The basic difference between Bridge and Router is that Bridge is a network device mainly operating at the data link layer of the OSI model with filtering and forwarding capabilities.
While Router is an internetworking device operating at the network layer of the OSI model. A router is attached to the two or more networks and forwards packets from one network to another.
Content: Bridge Vs Router
|Basis for comparison||Bridge||Router|
|Operates on||Data link layer||Network layer|
|Store and Forward||Frame||Packet|
|Transparency||Bridges are protocol independent and transparent to the end stations.||Routers do not provide station transparency.|
|Reads||MAC address of the device||IP address of the device|
|Works on||Single broadcast domain||More than one broadcast domain|
Definition of Bridge
A bridge is a networking device for connecting two segments of a network and transmitting data between them. Bridge operate in both the physical and the data link layers of OSI model. There is a compulsion of using identical protocols for the segments to communicate. The primary use of a bridge is to send, filter, or flood any arriving frame depending on the MAC address of that specific frame.
The frames can be transferred between two originally separate LANs by a bridge. However, bridges incorporate logic that permits them to retain the traffic for each segment separately. When a frame enters in a bridge interface, it checks the destination MAC address and forwards the late copy to the segment to which the address belongs. Bridges are also apparent to the end stations.
Bridges are hardware based, and it uses specialized hardware called ASIC (Application specific integrated circuit) chip to maintain MAC address table and to make filtering decision. Bridged network fragments collision domains, but do not fragment broadcast domains, instead forward all broadcasts.
Types of bridges:
- Simple Bridges are the predecessor of its other types and the least expensive type of bridge. A simple bridge connects two segments and contains a table that lists the addresses of all the stations included in each of them. What makes it primitive is that these addresses must be entered manually.
- Multiport Bridge is employed when we want to link more than two LANs, and each table is containing the physical addresses of stations approachable through the particular port.
- Transparent Bridge performs its bridging functions and creates its own table of station addresses.
Definition of Router
A router can be defined as a Network layer mechanism, be it software or hardware, using metrics to decide the best path to use for transmission of network traffic.
A router is a device that routes or forward data from one network to other based on their IP address. When Data packet is received from the router, the router inspects the data’s IP address and determines if the packet is meant for its own network then it receives the data, or if the data is for another network, then it transfers the data to the other network. It means that routers only forward the data if destination computer is the intended user.
Routers have access to network layer addresses and contain software that enables them to determine which of the several possible paths between those addresses is the best for the particular transmission.
Routers break up broadcast and collision domains. It means broadcasts are not forwarded through the router, by default. It also provides connections for the virtual LANs (VLANs).
Key Differences Between Bridge and Router
- Bridge functions at Data link layer while router operates at the Network layer of the OSI model.
- The bridge can relay frame from one segment to another whereas Router store and forward packets.
- Routers are not transparent to the end stations. In contrast, Bridges are transparent to the end stations and does not rely on the protocol.
- In a bridge, frames are forwarded on the basis of the MAC address of the frame. As against, Router checks logical address (i.e., IP address) of the packets.
- The router can work on more than broadcast domain while Bridge can work on a single broadcast domain.
Both bridge and router work on different layers of OSI model and differ in functionality too. But a router is more intelligent device than a bridge because routers can facilitate layer 2 bridging functions if required and can concurrently route through the same interface. Although it can not eliminate the use of bridge the reason is that it can not regenerate signals like a bridge.