Transcript 12-Namingx
Naming for Mobile Systems Karthik Dantu and Steve Ko Administrivia • “Embedded Android”, now available via library.buffalo.edu • Friday project meetings • Record/Replay • Latency Measurement • End-End Connectivity Naming Systems • What is Naming? • Examples • DNS/IP Address/MAC Address • CDNs e.g., Akamai • Filesystem • Phone Book • Features • Map known information to required information • Ease of registration/use Intentional Naming System • Naming System for Wireless/Mobile World • Challenges • Resource/Service Mobility • Client Mobility • Essential Features • Expressiveness • Responsiveness • Robustness • Easy Configuration INS: Features • Naming based on Intent as opposed to location • Architecture uses what service as opposed to where to find it • Clients request a service without listing end nodes – level of indirection • Integrates name resolution and message routing • Binding at message delivery time • Binding/message routing is best effort • Message routing • Intentional anycast • Intentional multicast • Runs on top of IP on an overlay network INS Architecture • Overlay of Intent Name Resolvers (INRs) • Clients can use network or intent naming • Name-specifiers: Hierarchical attribute-value pairs Name Discovery • INRs form overlay network • Replicate information via periodic and triggered updates • Services disseminate information via soft state • Clients request service via name discovery msg • Updates • Network address • Application adv metric • Next Hop INR • Unique AnnouncerID Name Lookup • Name Record: List of IP addresses of the destinations with next hop info • Name Tree: Super-position of all name specifiers with app-specific metrics Name Lookup • LOOKUP_NAME Algorithm: Search for sub-tree that corresponds to the requested name-specifier • Returns name-record with all such sub-trees • Domain Space Resolver to track all active INRs Unmanaged Internet Architecture (UIA) • Motivation • Provide secure peer-peer access for personal/social groups independent of different forms of network connectivity • Simplify naming in such personal groups • Provide robust connectivity independent of infrastructure • Challenges • Mobility • Scalability • Dynamics • UIA: Device Introduction • Simple multiple choice device introduction • Handshake puts devices in same personal group • Devices gossip amongst each other to discover other devices Group Management • Owned by one or more members, or by another group • Ownership is transitive • Ownership disputes resolved by putting disputing parties in two separate (new) groups, and revoking access to previously accessible groups • EID: Endpoint Identifiers are cryptographically unique IDs for devices • Name resolution resolves to EIDs • Separate EIDs for every user on every device Naming Principles • Resolved right to left • Phone.Alice • New additions appear as sub-groups • E.g., If Alice added Bob, Bob’s root group appears as a sub-group, and vice-versa • Can be circular e.g., Phone.Bob.Alice • Label conflicts: Resolution does not work until conflict is fixed Naming Management • UIA uses log records • Four types of records • Create: Initiate a new series • Link: Attach a human-readable label to EID/Series ID • Merge: Join two series to form a single group. Requires ownership or permission from both owners • Cancel: Nullifies a record • Example • Phone: Create • Laptop: Create • Phone: Merge • Alice: Merge Overlay Network • UIA builds an overlay network for connectivity • To reach an EID, it floods the network • Each device maintains up to a set number of connections with its peers • Peer connections picked according to stability and friendship distance • Maintains list of potential peers – initialized by gossiping • Token-limited flooding (instead of hop count) • Overlay has highly non-uniform degree • Not much point searching all devices in given network • Location request = (EID, IP,port list of devices traversed)