A Na Native C Content Di Discover ery Mechan anism f for or - - PowerPoint PPT Presentation

A Na Native C Content Di Discover ery Mechan anism f for

• r NDN

Onur Ascigil, Vasilis Sourlas, Ioannis Psaras, and George Pavlou Department of Electronic and Electrical Engineering, University College London, UK

1

Outlin line

• Content discovery
• Opportunistic Off-path Content Discovery
• Forwarding Strategies
• Results
• Future Work &Conclusions

2

Cont ntent nt D Discovery

3

Content Discovery

• Goal: Retrieve a nearby (ideally the nearest!) copy of the content
• Difficult to achieve without significant ``overhead’’ in practice
• Why?
• Placement of Data into the Content Stores happens frequently
• What does NDN/CCN do?
• Route Interests to content origins
• Search content opportunistically on-path (i.e., along the default path)
• Existing Solutions for Content Discovery:
• Opportunistic on-path
• Coordinated off-path

4

Content Discovery

• Opportunistic on-path: limited gain, without overhead
• Coordinated off-path: coordination and communication overhead
• Using control plane: Advertise content names
• Using a function: A Hash function determines the placement and routing
• …
• What do we propose?
• integrate an “opportunistic off-path content discovery mechanism” to the existing

Interest/Data processing pipeline of NDN

• With minimal changes to NDN packet processing
• Without introducing excessive overhead

5

Opportunistic Of Off-path C Content Discovery

6

Opportunistic off-path Content Discovery

• Satisfied Interest Table (SIT): Caches trails of Data packets

Interest /ndn/xyz R S T U Prefix Next-hop /ndn T Prefix Next-hop /ndn U

…

Data /ndn/xyz Interest /ndn/xyz Name Next-hop

/ndn/xyz

T Name Next-hop

/ndn/xyz

S H1 H2 Prefix Next-hop /ndn T FIB FIB SIT SIT FIB

7

For

• rwarding St

g Strategi egies es with F FIB & B & SI SIT

8

Forwarding Strategies with FIB & SIT

• Breadcrumb

R S T U Prefix Next-hop /ndn U

…

Data /ndn/xyz Name Next-hop

/ndn/xyz

S H1 H2 FIB SIT Interest /ndn/xyz Interest /ndn/xyz CS /ndn/xyz Wait in the PIT

9

Name Next-hop

/ndn/xyz

S, R

Forwarding Strategies with FIB & SIT

• Breadcrumb

R S T U Prefix Next-hop /ndn U

…

NACK /ndn/xyz Name Next-hop

/ndn/xyz

S H1 H2 FIB SIT Interest /ndn/xyz Interest /ndn/xyz CS Wait in the PIT

10

Name Next-hop

Forwarding Strategies with FIB & SIT

• Multicast

R S T U Prefix Next-hop /ndn U

…

Name Next-hop

/ndn/xyz

S H1 H2 FIB SIT Interest /ndn/xyz Interest /ndn/xyz CS /ndn/xyz Data /ndn/xyz Data /ndn/xyz

11

Name Next-hop

/ndn/xyz

S, R

Forwarding Strategies with FIB & SIT

• Multicast: Once forwarded downstream, an Interest follows a single SIT trail
• Forwarding Strategy: Pick the freshest matching SIT entry

R S T U Prefix Next-hop /ndn U

…

Name Next-hop

/ndn/xyz

S H1 H2 FIB SIT Interest /ndn/xyz Interest /ndn/xyz CS

12

Forwarding Strategies with FIB & SIT

• Multicast: Once forwarded downstream, an Interest follows a single SIT trail
• Forwarding Strategy: Pick the freshest matching SIT entry

R S T U Prefix Next-hop /ndn U

…

Name Next-hop

/ndn/xyz

S H1 H2 FIB SIT Interest /ndn/xyz CS

13

NACK /ndn/xyz Name Next-hop

Res esul ults - Multicast and Br Brea eadc dcrumb St Strategi egies es

14

Results- Settings

• Topology: Rocketfuel ISP topology
• Content Providers: Attached to 16 egress nodes are randomly chosen
• Link Latencies: Penalty for leaving ISP network: extra 50-100 msec
• Network Cache Capacity: %80 of content can be cached in the network
• Request Rate: 100 Requests/sec (origins selected randomly)
• Popularity Distribution: Zipf Parameter 0.7
• Experiment Duration: 1 Hour warm-up and 3 hours of experiment

AS 3257

15

Results with Breadcrumb & Multicast

Overlap

16

Results

• Modified Multicast Strategy:
• Each Interest is associated with a Forwarding Budget
• spend the budget on:
• sending a copy upstream (following FIB)
• sending a copy downstream (following SIT)
• spend it on both
• Cost of sending Interest upstream/downstream
• Static: Deduct one unit per each copy sent downstream.
• Dynamic: Deduct variable amount per each copy sent downstream

17

Multicast with Forwarding Budget (Static)

Name Next- hops /x/y/z Y Q Y R S T N Interest: /x/y/z

Budget = 6

Interest: /x/y/z

Budget = 7

Interest: /x/y/z OFF-PATH SIT Interest: /x/y/z Interest: /x/y/z

Budget = 5

18

Res esul ults - Multicas ast with F Forwar arding B g Budget

19

Res esul ults - Multicas ast with F Forwar arding B g Budget

20

Overlap Satisfaction

Conclus usions ns

• Opportunistic content discovery using SIT table
• Significant increase in the percentage of requests satisfied from

the caches

• Forwarding strategies using SIT/FIB are introduced
• Possible to limit the overhead with a Forwarding Budget and Dynamic Costs
• Requires minimal changes to the packet processing of NDN
• Security
• End-user/host caches are not exploited by the mechanism
• Exclude field can be used to ignore matching SIT entries
• Our scheme inherits the existing cache poisoning problems with NDN

21

Thank you! Questions?

22