Patent Application
20200267051
Embodiments described herein relate to the field of controlling network slices; and more specifically, to managing transmissions between hypervisors and network switches, which comprise network slices, through the use of a management server.
The next generation of mobile networks (e.g., 5th generation or 5G mobile networks) will enable the deployment of end-to-end network slices that may span across different operator networks. A network slice is an isolated segment of a set of operator networks that appears to a network device of a user as a single and complete mobile network. Thus, a network slice contains both a user plane and a control plane for a mobile network. Network slices can be controlled by operators as well as third parties (hereinafter “slice operators”). Software-Defined Networks (SDNs) will play a critical role in the deployment of network slices as SDNs enable slice operators to control and manage the network slices in a scalable manner.
In one example SDN architecture, a set of SDN controllers may be used to handle a network slice that is comprised of resources from a set of SDN switches. In this SDN architecture, to connect SDN switches to the SDN controllers, each SDN switch is configured with a list of internet protocol (IP) addresses of the SDN controllers that control the network slice. Therefore, all IP addresses for all SDN controllers should be predefined in the SDN switches. Based on the predefined IP addresses, the SDN switches make a connection (e.g., a Transmission Control Protocol (TCP) and additionally Transport Layer Security (TLS) connection) to all SDN controllers. If one SDN controller fails, another SDN controller takes over and manages the SDN switches. According to the OpenFlow specification, a SDN switch cannot itself decide which SDN controller will process requests, but instead tries to maintain a connection to each predefined SDN controller. Moreover, the SDN switches usually transmit requests for obtaining route information (e.g., packet-in messages in OpenFlow) to all SDN controllers that have equal and master roles. In addition to potentially being an inefficient transmission of requests, any changes to the predefined IP addresses of SDN controllers requires reconfiguration of all affected SDN switches.
Additionally, as described above, slice operators may manage their dedicated network slice with their own SDN controllers. However, this control by slice operators requires isolating network slices from each other and limiting their scope within the operator networks such that each slice operator can control their own network slice without the possibility of interfering with other network slices. To do so, some solutions, employ a hypervisor to translate control messages between SDN controllers and SDN switches of operator networks. However, this approach by itself is not scalable for large networks and it may even lead to severe security issues (particularly for network slices with higher security requirements) as each hypervisor must be manually setup and configured for each network slice.
A method for managing transmissions between hypervisors and network switches is described. The method may include receiving, by a management server, a message from a network switch operating in a network; and transmitting, by the management server, a first translation instruction, including a first hypervisor address, to a network address translation device in response to receiving the message, wherein the first translation instruction indicates to the network address translation device to forward traffic received from the network switch to the first hypervisor address.
A network device for managing transmissions between hypervisors and network switches is also described herein. The network device may include a non-transitory machine-readable storage medium having stored therein a management server; and a processor coupled to the non-transitory machine-readable storage medium, the processor configured to execute the management server, wherein the management server is configured to receive a control message from a network switch and transmit a first translation instruction, including a first hypervisor address, to a network address translation device in response to establishing a connection with the network switch, wherein the first translation instruction indicates to the network address translation device to forward control traffic from the network switch to the first hypervisor address.
A non-transitory machine-readable medium containing instructions that, when performed by a processor in a computing device is also described herein. The instructions may cause the computing device to receive a message from a network switch; and transmit a first translation instruction, including a first hypervisor address, to a network address translation device in response to message, wherein the first translation instruction indicates to the network address translation device to forward control traffic from the network switch to the first hypervisor address.
As described herein the devices and methods may dynamically manage connections (e.g., control connections) between hypervisors and network switches and without the need to reconfigure the network switches to account for or affect a change in the network system. In particular, by configuring the network switches with a fixed set of outgoing Internet Protocol (IP) addresses and allowing a management server control which of the fixed outgoing IP addresses is mapped to a hypervisor via a network address translation (NAT) device, each network switch does not need to be reconfigured to account for or affect a change to a policy of a network slice or a topology change in the network system. Since there may be numerous network switches (e.g., hundreds or thousands), the ability to change hypervisors without needing to reconfigure each affected network switch reduces overhead and allows for a more dynamic network system.
The systems, devices, structures, methods, and designs may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments. In the drawings:
The following description describes methods and apparatuses for managing network slices through the use of a management server. In some embodiments, the management server may (1) select and configure a hypervisor or instantiate a new hypervisor in the cloud for a Software Defined Network (SDN) switch and/or (2) modify entries in a network address translation (NAT) device to control communications from the SDN switch to a selected hypervisor. In the following description, numerous specific details such as logic implementations, opcodes, means to specify operands, resource partitioning/sharing/duplication implementations, types and interrelationships of system components, and logic partitioning/integration choices are set forth in order to provide a more thorough understanding of the present systems, devices, structures, methods, and designs. It will be appreciated, however, by one skilled in the art that the embodiments described herein may be practiced without such specific details. In other instances, control structures, gate level circuits and full software instruction sequences have not been shown in detail in order not to obscure the systems, devices, structures, methods, and designs described herein. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Bracketed text and blocks with dashed borders (e.g., large dashes, small dashes, dot-dash, and dots) may be used herein to illustrate optional operations that add additional features to embodiments. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. “Coupled” is used to indicate that two or more elements, which may or may not be in direct physical or electrical contact with each other, co-operate or interact with each other. “Connected” is used to indicate the establishment of communication between two or more elements that are coupled with each other.
As described above, in one embodiment, the operator network 102 may include a number of SDN switches 108. Although shown with two SDN switches 1081 and 1082, in other embodiments the operator network 102 may have any number of SDN switches 108 (e.g., hundreds or thousands of SDN switches 108). Each of the SDN switches 108 may be a combination of hardware and software that connects devices together on a computer network by using packet switching to receive, process, and forward data to a destination device. For example, each SDN switch 108 may be a multiport network bridge that uses hardware addresses to process and forward data at the data link layer (layer 2) of the Open Systems Interconnection (OSI) model. In the embodiments described herein, the SDN switches 108 may communicate with SDN controllers 104. In this configuration, the SDN controllers 104 and SDN switches 108 operate in an SDN architecture. In an SDN architecture, the data plane (e.g., packet forwarding) is decoupled from the control plane (e.g., configuration of routing tables). Accordingly, in the SDN architecture the data plane is implemented in the SDN switches 108 but the control plane is implemented in software by the SDN controllers 104. For example, the SDN controllers 104 may determine and/or control routing decisions for each of the SDN switches 108. In this example embodiment, the SDN switches 108 and the SDN controllers 104 may communicate using control messages passed between the SDN controllers 104 and the SDN switches 108. The control messages and the communications between the SDN controllers 104 and the SDN switches 108 may utilize any protocol, including the OpenFlow protocol, which gives access to the forwarding plane of the SDN switches 108.
In some embodiments, sets of the SDN switches 108 may be logically grouped together to form network slices 110. For example, as shown in
As noted above, in some embodiments, each network slice 110 may be controlled or managed using a set of SDN controllers 104. For example, the SDN controllers 104 may control routing decisions for corresponding network slices 110. In one embodiment, this management of network slices 110 may be performed via communications between the SDN switches 108 that make up network slices 110 and the SDN controllers 104 that manage the network slices 110. For example, the SDN controllers 104 may communicate with the SDN switches 108 using OpenFlow or a similar protocol to control routing decisions of the SDN switches 108. In some embodiments, multiple SDN controllers 104 may be used to manage a single network slice 110. For example, as shown in
As shown in
As used herein, messages exchanged between devices may be control messages used to manage the network slices 110, messages used to initiate connections between devices in the network system 100 (e.g., initiate a connection between the management server 106 and a SDN switch 108 or initiate a connection between a SDN switch 108 and a hypervisor 112), or any other similar type of message. The messages may be considered data packets or composed of data packets.
Although the OpenFlow protocol has been used here to describe messages exchanged between SDN controllers 104 and SDN switches 108, the use of translation by the hypervisors 112 allows the use of any set of protocols for communications between SDN controllers 104 and SDN switches 108. For example, the SDN controller 1041 may use OpenFlow messages while the SDN switch 1081 within the network slice 1101 managed by the SDN controller 1041 may use OpFlex for communications. In this example, the hypervisor 1121 may translate control messages into a protocol understood by a recipient of the message (e.g., translate between OpenFlow and OpFlex).
As shown in
Similarly, the hypervisor 1121 may transmit a message 406 with a source address of IP_HYPERVISOR1. Using a reverse mapping in the mapping table 300, the NAT device 114 may use the source address of IP_HYPERVISOR1 in the message 406 to determine the source address IP_PSEUDO1 for the modified message 408 that is transmitted to the SDN switch 1081. In some embodiments, the NAT device 114 may use a reverse mapping in the mapping table 300 to determine the address IP_SWITCH1 based on the destination address IP_NAT in the message 406 transmitted by the hypervisor 1121 and use the destination address IP_SWITCH1 for the modified message 408 that is transmitted to the SDN switch 1081.
In one embodiment, the management server 106 may transmit translation instructions to add entries 302 to the mapping table 300 in response to receipt of a message from an SDN switch 108. For example, each SDN switch 108 may include a set of two or more outgoing IP addresses as shown in
In contrast to the first outgoing IP address 502 that may not be associated with a particular device in the network system 100 at startup of the SDN switch 1081, the second outgoing IP address 504 may be associated with the management server 106 (e.g., IP_MANAGEMENT_SERVER). Upon start-up, the SDN switch 1081 may begin transmitting messages using each of the outgoing IP addresses 502 and 504. For instance, in the example of
With respect to a first message corresponding to the first outgoing IP address 502, the NAT device 114 may attempt to determine an entry 302 in a mapping table 300 with an incoming destination address 304 that matches a destination address of the first message (e.g., the first outgoing IP address 502). When the SDN switch 1081 initially starts to connect to a hypervisor 112, the mapping table 300 may not include such an entry 302. In response to failing to find an entry 302 within the mapping table 300 associated with a destination address of the first message (i.e., the first outgoing IP address 502), the NAT device 114 may drop the first message without forwarding to another device in the network system 100. Based on the NAT device 114 dropping the first message and consequently the SDN switch 1081 failing to receive an acknowledgement of receipt of the first message, the SDN switch 1081 may enter a timeout period before trying to retransmit the first message using the first outgoing IP address 502.
With respect to a second message corresponding to the second outgoing IP address 504, an entry 302 may be determined in the mapping table 300 that includes an incoming destination address 304 that matches the destination address of the second message (e.g., the second outgoing IP address 504). Based on this determined entry 302, the destination address of the second message, which matches an incoming destination address 304 of the determined entry 302, may be modified to the outgoing destination address 306 of the determined entry 302. In this example, the outgoing destination address 306 of the determined entry 302 is associated with the management server 106. The modified second message may thereafter be forwarded to the management server 106 such that the SDN switch 1081 may establish a connection with the management server 106 (e.g., a TCP with optional use of a TLS connection). Although described as the second message being transmitted to the management server via the NAT device 114, in some embodiments the second message may be transmitted directly to the management server 106 without moving through the NAT device 114.
In some embodiments, upon receipt of the second message, the management server 106 may check if a source of the second message is on an authorized list of source devices. For example, the management server 106 may be pre-configured with an authorized list of source devices that includes the SDN switch 1081 and the NAT device 114 such that the management server 106 will establish a connection with these authorized devices. In this fashion, the management server 106 will not enable unauthorized devices (e.g., unauthorized or fake switches) to communicate with SDN controllers 104, hypervisors 112, etc.
After using a handshake routine to establish a connection with the management server 106, the management server 106 may determine a hypervisor 112 for the SDN switch 1081. In one embodiment, the management server 106 may determine a hypervisor 112 for the SDN switch 1081 based on capacity and/or availability of the hypervisors 112. For example, the hypervisors 112 may periodically transmit registration messages containing capacity and/or availability information to the management server 106. The management server 106 may use this information to determine a hypervisor 112 that is capable of handling communications between the SDN switch 1081 and a SDN controller 104 (e.g., the SDN controller 1041 corresponding to the network slice 1101). In some embodiments, particularly embodiments in which cloud based hypervisors 112 are employed, the management server 106 may instantiate a new hypervisor 112 for use by the SDN switch 1081. In some embodiments in which a hypervisor 112 has already be established for a network slice 110 in which the SDN switch 1081 is part of, the management server 106 may determine that this established hypervisor 112 is to be used by the SDN switch 1081.
Upon determining a hypervisor 112 for the SDN switch 1081 (e.g., the hypervisor 1121), the management server 106 may configure the hypervisor 112. In one embodiment, this configuration may include configuring slicing policy for the attached SDN switches 108, where the slicing policy indicates types of functions or requests that are allowed in the network slice 110 and resources SDN controllers 104 can use in a network slice 110. In one embodiment, this configuration may include configuring access control for the hypervisor 112 (e.g., the set of devices that can access the hypervisor 112, including the NAT device 114, one or more controllers 104, and one or more SDN switches 108). For example, the hypervisor 1121 may be configured to accept connections with the NAT device 114, the SDN controller 1041, and/or the SDN switch 1081. For purposes of illustration, the hypervisor 1121 will be used to describe the functionality of the management server 106 in relation to the SDN switch 1081.
After configuration of the hypervisor 1121, the management server 106 may transmit a translation instruction to the NAT device 114 to establish a new entry 302 in the mapping table 300. The new entry 302 indicates a mapping between the first outgoing IP address 502 and an address of the hypervisor 1121. In particular, the incoming destination address 304 for the new entry 302 is set to the first outgoing IP address 502 of the SDN switch 1081 (e.g., IP_PSEUDO1) and the outgoing destination address 308 is set to an address of the hypervisor 1121 (e.g., IP_HYPERVISOR1). This new entry 302 will cause the NAT device 114 to modify all messages transmitted from the SDN switch 1081 with a destination address of the first outgoing IP address 502 (e.g., IP_PSEUDO1) to include the address of the hypervisor 1121 (e.g., IP_HYPERVISOR1). Accordingly, messages from the SDN switch 1081 using the first outgoing IP address 502 will be forwarded by the NAT device 114 to the hypervisor 1121.
As noted above, initial messages transmitted from the SDN switch 1081 with the first outgoing IP address 502 (e.g., the first message) will be dropped by the NAT device 114 as the first outgoing IP address 502 does not match an incoming destination address 304 of an entry 302 in the mapping table 300. After a timeout period, the SDN switch 1081 may retransmit the message with the first outgoing IP address 502 (e.g., the first message). Since the NAT device 114 now has an entry 302 with an incoming destination address 304 that matches the first outgoing IP address 502, the NAT device 114 may modify the message to include the address of the hypervisor 1121 (e.g., as shown in
The SDN switch 1081 may continue to exchange messages with the SDN controller 1041 via the NAT device 114 and the hypervisor 1121 such that the SDN controller 1041 may manage resources of the SDN switch 1081. The hypervisors 112 may be isolated from each other and each hypervisor 112 may deploy a specific policy and configuration for an associated network slice 110. Accordingly, the hypervisors 112 may improve security in the network system 100 by ensuring SDN controllers 104 communicate with assigned/allocated SDN switches 108 and according to network slice 110 policy.
In one embodiment, the SDN switch 1081 may continue to transmit messages to the management server 106. For example, the SDN switch 1081 may transmit all messages to all outgoing IP addresses preconfigured in the SDN switch 1081 (e.g., the first outgoing IP address 502 and the second outgoing IP address 504). In this embodiment, the management server 106 may use these received messages from the SDN switch 1081 along with messages from other SDN switches 108 in the operator network 102 (and potentially other operator networks) to determine information regarding the network system 100 (e.g., topology information of devices in the network system 100 or policy changes to the network slices 110). Based on this information that is passively obtained by the management server 106, the management server 106 may determine a better hypervisor 112 for the SDN switch 1081. For example, based on a change to a policy of the network slice 1101 that is detected by the management server 106 based on messages from the SDN switch 1081, the management server 106 may determine that the hypervisor 1121 may no longer be suitable for the SDN switch 1081 (e.g., the capacity of the hypervisor 1121 may be insufficient for the new policy). Instead, the management server 106 may determine to move the SDN switch 1081 to another hypervisor 112 in the network system 100. In some embodiments, this may include instantiating a new hypervisor 112.
In response to determining another hypervisor 112 for the SDN switch 1081, for example the hypervisor 1122, the management server 106 may transmit a translation instruction to the NAT device 114 to either modify a previous entry 302 in the mapping table 300 associated with the first outgoing IP address 502 of the SDN switch 1081 or delete a previous entry 302 associated with the SDN switch 1081 (e.g., an entry 302 with the first outgoing IP address 502 as the incoming destination address 304) and generate a new entry 302. The modified or new entry 302 includes an address of the hypervisor 1122 for the outgoing destination address 306 such that messages transmitted from the SDN switch 1081 using the first outgoing IP address 502 are forwarded to the hypervisor 1122. In one embodiment, the SDN switch 1081 may be unaware of the transition to the hypervisor 1122. Accordingly, the SDN switch 1081 may transmit messages that are dropped by the hypervisor 1122 since a connection has not been established between the hypervisor 1122 and the SDN switch 1081. In this embodiment, the hypervisor 1122 may transmit a TCP reset message to the SDN switch 1081 to cause the SDN switch 1081 to establish a new connection with the hypervisor 1122. Thereafter, a connection between the SDN switch 1081 and the hypervisor 1122 may be established such that messages between the SDN switch 1081 and the SDN controllers 1042 and 1043 may be managed by the hypervisor 1122.
Turning to
The method 600 may commence at operation 602 with receipt by the management server 106 of registration messages from one or more hypervisors 112 active in an operator network 102 (items 702A and 702B). In one embodiment, the registration messages indicate one or more of availability and capacity of the hypervisor 112 that transmitted the registration message. Each registration messages may register the hypervisor 112 with the management server 106, including an indication of initial availability and capacity, or the hypervisor 112 may already be registered with the management server 106 and the registration message updates availability and capacity of the hypervisor 112. In one embodiment, the management server 106 may be connected to the NAT device 114 such that the registration messages are forwarded to the management server 106 from the hypervisors 112 via the NAT device 114. Although described as the management server 106 receiving registration messages from the hypervisors 112, in some embodiments, the availability and/or capacity information for a hypervisor 112 may be manually entered into the management server 106 by an administrator of the management server 106 or the operator network 102.
At operation 604, the management server 106 may receive a message from the SDN switch 1081 to establish a connection between the management server 106 and the SDN switch 1081 (item 704). In one embodiment, the SDN switch 1081 may be configured with two outgoing IP addresses associated with devices with which the SDN switch 1081 will establish connections: a first outgoing IP address 502 and a second outgoing IP address 504. The first outgoing IP address 502 may be a pseudo IP address and the second outgoing IP address 504 may be an IP address of the management server 106. The first outgoing IP address 502 allows the SDN switch 1081 to establish a connection (e.g., a TCP connection alone or a TCP+TLS connection) with a hypervisor 112 via the NAT device 114 (once an appropriate entry 302 is present in the mapping table 300) while the second outgoing IP address 504 allows the SDN switch 1081 to establish a connection (e.g., a TCP connection or a TCP+TLS connection) with the management server 106. Until an appropriate entry 302 is present in the mapping table 300 of the NAT device 114, the NAT device 114 may drop (item 708) the attempted connection/handshake (item 706) and the SDN switch 1081 may enter a timeout period (item 710) before retrying to establish a connection. In one embodiment, the message received from the SDN switch 1081 may cause the management server 106 to initiate the establishment of a connection with the SDN switch 1081.
At operation 606, the management server 106 may select a hypervisor 112 for the SDN switch 1081 in response to a message from the SDN switch 1081 (item 712). The hypervisor 112 selected by the management server 106 may be used to manage communications between the SDN controller 1041 of the network slice 1101 that the SDN switch 1081 is associated. For example, the network slice 1101 may be composed of a number of SDN switches 108 (or resources of these SDN switches 108), including the SDN switch 1081. The management server 106 may select a hypervisor 112 at operation 606 based on availability and/or capacity information received from the hypervisors 112 or instantiate a new hypervisor 112 for use by the network slice 1101. In the example data exchange 700 and as used below to describe the method 600, the management server 106 may select the hypervisor 1121 at operation 606.
At operation 608, the management server 106 may configure the selected hypervisor 1121 (item 714). In one embodiment, this configuration may include configuring access control for the hypervisor 1121 (e.g., the set of devices that can access the hypervisor 1121, including the NAT device 114, one or more controllers 104, and one or more SDN switches 108). In one embodiment, this configuration may cause the hypervisor 1121 to initiate and establish a connection with a SDN controller 104 (e.g., the controller 1041).
At operation 610, the management server 106 may transmit a translation instruction to the NAT device 114 (item 716). The translation instruction may include an address of the hypervisor 1121 and may indicate to the NAT device 114 to forward messages received from the SDN switch 1081 to the address of the hypervisor 1121. In response to the translation instruction, the NAT device 114 may generate or update an entry 302 in the mapping table 300 to reflect a mapping between the first outgoing IP address 502 of the SDN switch 1081 and the address of the hypervisor 1121. Following a timeout period of the SDN switch 1081 (item 710), the SDN switch 1081 may re-attempt to establish a connection with the hypervisor 1121 via the NAT device 114 (item 718). In this case, since an entry 302 is present in the mapping table 300 of the NAT device 114, the NAT device 114 may forward messages transmitted by the SDN switch 1081 using the first outgoing IP address 502 to the hypervisor 1121 such that the hypervisor 1121 may establish a connection with the SDN switch 1081 (item 720) and the hypervisor 1121 may manage communications between the SDN controller 1041 and the SDN switch 1081.
After establishment of connections with both the management server 106 and the hypervisor 1121, the SDN switch 1081 may continue to transmit messages to both the hypervisor 1121 and the management server 106 via the first outgoing IP address 502 and the second outgoing IP address 504, respectively. At operation 612, the management server 106 may detect a change to status information of the network system 100 (e.g., topology information of devices in the network system 100 or a policy change to the network slices 110). Based on this information that is passively obtained by the management server 106, the management server 106 may determine a new hypervisor 112 for the SDN switch 1081 at operation 614. For example, the hypervisor 1122 may be selected to replace hypervisor 1121 for the SDN switch 1081 (item 722).
After selecting the hypervisor 1122 for the SDN switch 1081, the management server 106 may transmit a translation instruction to the NAT device 114 at operation 616 (item 724). The translation instruction transmitted to the NAT device 114 may either cause the NAT device 114 to modify a previous entry 302 in the mapping table 300 associated with the first outgoing IP address 502 of the SDN switch 1081 or delete the previous entry 302 and generate a new entry 302. The modified or new entry 302 includes an address of the hypervisor 1122 for the outgoing destination address 306 such that messages transmitted from the SDN switch 1081 using the first outgoing IP address 502 are forwarded to the hypervisor 1122.
In one embodiment, the SDN switch 1081 may be unaware of the transition to the hypervisor 1122. Accordingly, the SDN switch 1081 may transmit messages (item 726) that are dropped by the hypervisor 1122 since a connection has not been established between the hypervisor 1122 and the SDN switch 1081. In this embodiment, the hypervisor 1122 may transmit a TCP reset message to the SDN switch 1081 (item 728) to cause the SDN switch 1081 to enter a timeout period (item 730) before transmitting messages (item 732) to establish a connection with the hypervisor 1122 (item 734). Thereafter, the connection between the SDN switch 1081 and the hypervisor 1122 is established such that messages between the SDN switch 1081 and the SDN controllers 1042 and 1043 may be managed by the hypervisor 1122.
As described herein the management server 106 may dynamically manage connections between hypervisors 112 and SDN switches 108 and without the need to reconfigure the SDN switches 108 to account for or affect a change in the network system 100. In particular, by configuring the SDN switches 108 with a fixed set of outgoing IP addresses and allowing the management server 106 to control which of the fixed outgoing IP addresses is mapped to a hypervisor 112 via the NAT device 114, each SDN switch 108 does not need to be reconfigured to account for or affect a change to a policy of a network slice 110 or a topology change in the network system 100. Since there may be numerous SDN switches 108 (e.g., hundreds or thousands), the ability to change hypervisors 112 without needing to reconfigure each affected SDN switch 108 reduces overhead and allows for a more dynamic network system 100.
As noted above, the system and methods described herein may be performed by one or more electronic devices. An electronic device stores and transmits (internally and/or with other electronic devices over a network) code (which is composed of software instructions and which is sometimes referred to as computer program code or a computer program) and/or data using machine-readable media (also called computer-readable media), such as machine-readable storage media (e.g., magnetic disks, optical disks, solid state drives, read only memory (ROM), flash memory devices, phase change memory) and machine-readable transmission media (also called a carrier) (e.g., electrical, optical, radio, acoustical or other form of propagated signals—such as carrier waves, infrared signals). Thus, an electronic device (e.g., a computer) includes hardware and software, such as a set of one or more processors (e.g., wherein a processor is a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, other electronic circuitry, a combination of one or more of the preceding) coupled to one or more machine-readable storage media to store code for execution on the set of processors and/or to store data. For instance, an electronic device may include non-volatile memory containing the code since the non-volatile memory can persist code/data even when the electronic device is turned off (when power is removed), and while the electronic device is turned on that part of the code that is to be executed by the processor(s) of that electronic device is typically copied from the slower non-volatile memory into volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM)) of that electronic device. Typical electronic devices also include a set or one or more physical network interface(s) (NI(s)) to establish network connections (to transmit and/or receive code and/or data using propagating signals) with other electronic devices. For example, the set of physical NIs (or the set of physical NI(s) in combination with the set of processors executing code) may perform any formatting, coding, or translating to allow the electronic device to send and receive data whether over a wired and/or a wireless connection. In some embodiments, a physical NI may comprise radio circuitry capable of receiving data from other electronic devices over a wireless connection and/or sending data out to other devices via a wireless connection. This radio circuitry may include transmitter(s), receiver(s), and/or transceiver(s) suitable for radiofrequency communication. The radio circuitry may convert digital data into a radio signal having the appropriate parameters (e.g., frequency, timing, channel, bandwidth, etc.). The radio signal may then be transmitted via antennas to the appropriate recipient(s). In some embodiments, the set of physical NI(s) may comprise network interface controller(s) (NICs), also known as a network interface card, network adapter, or local area network (LAN) adapter. The NIC(s) may facilitate in connecting the electronic device to other electronic devices allowing them to communicate via wire through plugging in a cable to a physical port connected to a NIC. One or more parts of an embodiment may be implemented using different combinations of software, firmware, and/or hardware.
A network device (ND) is an electronic device that communicatively interconnects other electronic devices on the network (e.g., other network devices, end-user devices). Some network devices are “multiple services network devices” that provide support for multiple networking functions (e.g., routing, bridging, switching, Layer 2 aggregation, session border control, Quality of Service, and/or subscriber management), and/or provide support for multiple application services (e.g., data, voice, and video).
Two of the exemplary ND implementations in
The special-purpose network device 802 includes networking hardware 810 comprising a set of one or more processor(s) 812, forwarding resource(s) 814 (which typically include one or more ASICs and/or network processors), and physical network interfaces (NIs) 816 (through which network connections are made, such as those shown by the connectivity between NDs 800A-H), as well as non-transitory machine readable storage media 818 having stored therein networking software 820. During operation, the networking software 820 may be executed by the networking hardware 810 to instantiate a set of one or more networking software instance(s) 822. Each of the networking software instance(s) 822, and that part of the networking hardware 810 that executes that network software instance (be it hardware dedicated to that networking software instance and/or time slices of hardware temporally shared by that networking software instance with others of the networking software instance(s) 822), form a separate virtual network element 830A-R. Each of the virtual network element(s) (VNEs) 830A-R includes a control communication and configuration module 832A-R (sometimes referred to as a local control module or control communication module) and forwarding table(s) 834A-R, such that a given virtual network element (e.g., 830A) includes the control communication and configuration module (e.g., 832A), a set of one or more forwarding table(s) (e.g., 834A), and that portion of the networking hardware 810 that executes the virtual network element (e.g., 830A).
The special-purpose network device 802 is often physically and/or logically considered to include: 1) a ND control plane 824 (sometimes referred to as a control plane) comprising the processor(s) 812 that execute the control communication and configuration module(s) 832A-R; and 2) a ND forwarding plane 826 (sometimes referred to as a forwarding plane, a data plane, or a media plane) comprising the forwarding resource(s) 814 that utilize the forwarding table(s) 834A-R and the physical NIs 816. By way of example, where the ND is a router (or is implementing routing functionality), the ND control plane 824 (the processor(s) 812 executing the control communication and configuration module(s) 832A-R) is typically responsible for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) and storing that routing information in the forwarding table(s) 834A-R, and the ND forwarding plane 826 is responsible for receiving that data on the physical NIs 816 and forwarding that data out the appropriate ones of the physical NIs 816 based on the forwarding table(s) 834A-R.
Returning to
The instantiation of the one or more sets of one or more applications 864A-R, as well as virtualization if implemented, are collectively referred to as software instance(s) 852. Each set of applications 864A-R, corresponding virtualization construct (e.g., instance 862A-R) if implemented, and that part of the hardware 840 that executes them (be it hardware dedicated to that execution and/or time slices of hardware temporally shared), forms a separate virtual network element(s) 860A-R.
The virtual network element(s) 860A-R perform similar functionality to the virtual network element(s) 830A-R—e.g., similar to the control communication and configuration module(s) 832A and forwarding table(s) 834A (this virtualization of the hardware 840 is sometimes referred to as network function virtualization (NFV)). Thus, NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which could be located in Data centers, NDs, and customer premise equipment (CPE). While embodiments are illustrated with each instance 862A-R corresponding to one VNE 860A-R, alternative embodiments may implement this correspondence at a finer level granularity (e.g., line card virtual machines virtualize line cards, control card virtual machine virtualize control cards, etc.); it should be understood that the techniques described herein with reference to a correspondence of instances 862A-R to VNEs also apply to embodiments where such a finer level of granularity and/or unikernels are used.
In certain embodiments, the virtualization layer 854 includes a virtual switch that provides similar forwarding services as a physical Ethernet switch. Specifically, this virtual switch forwards traffic between instances 862A-R and the physical NI(s) 846, as well as optionally between the instances 862A-R; in addition, this virtual switch may enforce network isolation between the VNEs 860A-R that by policy are not permitted to communicate with each other (e.g., by honoring virtual local area networks (VLANs)).
The third exemplary ND implementation in
Regardless of the above exemplary implementations of an ND, when a single one of multiple VNEs implemented by an ND is being considered (e.g., only one of the VNEs is part of a given virtual network) or where only a single VNE is currently being implemented by an ND, the shortened term network element (NE) is sometimes used to refer to that VNE. Also in all of the above exemplary implementations, each of the VNEs (e.g., VNE(s) 830A-R, VNEs 860A-R, and those in the hybrid network device 806) receives data on the physical NIs (e.g., 816, 846) and forwards that data out the appropriate ones of the physical NIs (e.g., 816, 846). For example, a VNE implementing IP router functionality forwards IP packets on the basis of some of the IP header information in the IP packet; where IP header information includes source IP address, destination IP address, source port, destination port (where “source port” and “destination port” refer herein to protocol ports, as opposed to physical ports of a ND), transport protocol (e.g., user datagram protocol (UDP), Transmission Control Protocol (TCP), and differentiated services code point (DSCP) values.
The NDs of
A virtual network is a logical abstraction of a physical network (such as that in
A network virtualization edge (NVE) sits at the edge of the underlay network and participates in implementing the network virtualization; the network-facing side of the NVE uses the underlay network to tunnel frames to and from other NVEs; the outward-facing side of the NVE sends and receives data to and from systems outside the network. A virtual network instance (VNI) is a specific instance of a virtual network on a NVE (e.g., a NE/VNE on an ND, a part of a NE/VNE on a ND where that NE/VNE is divided into multiple VNEs through emulation); one or more VNIs can be instantiated on an NVE (e.g., as different VNEs on an ND). A virtual access point (VAP) is a logical connection point on the NVE for connecting external systems to a virtual network; a VAP can be physical or virtual ports identified through logical interface identifiers (e.g., a VLAN ID).
Examples of network services include: 1) an Ethernet LAN emulation service (an Ethernet-based multipoint service similar to an Internet Engineering Task Force (IETF) Multiprotocol Label Switching (MPLS) or Ethernet VPN (EVPN) service) in which external systems are interconnected across the network by a LAN environment over the underlay network (e.g., an NVE provides separate L2 VNIs (virtual switching instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network); and 2) a virtualized IP forwarding service (similar to IETF IP VPN (e.g., Border Gateway Protocol (BGP)/MPLS IPVPN) from a service definition perspective) in which external systems are interconnected across the network by an L3 environment over the underlay network (e.g., an NVE provides separate L3 VNIs (forwarding and routing instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network)). Network services may also include quality of service capabilities (e.g., traffic classification marking, traffic conditioning and scheduling), security capabilities (e.g., filters to protect customer premises from network—originated attacks, to avoid malformed route announcements), and management capabilities (e.g., full detection and processing).
For example, where the special-purpose network device 802 is used, the control communication and configuration module(s) 832A-R of the ND control plane 824 typically include a reachability and forwarding information module to implement one or more routing protocols (e.g., an exterior gateway protocol such as Border Gateway Protocol (BGP), Interior Gateway Protocol(s) (IGP) (e.g., Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), Routing Information Protocol (RIP), Label Distribution Protocol (LDP), Resource Reservation Protocol (RSVP) (including RSVP-Traffic Engineering (TE): Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol Label Switching (GMPLS) Signaling RSVP-TE)) that communicate with other NEs to exchange routes, and then selects those routes based on one or more routing metrics. Thus, the NEs 870A-H (e.g., the processor(s) 812 executing the control communication and configuration module(s) 832A-R) perform their responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by distributively determining the reachability within the network and calculating their respective forwarding information. Routes and adjacencies are stored in one or more routing structures (e.g., Routing Information Base (RIB), Label Information Base (LIB), one or more adjacency structures) on the ND control plane 824. The ND control plane 824 programs the ND forwarding plane 826 with information (e.g., adjacency and route information) based on the routing structure(s). For example, the ND control plane 824 programs the adjacency and route information into one or more forwarding table(s) 834A-R (e.g., Forwarding Information Base (FIB), Label Forwarding Information Base (LFIB), and one or more adjacency structures) on the ND forwarding plane 826. For layer 2 forwarding, the ND can store one or more bridging tables that are used to forward data based on the layer 2 information in that data. While the above example uses the special-purpose network device 802, the same distributed approach 872 can be implemented on the general purpose network device 804 and the hybrid network device 806.
For example, where the special-purpose network device 802 is used in the data plane 880, each of the control communication and configuration module(s) 832A-R of the ND control plane 824 typically include a control agent that provides the VNE side of the south bound interface 882. In this case, the ND control plane 824 (the processor(s) 812 executing the control communication and configuration module(s) 832A-R) performs its responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) through the control agent communicating with the centralized control plane 876 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 879 (it should be understood that in some embodiments, the control communication and configuration module(s) 832A-R, in addition to communicating with the centralized control plane 876, may also play some role in determining reachability and/or calculating forwarding information—albeit less so than in the case of a distributed approach; such embodiments are generally considered to fall under the centralized approach 874, but may also be considered a hybrid approach).
While the above example uses the special-purpose network device 802, the same centralized approach 874 can be implemented with the general purpose network device 804 (e.g., each of the VNE 860A-R performs its responsibility for controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by communicating with the centralized control plane 876 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 879; it should be understood that in some embodiments, the VNEs 860A-R, in addition to communicating with the centralized control plane 876, may also play some role in determining reachability and/or calculating forwarding information—albeit less so than in the case of a distributed approach) and the hybrid network device 806. In fact, the use of SDN techniques can enhance the NFV techniques typically used in the general purpose network device 804 or hybrid network device 806 implementations as NFV is able to support SDN by providing an infrastructure upon which the SDN software can be run, and NFV and SDN both aim to make use of commodity server hardware and physical switches.
While
While
On the other hand,
While some embodiments implement the centralized control plane 876 as a single entity (e.g., a single instance of software running on a single electronic device), alternative embodiments may spread the functionality across multiple entities for redundancy and/or scalability purposes (e.g., multiple instances of software running on different electronic devices).
Similar to the network device implementations, the electronic device(s) running the centralized control plane 876, and thus the network controller 878 including the centralized reachability and forwarding information module 879, may be implemented a variety of ways (e.g., a special purpose device, a general-purpose (e.g., COTS) device, or hybrid device). These electronic device(s) would similarly include processor(s), a set or one or more physical NIs, and a non-transitory machine-readable storage medium having stored thereon the centralized control plane software. For instance,
In embodiments that use compute virtualization, the processor(s) 942 typically execute software to instantiate a virtualization layer 954 (e.g., in one embodiment the virtualization layer 954 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 962A-R called software containers (representing separate user spaces and also called virtualization engines, virtual private servers, or jails) that may each be used to execute a set of one or more applications; in another embodiment the virtualization layer 954 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and an application is run on top of a guest operating system within an instance 962A-R called a virtual machine (which in some cases may be considered a tightly isolated form of software container) that is run by the hypervisor; in another embodiment, an application is implemented as a unikernel, which can be generated by compiling directly with an application only a limited set of libraries ((e.g., from a library operating system (LibOS) including drivers/libraries of OS services) that provide the particular OS services needed by the application, and the unikernel can run directly on hardware 940, directly on a hypervisor represented by virtualization layer 954 (in which case the unikernel is sometimes described as running within a LibOS virtual machine), or in a software container represented by one of instances 962A-R). Again, in embodiments where compute virtualization is used, during operation an instance of the CCP software 950 (illustrated as CCP instance 976A) is executed (e.g., within the instance 962A) on the virtualization layer 954. In embodiments where compute virtualization is not used, the CCP instance 976A is executed, as a unikernel or on top of a host operating system, on the “bare metal” general purpose control plane device 904. The instantiation of the CCP instance 976A, as well as the virtualization layer 954 and instances 962A-R if implemented, are collectively referred to as software instance(s) 952.
In some embodiments, the CCP instance 976A includes a network controller instance 978. The network controller instance 978 includes a centralized reachability and forwarding information module instance 979 (which is a middleware layer providing the context of the network controller 878 to the operating system and communicating with the various NEs), and an CCP application layer 980 (sometimes referred to as an application layer) over the middleware layer (providing the intelligence required for various network operations such as protocols, network situational awareness, and user-interfaces). At a more abstract level, this CCP application layer 980 within the centralized control plane 876 works with virtual network view(s) (logical view(s) of the network) and the middleware layer provides the conversion from the virtual networks to the physical view.
The centralized control plane 876 transmits relevant messages to the data plane 880 based on CCP application layer 980 calculations and middleware layer mapping for each flow. A flow may be defined as a set of packets whose headers match a given pattern of bits; in this sense, traditional IP forwarding is also flow-based forwarding where the flows are defined by the destination IP address for example; however, in other implementations, the given pattern of bits used for a flow definition may include more fields (e.g., 10 or more) in the packet headers. Different NDs/NEs/VNEs of the data plane 880 may receive different messages, and thus different forwarding information. The data plane 880 processes these messages and programs the appropriate flow information and corresponding actions in the forwarding tables (sometime referred to as flow tables) of the appropriate NE/VNEs, and then the NEs/VNEs map incoming packets to flows represented in the forwarding tables and forward packets based on the matches in the forwarding tables.
Standards such as OpenFlow define the protocols used for the messages, as well as a model for processing the packets. The model for processing packets includes header parsing, packet classification, and making forwarding decisions. Header parsing describes how to interpret a packet based upon a well-known set of protocols. Some protocol fields are used to build a match structure (or key) that will be used in packet classification (e.g., a first key field could be a source media access control (MAC) address, and a second key field could be a destination MAC address).
Packet classification involves executing a lookup in memory to classify the packet by determining which entry (also referred to as a forwarding table entry or flow entry) in the forwarding tables best matches the packet based upon the match structure, or key, of the forwarding table entries. It is possible that many flows represented in the forwarding table entries can correspond/match to a packet; in this case the system is typically configured to determine one forwarding table entry from the many according to a defined scheme (e.g., selecting a first forwarding table entry that is matched). Forwarding table entries include both a specific set of match criteria (a set of values or wildcards, or an indication of what portions of a packet should be compared to a particular value/values/wildcards, as defined by the matching capabilities—for specific fields in the packet header, or for some other packet content), and a set of one or more actions for the data plane to take on receiving a matching packet. For example, an action may be to push a header onto the packet, for the packet using a particular port, flood the packet, or simply drop the packet. Thus, a forwarding table entry for IPv4/IPv6 packets with a particular transmission control protocol (TCP) destination port could contain an action specifying that these packets should be dropped.
Making forwarding decisions and performing actions occurs, based upon the forwarding table entry identified during packet classification, by executing the set of actions identified in the matched forwarding table entry on the packet.
However, when an unknown packet (for example, a “missed packet” or a “match-miss” as used in OpenFlow parlance) arrives at the data plane 880, the packet (or a subset of the packet header and content) is typically forwarded to the centralized control plane 876. The centralized control plane 876 will then program forwarding table entries into the data plane 880 to accommodate packets belonging to the flow of the unknown packet. Once a specific forwarding table entry has been programmed into the data plane 880 by the centralized control plane 876, the next packet with matching credentials will match that forwarding table entry and take the set of actions associated with that matched entry.
A network interface (NI) may be physical or virtual; and in the context of IP, an interface address is an IP address assigned to a NI, be it a physical NI or virtual NI. A virtual NI may be associated with a physical NI, with another virtual interface, or stand on its own (e.g., a loopback interface, a point-to-point protocol interface). A NI (physical or virtual) may be numbered (a NI with an IP address) or unnumbered (a NI without an IP address). A loopback interface (and its loopback address) is a specific type of virtual NI (and IP address) of a NE/VNE (physical or virtual) often used for management purposes; where such an IP address is referred to as the nodal loopback address. The IP address(es) assigned to the NI(s) of a ND are referred to as IP addresses of that ND; at a more granular level, the IP address(es) assigned to NI(s) assigned to a NE/VNE implemented on a ND can be referred to as IP addresses of that NE/VNE.
Next hop selection by the routing system for a given destination may resolve to one path (that is, a routing protocol may generate one next hop on a shortest path); but if the routing system determines there are multiple viable next hops (that is, the routing protocol generated forwarding solution offers more than one next hop on a shortest path—multiple equal cost next hops), some additional criteria is used—for instance, in a connectionless network, Equal Cost Multi Path (ECMP) (also known as Equal Cost Multi Pathing, multipath forwarding and IP multipath) may be used (e.g., typical implementations use as the criteria particular header fields to ensure that the packets of a particular packet flow are always forwarded on the same next hop to preserve packet flow ordering). For purposes of multipath forwarding, a packet flow is defined as a set of packets that share an ordering constraint. As an example, the set of packets in a particular TCP transfer sequence need to arrive in order, else the TCP logic will interpret the out of order delivery as congestion and slow the TCP transfer rate down.
A Layer 3 (L3) Link Aggregation (LAG) link is a link directly connecting two NDs with multiple IP-addressed link paths (each link path is assigned a different IP address), and a load distribution decision across these different link paths is performed at the ND forwarding plane; in which case, a load distribution decision is made between the link paths.
Some NDs include functionality for authentication, authorization, and accounting (AAA) protocols (e.g., RADIUS (Remote Authentication Dial-In User Service), Diameter, and/or TACACS+(Terminal Access Controller Access Control System Plus). AAA can be provided through a client/server model, where the AAA client is implemented on a ND and the AAA server can be implemented either locally on the ND or on a remote electronic device coupled with the ND. Authentication is the process of identifying and verifying a subscriber. For instance, a subscriber might be identified by a combination of a username and a password or through a unique key. Authorization determines what a subscriber can do after being authenticated, such as gaining access to certain electronic device information resources (e.g., through the use of access control policies). Accounting is recording user activity. By way of a summary example, end user devices may be coupled (e.g., through an access network) through an edge ND (supporting AAA processing) coupled to core NDs coupled to electronic devices implementing servers of service/content providers. AAA processing is performed to identify for a subscriber the subscriber record stored in the AAA server for that subscriber. A subscriber record includes a set of attributes (e.g., subscriber name, password, authentication information, access control information, rate-limiting information, policing information) used during processing of that subscriber's traffic.
Certain NDs (e.g., certain edge NDs) internally represent end user devices (or sometimes customer premise equipment (CPE) such as a residential gateway (e.g., a router, modem)) using subscriber circuits. A subscriber circuit uniquely identifies within the ND a subscriber session and typically exists for the lifetime of the session. Thus, a ND typically allocates a subscriber circuit when the subscriber connects to that ND, and correspondingly de-allocates that subscriber circuit when that subscriber disconnects. Each subscriber session represents a distinguishable flow of packets communicated between the ND and an end user device (or sometimes CPE such as a residential gateway or modem) using a protocol, such as the point-to-point protocol over another protocol (PPPoX) (e.g., where X is Ethernet or Asynchronous Transfer Mode (ATM)), Ethernet, 802.1Q Virtual LAN (VLAN), Internet Protocol, or ATM). A subscriber session can be initiated using a variety of mechanisms (e.g., manual provisioning a dynamic host configuration protocol (DHCP), DHCP/client-less internet protocol service (CLIPS) or Media Access Control (MAC) address tracking). For example, the point-to-point protocol (PPP) is commonly used for digital subscriber line (DSL) services and requires installation of a PPP client that enables the subscriber to enter a username and a password, which in turn may be used to select a subscriber record. When DHCP is used (e.g., for cable modem services), a username typically is not provided; but in such situations other information (e.g., information that includes the MAC address of the hardware in the end user device (or CPE)) is provided. The use of DHCP and CLIPS on the ND captures the MAC addresses and uses these addresses to distinguish subscribers and access their subscriber records.
A virtual circuit (VC), synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication. Virtual circuit communication resembles circuit switching, since both are connection oriented, meaning that in both cases data is delivered in correct order, and signaling overhead is required during a connection establishment phase. Virtual circuits may exist at different layers. For example, at layer 4, a connection oriented transport layer datalink protocol such as Transmission Control Protocol (TCP) may rely on a connectionless packet switching network layer protocol such as IP, where different packets may be routed over different paths, and thus be delivered out of order. Where a reliable virtual circuit is established with TCP on top of the underlying unreliable and connectionless IP protocol, the virtual circuit is identified by the source and destination network socket address pair, i.e. the sender and receiver IP address and port number. However, a virtual circuit is possible since TCP includes segment numbering and reordering on the receiver side to prevent out-of-order delivery. Virtual circuits are also possible at Layer 3 (network layer) and Layer 2 (datalink layer); such virtual circuit protocols are based on connection oriented packet switching, meaning that data is always delivered along the same network path, i.e. through the same NEs/VNEs. In such protocols, the packets are not routed individually and complete addressing information is not provided in the header of each data packet; only a small virtual channel identifier (VCI) is required in each packet; and routing information is transferred to the NEs/VNEs during the connection establishment phase; switching only involves looking up the virtual channel identifier in a table rather than analyzing a complete address. Examples of network layer and datalink layer virtual circuit protocols, where data always is delivered over the same path: X.25, where the VC is identified by a virtual channel identifier (VCI); Frame relay, where the VC is identified by a VCI; Asynchronous Transfer Mode (ATM), where the circuit is identified by a virtual path identifier (VPI) and virtual channel identifier (VCI) pair; General Packet Radio Service (GPRS); and Multiprotocol label switching (MPLS), which can be used for IP over virtual circuits (Each circuit is identified by a label).
Certain NDs (e.g., certain edge NDs) use a hierarchy of circuits. The leaf nodes of the hierarchy of circuits are subscriber circuits. The subscriber circuits have parent circuits in the hierarchy that typically represent aggregations of multiple subscriber circuits, and thus the network segments and elements used to provide access network connectivity of those end user devices to the ND. These parent circuits may represent physical or logical aggregations of subscriber circuits (e.g., a virtual local area network (VLAN), a permanent virtual circuit (PVC) (e.g., for Asynchronous Transfer Mode (ATM)), a circuit-group, a channel, a pseudo-wire, a physical NI of the ND, and a link aggregation group). A circuit-group is a virtual construct that allows various sets of circuits to be grouped together for configuration purposes, for example aggregate rate control. A pseudo-wire is an emulation of a layer 2 point-to-point connection-oriented service. A link aggregation group is a virtual construct that merges multiple physical NIs for purposes of bandwidth aggregation and redundancy. Thus, the parent circuits physically or logically encapsulate the subscriber circuits.
Each VNE (e.g., a virtual router, a virtual bridge (which may act as a virtual switch instance in a Virtual Private LAN Service (VPLS) is typically independently administrable. For example, in the case of multiple virtual routers, each of the virtual routers may share system resources but is separate from the other virtual routers regarding its management domain, AAA (authentication, authorization, and accounting) name space, IP address, and routing database(s). Multiple VNEs may be employed in an edge ND to provide direct network access and/or different classes of services for subscribers of service and/or content providers.
Within certain NDs, “interfaces” that are independent of physical NIs may be configured as part of the VNEs to provide higher-layer protocol and service information (e.g., Layer 3 addressing). The subscriber records in the AAA server identify, in addition to the other subscriber configuration requirements, to which context (e.g., which of the VNEs/NEs) the corresponding subscribers should be bound within the ND. As used herein, a binding forms an association between a physical entity (e.g., physical NI, channel) or a logical entity (e.g., circuit such as a subscriber circuit or logical circuit (a set of one or more subscriber circuits)) and a context's interface over which network protocols (e.g., routing protocols, bridging protocols) are configured for that context. Subscriber data flows on the physical entity when some higher-layer protocol interface is configured and associated with that physical entity.
Some NDs provide support for implementing VPNs (Virtual Private Networks) (e.g., Layer 2 VPNs and/or Layer 3 VPNs). For example, the ND where a provider's network and a customer's network are coupled are respectively referred to as PEs (Provider Edge) and CEs (Customer Edge). In a Layer 2 VPN, forwarding typically is performed on the CE(s) on either end of the VPN and traffic is sent across the network (e.g., through one or more PEs coupled by other NDs). Layer 2 circuits are configured between the CEs and PEs (e.g., an Ethernet port, an ATM permanent virtual circuit (PVC), a Frame Relay PVC). In a Layer 3 VPN, routing typically is performed by the PEs. By way of example, an edge ND that supports multiple VNEs may be deployed as a PE; and a VNE may be configured with a VPN protocol, and thus that VNE is referred as a VPN VNE.
Some NDs provide support for VPLS (Virtual Private LAN Service). For example, in a VPLS network, end user devices access content/services provided through the VPLS network by coupling to CEs, which are coupled through PEs coupled by other NDs. VPLS networks can be used for implementing triple play network applications (e.g., data applications (e.g., high-speed Internet access), video applications (e.g., television service such as IPTV (Internet Protocol Television), VoD (Video-on-Demand) service), and voice applications (e.g., VoIP (Voice over Internet Protocol) service)), VPN services, etc. VPLS is a type of layer 2 VPN that can be used for multi-point connectivity. VPLS networks also allow end use devices that are coupled with CEs at separate geographical locations to communicate with each other across a Wide Area Network (WAN) as if they were directly attached to each other in a Local Area Network (LAN) (referred to as an emulated LAN).
In VPLS networks, each CE typically attaches, possibly through an access network (wired and/or wireless), to a bridge module of a PE via an attachment circuit (e.g., a virtual link or connection between the CE and the PE). The bridge module of the PE attaches to an emulated LAN through an emulated LAN interface. Each bridge module acts as a “Virtual Switch Instance” (VSI) by maintaining a forwarding table that maps MAC addresses to pseudowires and attachment circuits. PEs forward frames (received from CEs) to destinations (e.g., other CEs, other PEs) based on the MAC destination address field included in those frames.
In one embodiment, one or more of operations and functionality described above in relation to
In some embodiments, virtualization may be utilized to provide NFV. For example, the management server 106, the SDN switches 108, and/or the SDN controllers 104 may be a computing device configured to execute one or more virtual machines, containers, and/or microservices to provide NFV. In some embodiments, the SDN controllers 104 may be control plane devices (e.g., the general purpose control plane device 904) that are configured to implement a control plane of SDN.
While the systems, devices, structures, methods, and designs herein have been described in terms of several embodiments, those skilled in the art will recognize that the systems, devices, structures, methods, and designs are not limited to the embodiments described, can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.
Additionally, while the flow diagrams in the figures show a particular order of operations performed by certain embodiments, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2017/056201 | 10/6/2017 | WO | 00 |
