This section describes how to use and configure multiple logical networks on your bridge/router.

Concepts of Multiple Logical Networks

On the NETBuilder II bridge/router, the multiple logical network (MLN) feature allows you to:

• Group together multiple ports on a single bridge/router, and the LAN segments attached to them, to form a logical network. NETBuilder software can use groups in its network topology in the same way it uses virtual ports.

• Bridge network protocols, such as IP, among ports within a group.

• Route network protocols outside the group to other ports, virtual ports, or logical networks.

• Configure different MLN configurations for different protocols.

• Maintain configurations for protocols not configured for MLN, so that they bridge and route as usual, independent of the port groupings for other protocols.

Unlike conventional bridge/router operation, MLN provides simultaneous bridging and routing for the same network protocol. MLN enables you to integrate a number of bridged networks by routing from the bridged environments (configured as logical networks) across a LAN or WAN backbone. It also allows you to assign the same network number or subnet number to multiple physical paths. You can think of the logical network as a group of LAN segments that have been joined together to form a single network-level addressing domain.

When a conventional bridge/router is configured to bridge a particular protocol, all traffic for that protocol is bridged, and the router component is inactive, as shown in Figure 11. When it is configured to route that protocol, correctly addressed traffic for the protocol is routed, and the bridge component is inactive, as shown in Figure 12.

Bridging can occur even when the bridge/router is configured as a router. If a bridge/router receives packets of a protocol type that has not been configured on it, the bridge/router bridges the packets. If the -BRidge CONtrol parameter has been set to NoFireWall, incorrectly addressed routed packets are also bridged. The bridge/router can also be configured to bridge some protocols and route others. However, a conventional bridge/router without MLN cannot selectively bridge or route the same protocol, depending on destination.

Figure 11 Bridge/Router in Bridging Mode

Figure 12 Bridge/Router in Routing Mode

Figure 13 is an example of the simultaneous bridging and routing capability provided by MLN. Six networks are attached to a NETBuilder bridge/router. Each of the six networks has IP nodes, IPX nodes, and AppleTalk nodes. Ports 1, 2, and 3, and the LANs attached to them, have been grouped together into one logical network or port group, called V1. The logical interface between Enterprise OS software and this group is called a group port, and it is also identified as V1. The IP protocol has been configured on group port V1 (that is, V1 has been given an IP address). This IP address also applies to all ports in the group.

Group ports are numbered as if they were virtual ports.

Ports 5 and 6, and the LANs attached to them, have been grouped into another logical network, V2. IP has also been configured on this group. IP has been configured individually on port 4, which has not been assigned to a group (that is, port 4 has been given an IP address).

Port groups have not been defined for IPX and AppleTalk. The bridge/router has been configured to route IPX. It has not been configured to route AppleTalk.

Figure 13 Multiple Logical Networks

Figure 14 shows how IP traffic is handled in this configuration. IP is bridged among ports 1, 2, and 3 (as indicated in the figure by the MLN bridge, which is not a physical bridge but an internal software function). IP traffic is also bridged between ports 5 and 6. IP is routed between group V1 and all ports outside the group, including port 4 and group port V2. IP is also routed between group V2 and all ports outside the group, including port 4 and group port V1.

Figure 14 IP Configuration Under MLN

Figure 15 shows how the network looks to IPX. IPX traffic is routed among all ports, independent of the port groups defined for IP.

Figure 15 IPX Configuration Under MLN

AppleTalk routing is not enabled, so AppleTalk traffic is bridged among all six ports, as shown in Figure 16.

Figure 16 AppleTalk Configuration Under MLN

Only network protocols that configure a port group are affected by MLN. A protocol that does not participate in MLN can continue to configure its network topology at the port and virtual port level, including ports that belong to a port group for some other protocol. Bridged protocols such as NetBIOS and Logical Link Control, type 2 (LLC2) are also not affected by MLN.

MLN does not bridge between port groups, between a port group and a port, or between a port group and a virtual port. All of this type traffic is routed.

Software version 8.3 and later supports MLN for IP routing and transparent bridging over Ethernet. To configure logical networks, see the next section.

Configuring Multiple Logical Networks

This section describes how to set up MLNs by creating port groups and assigning ports to them. In software version 8.2 through version 9.1, you can create port groups only for Ethernet ports. Because version 8.2 through 9.1 supports MLN only for the IP protocol, create port groups only for ports over which you intend to route IP.

To create port groups, follow these steps:

1 .   To assign ports to a port group, use:

ADD !<port> -PORT LogicalNET ETHernet <port> [,] ["<string>"] (1-50 characters]

where the first <port> is the group port that interfaces to the logical network. This port is always numbered as if it were a virtual port (Vn). The ports that follow the ETHernet parameter are assigned to the port group. These ports are called member ports, they cannot be virtual ports.

The last argument, "<string>", which must be enclosed in quotation marks, is an optional descriptive name for the group port. It is displayed by entering the SHow -PORT LogicalNET CONFiguration command.

For example, to add ports 1 and 2 to port group V1 enter:

ADD !V1 -PORT LogicalNET ETHernet 1,2 "Test Network B200 4th floor"

If port group V1 does not already exist, it is created and ports 1 and 2 are added to it. V1 also identifies the group port that references the group.

To add ports 3 and 4 to port group V2, enter:

ADD !V2 -PORT LogicalNET ETHernet 3,4

Port groups cannot overlap, that is, the same port cannot be configured as part of two different port groups.

2 .   If necessary, enable the group port.

Group ports are enabled by default. If group port V2 has been disabled, re-enable it by entering:

SETDefault !V2 -PORT CONTrol = Enabled

3 .   Assign a name to the group port (optional).

For example, to assign group port V2 the name "Bayfront," enter:

SETDefault !V2 -PORT NAme = "Bayfront"

Some restrictions apply to the name you assign. For more information, see the -PORT NAme parameter in Reference for Enterprise OS Software.

4 .   Repeat steps 1 through 3 for each group port you configure.

This completes the configuration of group ports. The new settings take effect immediately.

In addition to the CONTrol, NAme, and LogicalNET parameters, you can use the -PORT CONFiguration parameter on group ports. To configure other port characteristics, configure them on member ports rather than the group port.

When you configure a logical network, you must enable global bridging and per-port transparent bridging on all member ports.

When a network routing protocol configures the group port in its network topology, it configures attributes for the entire port group.