ECE 544 Project 3 Content-based Routing

Transcription

1 ECE 544 Project 3 Content-based Routing Aishwarya Babu Rakesh Ravuru Sudarshan Kandi

2 Assumptions and Address Scheme Assumptions End hosts can only connect to routers Each host is directly connected to single router Same content available at multiple end nodes When new node is added, connections are setup Topology cannot change, content can. Addressing Content ID based addressing No dependence on IP address Hosts identified by router port numbers

3 Bootstrapping and Discovery Algorithm Routers and end hosts exchange advertisements at boot up and when contents change Distance vector based Discovery Routers already know about other routers and hosts.

4 Content routing algorithm Tables maintained at router Routing table to process requests Request tables to process responses Size of tables fixed Tables are based on ace numbers and Content IDs

5 Routing Table Content ID Out ace/ Port # of Hops C Content ID is the Key of this table Out ace/ Port indicates direction to forward the request of Content ID # of hops is the minimum number of hops from the router to the content. Lowest hop count is maintained for any given content ID. Size of the table is limited to the number of Content IDs If packet header = REQ, consult Routing table

6 Request Table In Port/ ace Request Content ID C7 C9 55 C7 In Port/ ace is the Key of this table Request Content ID maintains request - interface mapping indicates if the request is still active and accordingly multicasts response Size of the table is limited to the number of Ports If packet header = RES, consult Request Table

7 Advantages fixed sized tables No need for dynamically resizing tables Request table has one table row dedicated to each port/ interface Avoids overwriting/ merging issues when multiple threads access the same resource (request table)

8 Request - H: get() H C H R R

9 Request - H: get() H C H R R

10 Request - H: get() H C H R R

11 Request - H: get() H C H R R

12 Request - H: get() H C H R R

13 Response H C H R R

14 Response H C H R R

15 Response H C H R R

16 Response H C H R R

17 Multiple requests Content ID Out ace/ Port # of Hops C In Port/ ace Request Content ID 55 C7

18 Request - H: get() H C H R R C

19 Request - H: get() H C H R R C

20 Request - H: get() H C H R R C

21 Response H C H R R

22 Response H C H R R

23 Response H C H R R

24 Response H C H R R

25 Packet Formats Content updating algorithm Send ADX packet to all neighbors only when the node undergoes an update (i.e change in routing table) Message Types: ADR Advertisement Router ADH Advertisement Host RES Response REQ Request

26 Packet Formats Type ADR / ADH 3 Bytes RT Hop Count bit Bytes Type Message Type Payload REQ Get RES Content Data 3 Bytes Byte 3 Bytes Byte 496 Bytes

27 ADH Alternative Type ADH 3 Bytes Content Binary 3 bytes Content field contains 56 bits Each bit represents the presence of or lack of the said content. Hop count will only exist for those contents listed as. Works best for host advertisements who are less likely to host the entire library ( < < 55)

28 Data Transfer and Reliability Periodic hello packets To indicate that node is still alive it sends a small hello packet periodically to it s neighbors and expects a hello packet back If no Hello for certain time resend a hello packet and if no response after fixed tries/ time out, update routing table to NULL/ inf and then advertise

29 Data Transfer and Reliability Message Forward Multicast when multiple Content ID entries ARQ Scheme End-to-end Stop-and-wait; receiver requests content again. To avoid caching at the router

30 Disconnected node H Update Advertisement ADH.. H C H R R

31 Disconnected node H Update Advertisement ADR 3 inf 4 C H R R

32 Disconnected node H Update Advertisement ADR 3 inf 4 C H R R R Update Advertisement ADR 3 3

33 Disconnected node H Update Advertisement ADR C H R R R Update Advertisement ADR 3 3