename command. Static routes pointing to the site must be configured for each of the
incoming caller’s IP networks.