Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 1 Questions about Programming the Internet Ken Calvert University of Kentucky USA Why? How? What? Collaborators: Jim Griffioen, students Su Wen, Amit Sehgal, Billy Mullins, and Leon Poutievski

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 2 Question: Why? Why do we want a programmable Internet? –To speed evolution, overcome “ossification” But... stability of basic processing is crucial for the fast path –To customize processing along the network path What do we need beyond forwarding, scheduling? –To improve scalability of group applications Example: Concast –To overcome limitations (info hiding) of the best- effort service abstraction Example: Using Ephemeral State Processing to identify branch points in multicast trees

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 3 Concast Scalability through abstraction –Inverse of multicast Single address represents an arbitrary number of senders. –Network merges messages from the group According to user-supplied merge specification (=program) Benefits both receiver and network –Multiple sends result in a single message delivery –Reduced bandwidth requirements Merging happens exactly where required (on direct path to R) S R S S S S S R R R R R Multicast Concast

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 4 Question: Why? Why would providers want a programmable Internet? –Because users will pay to get it (see also Wakeman) Why trust shared infrastructure to... –Forward packets to specified destinations? –Reserve end-to-end bandwidth/buffering for their packets? –Process user data to improve scalability? Example: multicast feedback aggregation/filtering –Process content en route from content provider? Example: transcoding news video for low-bandwidth links –Enforce user policies? Example: controlling concast group membership

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 5 Concast Security Policies User (Receiver) Concern: Data integrity, authenticity, confidentiality –Application-level policy: Which senders can participate –Network-level policy: Which routers (domains) can participate in the flow (i.e. be upstream) Perform merging Enforce policies! Provider (Router) Concern: Only paying customers get access to the service –Network-level policy: Which entities can participate as senders/receivers –Network-level policy: Which routers (domains) can be downstream/upstream

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 6 R0 Sender Policy R0 Downstream Policy R0 Upstream Policy Policy Monotonicity Requirements Sender Receiver 4. Merge Specification R0 1. Join Flow Request 2. Request for Merge Spec Rcvr Sender Policy Rcvr Upstream Policy 3. Apply policies Rcvr Sender Policy R0 Sender Policy R0 Downstream Policy R0+Rcvr Upstream Policy Merge Spec 5. Apply policies, install merge spec 6. Join Flow Succeeded R1 Domain Boundary R1 Downstream Policy R1 Upstream Policy

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 7 R1 Downstream Policy R1 Upstream Policy Policy Monotonicity Requirements Sender Receiver Rcvr Sender Policy Rcvr Upstream Policy 4. Merge Specification Rcvr Sender Policy R0 Sender Policy R0 Downstream Policy R0+Rcvr Upstream Policy Merge Spec R0 1. Join Flow Request 2. Request for Merge Spec 3. Apply policies 5. Apply policies, install merge spec 6. Join Flow Succeeded R1 Rcvr Sender Policy R0+R1 Sender Policy R1 Downstream Policy R0+R1+Rcvr Upstream Policy 8. Merge Specification 7. Request for Merge Spec Domain Boundary

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 8 Question: How? How should the network be programmed? –Lots of possible answers; depends on assumptions –We have only begun to explore this (see also Tschudin, Smirnov) How to charge for a programmable Internet? –At signaling time, not forwarding time Untrusted  trusted transformation, policy application too costly for data plane –Locally, not end-to-end At least two providers involved in end-to-end service Avoid multilateral settlement protocols, transitive trust

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 9 Two-level Model of Programmability Node-local functions enabled directly by user Examples: duplicate, redirect, drop –Controlled via secure signaling protocol –Affect only packets “belonging to” the paying user –Paid for at signaling time via bilateral agreement between end user and node administration End-to-end functions available to all packets –IP-like resource requirements (“too cheap to meter”) –Fixed set of computations Close to fast path –Sequence of per-packet computations + ephemeral state = global computations

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 10 Lightweight Processing Modules and Ephemeral State Processing LWP: fixed-function per-flow modules –Invoke at particular node(s) –User supplies flowspec, function + params, credit card –Maintain via soft-state –Use to implement: multicast, mobility, anti-DoS ESP: allow packets to create, manipulate small amounts of state in routers at forwarding time Example: increment a counter, drop packet if > threshold –Fixed instruction set; one instruction per packet –Per-packet processing, storage requirements bounded due to state lifetime –Narrow interface to forwarding function: drop or forward –Use to: probe topology, aggregate user data (a la concast),...

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 11 Example: Multicast via ESP+LWP LWP “dup()” function installed by receivers to duplicate and forward marked packets to themselves To join the tree: –Discover closest existing branch point (via ESP) –Activate a dup() to self there –Find optimal branch point (via ESP), move dup() there r2 A B r1 C r3 DE S dup  B () dup  C () Join

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 12 Example: Multicast via ESP+LWP LWP “dup()” function installed by receivers to duplicate and forward marked packets to themselves To join the tree: –Discover closest existing branch point (via ESP) –Activate a dup() to self there –Find optimal branch point (via ESP), move dup() there r2 A B r1 C r3 DE S dup  B () dup  C () r1

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 13 Example: Multicast via ESP+LWP LWP “dup()” function installed by receivers to duplicate and forward marked packets to themselves To join the tree: –Discover closest existing branch point (via ESP) –Activate a dup() to self there –Find optimal branch point (via ESP), move dup() there r2 A B r1 C r3 DE S dup  B () dup  C () dup  E ()

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 14 Example: Multicast via ESP+LWP LWP “dup()” function installed by receivers to duplicate and forward marked packets to themselves To join the tree: –Discover closest existing branch point (via ESP) –Activate a dup() to self there –Find optimal branch point (via ESP), move dup() there r2 A B r1 C r3 DE S dup  B () dup  C () dup  E () r2

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 15 Example: Multicast via ESP+LWP LWP “dup()” function installed by receivers to duplicate and forward marked packets to themselves To join the tree: –Discover closest existing branch point (via ESP) –Activate a dup() to self there –Find optimal branch point (via ESP), move dup() there r2 A B r1 C r3 DE S dup  B () dup  C () dup  E ()

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 16 Programmability via LWP and ESP Deployment strategy –Recover costs via LWP Value-added: end-to-end services like multicast –Deploy ESP to enable LWP End-to-End Services –Multicast –Layered multicast congestion control –Open issue: what others? –Can we do QoS with custom processing at 1-2 nodes? –Are congestion location/timescales consistent with LWP- based approach?

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 17 Question: What? What to program? Do processing here not here Channel –Global fault-tolerance –Run at channel speed –Simple interface to forwarding path Interconnect –Not fail-safe –Maintain forwarding state –Run at interconnect speed = (wire speed) n How to structure services as channel computations? (See also Tschudin, Che)

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 18 Research Issues Design of “trustworthy” infrastructures for combined communication/processing –Incentive/trust acquisition/revocation? –Composable policies, proxy enforcement? “Policy: the Next Frontier” Connection to ad hoc, P2P Programming models for relay systems (consider trust)! –Necessary and sufficient set of (channel-oriented) functions? –What can be done with local enhancements? Is local differentiation sufficient for E2E QoS? Congestion episode timescales, bottleneck movement Connection to measurement, modeling –Design of “best effort” end-to-end computations

Calvert Ne X tworking’03 June 23-25,2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN N ETWORKING 19 References Concast: Design and Implementation of an Active Network Service, K. Calvert, J. Griffioen, B. Mullins, L. Poutievski, A. Sehgal, S. Wen, IEEE JSAC 19(3), March 2001 Lightweight Network Support for Scalable End-to-end Services, K. Calvert, J. Griffioen, S. Wen, Proceedings of ACM SIGCOMM 2002 Building Multicast Services from Lightweight Processing Modules and Ephemeral State, J. Griffioen, S. Wen, K. Calvert, Computer Networks 38(3), February 2002 CALM: Congestion-Aware Layered Multicast, S. Wen, j. Griffioen, K. Calvert, Proceedings of IEEE OPENARCH 2002