Hitachi GR2000 manual Bridge Definition on Isdn Interface

When bridge is defined on an interface where multiple VCs are grouped, BPDUs or relay frames not learned are broadcast to all the VCs in the group. Consequently, it is cautioned that an inadvertent addition of bridge definition to an existing grouped interface may cause unnecessary traffic to flow through the interface if the group includes a VC not using protocols other than IP. To avoid such occurrence of unnecessary traffic, it is advised to separate the group into two—one comprising VCs to use the bridge function, and the other not using protocols other than IP—and define these groups to respective interfaces. The same is advised when you further add IPX definition to the existing interface.

4.11.6Bridge Definition on ISDN Interface

Bridge definition on an ISDN interface is available only on such interface where IP interface is defined to a single ISDN peer. The IP interface should be point-to-point type. Bridge definition on an ISDN interface with ISDN peer group is not available.

Since the spanning-tree protocol is not available on an ISDN interface, each bridge interface can be defined “yes” or “no.” In addition, when you plan a new ISDN network where the bridge interface definition is anticipated, it is advised that you explicitly avoid a loop configuration in the network.