A transparent bridge is a type of network bridge that operates at the data link layer (layer 2) of the OSI model. It is designed to connect two or more network segments together to allow communication between devices on different segments.
The primary function of a transparent bridge is to forward traffic between network segments based on the destination MAC address.
When a device on one segment sends a packet to a device on another segment, the transparent bridge will examine the destination MAC address of the packet and forward it to the appropriate segment. The bridge will also read the MAC addresses of devices on each segment as traffic is sent through it, and will use this information to more efficiently forward traffic in the future.
- They can help to improve network security by preventing unauthorized access.
- They can filter traffic based on MAC address, which can prevent rogue devices from accessing the network.
- They can also help to reduce network congestion by limiting unnecessary traffic between segments.
Source Routing Bridge
A source routing bridge (SRB) is a type of bridge used in computer networks to forward data packets between network segments. Unlike traditional bridges that use a forwarding algorithm based on the destination MAC address of the packet, SRBs use a source routing algorithm that forwards packets based on the complete route of the packet from its source to its destination.
In an SRB network, each packet contains a source route that specifies the complete path the packet must follow from its source to its destination. This source route is included in the packet header and is used by the SRB to forward the packet through the network. When a packet arrives at an SRB, the bridge examines the source route and forwards the packet to the next hop specified in the route. This process continues until the packet reaches its final destination.
Differences between transparent bridge and source routing bridge:
|Parameters||Transparent bridge||Source routing bridge|
|Operation||A transparent bridge operates at the data link layer (layer 2) of the OSI model and forwards traffic based on the destination MAC address.||Source routing bridge operates at the network layer (layer 3) of the OSI model and forwards traffic based on the source and destination IP addresses.|
|Addressing||A transparent bridge uses MAC addresses to forward traffic.||Source routing bridge uses IP addresses.|
|Configuration||A transparent bridge is typically configured to automatically learn the MAC addresses of devices on each network segment it connects.||Source routing bridge requires manual configuration of source routing tables.|
|Functionality||A transparent bridge is able to filter traffic based on MAC address, which can improve network security by preventing unauthorized access.||A source routing bridge, on the other hand, is able to support complex network topologies and is often used in larger networks.|
|Compatibility||Transparent bridges are compatible with virtually any network device that uses MAC addresses.||Source routing bridges may require specific configuration and support from network devices in order to function properly.|
|Protocol support||Transparent bridges typically support a wide range of protocols, including Ethernet, Token Ring, and FDDI.||Source routing bridges are primarily used in IP networks.|
|Network traffic||Transparent bridges forward all traffic received on one port to all other ports, except for the port on which the traffic was received.||Source routing bridges only forward traffic that matches the source routing table.|
|Performance||Transparent bridges can introduce some latency into the network as they need to learn the MAC addresses of devices on each network segment before forwarding traffic.||Source routing bridges can introduce even more latency as they need to perform a lookup on the source routing table to determine the path for each packet.|
|Security||Transparent bridges can be vulnerable to MAC address spoofing attacks, where an attacker pretends to have a different MAC address in order to gain unauthorized access to the network.||Source routing bridges can be vulnerable to IP spoofing attacks, where an attacker pretends to have a different IP address in order to bypass network security measures.|
In conclusion, while both transparent bridges and source routing bridges are used to connect network segments, they operate at different layers of the OSI model and use different methods for forwarding packets. Transparent bridges use MAC addresses to learn the location of nodes in the network and forward packets accordingly, while source routing bridges use information in the packet header to determine the path a packet should take through the network.