bridge app implements a basic Ethernet bridge with split-horizon
semantics. It has an arbitrary number of ports. For each input port there
must exist an output port with the same name. Each port name is a member
of at most one split-horizon group. If it is not a member of a
split-horizon group, the port is also called a free port. Packets
arriving on a free input port may be forwarded to all other output
ports. Packets arriving on an input port that belongs to a split-horizon
group are never forwarded to any output port belonging to the same
split-horizon group. There are two
bridge implementations available:
apps.bridge.flooding and apps.bridge.learning`.
DIAGRAM: bridge +----------+ port1 ---->* *----> port1 | | port2 ---->* *----> port2 | bridge | ... ---->* *----> ... | | portN ---->* *----> portN +----------+
bridge app accepts a table as its configuration argument. The
following keys are defined:
— Key ports
Optional. An array of free port names. The default is no free ports.
— Key split_horizon_groups
Optional. A table mapping split-horizon groups to arrays of port names. The default is no split-horizon groups.
— Key config
Optional. The configuration of the actual bridge implementation.
Flooding bridge (apps.bridge.flooding)
bridge app implements the simplest possible bridge, which
floods a packet arriving on an input port to all output ports within its
scope according to the split-horizon topology.
bridge app ignores the config key of its configuration.
Learning bridge (apps.bridge.learning)
bridge app implements a learning bridge using a
custom hash table to store the set of MAC source addresses of packets
arriving on each input port. When a packet is received it is forwarded
to all output ports whose corresponding input ports match the packet's
destination MAC address. When no input port matches, the packet is
flooded to all output ports. Multicast MAC addresses are always
flooded to all output ports associated with the input port. The
scoping rules according to the split-horizon topology apply unchanged.
bridge app accepts a table as the value of the config
key of its configuration. The following keys are defined:
— Key mac_table
Optional. This is a table that defines the characteristics of the MAC table. The following keys are defined
— Key size
Optional. The number of MAC addresses to be stored in the table. Default is 256. The size of the table is increased automatically if this limit is reached or if an overflow in one of the hash buckets occurs. This value is capped by resize_max.
— Key timeout
Optional. Timeout for learned MAC addresses in seconds. Default is 60.
— Key verbose
Optional. A boolean value. If true, statistics about table usage is logged during each timeout interval. Default is
— Key copy_on_resize
Optional. A boolean value. If true, the contents of the table is copied to the newly allocated table after a resize operation. Default is
— Key resize_max
Optional. An upper bound for the size of the table. Default is 65536.