Internet Indirection Infrastructure Ion Stoica and many others… UC Berkeley

2 Motivation Today’s Internet is built around a unicast point-to-point communication abstraction: –Send packet “p” from host “A” to host “B” This abstraction allows Internet to be highly scalable and efficient, but… … not appropriate for applications that require other communications primitives: –Multicast –Anycast –Mobility –Service composition

3 Our solution: Internet Indirection Infrastructure (i3) Each packet is associated an identifier id To receive a packet with identifier id, receiver R maintains a trigger ( id, R) into the overlay network Sender idR trigger iddata Receiver (R) iddata R

4 Service Model API –sendPacket( p ); –insertTrigger( t ); –removeTrigger( t ) // optional Best-effort service model (like IP) Triggers periodically refreshed by end-hosts ID length: 256 bits

5 Mobility Host just needs to update its trigger as it moves from one subnet to another Sender Receiver (R1) Receiver (R2) idR1 idR2

6 iddata Multicast Receivers insert triggers with same identifier Can dynamically switch between multicast and unicast Receiver (R1) idR1 Receiver (R2) idR2 Sender R1data R2data iddata

7 Anycast Use longest prefix matching instead of exact matching –Prefix p: anycast group identifier –Suffix s i : encode application semantics, e.g., location Sender Receiver (R1) p|s 1 R1 Receiver (R2) p|s 2 R2 p|s 3 R3 Receiver (R3) R1 data p|a data p|a data

8 Service Composition: Sender Initiated Use a stack of IDs to encode sequence of operations to be performed on data path Advantages –Don’t need to configure path –Load balancing and robustness easy to achieve Sender Receiver (R) id T T id R Transcoder (T) T,id data iddata R id T,id data id T,id data

9 Service Composition: Receiver Initiated Receiver can also specify the operations to be performed on data Receiver (R) id id F,R Firewall (F) Sender id F F id F,R data R F,R data id data id data

10 Basic Design Decisions 1)Host-controlled routing 2)Semanticless IDs 3)ID matching scheme

11 1) Host-Controlled Routing i3 gives end-hosts or/and 3 rd parties the ability to control routing –A trigger is like a routing entry Highly flexible: after all routing is the main functionality provided by a network! –Use cryptographic techniques to prevent most attacks on infrastructure Security implications: –Protection against DoS: at i3 level a host is not reachable unless it inserts a “path” that points to itself –Anonymity: easy to use onion-like routing

12 2) Semanticless Identifiers An ID can identify “anything” –Interface –Router or end-host –Service –Session end-point –A packet –… The meaning of the ID is determined by applications (or higher layers) –Think of application-level resolution of IDs

13 3) ID Matching Longest prefix matching Matching multiple entries

14 Implication of Design Decisions Host-controlled routing Sementicless IDs ID Matching Mobility Anycast Multicast Service composition

15 Open Questions Management Economic model Quality of service …

16 Status i3 available as a service on Planetlab Support for legacy applications in Linux and Windows XP/2000 – OCALA (Overlay Convergence Architecture for Legacy Applications) Current applications –Mobility –Transparent access to machines behind NATs –Secure and transparent access to services behind firewalls Available: – –