3Com 3C780 User Guide - Page 82

3-14 Configuring the Hub Table 3-3. Port Connection Rules Attachment Neighbor Ports Ports A A V, U, T B V M V, W S V, U, W B V V, U, T V, W V, U, W M V, P, W V, P, W X V S V, U, W V, U, W V V Table 3-4. Definitions for the Port Connection Rules Condition Indicator Port Connection Condition Definition of Port Condition P Prevents thru state Exists when both rings are not fully functional. Thru state is the normal condition of an FDDI station. U Undesirable connection Exists because the connection creates undesirable hub configurations, such as a twisted ring; not prevented by the connection rules. V Valid connection Creates two logical token rings; provides a consistent designation of the primary ring among all stations. X Illegal connection Exists when an M-to-M connection is formed. It isolates a portion of the network onto a separate token ring nested in the tree of rings. (continued)