Source Level Routing and OpenAdapter Issues (60845)

SUMMARY

The following are questions and answers about LAN Manager source level routing and OpenAdapter issues:

1. Q. What does it mean when an NDIS driver says it supports source routing? Does this mean the NDIS driver keeps a table of routing information for subsequent use, or does it mean that the token-ring chipset the NDIS driver talks to keeps the routing information? Or, does this signal JETBEUI that the data it is receiving from the NDIS driver may have source routing information? This would mean that when JETBEUI receives the data, it has to know how to determine whether the source routing field exists, and determine the length of the source routing field in order to determine where the real data in the frame begins.
   
   A. If IBM source routing is used (bit 9 in MACservice specific characteristics), it is the protocol module's responsibility to encode and interpret appropriate source routing information. This bit merely implies that the device is capable of sending packets with the source routing bit set in the source address so that a protocol may recognize such a packet.
2. Q. If a Token-ring NDIS driver says it supports the open adapter, is it JETBEUI's responsibility to call OpenAdapter to get onto the ring? Or should the NDIS driver open the adapter itself once the NDIS driver has initialized the adapter?
   
   A. If OpenAdapter (bit 11) is set, the protocol driver must ensure that the adapter is open. The open status of an adapter can be determined by examining bit 4 of the MAC status in the MAC-specific status table. If the adapter is not open, the protocol must issue an OpenAdapterRequest (normally during bind-time processing).