Although VTAM® supports sending and receiving APPN Locate searches with a size up to a maximum of 16 KB, other products that act as APPN network nodes or end nodes might support much smaller maximum APPN Locate sizes (as small as 1 KB). This can cause problems for ENs that have many links (described by TG Vectors) to other nodes in the network, because these TG Vectors often must be included on the APPN Locate search in order to compute the best session path.

If any such APPN products are present along the path of an APPN Locate search, and the APPN Locate search that is to be sent exceeds the maximum Locate size allowed by these products, then some of these TG Vectors will be removed from the APPN Locate search in order to prevent the maximum Locate size from being exceeded. (VTAM typically copies the TG Vectors for active links to the APPN Locate search in the order these TGs were activated, which means the most recently activated TGs are removed first.) When this occurs, the network node server responsible for computing the session path might not choose the best possible path or the route computation could fail entirely (if the TG Vector describing the best or only path was removed). To avoid this problem, whenever possible, minimize the number of links (TGs) that end nodes have to other nodes. Using a connection network to reduce the number of EN TG Vectors can also be helpful.