Bridge is a device that is attached to connect two or more LANs to create continued LAN. A bridge works at data link layer of the OSI reference model.
Transparent Bridge:
Transparent bridge automatically maintains a routing table and update table in response to maintain changing topology. Transparent bridge mechanism consists of three mechanisms:
1. Frame forwarding 2. Address Learning 3. Loop Resolution
Transparent bridge is easy to use, install the bridge and no software changes are needed in hosts. In all the cases, transparent bridge flooded the broadcast and multicast frames.
Advantages:
- Simplicity: Transparent bridges are relatively simple devices that do not require much configuration or maintenance.
- Compatibility: Transparent bridges are compatible with all network protocols and can be used to connect different types of networks.
- Scalability: Transparent bridges can be easily added to a network to expand its capacity and reach.
- Reliability: Transparent bridges are reliable and can provide redundant paths for network traffic.
- Security: Transparent bridges can help to prevent network attacks by filtering traffic based on MAC addresses.
Disadvantages:
- Limited functionality: Transparent bridges do not have the same level of functionality as more advanced network devices, such as routers.
- Limited control: Transparent bridges provide limited control over network traffic, as they only filter traffic based on MAC addresses.
- Broadcast traffic: Transparent bridges can increase broadcast traffic on a network, which can lead to congestion and performance issues.
- Spanning tree protocol: Transparent bridges rely on the spanning tree protocol to prevent network loops, which can cause delays and network outages.
- Performance: Transparent bridges can introduce latency and reduce network performance due to their reliance on MAC addresses for filtering traffic.
Source Routing Bridge:
Source routing bridge decides the route between two hosts. Source routing bridge uses the MAC destination address of a frame to direct it by the source routing algorithm. In source routing, the route over which the frame is to send is Known to every station on the extended LAN. The routing information is stored in the frames.
Advantages:
- Control: Source routing bridges provide more control over network traffic than transparent bridges, as they can route traffic based on the path specified in the source routing header.
- Compatibility: Source routing bridges are compatible with all network protocols and can be used to connect different types of networks.
- Scalability: Source routing bridges can be easily added to a network to expand its capacity and reach.
- Security: Source routing bridges can help to prevent network attacks by filtering traffic based on the source routing header.
- Performance: Source routing bridges can provide better network performance than transparent bridges, as they can route traffic more efficiently.
Disadvantages:
- Complexity: Source routing bridges are more complex devices than transparent bridges and require more configuration and maintenance.
- Limited support: Source routing bridges are not supported by all network devices and protocols.
- Security: Source routing bridges can be vulnerable to attacks that modify the source routing header.
- Broadcast traffic: Source routing bridges can increase broadcast traffic on a network, which can lead to congestion and performance issues.
- Spanning tree protocol: Source routing bridges rely on the spanning tree protocol to prevent network loops, which can cause delays and network outages.
Similarities between Transparent Bridge and Source Routing Bridge are as following:
- Both transparent bridges and source routing bridges are used to connect different types of networks.
- Both types of bridges can be added to a network to expand its capacity and reach.
- Both transparent bridges and source routing bridges can help to prevent network attacks by filtering traffic.
The difference between Transparent Bridge and Source Routing Bridge are as following:
| S.No. | Transparent Bridge | Source Routing Bridge |
|---|---|---|
| 1. | Transparent bridge service is connectionless. | Source Routing Bridge service is connection oriented. |
| 2. | In transparent bridge mechanism bridges automatically develop a routing table. | In source routing bridge, bridges do not maintain any routing information. |
| 3. | Transparent bridge does not support multipath routing. | Source routing bridge can make use of multiple path to same destination. |
| 4. | The path used by transparent bridge between any two hosts may not be the optimal path. | Source route bridge always uses the optimal path. |
| 5. | Failures are handled by the transparent bridge on its own. | Host handle the failure of bridge on its own. |
| 6. | Transparent bridges are fully transparent to the users. | Source routing bridges are not visible to the hosts. |
| 7. | The frame processing delay is more. | The frame processing delay is less. |
| 8. | Load sharing is not possible through blocked routes. | Load sharing is possible by judicious choice of routes. |
Conclusion :
while both transparent bridges and source routing bridges serve the same purpose of connecting two or more network segments to form a single network, they operate at different layers of the OSI model and have different advantages and disadvantages. A transparent bridge is easy to set up and reliable, but provides no mechanism for controlling traffic or optimizing network performance. A source routing bridge provides a high degree of control over network traffic, but is more complex to set up and can be less reliable. The choice between the two types of bridges depends on the specific needs of the network and the trade-offs between ease of use, reliability, and control over network traffic.