# Patent

## Title
Explicit strategy feedback in name-based forwarding

## Abstract

One embodiment provides a system that facilitates explicit strategy feedback in a Content-Centric Network (CCN). During operation, the system sends a first interest associated with an explicit strategy feedback request via an egress interface. This egress interface is in a plurality of egress interfaces associated with a same name in a forwarding table. An interest is location-independent and uniquely identifies the content object in the CCN and is routed based on the name in the CCN. The system stores one or more parameters received in response to the explicit strategy feedback request in an entry, which includes the name and the egress interface, in the forwarding table. The one or more parameters are associated with a first device. The system determines, for a second interest for a content object associated with the name, an egress interface from the plurality of egress interfaces based on the stored parameters.

## Background
BACKGROUND
Field
This disclosure is generally related to forwarding in a network. More specifically, this disclosure is related to strategy feedback for network-name-based forwarding.
Related Art
In many computing applications, it is often important for devices in a network to express interests for their respective collections of data. The proliferation of digital content creates a vast number of collections, which require reconciliation. Content-Centric Network (CCN) architectures have been designed to facilitate accessing such digital content. These networks include entities, or nodes, such as network clients, forwarders (e.g., routers and switches), and content producers, which communicate with each other by sending “interest” packets for various content items and receiving “response” packets comprising content objects in return. Unlike a traditional Internet Protocol (IP) network, where an object is tied to its location and its IP address, the content objects in a CCN are identified based on a specific name, which is location-independent.
For example, a border router that is connected to multiple areas of a computer network can subscribe to namespaces for those areas (e.g., “Area 1” and “Area 2”). Other routers that are not border routers may only subscribe to a single area. This way, a router that subscribes to the namespace “Area 1” only obtains network-configuration items for Area 1, and a router that subscribes to the namespace “Area 2” only obtains network-configuration items for Area 2. The border router that subscribes to both namespaces can obtain network-configuration items for Area 1 and Area 2.
Because a network-configuration item's structured name is unique and persistent, a node in a CCN can generate a hash value for each network-configuration item based on the structured name, without having to process the data for each content item. The node can also generate an additive hash for each routing-data collection, based on the hashes for the individual network-configuration items of a routing-data collection, so that the additive hash represents the contents of the routing-data collection. For example, the node can generate the additive hash by using an addition operation (or some other mathematical function) to process the hashes for the individual network-configuration items of the routing-data collection.
In a CCN, a node requests an object using an interest based on the persistent name of the object. A node requesting the object can be referred to as a consumer. This interest can be forwarded to any producer node of the object. As a result, a node in the CCN can have a forwarding database comprising a plurality of producer nodes for the same content name. For efficient forwarding, the node relies on a forwarding strategy to select the producer node to which the interest should be forwarded. Hence, the node can use a forwarding strategy to perform this selection. Though CCN brings many desirable features to a network, some issues remain unsolved for an efficient forwarding strategy.
SUMMARY
One embodiment provides a system that facilitates explicit strategy feedback in a Content-Centric Network (CCN). During operation, the system sends a first interest associated with an explicit strategy feedback request via an egress interface. This egress interface is in a plurality of egress interfaces associated with a same name in a forwarding table. An interest is location-independent and uniquely identifies the content object in the CCN and is routed based on the name in the CCN. The system stores one or more parameters received in response to the explicit strategy feedback request in an entry, which includes the name and the egress interface, in the forwarding table. The one or more parameters are associated with a first device. The system determines, for a second interest for a content object associated with the name, an egress interface from the plurality of egress interfaces based on the stored parameters.
In a variation on this embodiment, the first interest is an individual interest for the explicit strategy feedback request.
In a variation on this embodiment, the first interest is for a content object associated with the name and the explicit strategy feedback request is piggybacked in the first interest.
In a variation on this embodiment, the one or more parameters are received from an underlying Routing Information Base (RIB) storing a route associated with the name.
In a variation on this embodiment, the parameters received in response to the explicit strategy feedback request are one or more of: server load, server disk space, server cost, storage cost, server processing power, network cost, expected service time, network congestion, network reliability, server energy load, server energy consumption, network energy load, and network energy consumption.
In a variation on this embodiment, the system removes the one or more parameters from a response message associated with the first interest in response to the response message reaching a boundary of an administrative domain.
In a variation on this embodiment, the one or more parameters are further associated with a second device, and aggregated for the first and second devices based on an aggregation policy.
In a further variation, the aggregation policy includes one or more of: a mean, a median, the minimum, the maximum, and an inclusive list.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 illustrates an exemplary Content-Centric Network (CCN) with explicit strategy feedback support, in accordance with an embodiment of the present invention.
FIG. 2A illustrates an exemplary forwarding strategy in a CCN with explicit strategy feedback support, in accordance with an embodiment of the present invention.
FIG. 2B illustrates an exemplary communication of piggybacked explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention.
FIG. 2C illustrates an exemplary communication of individual explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention.
FIG. 3A presents a flowchart illustrating the process of a node generating a piggybacked explicit strategy feedback request, in accordance with an embodiment of the present invention.
FIG. 3B presents a flowchart illustrating the process of a node generating an individual explicit strategy feedback request, in accordance with an embodiment of the present invention.
FIG. 3C presents a flowchart illustrating the process of a node generating a piggybacked explicit strategy feedback, in accordance with an embodiment of the present invention.
FIG. 3D presents a flowchart illustrating the process of a node generating an individual explicit strategy feedback, in accordance with an embodiment of the present invention.
FIG. 4A presents a flowchart illustrating the process of an intermediate node forwarding an interest with an explicit strategy feedback request, in accordance with an embodiment of the present invention.
FIG. 4B presents a flowchart illustrating the process of an intermediate node forwarding a response with explicit strategy feedback, in accordance with an embodiment of the present invention.
FIG. 5 illustrates exemplary service clusters in a CCN with explicit strategy feedback support, in accordance with an embodiment of the present invention.
FIG. 6 illustrates an exemplary computer and communication system facilitating explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention.



In the figures, like reference numerals refer to the same figure elements.
DETAILED DESCRIPTION
The following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
Overview
In embodiments of the present invention, the problem of facilitating an efficient forwarding strategy is solved by providing explicit strategy feedback to a forwarding node. In a Content-Centric Network (CCN), a consumer node can obtain a content object (CO) (i.e., a new content item), or an object, at any time by broadcasting an interest packet comprising the persistent name of the object. This interest packet can be referred to as an interest. In this disclosure, the terms “content object” and “object” are used interchangeably. Any producer node (e.g., a server) hosting the content object can respond to that interest and send a response packet comprising the content object to the consumer node. This response packet can be referred to as a response.
A forwarding node (e.g., the consumer node or an intermediate node) can forward the interest to any of the producer nodes. Hence, the forwarding table in the forwarding node can include a plurality of entries for the same content object (i.e., the same name) corresponding to the plurality of producer nodes. As a result, the forwarding node decides the producer node to which the interest should be forwarded based on a forwarding strategy. Without an efficient forwarding strategy, the forwarding node may not be able to select the entry in its forwarding table that is most suitable for the CCN (e.g., has a lower latency or congestion).
To solve this problem, embodiments of the present invention facilitate explicit strategy feedback for a forwarding node. The forwarding node sends an explicit feedback request in an interest to a respective producer node of a content object (i.e., for a respective entry for the name of the content object). This feedback request can be for one or more parameters (e.g., server resource or network condition). Upon receiving the feedback request, the corresponding producer node can send a response comprising the requested feedback. The feedback request and/or the feedback can be in an individual or piggybacked message. The forwarding node can store the feedback in the corresponding forwarding table entry and use the feedback to determine the producer node to which the interest should be forwarded. In this way, a forwarding node becomes aware of the parameters that determine efficient forwarding and can use the parameters to efficiently forward an interest in a CCN.
In some embodiments, the network clients, network nodes (e.g., forwarders such as routers), and publishers communicate over an information-centric network (ICN). In ICN, each piece of content is individually named, and each piece of data is bound to a unique name that distinguishes the data from any other piece of data, such as other versions of the same data or data from other sources. This unique name allows a network device to request the data by disseminating a request or an interest that indicates the unique name, and can obtain the data independently from the data's storage location, network location, application, and means of transportation. In other words, the name can be used to route the interest and the data in ICN. A Named-Data Network (NDN) or a CCN are examples of ICN architecture; the following terms describe elements of an NDN or CCN architecture:
Content Object: A single piece of named data, which is bound to a unique name. Content Objects are “persistent,” which means that a Content Object can move around within a computing device, or across different computing devices, but does not change. If any component of the Content Object changes, the entity that made the change creates a new Content Object that includes the updated content, and binds the new Content Object to a new unique name.
Unique Names: A name in an ICN is typically location-independent and uniquely identifies a Content Object. A data-forwarding device can use the name or name prefix to forward a packet toward a network node that generates or stores the Content Object, regardless of a network address or physical location for the Content Object. In some embodiments, the name may be a hierarchically structured variable-length identifier (HSVLI). The HSVLI can be divided into several hierarchical components, which can be structured in various ways. For example, the individual name components parc, home, ndn, and test.txt can be structured in a left-oriented prefix-major fashion to form the name “/parc/home/ndn/test.txt.” Thus, the name “/parc/home/ndn” can be a “parent” or “prefix” of “/parc/home/ndn/test.txt.” Additional components can be used to distinguish among different versions of the content item, such as a collaborative document.
In some embodiments, the name can include a non-hierarchical identifier, such as a hash value that is derived from the content object's data (e.g., a checksum value) and/or from elements of the content object's name. A hash-based name is described in U.S. patent application Ser. No. 13/847,814, titled “Ordered-Element Naming for Name-Based Packet Forwarding,” by inventor Ignacio Solis, filed 20 Mar. 2013, the disclosure of which is incorporated by reference herein. A name can also be a flat label. Hereinafter, “name” is used to refer to any name for a piece of data in an NDN, such as a hierarchical name or name prefix, a flat name, a fixed-length name, an arbitrary-length name, or a label (e.g., a Multiprotocol Label Switching (MPLS) label).
Interest: A packet that indicates a request for a piece of data, and includes a name (or a name prefix) for the piece of data. A data consumer can disseminate a request or interest across an information-centric network, which CCN/NDN routers can propagate toward a storage device (e.g., a cache server) or a data producer that can provide the requested data to satisfy the request or interest.
In some embodiments, the ICN system can include a CCN architecture. However, the methods disclosed herein are also applicable to other ICN architectures as well. A CCN architecture is described in U.S. patent application Ser. No. 12/338,175, titled “Controlling the Spread of Interests and Content in a Content Centric Network,” by inventors Van L. Jacobson and Diana K. Smetters, filed 18 Dec. 2008, the disclosure of which is incorporated by reference herein.
In this disclosure, the term “feedback” is used in a generic sense. Any information that is associated with a device capable of receiving and/or transmitting based on network names can be referred to as “feedback.” Examples of feedback include, but are not limited to, server load, server disk space, server cost, storage cost (e.g., in monitory value), server processor/processing power, network cost (e.g., in monitory value), expected service time, network congestion, network reliability, server energy load, server energy consumption, network energy load, and network energy consumption.
Network Architecture
FIG. 1 illustrates an exemplary Content-Centric Network (CCN) with explicit strategy feedback support, in accordance with an embodiment of the present invention. Network 100 includes nodes 102, 104, 106, 108, 110, 112, and 114. These nodes can be CCN routers or other forwarders, and consumer and/or producer nodes. For example, content-producing devices 122, 124, 126, and 128 can operate as producer nodes. On the other hand, nodes 102 and 104 are coupled to an external network 130 (e.g., an Internet Protocol (IP) network) and serve as ingress nodes for a request for a content object from device 132.
During operation, device 132 requests a content object for which devices 122 and 124 are producer nodes. If device 132 is a node that supports forwarding and/or routing based on network names (e.g., a CCN node), this request can be an interest for the content object expressed in a routable name associated with the content object. In some embodiments, this name is an HSVLI. If network 130 does not support forwarding and/or routing based on network names (e.g., an IP network, which supports routing based on IP addresses), the interest can be tunneled through network 130 to nodes 102 or 104. On the other hand, if device 132 does not support forwarding and/or routing based on network names, the request can be an IP packet (which can be in an Ethernet frame). In some embodiments, upon receiving this IP packet, node 102 or 104 generates the corresponding interest for the content object in network 100.
In network 100, nodes forward interests to destinations via prefix name matching. Suppose that node 104 receives the interest for a content object, which is associated with a network name “/movies/blockbuster/mp4/.” Node 104 can forward this interest to any producer node that advertises the prefix “/movies.” In other words, node 104 can forward this interest via any route which advertises the prefix “/movies.” Suppose that devices 122 and 124 advertise the prefix “/movies.” Upon receiving the advertisements, node 104 creates corresponding forwarding entries for devices 122 and 124.
For the received interest, node 104 determines whether to forward the interest to device 122 or to device 124 based on a forwarding strategy. This determination is based on the forwarding strategy taken by a strategy layer. The strategy layer makes decisions based on one or more forwarding strategies. Since both devices 122 and 124 advertise the prefix “/movies,” node 104 has multiple options for forwarding the interest in its forwarding table. The strategy layer determines which entry associated with the prefix “/movies” in the forwarding table should be used to forward the interest.
For example, a forwarding strategy can be selecting alternate entries in the forwarding table for devices 122 and 124 based on a round robin model. Another forwarding strategy can be selecting the first forwarding entry added (or discovered) to the forwarding table, and selecting a second forwarding entry if the egress link of the first forwarding entry becomes unavailable. A more complex forwarding strategy can to maintain statistics of the traffic forwarded using a respective forwarding entry and use those statistics to select the forwarding entry. For example, if the maintained statistics records the average latency associated with a respective forwarding entry for devices 122 and 124, the strategy layer can forward using the forwarding entry with the lowest latency. In this way, the strategy layer of node 104 can obtain feedback from the network implicitly based on the traffic that goes through node 104. This way of obtaining strategy feedback can be referred to as implicit strategy feedback.
Another way of obtaining these statistics involves explicitly requesting and receiving the strategy feedback, which can be referred to as explicit strategy feedback. For example, node 104 can request explicit strategy feedback for one or more parameters (e.g., available resources and network conditions) from devices 122 and 124. Suppose that the strategy feedback is for the server load of devices 122 and 124. During operation, node 104 can send an interest comprising the strategy feedback request to device 122. Node 104 can generate an individual interest comprising the explicit strategy feedback request or piggyback (e.g., append or prepend) the explicit strategy feedback request in an interest forwarded to device 122. For example, if node 104 receives an interest for a content object from device 132, node 104 can include the explicit strategy feedback request in the interest and forward the interest toward device 122.
Upon receiving the request, device 122 can generate a response comprising the server load of device 122. Device 122 can generate an individual response comprising the server load as the content object (e.g., a signed content object of CCN) or piggyback (e.g., append or prepend) the server load in a response forwarded to node 104. For example, this response can carry the content object referred to by the name in the interest, and the server load can be piggybacked in the response. In some embodiments, node 104 can obtain the explicit strategy feedback from an underlying Routing Information Base (RIB), which stores locally computed routes for different name prefixes. It should be noted that the RIB can also include routes for different IP prefixes.
Upon receiving the server load of device 122, in some embodiments, node 104 can store the server load in the forwarding table entry for device 122 associated with the prefix “\movies.” Similarly, node 104 can receive the server load from device 124 and stores the server load in the forwarding table entry for device 124 associated with the prefix “\movies.” Upon receiving another interest, the strategy layer compares the server loads of devices 122 and 124 and determines the forwarding entry that includes a lower server load. Node 104 then identifies an egress interface associated with the determined forwarding entry and forwards the interest via the identified egress interface. In this disclosure, the terms “interface” and “ports” are used interchangeably. In some embodiments, the forwarding entry includes the prefix (e.g., “\movies”), an egress interface (e.g., the interface via which an advertisement for the prefix has been received), and the explicit strategy feedback (e.g., server load). In this example, node 104 receives the explicit strategy feedback from devices 122 and 124 via respective interfaces associated with devices 122 and 124, and stores the received explicit strategy feedback in corresponding entries of its forwarding table.
Suppose that node 102 receives the interest for another content object, which is associated with a network name “/music/topchart/mp3/.” Node 102 can forward this interest to any producer node that advertises the prefix “/music.” In other words, node 102 can forward this interest via any route which advertises the prefix “/movies.” Suppose that devices 126 and 128 advertise the prefix “/music.” Upon receiving the advertisements, node 102 creates corresponding forwarding entries for devices 126 and 128. For the received interest, the strategy layer of node 102 determines whether to forward the interest to device 126 or to device 128 based on a forwarding strategy. Since both devices 126 and 128 advertise the prefix “/music,” node 102 has multiple options for forwarding the interest in its forwarding table. The strategy layer determines which entry associated with the prefix “/music” in the forwarding table should be used to forward the interest.
Similarly, intermediate node 106 also receives an advertisement for the prefix “/music” from devices 126 and 128. Upon receiving the advertisements, node 106 creates corresponding forwarding entries for devices 126 and 128. For the received interest, the strategy layer of node 106 determines whether to forward the interest to device 126 or to device 128 based on a forwarding strategy. If node 102 sends individual or piggybacked strategy feedback requests to devices 126 and 128, node 106 receives these strategy feedback requests. In some embodiments, node 102 sends the explicit strategy feedback request via an interface from which node 102 has received the advertisement for the prefix “/music,” and whichever node or device has sent an advertisement for the prefix “/music” can send explicit strategy feedback.
Upon receiving the explicit strategy feedback request, node 106 forwards the strategy feedback request via a respective interface from which it has received an advertisement for the prefix “/music.” For example, node 106 forwards an explicit strategy feedback request via the interface that couples device 126 for the advertisement from device 126, and via the interface that couples node 112 for the advertisement from device 128. Device 126 receives the strategy feedback request and sends individual or piggybacked strategy feedback to node 106.
When node 112 receives the strategy feedback request from node 106, node 112 forwards the strategy feedback request via a respective interface from which it has received an advertisement for the prefix “/music.” For example, node 112 forwards the strategy feedback request via the interface that couples device 128 for the advertisement from device 128. Device 128 receives the strategy feedback request and sends individual or piggybacked strategy feedback to node 112, which, in turn, sends strategy feedback to node 106. In some embodiments, node 106 can send respective strategy feedback from devices 126 and 128 to node 102. In some further embodiments, node 106 aggregates the strategy feedback from devices 126 and 128 based on an aggregation policy. Examples of an aggregation policy include, but are not limited to, a mean, a median, a minimum, a maximum, and a list (or vector) of the strategy feedback from devices 126 and 128. Node 106 then sends the aggregated strategy feedback to node 102 in an individual or piggybacked response. This allows node 106 to send fewer messages and provides faster convergence.
In some embodiments, strategy feedback is specifically for a node, and an intermediate node may not recognize the strategy feedback. This intermediate node simply forwards the strategy feedback via the interface from which it has received the strategy feedback request. For example, strategy feedback from device 128 can be specifically for node 106. Intermediate node 112 may not recognize the strategy feedback, and sends the strategy feedback via the interface from which node 112 has received the explicit strategy feedback request from node 106.
In some embodiments, explicit strategy feedback remains within an administrative domain. For example, if network 100 is an administrative domain, explicit strategy feedback from device 122 or 126 reaches up to node 102 or 104, and does not leave network 100. When device 132 sends an interest to node 104, and node 104 piggybacks explicit strategy feedback request in that interest, devices 122 or 124 can also send explicit strategy feedback piggybacking in a response, which can include a content object, to the interest for device 132. However, when that response reaches node 104, node 104 extracts the explicit strategy feedback from the response, and forwards the response comprising the content object to device 132. This keeps the parameters associated with the explicit strategy feedback within network 100. In this way, these parameters do not leave an administrative domain and remain hidden from external devices (e.g., device 132).
Communication for Explicit Strategy Feedback
FIG. 2A illustrates an exemplary forwarding strategy in a CCN with explicit strategy feedback support, in accordance with an embodiment of the present invention. Node 104 includes a Forwarding Information Base (FIB) 202. FIB 202, which is a forwarding table, includes one or more entries, wherein a respective entry includes a prefix and an egress interface for the prefix. In some embodiments, the entry also includes one or more parameters associated with the prefix and the egress interface. During operation, node 104 receives advertisements for a network name 222 (e.g., “/movies/abc”) from devices 122 and 124 via interfaces 212 and 214, respectively. Switch 104 creates forwarding entries in FIB 202 for a respective advertisement for name 222 received from distinct interfaces. For example, FIB 202 includes two entries for name 222 corresponding to devices 122 and 124, and their corresponding interfaces 212 and 214. This allows switch 104 to forward an interest for name 222 via one of interfaces 212 and 214.
The strategy layer of switch 104 determines the interface to which switch 104 should forward an interest for name 222. Switch 104 can send individual or piggybacked explicit strategy feedback requests to devices 122 and 124 for one or more parameters. Devices 122 and 124, in turn, send individual or piggybacked explicit strategy feedback to switch 104. In some embodiments, switch 104 stores the received parameters in FIB 202 in corresponding entries. For example, switch 104 can obtain parameters 226 and 228 from devices 122 and 124, respectively, and store parameters 226 and 228 in entries associated with devices 122 and 124, respectively, in FIB 202. Suppose that parameters 226 and 228 represent server loads of devices 122 and 124, respectively. The corresponding entries associated with devices 122 and 124 in FIB 202 then include the respective server loads of devices 122 and 124.
In some embodiments, node 104 can obtain the explicit strategy feedback from an underlying Routing Information Base (RIB) 204, which stores locally computed routes for different name prefixes. During this route computation for RIB 204, switch 104 can discover a “path cost” associated with a route, and this cost can in included in RIB 204. Switch 104 can obtain this cost from RIB 204 and store that cost in a corresponding entry in FIB 202. For example, when switch 104 computes a route to device 122, switch 104 computes a path cost to device 122, and this cost can be parameter 226 associated with device 122 in FIB 202. It should be noted that RIB 204 can also include routes for different IP prefixes.
If node 104 receives an interest 230 for name 222 (e.g., “/movies/abc”) from network 130 (e.g., from device 132) via interface 216, switch 104 creates an entry in a Pending Interest Table (PIT) 206 for interest 230. In some embodiments, the entry includes interest 230 (e.g., name 222) and the ingress interface 216 of interest 230. Based on parameters 226 and 228, the strategy layer of switch 104 selects an egress interface for interest 230 from interfaces 212 and 214. Suppose that the strategy layer selects interface 212, which corresponds to device 122. Switch 104 forwards interest 230 via interface 212. Switch 104 can include (i.e., piggyback) an explicit strategy feedback request in interest 230 for device 122. This explicit strategy feedback request can be signed by switch 104 and can be part of the name in interest 230. This explicit strategy feedback request can be also be unsigned and can be appended or prepended to the name in interest 230.
Device 122 receives the interest and identifies the content object associated with name 222. Device 122 generates a response 240 comprising name 222 and the corresponding content object. Device 122 sends response 240 to switch 104. If interest 230 includes an explicit strategy feedback request, device 122 can include (i.e., piggyback) the corresponding explicit strategy feedback in response 240. This explicit strategy feedback request can be signed by device 122 and can be part of the content object in response 240. This explicit strategy feedback request can be also be unsigned and can be appended or prepended to the signed content object in response 240. Upon receiving response 240, switch 104 identifies the entry in PIT 206 comprising name 222, identifies interface 216 based on the entry, and forwards response 240 via interface 216.
FIG. 2B illustrates an exemplary communication of piggybacked explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention. During operation, node 104 in CCN 100 receives interest 250 comprising a content object name. Node 104 performs procedure include_feedback_req 252 to include a piggybacked explicit strategy feedback request in request 250. In this way, node 104 generates an interest 254 comprising the content object name and the piggybacked explicit strategy feedback request. In some embodiments, the explicit strategy feedback request can be a network name, which can be used to route in CCN 100. Node 104 then transmits interest 254. As interest 254 moves through CCN 100 from node 104, device 122 or 124 receives interest 254 and, based on the content object name in interest 254, determines that the local device (i.e., device 122 or 124) hosts the content object.
Device 122 or 124 performs procedure generate_response 256 to generate a response message 260 comprising the content object. In some embodiments, this content object is signed by device 122. Device 122 or 124 then performs include_feedback 258 to include the corresponding explicit strategy feedback in response 260. Upon inclusion, device 122 or 124 sends response 260 comprising the signed content object and the unsigned explicit strategy feedback. Upon receiving response 260, node 104 performs procedure update_FIB 262 to update the local FIB based on the explicit strategy feedback in response 260. For example, if the explicit strategy feedback is the server load, node 104 includes the received server load in the FIB entry corresponding to the device from which the explicit strategy feedback is received.
FIG. 2C illustrates an exemplary communication of individual explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention. During operation, node 104 in CCN 100 performs procedure generate_feedback_req 272 to generate an individual explicit strategy feedback request by generating an interest 274 comprising the explicit strategy feedback request. In some embodiments, the explicit strategy feedback request can be a network name, which can be used to route in CCN 100. Node 104 then transmits interest 274. As interest 274 moves through CCN 100 from node 104, device 122 or 124 receives interest 274 and, based on the explicit strategy feedback request, determines that the local device (i.e., device 122 or 124) should send a response comprising explicit strategy feedback.
Device 122 or 124 performs procedure generate_feedback 276 to generate a response message 278 comprising the explicit strategy feedback. In some embodiments, this explicit strategy feedback is signed by device 122. In other words, this explicit strategy feedback can be a content object. This content object can correspond to the network name in the explicit strategy feedback request from node 104. Upon generating response 278, device 122 or 124 sends response 278 comprising the explicit strategy feedback. Upon receiving response 278, node 104 performs procedure update_FIB 280 to update the local FIB based on the explicit strategy feedback in response 278. For example, if the explicit strategy feedback is the server load, node 104 includes the received server load in the FIB entry corresponding to the device from which the explicit strategy feedback is received.
Operations of Explicit Strategy Feedback
FIG. 3A presents a flowchart illustrating the process of a node generating a piggybacked explicit strategy feedback request, in accordance with an embodiment of the present invention. During operation, the node receives an interest for a content object (operation 302). The node generates an explicit strategy feedback request (operation 304) and includes the explicit strategy feedback request in the interest (operation 306), as described in conjunction with FIG. 2B. The node identifies an egress interface for the interest based on a prefix match in the local FIB (operation 308). For example, the node matches the name in the interest with the prefixes in its FIB, and based on a prefix match (e.g., the longest prefix match), identifies an egress interface.
The node then transmits the interest via the identified egress interface (operation 310). The node receives a response comprising a content object and explicit strategy feedback (operation 312). The node obtains the explicit strategy feedback, which can be unsigned, from the response (operation 314) and updates the local FIB based on the explicit strategy feedback (operation 316), as described in conjunction with FIG. 2B.
FIG. 3B presents a flowchart illustrating the process of a node generating an individual explicit strategy feedback request, in accordance with an embodiment of the present invention. During operation, the node generates an explicit strategy feedback request (operation 332) and generates an interest comprising the explicit strategy feedback request (operation 334), as described in conjunction with FIG. 2B. The node receives a response comprising the explicit strategy feedback (operation 336), obtains the explicit strategy feedback from the response message (operation 338), and updates the FIB based on the received explicit strategy feedback (operation 340).
FIG. 3C presents a flowchart illustrating the process of a node generating a piggybacked explicit strategy feedback, in accordance with an embodiment of the present invention. During operation, the node receives an interest for a content object via a local interface (operation 352). The node generates a response comprising the content object (operation 354). In some embodiments, this content object can be signed (e.g., with a public key). The node then checks whether the interest includes an explicit strategy feedback request (operation 356). If so, the node generates unsigned explicit strategy feedback (operation 358) and includes the explicit strategy feedback in the response (operation 360). If the interest does not include an explicit strategy feedback request (operation 356) or explicit strategy feedback has been included in the response (operation 360), the node sends the response via the local interface (operation 362). This local interface can be the same interface via which the node received the interest.
FIG. 3D presents a flowchart illustrating the process of a node generating an individual explicit strategy feedback, in accordance with an embodiment of the present invention. During operation, the node receives an interest for explicit strategy feedback (e.g., an explicit strategy feedback request expressed in a network name) via a local interface (operation 372). The node generates a response comprising explicit strategy feedback (operation 374). The node then sends the response comprising the explicit strategy feedback via the local interface (operation 376). This local interface can be the same interface via which the node received the interest. In some embodiments, the explicit strategy feedback can be signed by the node (e.g., with the public key of the node) and is represented as a content object.
FIG. 4A presents a flowchart illustrating the process of an intermediate node forwarding an interest with an explicit strategy feedback request, in accordance with an embodiment of the present invention. During operation, the node receives an individual or piggybacked explicit strategy feedback request (operation 402). The node then checks whether the FIB of the node includes a downstream device associated with the explicit strategy feedback request (e.g., is advertising a prefix for which the explicit strategy feedback request has been generated) (operation 404). If so, the node identifies a respective egress interface associated with a respective associated downstream device (operation 406) and sends an individual or piggybacked interest comprising an explicit strategy feedback request via a respective identified egress interface (operation 408).
FIG. 4B presents a flowchart illustrating the process of an intermediate node forwarding a response with explicit strategy feedback, in accordance with an embodiment of the present invention. During operation, the node receives individual or piggybacked explicit strategy feedback (operation 452) and checks whether the node has received explicit strategy feedback from a respective downstream device (operation 454). If not, the node continues to receive individual or piggybacked explicit strategy feedback (operation 452). In some embodiments, explicit strategy feedback from different downstream devices can be different (e.g., individual or piggybacked). If the node has received explicit strategy feedback from a respective downstream device, the node aggregates the received explicit strategy feedback based on an aggregation policy (operation 456). Examples of an aggregation policy include, but are not limited to, a mean, a median, a minimum, a maximum, and a list (or vector) of the strategy feedback from devices. The node sends the aggregated explicit strategy feedback to an upstream node via an individual or piggybacked response (operation 458), as described in conjunction with FIG. 1.
Explicit Strategy Feedback for Service Clusters
In some embodiments, a node in a CCN can provide cloud services to a coupled device. However, this cloud service can be obtained from a plurality of service clusters. The node can use explicit strategy feedback to select a service cluster for cloud services. A service cluster can include one or more devices providing one or more services (e.g., content storage, security, etc). FIG. 5 illustrates exemplary service clusters in a CCN with explicit strategy feedback support, in accordance with an embodiment of the present invention. A network 500, which can be a CCN, is coupled to nodes 502, 504, and 506. Node 502 can communicate with nodes 504 and 506 via network 500. Node 502 provides cloud services to a device 512 coupled to node 502. Nodes 504 and 506 can operate as gateway nodes for service clusters 522 and 524, respectively.
During operation, service clusters 522 and 524 coupled to nodes 504 and 506, respectively, advertise that service clusters 522 and 524 provide a cloud service (e.g., using an interest comprising a network name associated with the service). Node 502 receives the advertisements and creates corresponding FIB entries. Node 502 can then forward an interest for the cloud service to service cluster 522 or 524. Upon receiving an interest for a cloud service from device 512, node 502 selects service cluster 522 or 524 for forwarding that service request. In other words, node 502 determines whether to send the service request via the egress interface associated with node 504 or 506.
This determination is based on the forwarding strategy taken by a strategy layer of node 502. The strategy layer makes decisions based on one or more forwarding strategies. Since both service clusters 522 and 524 advertise the service, node 502 has multiple options for forwarding the interest in its FIB. The strategy layer determines which entry associated with the service in the FIB should be used to forward the interest. Node 502 can request and receive explicit strategy feedback to determine the service cluster to which node 502 should send the interest. Node 502 sends an individual or piggybacked interest comprising the explicit strategy feedback request to nodes 504 and 506.
Upon receiving the explicit strategy feedback request, nodes 504 and 506 can further propagate the explicit strategy feedback request in service clusters 522 and 524, respectively. Nodes 504 and 506 receive explicit strategy feedback from service clusters 522 and 524, respectively. The explicit strategy feedback from a service cluster can include explicit strategy feedback from a plurality of servers. In some embodiments, nodes 504 and 506 aggregate the received explicit strategy feedback based on an aggregation policy, and send the aggregated explicit strategy feedback to node 502.
Upon receiving the aggregated explicit strategy feedback from nodes 504 and 506, in some embodiments, node 502 can store the aggregated explicit strategy feedback in the corresponding forwarding entries in its local FIB. If node 502 receives an interest for a service from device 512, the strategy layer of node 502 compares the aggregated explicit strategy feedback of service clusters 522 and 524, and determines the forwarding entry comprising a better aggregated explicit strategy feedback. Node 502 then identifies an egress interface associated with the determined forwarding entry and forwards the interest via the identified egress interface.
Apparatus and Computer System
FIG. 6 illustrates an exemplary computer and communication system facilitating explicit strategy feedback in a CCN, in accordance with an embodiment of the present invention. Computer and communication system 602 includes a processor 604, a memory 606, and a storage device 608. Memory 606 can include a volatile memory (e.g., RAM) that serves as a managed memory, and can be used to store one or more memory pools. Furthermore, computer and communication system 602 can be coupled to a display device 610, a keyboard 612, and a pointing device 614. Storage device 608 can store an operating system 616, an explicit strategy feedback system 618, and data 632.
Explicit strategy feedback system 618 can include instructions, which when executed by computer and communication system 602, can cause computer and communication system 602 to perform methods and/or processes described in this disclosure. Specifically, explicit strategy feedback system 618 can facilitate explicit strategy feedback for the strategy layer of a node in a CCN. In some embodiments, explicit strategy feedback system 618 can be executed on a plurality of computer and communication systems, which are able to exchange data that describes the state of the operation associated with explicit strategy feedback system 618.
In summary, embodiments of the present invention provide a computer system and a method that facilitates explicit strategy feedback in a CCN. During operation, the system sends a first interest associated with an explicit strategy feedback request via an egress interface. This egress interface is in a plurality of egress interfaces associated with a same name in a forwarding table. An interest is location-independent and uniquely identifies the content object in the CCN and is routed based on the name in the CCN. The system stores one or more parameters received in response to the explicit strategy feedback request in an entry, which includes the name and the egress interface, in the forwarding table. The one or more parameters are associated with a first device. The system determines, for a second interest for a content object associated with the name, an egress interface from the plurality of egress interfaces based on the stored parameters.
The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. The computer-readable storage medium includes, but is not limited to, volatile memory, non-volatile memory, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or other media capable of storing computer-readable media now known or later developed.
The methods and processes described in the detailed description section can be embodied as code and/or data, which can be stored in a computer-readable storage medium as described above. When a computer system reads and executes the code and/or data stored on the computer-readable storage medium, the computer system performs the methods and processes embodied as data structures and code and stored within the computer-readable storage medium.
Furthermore, the methods and processes described above can be included in hardware modules or apparatus. The hardware modules or apparatus can include, but are not limited to, application-specific integrated circuit (ASIC) chips, field-programmable gate arrays (FPGAs), dedicated or shared processors that execute a particular software module or a piece of code at a particular time, and other programmable-logic devices now known or later developed. When the hardware modules or apparatus are activated, they perform the methods and processes included within them.
The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the present invention is defined by the appended claims.

## Claims

1. A computer-executable method, comprising: sending, by a computing device, a first interest associated with an explicit strategy feedback request, which is generated by the computing device, via a first egress interface, wherein the first egress interface is in a plurality of egress interfaces mapped to a same name in a forwarding table, wherein an interest indicates the content object in a Content-Centric Network (CCN), wherein the interest is routed based on the name in the CCN, and wherein the explicit strategy feedback request indicates a request for a feedback regarding a forwarding strategy for the name; storing one or more parameters received in response to the explicit strategy feedback request in an entry in the forwarding table, wherein the one or more parameters are associated with a first device, wherein the entry comprises the name and the first egress interface, and wherein the one or more parameters relate to server and/or network cost and/or performance; determining, for a second interest for a content object associated with the name, the first egress interface from the plurality of egress interfaces based on the entry comprising the name, the first egress interface, and the stored parameters; and forwarding the second interest via the first egress interface to a producer node based on the explicit forwarding strategy received in response to the first interest request.

2. The method of claim 1, wherein the first interest is an individual interest for the explicit strategy feedback request.

3. The method of claim 1, wherein the first interest is for a content object associated with the name, and the explicit strategy feedback request is piggybacked in the first interest.

4. The method of claim 1, wherein the one or more parameters are received via an underlying Routing Information Base (RIB) storing a route associated with the name.

5. The method of claim 1, wherein the parameters received in response to the first interest associated with the explicit strategy feedback request are one or more of: server load, server disk space, server cost, storage cost, server processing power, network cost, expected service time, network congestion, network reliability, server energy load, server energy consumption, network energy load, and network energy consumption.

6. The method of claim 1, further comprising removing the one or more parameters from a response message associated with the first interest in response to determining that the response message has reached a boundary of an administrative domain.

7. The method of claim 1, wherein the one or more parameters are further associated with a second device, and wherein the one or more parameters are aggregated for the first and second devices based on an aggregation policy.

8. The method of claim 7, wherein the aggregation policy includes one or more of: a mean, a median, a minimum, a maximum, and an inclusive list.

9. A non-transitory computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method, the method comprising: sending a first interest associated with an explicit strategy feedback request, which is generated by a computing device, via a first egress interface of the computing device, wherein the first egress interface is in a plurality of egress interfaces mapped to a same name in a forwarding table, wherein an interest indicates the content object in a Content-Centric Network (CCN), wherein the interest is routed based on the name in the CCN, wherein the explicit strategy feedback request indicates a request for a feedback regarding a forwarding strategy for the name; storing one or more parameters received in response to the explicit strategy feedback request in an entry in the forwarding table, wherein the one or more parameters are associated with a first device, wherein the entry comprises the name and the first egress interface, and wherein the one or more parameters relate to server and/or network cost and/or performance; determining, for a second interest for a content object associated with the name, the first egress interface from the plurality of egress interfaces based on the entry comprising the name, the first egress interface, and the stored parameters; and forwarding the second interest via the first egress interface to a producer node based on the explicit forwarding strategy received in response to the first interest request.

10. The non-transitory computer-readable storage medium of claim 9, wherein the first interest is an individual interest for the explicit strategy feedback request.

11. The non-transitory computer-readable storage medium of claim 9, wherein the first interest is for a content object associated with the name, and the explicit strategy feedback request is piggybacked in the first interest.

12. The non-transitory computer-readable storage medium of claim 9, wherein the one or more parameters are received via an underlying Routing Information Base (RIB) storing a route associated with the name.

13. The non-transitory computer-readable storage medium of claim 9, wherein the parameters received in response to the first interest associated with the explicit strategy feedback request are one or more of: server load, server disk space, server cost, storage cost, server processing power, network cost, expected service time, network congestion, network reliability, server energy load, server energy consumption, network energy load, and network energy consumption.

14. The non-transitory computer-readable storage medium of claim 9, wherein the method further comprises removing the one or more parameters from a response message associated with the first interest in response to determining that the response message has reached a boundary of an administrative domain.

15. The non-transitory computer-readable storage medium of claim 9, wherein the one or more parameters are further associated with a second device, and wherein the one or more parameters are aggregated for the first and second devices based on an aggregation policy.

16. The non-transitory computer-readable storage medium of claim 15, wherein the aggregation policy includes one or more of: a mean, a median, a minimum, a maximum, and an inclusive list.

17. A computer system, comprising: a processor; and a storage device coupled to the processor and storing instructions that when executed by a computer cause the computer to perform a method, the method comprising: sending, by a computing device, a first interest associated with an explicit strategy feedback request, which is generated by a computing device, via a first egress interface of the computing device, wherein the first egress interface is in a plurality of egress interfaces mapped to a same name in a forwarding table, wherein an interest indicates the content object in a Content-Centric Network (CCN), wherein the interest is routed based on the name in the CCN, and wherein the explicit strategy feedback request indicates a request for a feedback regarding a forwarding strategy for the name; storing one or more parameters received in response to the explicit strategy feedback request in an entry in the forwarding table, wherein the one or more parameters are associated with a first device, wherein the entry comprises the name and the first egress interface, and wherein the one or more parameters relate to server and/or network cost and/or performance; determining, for a second interest for a content object associated with the name, first egress interface from the plurality of egress interfaces based on the entry comprising the name, the first egress interface, and the stored parameters, and forwarding the second interest via the first egress interface to a producer node based on the explicit forwarding strategy received in response to the first interest request.

18. The computer system of claim 17, wherein the first interest is an individual interest for the explicit strategy feedback request.

19. The computer system of claim 17, wherein the first interest is for a content object associated with the name, and the explicit strategy feedback request is piggybacked in the first interest.

20. The computer system of claim 17, wherein the one or more parameters are received via an underlying Routing Information Base (RIB) storing a route associated with the name.

21. The computer system of claim 17, wherein the parameters received in response to the first interest associated with the explicit strategy feedback request are one or more of: server load, server disk space, server cost, storage cost, server processing power, network cost, expected service time, network congestion, network reliability, server energy load, server energy consumption, network energy load, and network energy consumption.

22. The computer system of claim 17, wherein the method further comprises removing the one or more parameters from a response message associated with the first interest in response to determining that the response message has reached a boundary of an administrative domain.

23. The computer system of claim 17, wherein the one or more parameters are further associated with a second device, and wherein the one or more parameters are aggregated for the first and second devices based on an aggregation policy.

24. The computer system of claim 23, wherein the aggregation policy includes one or more of: a mean, a median, a minimum, a maximum, and an inclusive list.