Transcript Slides
Ants The Active Node Transfer System By Chris McAnally & Manu Mittal 1 The Current Network Architecture • Currently routing behavior is fixed – But performance is heavily dependant on network services – New protocols and services are rapidly being developed but deployment is long and difficult • One Solution – Standardize the communications model rather than individual protocols. 2 Ants Overview • Treats the network as a restricted distributed computing environment. – Provides a scripting language model to express new protocols as operations at nodes. – Allows dynamic deployment 3 Goals • 3 Goals – Simultaneously support a variety of protocols and services – Support the construction of new protocols through mutual agreement – Support dynamic deployment of new protocols 4 The model • Capsule – To replace the packet we use capsules which refer to the forwarding routine used to process them. • Code Groups – A collection of Capsules whose forwarding routines are transferred as a group by the code distribution system. • Protocols – A collection of related code groups that are treated as a single unit of protection. 5 Architecture • INSERT PICTURES HERE 6 Type Field • An Identifier that tells the associated protocol and forwarding routine. – Based on a secure hash of the forwarding routine. • MD5 hash function – Provides a fingerprint of code for security • Prevents protocol spoofing 7 Active Nodes • The biggest problem with a programmable network is ensuring the safety of forwarding routines. • Solution – Each node provides a set of primitives that are used to construct forwarding routines – Active nodes limit access to resources 8 Node Primitives • 10 Primitives that fall into 3 categories – Environment Calls • Return local information, such as address, etc. – Storage calls • Objects stored in a “soft-state” i.e. cached • Application determines the caching interval – Control Operations • If no control operation is called, it’s discarded. 9 Execution Model • Four main Characteristics – Fixed Forwarding Routine • The forwarding routine is fixed at the sender • Designed to prevent a bandit from hijacking another application’s capsules – Selective Execution • Capsules belonging to protocols the active node chooses not to execute are handled as regular IP packets 10 Execution Model(continued) • Resource Limits – Cache time – Soft-state storage space – Network bandwidth • Protocol-based Protection – Only capsules belonging to the same protocol can share state 11 Code Distribution System • 1). Capsules identify their type • 2). When a capsule arrives at a node the cache is checked. If it’s not there the previous node is queried and execution is suspended. • 3). When a node receives a load request it responds immediately. • 4). When a node receives a load response it places it into the cache and activates the sleeping capsules. 12 13