Bridging is the term used when a device transparently forwards network layer 2 packets from one broadcast domain to another. In essence, it can make the Solaris server act like an Ethernet switch (or in some cases, other layer 2 protocol switches).
Note
Bridging makes the involved physical interfaces to always run in promiscuous mode, which has the effect of degrading effective interface throughput.
Normally, I would consider bridging on a Solaris box to not be used enough to include here, but the improvements in Solaris 11 are so impressive that they are worth mentioning.
The old way of making a Solaris machine act as a bridge was to set ip_forwarding=1 on the interfaces you wished, then telling other machines to use the Solaris machine as a bridge, and blindly hope for the best.
The new way is much improved. There are real administrative commands instead of ndd, and the OS has been enhanced to properly support the following standard bridging protocols: