To communicate with other nodes in an SNA network, you must configure the characteristics of a link station (LS) to an adjacent node in the SNA network. Before you can define a link station, you must define a port for the adapter (and link protocol) you are using. Most of the information needed to configure a link station is the same, whatever protocol is being used.
A link station represents the logical path through the SNA network between the CS/AIX local node and a remote computer. The remote computer can be any of the following:
A link station is associated with a specific port; you can define one or more link stations on each port.
Each link station that supports dependent traffic has an associated PU (physical unit). Because PUs are associated with link stations, CS/AIX does not treat them as separate resources; they are configured as part of link station configuration, and are started and stopped as part of starting and stopping link stations. Link stations are shown in the connectivity section of the Node window; PUs are not shown in any window.
| Note: | In most circumstances, you need to add a link station to the port.
However, if you want to use a dynamically created link station for downstream
SNA gateway or for APPC traffic only, for situations in which the link is
always activated from the remote node, you do not need to explicitly configure
one.
If a remote node attempts to connect to the local node, but no link station is defined that matches the address specified on the incoming call, CS/AIX can define one implicitly if a suitable port has been defined on the local node. This dynamically created link station appears in the connectivity section of the Node window for the duration of the connection. |
To configure a link station, use one of the following methods:
In this command, type indicates the link protocol type (sdlc, tr, ethernet, fddi, qllc, channel, mpc, mpc_plus, ip).
Advanced parameters for link stations provide additional control over transmission characteristics, XID exchange, optional link facilities, and reactivation procedures.
In Motif, the Link Station Configuration dialog contains the following sections, each containing different categories of configuration parameters:
The following parameters are required for all link stations, whether they support dependent traffic, independent traffic, or both.
For more information about the parameters on this dialog, refer to the online help or to Communications Server for AIX Administration Command Reference.
Link stations are activated separately from ports, so the link station must be activated even if the port is already active. Activating the port does not itself activate any link stations, and configuring the port to be initially active does not mean that any of its link stations are activated automatically when the node starts up. However, activating a port does make it possible to activate link stations. A link station cannot be activated unless the ports are active on both the local node and the adjacent node.
If the link is one for which you are charged for usage, avoid activating the link unnecessarily, in order to keep the cost down.
If you are not sure how to set this field, consult your SNA network planner.
This parameter is not used for an Enterprise Extender (HPR/IP) or MPC+ link, because this link type supports only independent traffic.
You also need to provide addressing information for contacting the adjacent node. The type of addressing information needed depends on the DLC type of the port. If you do not supply an address for the remote node, the link station acts as a nonselective listening link station, accepting incoming calls from any remote node.
The poll addresses at both ends of the link must match. Contact your SNA network planner if you do not know the address configured at the remote system.
On a VTAM host, the poll address is configured as the ADDR= parameter in the VTAM PU definition.
On an AS/400 system, the poll address is the STNADR parameter of the Line Description.
On a switched outgoing port, the line encoding can be set independently for each link station. For other types of ports, the line encoding setting is taken from the port, so this field does not apply.
On a switched outgoing port, the duplex setting can be set independently for each link station. For other port types the duplex setting is configured on the port, so this field does not apply.
For switched incoming ports, the dial string is configured on the port. For leased ports, this field does not apply.
For details of the format of the dial string, refer to your modem's documentation.
If you do not know what value to use, consult your SNA network planner.
If the remote end of this link is a VTAM host, you can find its MAC address in the MACADDR= parameter of the VTAM Port definition.
If you are configuring a link to an AS/400 system, the MAC address is the ADPTADR parameter in the Line Description.
If you do not know what value to use, consult your SNA network planner.
If the remote end of this link is a VTAM host, the SAP number is the SAPADDR= parameter of the VTAM PU definition.
If you are configuring a link to an AS/400 system, the SAP number is the SSAP parameter in the Line Description.
You need the following information to configure this link station for use by independent LUs (LUs of type 6.2 for use by APPC, 5250, or CPI-C applications):
If the remote system is a VTAM host, you can find the network name (the first eight characters of the fully qualified name) in the NETID parameter of the VTAM start list. The last eight characters are in the SSCPNAME parameter of the VTAM start list.
| Note: | If you enter the name of a new remote node, you can add a definition for the
remote node to enable you to define partner LUs on the new remote node.
If the local node is a LEN node, you do not need to specify the remote node
type, and the Remote node type field does not apply.)
To define a new remote node in this way, specify the remote node type as a value other than Discover, as well as specifying the remote node name. Alternatively, you can specify Discover and leave the remote node name empty. This means that any adjacent node can use the link station. The Discover option is not available if the local node is a LEN node. |
If you do not know whether the remote node is a LEN node or end node or whether it is a network node, you can choose Discover. Discovering the level of APPN support on the remote node can delay link activation slightly, so if you do know the type it is better to specify it. This also helps to ensure network configuration consistency.
You cannot choose Discover if the link station is activated on demand.
If the local node is a LEN node, this field does not apply.
If the remote node is a network node within the main APPN backbone, choose Uplink (to backbone). If the remote node is an end node within the branch, choose Downlink (within branch).
If the remote node is configured to be a network node, the branch link type is automatically set to Uplink (to backbone) and you cannot change it.
These parameters do not apply to an Enterprise Extender (HPR/IP) or MPC+ link, because this link type supports only independent traffic.
Configuring a link station for dependent LU traffic automatically creates an appropriate PU with the same name as the link station.
You need the following information to configure a link station for use by dependent LUs (LUs of type 0-3 for 3270 or LUA applications):
You can usually use the same node ID (the default value) for all the links on the same node. However, if you need more than 255 dependent LUs to access a specific host, you must configure multiple link stations to the host, each with up to 255 dependent LUs, and each with a different local node ID.
To ensure that the remote node is configured to recognize the local node ID, contact your SNA network planner.
In a VTAM configuration, the first three digits should match the IDBLK parameter in the PU definition, and the last five should match the IDNUM parameter.
On an AS/400 system, the node ID is configured in the EXCHID parameter.
If you do not specify the remote node ID, the node ID of the remote node is not checked when the link is activated.
Such links can be used only if the local node is an APPN network node.
This field is not used for Channel link stations.
This field applies only if you specified that this link station is to a downstream PU that will communicate with a host using the DLUR capabilities of the local node. You can indicate this by specifying Downstream (DLUR) for the Remote node role field.
For more information, see Defining DLUR PUs.
This field applies only if you specified that this link station is to a downstream PU that will communicate with a host using the DLUR capabilities of the local node. You can indicate this by specifying Downstream (DLUR) for the Remote node role field.
After performing the link station configuration, continue with the following configuration tasks: