Advanced computer network

Project Code

Project A: Distance-Vector-Algorithm

A Policy-Based Routing (PBR) Router based on Distance-Vector Algorithm

Distance vector algorithm

Distance vector algorithm was described in RFC 2453.

To summarize, here is the basic distance vector algorithm as it has been developed so far.

• Keep a table with an entry for every possible destination in the system. The entry contains the distance D to the destination, and the first router G on the route to that network. Conceptually, there should be an entry for the entity itself, with metric 0, but this is not actually included.
• Periodically, send a routing update to every neighbor. The update is a set of messages that contain all of the information from the routing table. It contains an entry for each destination, with the distance shown to that destination.
• When a routing update arrives from a neighbor G', add the cost associated with the network that is shared with G'. (This should be the network over which the update arrived.) Call the resulting distance D'. Compare the resulting distances with the current routing table entries. If the new distance D' for N is smaller than the existing value D, adopt the new route. That is, change the table entry for N to have metric D' and router G'. If G' is the router from which the existing route came, i.e., G' = G, then use the new metric even if it is larger than the old one.

In practise, there are some problems when implement that such as changes in topology, instability and so on.We can find all answers in RFC 2453.

Run

Run like go run ./DV_algorithm/router.go 3,3003,3004

Issues

Maybe some bugs. Set priority route maybe some faults.

Project B: Reliable Data Transfer over UDP (RDT-UDP)

Build a reliable transport protocol “RDT-UDP” over unreliable UDP. Also, the protocol provide in-order, reliable delivery of UDP datagrams, and must do so in the presence of packet loss, delay, corruption, duplication, and re-ordering.

Requirements

• Use TCP-style connection maintenance, including establishment, maintains and release.
• The header includes the following fields:
  1. Sequence Number (32 bits)
  2. Acknowledgement Number (32 bits)
  3. ConnectionID(16bits)(if exists)
  4. A (ACK, 1 bit)
  5. S (SYN, 1 bit)
  6. F (FIN, 1 bit)
• Avoid losing messages.
• In case of lost message, detect and recover it.
• Handle messages reordering.
• (Optional) Add Congestion Control. The control algorithm is AIMD (like TCP)
• The maximum UDP packet size is 524 bytes including a header (512 bytes for the payload).
• The maximum sequence and acknowledgment number should be 102400 and be reset to zero whenever it reaches the maximum value.

Run

Run like

go run -race server.go config.go

go run -race client.go config.go 1 test.txt