What is the bridge?
In telecommunication networks, a bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol. Having a single incoming and outgoing port and filters traffic on the LAN by looking at the MAC address, bridge is more complex than hub. Bridge looks at the destination of the packet before forwarding unlike a hub. It restricts transmission on other LAN segment if destination is not found.
This image tells you where the bridge in network is.
A bridge works at the data-link (physical network) level of a network, copying a data frame from one network to the next network along the communications path.
What is the Network Layer of the Bridge?
This table shows that the Bridge is in the Second (Data) Network Layer.
|
Device |
Hub |
Bridge |
Switch |
Router |
Wireless Access Point |
Repeater |
|
Network Layer |
1 (Physical) |
2 (Data) |
2 (Data) or 3 (Network) |
3 (Network) |
1 (Physical) or 2 (Data) |
1 (Physical) ,2 (Data) or 3 (Network) |
What is the difference between a bridge and a router?
|
Bridge Mode |
Router Mode |
|
▶ Does not block any broadcast or multicast |
▶ Blocks and provide protection against broadcast storms |
|
▶ Transparent bridge and can pass Non-IP protocols |
▶ Only IP protocol is supported |
|
▶ PPPOE protocol Pass-through |
▶ No PPPOE protocol pass-through |
|
▶ Able to transport VLAN tagging |
▶ Doesn’t supports VLAN |
|
▶ No network segmentation, One broadcast domain |
▶ Network segmentation (Clients can be on different IP subnet) |
|
▶ Can only relay the DHCP client’s request to the external DHCP server |
▶ Can Act as DHCP server & relay which Prevents IP conflict & DHCP Injection |
|
▶ Bridges maintains bridging table (Mac) & STP can be used to avoid loops |
▶ No STP feature; maintains routing table |
|
▶ External bandwidth Controller can be used to control the speed of the clients by Mac or IP address |
▶ External bandwidth Controller can be used to control the speed of the clients by IP only |
|
▶ In client device, it uses MAC address to associate which requires WDS compatible AP |
▶ Use SSID to associate, work with any 802.11a/b/g AP |