Technical data

www.westermo.com Theoretical and general applications 125
dynamic or static. A dynamic routing table is updated automatically based on the struc-
ture of the surroundings.
How the traffic should be routed is controlled by a routing protocol, e.g. RIP
(Routing Information Protocol) or OSPF (Open Shortest Path First).
Brouter
There are many standards on the market, the most common are Ethernet, Token ring
and FDDI. All these use different communication techniques and formats, but address-
ing is common and standardised by IEEE.
A Brouter is a combina-
tion of a bridge and a router
in the same device, many
routers are really brouters.
When the device needs to
transfer the same protocol
within a LAN, or to another
LAN, the bridge function
manages this. Alternatively,
when a PC is connected to a WAN
(Wide Area Network), more informa-
tion is needed about alternative connec-
tions so the device requires a routing table, in this way the brouter becomes a combi-
nation of a router and bridge.
Hub
As the name implies this is a network device used as the central connection in a net-
work. A hub works as a star coupler for network traffic. Data that comes in on one
port, is sent to all others irrespective of who the recipient is. The hub was the net-
work device that made 10baseT a success. It created completely new options for
building networks, with centrally placed equipment and connection points at each
workplace. There are two types of hubs, active and passive. A passive hub joins
together network segments without amplifying the signal. An active hub acts in the
same way as a passive hub, but also amplifies the signal.
Brouter A
Ethernet
Address 1.1
Address 4.2
1.2 2.1 2.2 3.1 3.2 4.1
Brouter B Brouter C
To k e n
ring
To k e n
ring
Hub
B A C K