VTAM® deactivates a cross-subarea link station adjacent to a host processor when the channel-attachment major node or the associated channel, SDLC, LAN, or X.25 link is deactivated (even if the associated link is currently carrying session traffic). Deactivating such a link station drops any sessions using a route going through that link station, possibly including the SSCP session with another subarea node. Also, VTAM might be an intermediate routing node for cross-domain sessions that pass through the link station. Care should be taken not to deactivate a cross-subarea link station that could be supporting session traffic.

The NCP deactivates an SDLC, LAN, or X.25 cross-subarea link and its subordinate link station when the last of the link SSCP owners deactivates the link. When the last active link station in a transmission group is deactivated, any session traffic being carried by that transmission group is disrupted. Therefore, if the VTAM operator has not activated a cross-subarea link and link station, and VTAM is using that link transmission group to carry session traffic, those sessions are disrupted when the link owners all deactivate the link and link station and there are no other active link stations in the transmission group. However, if the VTAM operator activates the link and link station, VTAM shares the ownership of them, and the link and link station remain active, regardless of the deactivation requests of other domain operators.

If the VARY INACT command is used to deactivate a channel link owned only by VTAM, and the link station of that link is the only active link station in a transmission group, deactivating that link destroys any sessions using a route containing that transmission group, possibly including the SSCP session with another SSCP or with the NCP containing the link being deactivated. For this reason, care should be taken not to deactivate such a cross-subarea link.

Deactivation of a cross-domain link also causes the deactivation of its subordinate link station.