ECE 544 Protocol Design Project 2016

1. ECE 544 Protocol Design Project 2016 Siddharth Rupavatharam Bhargav Gokalgandhi

2. Network Architecture & Topology Assumptions • Service Objective: k(1, 2 or 3)-out-of-n “packet datagram” multicast on the basis of Area and Number of hops required to reach destination. • Assumptions • Unreliable network with packet loss prob. per link of p. • Each end node is attached to only one router. • All links have same characteristics (i.e. hop cost 1 and same MTU 1500 bytes). • Small maximum number of nodes (i.e. 50 - 100) • Nodes are divided in areas with Area IDs assigned to each node. • Router and user addresses are differentiable.

3. Protocol Concept Protocol summary: • Protocol similar to Link State to identify and map routers in the network • User nodes have fixed address. • Multiple destination address fields in each packet sent by the source node. • ARQ Scheme – Go-Back-N

4. USER USER R1 R3 R2 USER R4 R5 USER USER R7 R8 USER R6 USER

5. Syntax and Semantics Routing Packet Format Data Packet Format

6. Syntax and Semantics • Type: Data, Hello or Update Request. • Packet length: to signify length of packet. • Area ID: Demarcate routers present in different areas. • Source Address: Address of source user node. • Dest. Address: Address of destination user node. • Both the addresses will have extra byte to differentiate between router and user nodes. • Link ID: Router ID of router present at end of link. • Hop Length: distance to router. • K Value: number of routers to send.

7. Routing Algorithm Table Building and Updation: • Similar to Link State. • Periodic Hello messages are sent. • If the address in the Link ID is user address of same area, store the link ID and hop count even if it is not shortest path. • If user address is of different area, store only shortest path. • If address in Link ID is router address, store shortest path only.

8. Routing Algorithm Packet Forwarding: • Depends on k and Area ID. • K = 1 => Send to lowest distance. • K = 2 => Check Area and then send. • If 2 addresses are in the same area as the default router and 1 in a different area, then send to two in same area. • Path decided via comparing total hop count. • If 2 addresses in different area than default router and 1 in the same area, if distance < threshold send to those addresses in different area else send to 1 address in same area and least distant address in other area • K = 3 => Send to all using best possible path i.e. total hop count to be least

9. Data Plane Forwarding R5 R2 R1 Network 1: All are in same area R3 R6 R4 R7 • Router will check total hop count for each destination. • Table at R1 will have all possible routes to all three destinations. • Will select the best path based on total hop count. • Based on that will send to R3 which will forward it to R6 and so on.

10. Data Plane Forwarding R2 R1 R4 Network 2 R3 R5 R6 • Router R1 will have all possible paths to D1. • But, will have only single path to D2 and D3 as they are in different area. • Checks best path for D1 and matches it with paths to D2 and D3. • So, split occurs at R3.

11. Summary • Key protocol design features (recap) • Uses Area ID and Number of Hops(Distance) for decision of number of destinations to send. • Checks and compares next total hop count to split packet. • Performance (For the above two examples) • Overhead increases as bytes are added for area ID and address differentiation. • For large networks, memory requirements will NOT increase exponentially because of differentiation in area. • Router processing time increases. • Implementation complexity • Header length for each packet increases. • Extra storage requirements for entries within area. • Router computational complexity is high.