3Com NETBuilder SI, SuperStack II Topologies that Require Virtual Ports, Node That Virtual Ports

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Multiple Static Paths If you assign multiple paths to a port, the port must be running PPP. per Port

To use both B channels together on a built-in ISDN connector, to reserve a path for disaster recovery, or to use another path for dial-on-demand, failover, or bandwidth-on-demand, you can assign both paths to one port and use Multilink PPP using:

ADD !<port> -PORT PAths <path> [,<path>...]

You may want to use static ports instead of a dial pool if you are only dialing one destination and do not need the versatility of a dial pool.

See “Configuring Bandwidth Management for PPP” on page 89 for more information about bandwidth management features such as dial-on-demand.

Virtual Ports To configure multiple ports over one path, you create virtual ports. A virtual port can be assigned to a static path, or for PPP, it can be assigned to the SysCallerID of a remote site. SysCallerID virtual ports use paths in a dial pool and are not associated to any one path.

A virtual port functions the same way as a nonvirtual port does, that is, as a logical interface that represents a connection to a network.

For example, if a SuperStack II bridge/router central node needs to connect to two separate boundary routers over the same ISDN port at different times, you can create a virtual port for each boundary router. The virtual ports would have all the connection information for each boundary router.

Table 12 provides information on topologies that require virtual ports and the node on which the virtual ports should be created.

Table 12 Topologies that Require Virtual Ports

		Node That Virtual Ports
Topology	Virtual Ports Required?	Should Be Created On
Boundary Routing over Frame Relay or X.25	Yes.	Central node

Traditional routed environment: partially meshed or nonmeshed Frame Relay and X.25 topologies

Depends on bridging or routing Any router protocol. See “Virtual Ports over

Frame Relay and X.25” for more information.

Multidestination dialing (modem pooling) over PPP	Yes, for dynamic dial-up lines.	Central node
Frame Relay topology with disaster recovery	Yes.	Nodes on both ends of serial
configured		line running Frame Relay