Akamai Technologies, Inc.

Massachusetts Institute of Technology

Akomai Technologies, Inc.

Matthew S Levine

F Thomson Leighton

Daniel M Lewin

Adrian Soviani

Ravi Sundaram

David R Karger

Eric Lehman

Robert D Kleinberg

Rina Panagrahy

Andrew Parker

Rizwan S Dhanidina

James M Kretchmar

Srikanth Thirumalai

Rina Panigrahy

Jay Parikh

Hariharan Rahul

Bruce Maggs

Yoav O Yerushalmi

Anne E Lewin, Legal Representative

Arthur Wagner Berger

Rizwan S Dhanldina

Silvina Hanono-Wachman

Hariharan Shankar Rahul

Andrian Soviani

Madhukar R Korupolu

Jay Gunvantrai Parikh

Nameserver addresses are correlated in a multi-tier name server hierarchy comprising a first level authority for a domain, and one or more second level authorities to which the first level authority delegates with respect to a particular sub-domain associated with the domain. Preferably, the first level authority is IPv4-based and at least one second level authority is IPv6-based. The first level authority responds to a request issued by a client caching nameserver (a 'CCNS') and returns an answer that includes both IPv4 and IPv6 authorities for the domain. The CCNS is located at an IPv4 source address that is passed along to the first level authority with the CCNS request. The first level authority encodes the CCNS IPv4 source address in the IPv6 destination address of at least one IPv6 authority. Then, when the CCNS then makes a follow-on IPv6 request (with respect to the sub-domain) directed to the IPv6 authority, the IPv6 authority knows both the IPv6 address of the CCNS (as well as its IPv4 address. The IPv6 authority maintains the IPv4-IPv6 correlation. Over time, the IPv6 authority builds up a database of these CCNS IPv6-IPv4 associations.

Correlating nameserver IPv6 and IPv4 addresses

A method for Internet delivery in a delivery network established at network locations, the delivery network comprising a plurality of content servers for serving resources. The servers include a plurality of subsets, each subset being located at one of a plurality of Internet data centers. For each Internet Protocol (IP) address block from which requests for content resources are expected to be received, the method generates a candidate list of data centers to be used to service the requests. For the IP address block, the method selects at least one of the data centers from the candidate list. The selected Internet data center for the IP address block is written into a network map. In response to a DNS query, the map is used to identify one of the Internet data centers from the candidate list to be used to service a request for a content resource.

Network performance monitoring in a content delivery system

A method of correlating nameserver addresses is implemented in a multi-tier name server hierarchy comprising a first level authority for a domain, and one or more second level authorities to which the first level authority delegates with respect to a particular sub-domain associated with the domain. Preferably, the first level authority is IPv4-based and at least one second level authority is IPv6-based. The first level authority responds to a request issued by a client caching nameserver (a 'CCNS') and returns an answer that includes both IPv4 and IPv6 authorities for the domain. The CCNS is located at an IPv4 source address that is passed along to the first level authority with the CCNS request. According to a feature of this disclosure, the first level authority encodes the CCNS IPv4 source address in the IPv6 destination address of at least one IPv6 authority. Then, when the CCNS then makes a follow-on IPv6 request (with respect to the sub-domain) directed to the IPv6 authority, the IPv6 authority knows both the IPv6 address of the CCNS (by virtue of having received it in association with the request) as well as its IPv4 address (by virtue of the encoding). The IPv6 authority maintains the IPv4-IPv6 correlation. Over time (i.e., as other CCNSs make requests), the IPv6 authority builds up a database of these CCNS IPv6-IPv4 associations.

Method and apparatus for correlating nameserver IPv6 and IPv4 addresses

The invention relates to an apparatus for responding to data requests made by a client. The apparatus includes an input receiving a first data request that includes a sequence of nodes corresponding to a sequence of servers. The apparatus also includes decision logic determining whether the data specified in the data request is available on a selected server, and if the data is not available determining a next node from the sequence of nodes. The apparatus also includes a mapper mapping a server to the next node, and an output requesting the data by transmitting a second data request to the server mapped to the next node.

Method and apparatus for distributing requests among a plurality of resources

A method for Internet content delivery in a content delivery network established at network locations, the content delivery network comprising a plurality of content servers for serving content resources. The plurality of content servers includes a plurality of subsets of content servers, each subject being located at one of a plurality of Internet data centers. For each Internet Protocol (IP) address block from which requests for content resources are expected to be received, the method generates a candidate list of Internet data centers to be used to service the requests for content resources. For the IP address block, the method selects at least one of the Internet data centers from the candidate list to be used to service the requests for content resources. The selected Internet data center for the IP address block is written into a network map. The selecting step is carried out concurrently for each IP address block from which requests for content resources are expected to be received such that the network map comprises the selected Internet data center for each IP address block. The network map is then provided to a domain name service (DNS) associated with the content delivery network. In response to a DNS query received at the domain name service associated with the content delivery network, the network map is used to identify one of the Internet data centers from the candidate list to be used to service a request for a content resource.

The invention relates to a method and apparatus for distributing a request to one of a plurality of resources. A request is mapped to a location in circular mapping space using a hash function. Each of the plurality of resources is mapped to a respective location or locations in the circular mapping space. The request is allocated to one of the resources based on the given request location and the resource location in the circular mapping space.

The invention is an intelligent traffic redirection system that does global load balancing. It can be used in any situation where an end-user requires access to a replicated resource. The method directs end-users to the appropriate replica so that the route to the replica is good from a network standpoint and the replica is not overloaded. The technique preferably uses a Domain Name Service (DNS) to provide IP addresses for the appropriate replica. The most common use is to direct traffic to a mirrored web site.

Global load balancing across mirrored data centers

A network architecture or framework that supports hosting and content distribution on a truly global scale allows a Content Provider to replicate and serve its most popular content at an unlimited number of points throughout the world. The inventive framework comprises a set of servers operating in a distributed manner. The actual content to be served is preferably supported on a set of hosting servers (sometimes referred to as ghost servers). This content comprises HTML page objects that, conventionally, are served from a Content Provider site. A base HTML document portion of a Web page is served from the Content Provider's site while one or more embedded objects for the page are served from the hosting servers, preferably, those hosting servers near the client machine. By serving the base HTML document from the Content Provider's site, the Content Provider maintains control over the content.

Network performance monitoring in a content delivery service

The invention relates to a method for requesting data from one of a plurality of actual servers. A virtual network of servers is generated in response to a data request. A first virtual server in the virtual network is chosen randomly, and a path generated from the first virtual server to a root virtual server. At least one virtual server on the path is mapped to a respective one of the plurality of actual servers and data is requested therefrom.

An intelligent traffic redirection system performs global load balancing for Web sites located at mirrored data centers. The system relies on a network map that is generated continuously, preferably for the user-base of the entire Internet. Instead of probing each local name server (or other host) that is connectable to the mirrored data centers, the network map identifies connectivity with respect to a much smaller set of proxy points, called 'core' (or 'common') points. A core point is representative of a set of local name servers (or other hosts) that, from a data center's perspective, share the point. To discover a core point, an incremental trace route is executed from each of the set of mirrored data centers to a local name server that may be used by client to resolve a request for a replica stored at the data centers. An intersection of the trace routes at a common routing point is then identified. Thus, for example, the common routing point may be the first common point for the trace routes when viewed from the perspective of the data centers (or the last common point for the trace routes when viewed from the perspective of the local name server). The common routing point is then identified as the core point for the local name server.

Method for generating a network map

The invention relates to distributing a request to one a plurality of resources. A request is mapped to a location in mathematical mapping space. Each of the plurality of resources is mapped to a respective location or locations in the mathematical mapping space. The request is allocated to one of the resources based on a mathematical relationship between the request location and the resource location in the mathematical mapping space.

An intelligent traffic redirection system performs global load balancing for Web sites located at mirrored data centers. The system relies on a network map that is generated continuously for the user-base of the entire Internet. Instead of probing each local name server (or other host) that is connectable to the mirrored data centers, the network map identifies connectivity with respect to a much smaller set of proxy points, called 'core' (or 'common') points. A core point then becomes representative of a set of local name servers (or other hosts) that, from a data center's perspective, share the point. Once core points are identified, a systematic methodology is used to estimate predicted actual download times to a given core point from each of the mirrored data centers. Preferably, ICMP (or so-called &#x201c;ping&#x201d; packets) are used to measure roundtrip time (RTT) and latency between a data center and a core point. Using such data, an average latency is calculated, preferably using an exponentially time-weighted average of all previous measurements and the new measurement. A similar function is used to calculate average packet loss. Using the results, a score is generated for each path between one of the data centers and the core point, and the score is representative of a file download time. Preferably, the score is generated by modifying an average latency with a penalty factor dependent on the time-weighted average loss function. Whichever data center has the best score (representing the best-performing network connectivity for that time slice) is then associated with the core point.

Method for predicting file download time from mirrored data centers in a global computer network

An intelligent traffic redirection system performs global load balancing. The system uses a network map that is generated in part by extending a 'sparse' IP address data map. In particular, a method of extending an IP address block map begins by defining a set of one or more upper bound block(s). These upper bound blocks are then used to partition a space of IP addresses into subsets or 'territories', wherein each territory represents a largest set of IP addresses to which a piece of mapping data may be extended. The &#x201c;piece&#x201d; of mapping data typically consists of a host (usually a &#x201c;name server&#x201d; identified by the core point discovery process) IP address and some data about that host, namely, a &#x201c;nearest&#x201d; data center or a flag indicating that either &#x201c;no data&#x201d; exists for that host or that the system is &#x201c;indifferent&#x201d; as to which of a set of mirrored data centers the host should be mapped. A unification algorithm partitions the territory of each upper bound block into the largest possible sub-blocks in which a given unanimity criterion is satisfied and extends the mapping data in each such sub-block to all of the territory of that sub-block.

Growing community of inventors

Brookline, MA, United States of America

Matthew S Levine