a. Bridges cannot provide any form of flow control
and
b. Bridges cannot provide congestive feedback information to end nodes
Flow Control and Congestive Feedback are functions of the Network
layer. As bridges operate at the Data Link layer, these responsi-
bilities fall to the end stations in a bridged environment. Most
bridges do offer some filtering capabilities, at least on MAC addresses,
and they are much simpler to administer. At first glance, it may
appear that bridges create more overhead than routers, due to the
BPDU frame that is sent out every second. However, these frames are
very small compared to route advertisements sent out by routers,
which can grow to be quite large in complex networks. Also, routers
must tie Network addresses to Data Link addresses, which often creates
more overhead (Example: IP ARP).
Reference: Perlman, Interconnections, Chapter 12.