This section describes how to configure the bridge/router for both ends of an SNA connection using the DLSw protocol.

Prerequisites

Before beginning this procedure, complete the following tasks:

• Log on to the system with Network Manager privilege.

• Set up the ports and paths of your bridge/router according to the Configuring Basic Ports and Paths chapter and the Configuring Advanced Ports and Paths chapter.

• Configure the token ring LAN as described in the Configuring Source Route Bridging chapter.

• Configure the IP addressing and IP routing protocols on the appropriate ports according to the Configuring IP Routing chapter.

• Obtain the IP addresses for bridge/routers on each side of the TCP/IP connection.

Figure 234 shows a sample data link switching configuration for an SNA environment.

Figure 234 Configuring Data Link Switching for SNA

Table 68 lists the commands used to configure the example in Figure 234.

Table 68 Commands to Configure Data Link Switching for SNA

Commands Entered on Bridge/Router A	Commands Entered on Bridge/Router B
SETDefault -TCP CONTrol = KeepALive	SETDefault -TCP CONTrol = KeepALive
SETDefault -TCP KeepALive = 3	SETDefault -TCP KeepALive = 3
SETDefault !1 -LLC2 CONTrol = Enable	SETDefault !2 -LLC2 CONTrol = Enable
SETDefault !1 -SR RouteDiscovery = LLC2	SETDefault !2 -SR RouteDiscovery = LLC2
SETDefault -LLC2 TUNnelVRing = 100	SETDefault -LLC2 TUNnelVRing = 100
SETDefault -DLSw MOde = Secure	SETDefault -DLSw MOde = Secure
SETDefault -DLSw Interface = 129.213.1.1	SETDefault -DLSw Interface = 129.213.1.2
ADD !1 -DLSw PEer 129.213.1.2	ADD !1 -DLSw PEer 129.213.1.1
SETDefault -DLSw CONTrol = EnableSNA, DisableNetBios	SETDefault -DLSw CONTrol = EnableSNA, DisableNetBios

Procedure

To configure data link switching for SNA bridge/router A, see Figure 234 and follow these steps:

1 .   Enable transmission of Transmission Control Protocol (TCP) keepalive packets by entering:

SETDefault -TCP CONTrol = KeepAlive

TCP keepalive packets notify the bridge/router when the TCP connection has ended. Without TCP keepalive packets, the bridge/router will not detect that the TCP connection is down due to an abnormal situation. This can result in data link switching sessions being kept active even though the corresponding TCP session has ended.

2 .   Specify the number of contiguously missed keepalive packets that will bring down the TCP session.

For example, if you want three retries, enter:

SETDefault -TCP KeepAliveLimit = 3

3 .   Enable LLC traffic from a port to be tunneled through data link switching by entering:

SETDefault !1 -LLC2 CONTrol = Enable

This command enables LLC2 traffic on port 1.

Enable route discovery by entering:

SETDefault !1 -SR RouteDiscovery = LLC2

This command enables route discovery for LLC2 on port 1.

Repeat this step for each port you are configuring.

DLSw is affected by parameter settings in other services. For more information, see "Configuring LLC2 with Other Services" in the Configuring the LLC2 Data Link Interface chapter.

4 .   Assign a unique virtual ring number for the data link switching cloud.

This ring number is used by source routing and some data link switching Switch-to-Switch Protocol (SSP) messages. For example, to configure the virtual tunnel ring, enter:

SETDefault -LLC2 TUNnelVRing = 100

When using source routing, the internetwork becomes a virtual ring. If your end systems are using token ring source routing, the bridge/router and the IP tunnel appear to the end systems as a source route bridge with a token ring network attached to the other side of the bridge/router.

This virtual ring number must match on all peer bridge/routers used for tunneling and must be unique within the token ring network.

5 .   Configure the desired mode of operation.

To configure secure mode, enter:

SETDefault -DLSw MOde = Secure

The router accepts connections only from data link switches defined in the ADD PEer parameter.

To configure for default prioritization, enter:

SETDefault -DLSw MOde = Secure, DefaultPRioritized

You can also configure the mode to multicast. For more information, see the Configuring Multicast Data Link Switching for NetBIOS and SNA Networks chapter.

6 .   Configure an IP address to connect traffic to and from the router.

The address must be one that has been defined in the router using the SETDefault !<port> -IP NETaddr syntax. This address is the only address used for data link switching.

If you are configuring your NETBuilder II bridge/router as an IP router, the port associated with this IP address must be active before any packets can be sent to or received by this IP address. Select an IP address associated with a port that is always up or is the most reliable, such as a LAN port.

To map the specified DLSw tunnel to the local IP address of bridge/router A, enter:

SETDefault -DLSw Interface = 129.213.1.1

All Internet addresses for connected bridge/routers must be known in the routing table of the local bridge/router, either dynamically through RIP or OSPF, or statically configured in the IP routing tables.

7 .   Enable data link switching for SNA traffic on the port by entering:

SETDefault -DLSw CONTrol = (EnableSNA, DisableNetBIOS)

This setting allows SNA traffic to flow through the data link switch and disables NetBIOS traffic.

If you are going to use the prioritization feature of DLSw, see "Prioritizing DLSw Traffic" later in this chapter before proceeding to step 8.

8 .   Configure the DLSw tunnel peer IP connection by entering:

ADD !1 -DLSw PEer 129.213.1.2

When configuring the Internet address for the tunnel peer, you do not specify the port number of the bridge/router where the connection will be made. When a tunnel connection is made, the bridge/router determines the port through which the peer Internet address can be reached. When a peer has been defined and enabled, the system continuously retries to connect to the peer until a TCP connection is established between the system and the peer.

9 .   To configure bridge/router B, repeat steps 1-8.