Simple Network Routing and Addressing Scheme for Efficient Packet Forwarding

ECE 544 Project3 Team member: BIAO LI, BO QU, XIAO ZHANG

Assumptions and Address Scheme • Assumptions • End hosts can only connect to one router • Same content available at multiple end nodes • the path cost between adjacent router is 1. • Host and content can move at any time • Naming scheme and eventual address scheme • Router ID (statically assigned, range 0~255) • End hosts ID (statically assigned, range 0~255) • Content ID (statically assigned, range 0~255)

Our Goal Keep it simple

We Don't care • How to assign a Address to a Host • How to assign a Address to a Router • How to generate a ID for a Content

We Do care • How to forward a packet • How to build a forwarding table

Forwarding Table (@ R1) H2 C1 C2 R5 C3 H1 2 2 1 1 3 R1 R2 R3 R4 H3

Scenario 1: @host_H1: get (content_C2) Packet FilePacket C2 H2 1 C1 R5 2 C3 H1 2 1 2 1 3 R1 R2 R3 R4 H3

Then … ... How to build a Forwarding table?

Resource Table • maintained at each router • contains the location information regarding host and content • when ID is content, owner ID is a list of hosts. • when ID is host, owner ID is its directly connected router. H2 C1 C2 R5 C3 H1 2 2 1 1 3 R1 R2 R3 R4 H3

Routing Table • need not to be computed every time unless something changed in link-state table H2 C1 C2 R5 C3 H1 2 2 1 1 3 R1 R2 R3 R4 H3

Then … ... How to build a Routing table?

Routing Table (shortest path) • need not to be computed every time unless something changed in link-state table (for example: @R2) H2 R5 2 2 1 3 R1 R2 R3 R4

Link-State Table ( the same at each router ) • remain unchanged after routers boot up unless some new router is added or failure of some router is detected. R5 2 2 1 3 R1 R2 R3 R4

Router Bootstrapping and Discovery • Each Router find its directly connected neighbors • Exchange the information of neighbors • Each router would have the same view of the global topology • Each router can computes its shortest path to reach other router

Neighbor R5 2 2 1 3 R1 R2 R3 R4

Neighbor @ R5 @R5 H2 C1 C2 R5 C3 1 2 H1 1 2 1 1 2 2 3 R1 H3 R2 R3 R4

Loop-free Note that we includes the complete paths as a enumerated list of routers when flooding the message.As long as a router finds itself included in the path, it would ignore this message to avoid path loop. When R1 receives the message sent by R2 that <R1 is neighbor of @R2, PATH: R1- R2>, R1 no longer relays the message. R5 2 2 1 3 R1 R2 R3 R4

Then … ... How to build a Resource table?

Host Bootstrapping and Discovery Consider H1 that first gets configured in R1 R5 R5 H1 H1 2 2 2 2 2 1 1 1 1 3 3 R1 R1 R2 R2 R3 R3 R4 R4

Resource table in each router R5 R5 H1 H1 2 2 2 2 2 1 1 1 1 3 3 R1 R1 R2 R2 R3 R3 R4 R4

Disconnection of host Do it in the same way! R5 R5 H1 H1 2 2 2 2 X 1 1 1 2 1 3 3 R1 R1 R2 R2 R3 R3 R4 R4

Content Bootstrapping and Discovery Use the same approach as host advertisement H2 H2 C1 R5 R5 H1 H1 2 2 2 2 1 1 1 1 2 1 3 3 R1 R1 R2 R2 R3 R3 R4 R4 H3 H3

One forwarding table does all !!! • For every packet, the destination is either Host ID or Content ID. The router always find the next-hop from the forwarding table.

Packet format

Header format All packets have the same header structure! Header | Version 3 bit | Type 5 bits | | Dest ID 8 bits | | Src ID 8 bits | | Type: • Heartbeat: monitor the liveness of router and host • Neighbor: exchange the neighbor info. • Host Discovery: host actively joins or leaves the network • Content Discovery: content adds to or withdraw from the network • Get Content Request • Get Content Respond: reply with content data • ACK

Data Transfer and Reliability • Message Forward • Not support Multicast • ARQ Scheme • receive windows • timeout for each data request packet • ACK for routing information packet • NO ACK for data packet

Scenario 2: @host_H1: get (content_C2) C2 H2 C3 C1 C2 R5 C3 H1 R1 R2 R3 R4 H3 C

Scenario 3: @host_H1: get (content_C1) X H1 Send C1 H2 H3 H4 Send C1 C2 C3 Get C1 C1 C1 C1 Get C1

Advantages and Disadvantages Pros • Simple and Scalable • Efficient: can choose the nearest provider • Automatically forward a packet to other provider if the original one unavailable. Cons • Throughput is not perfect by using timeout scheme for data packet.

Simple Network Routing and Addressing Scheme for Efficient Packet Forwarding