Bridge Route Discovery

DLCFDDI caches any returned bridge-routing information from a remote station for each command or datagram packet received and generates send-packet headers with the reverse route.

This operation allows dynamic alteration of the bridge route taken throughout the link station attachment. There is also a provision to alter the cached routing field with the DLC_ALT_RTE ioctl operation. This ioctl operation allows the user to dynamically change the bridge route taken by link station send packets. Once the DLC_ALT_RTE ioctl operation is issued and accepted by the link station, dynamic caching of the received route is stopped, and subsequent send packets carry the ioctl operation's routing value.

Network data packets are not associated with a link station attachment, so any bridge routing field has to come from the user sending the packet. DLCFDDI has no involvement in the bridge routing of network data packets.