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Dual Trunk E1 Router
Dual Trunk E1 Router User’s Guide TECHNICAL: 0118 96 56 000 47
Bridging Configuration 5
OVERVIEW OF THE CONFIGURATION
The LRU4240 supports bridging and routing packet processing modes. This chapter contains
procedures on configuring your device for layer 2 bridging applications.
Bridging provides the capability to connect two or more physically separate LAN segments over the
WAN, to create a single logical LAN. Bridging occurs at layer 2 and uses the MAC address
assigned to each LAN device, to either forward or filter frames. Routing forwards IP packets
between two or more IP networks.
NOTE: With the availability of Bridging mode, the proprietary IP Fast Forwarding mode available in the menu will no
longer be supported in the future, and is thereore not documented..
.
BRIDGING CONFIGURATION
Bridging operates at layer 2 of the OSI model to bridge Ethernet traffic between the LAN and the
WAN and requires little configuration. All traffic types including IP is bridged. The bridge learns
which addresses lay on each side of the bridge and maintains the following information in a MAC
to port map table:
• MAC address
• Physical interface (Ethernet or Network ports)
• DLCI, in Frame Relay mode
The MAC to port map table is used by the bridge in its forwarding decisions.
On a Frame Relay connection, using InverseARP, the bridge discovers the remote subnets connected
on each DLCI and fills the remote end router’s MAC address and the DLCI on which it was
discovered.
On the LAN side as packets flow on the Ethernet, the bridge learns which hosts resides on the local
LAN by storing the source host address in its MAC to port table.
Table 5-1 Bridging configuration procedure
Procedure Description Menu Reference
Setting bridging mode To configure the unit for Bridging or VLAN Bridging.
In bridging mode, all traffic types including IP is
bridged.
Menu-$A page 50
Configuring static MAC
Bridge routes
To map statically up to 50 MAC addresses to specific
ports in the MAC to port map table. The entries will be
stored in non-volatile RAM (NVRAM) and are
restored at boot time.
Menu -$GA page 50
Displaying MAC to port
map table
To display the MAC to port map table. View both
learnt and static MC to port mapping entries.
Menu -$GB page 51