1. The E.N.a.A. (Ed Needs an A) Network Bridge
An ELE 408 / URI / Miller Brewing Company Presentation

2. What is a network bridge?
The key component of a multi - tiered network architecture.
Connects different Local Area Networks (LANs ) together…..
…… while at the same time keeping each LAN independent of the other one.

3. Multi - Tier Architecture
Bridge
Hub
Hub
LAN 1
LAN 2

4. What does this mean?
Overall, makes the LAN “better” by extending the “Collision Domain”:
Employs CSMA / CD
Distance
Number of Users
LAN can use its full bandwidth
Less Collisions
All of this is accomplished because the bridge isolates each LAN and is smart enough to tell where to route a packet.

5. The Bridge Table Table held in RAM that is dynamically updated.
Holds all LAN addresses that have used the bridge, along with which interface they used.
Interface 1
Interface 2
A-BC 1
A-BC

6. The Program Initialize both Boards in Receive Mode
When a packet is received through the ethernet port, the data is stored in memory.
If the source address is not in the table, it is added.
If the destination address is not in the table, the packet is sent to the UART transmit buffer, and the transmitter is enabled.

7. More of the program….
The packet is stored in memory, if the source address is not in the bridge table, it is added.
The packet is then transferred to the ethernet transmit buffer and passed to the connected LAN.

8. One problem….
The son of a - ^ ETHERNET CONTROLLER!
Possibly over 2 million registers to program
Difficult to strip away headers from different network layers

9. The (temporary) solution
Packets will enter the bridge through the terminal.
Data will be typed in, header information will be stored in memory and then combined with the data to form a simulated packet.

10. Other problems…...
Scalability
Bandwidth Bottleneck

11. Future implementations...
Security features
LAN address filtering
Interface firewall
Trusts
Implement Spanning Tree Protocol to facilitate expansion

12. Conclusion Effective way to bridge to LANs
Cheap to build, easy (in theory) to implement
Mass production easy due to the fact that its highly software driven
Ed definitely deserves an A