For type DL_TPR devices, GLD implements minimal support for source routing. Source routing enables a station that is sending a packet across a bridged medium to specify (in the packet MAC header) routing information that determines the route that the packet will take through the network.
Functionally, the source routing support provided by GLD learns routes, solicits and responds to requests for information about possible multiple routes, and selects among the multiple routes that are available. It adds Routing Information Fields to the MAC headers of outgoing packets and recognizes such fields in incoming packets.
GLD's source routing support does not implement the full Route Determination Entity (RDE) specified in Section 9 of ISO 8802-2 (IEEE 802.2). However, it is designed to interoperate with any such implementations that might exist in the same (or abridged) network.