Patent Publication Number: US-11032107-B2

Title: GRE tunneling with reduced packet encryption at intermediate routers

Description:
BACKGROUND 
     A network tunnel is a mechanism for secure transmission of private information through a public network in such a way that network devices of the public network are unaware of the private information. A tunneling protocol is a communications protocol that enables creation of a network tunnel. The tunneling protocol enables private information to be sent across a public network through a process called encapsulation. 
     SUMMARY 
     According to some implementations, a method may include receiving, by a network node, a packet having an inner internet protocol (IP) header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, wherein the inner IP header is encrypted; generating, by the network node after receiving the packet, a copy of the packet to obtain a copied packet; performing, by the network node, decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header; updating, by the network node, the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address; and routing, by the network node, the updated packet according to the updated outer IP header. 
     According to some implementations, a network node may include one or more memories and one or more processors to receive a packet having an inner IP header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, wherein the inner IP header is encapsulated by a Generic Routing Encapsulation (GRE) header, the GRE header is encapsulated by an Encapsulating Security Payload (ESP) header that provides encryption, and the ESP header is encapsulated by the outer IP header; generate a copy of the packet to obtain a copied packet; perform decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header; update the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address; and route the updated packet according to the updated outer IP header. 
     According to some implementations, a non-transitory computer-readable medium may store one or more instructions that, when executed by one or more processors, may cause the one or more processors to receive a packet having an inner IP header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of an intermediate network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, wherein the inner IP header is encrypted; generate a copy of the packet to obtain a copied packet; perform decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header; determine a tunnel endpoint of a receiving network node that is associated with the recipient address; update the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the intermediate network node, and the destination address of the updated outer IP header is updated to the tunnel endpoint of the receiving network node; and route the updated packet according to the updated outer IP header. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1E  are diagrams of one or more example implementations described herein. 
         FIG. 2  is a diagram of an example environment in which systems and/or methods described herein may be implemented. 
         FIG. 3  is a diagram of example components of one or more devices of  FIG. 2 . 
         FIGS. 4-6  are flowcharts of example processes for GRE tunneling with reduced packet encryption at intermediate routers. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     A virtual private network (VPN) may be supported by a software-defined wide area network (SD-WAN) to extend a private network across a public network (e.g., the Internet). In particular, the VPN may establish a virtual point-to-point connection over the public network through use of a tunneling protocol. For example, GRE is a tunneling protocol that may be used to transport an IP packet with private addresses over the public network using a delivery packet with public IP addresses that represent GRE tunnel endpoints. The IP packet (e.g., the IP packet encapsulated within the delivery packet) may be encrypted by a transmitting network node and decrypted by a receiving network node using a secure network protocol suite, such as IP Security (IPSec). 
     In some instances, the delivery packet originating from the transmitting network node may be transported through a hub, or one or more other intermediate routers, before reaching the receiving network node. In such a case, according to current techniques, the transmitting network node may encrypt the IP packet with an encryption key negotiated with the hub, encapsulate the IP packet in a delivery packet addressed to the hub, and transmit the delivery packet to the hub. The hub may decapsulate the IP packet and decrypt the IP packet using a decryption key negotiated with the transmitting network node. Based on the decrypted IP packet, the hub may determine that a destination of the IP packet is behind the receiving network node. Accordingly, the hub may re-encrypt the IP packet using an encryption key negotiated with the receiving network node, re-encapsulate the IP packet with a delivery packet addressed to the receiving network node, and transmit the delivery packet to the receiving network node. The receiving network node may decapsulate the IP packet, decrypt the IP packet using a decryption key negotiated with the hub, and transmit the IP packet to the destination. 
     Accordingly, current techniques require one or more re-encryption and re-encapsulation steps when transporting a packet through one or more intermediate routers (e.g., multiple intermediate routers would require multiple re-encryption and re-encapsulation steps). This additional processing wastes computing resources (e.g., processor resources, memory resources, and/or the like) and causes network congestion, thereby reducing network throughput. 
     According to some implementations described herein, one or more intermediate network nodes (e.g., intermediate routers between a transmitting router and a receiving router) may process a packet originating at the transmitting network node and destined for the receiving network node without performing re-encryption and re-encapsulation on the packet. In some implementations, an intermediate network node (e.g., an intermediate router) may receive a packet (e.g., a GRE packet), with an outer IP header that encapsulates an inner packet with an inner IP header. The intermediate network node may generate a copy of the packet to obtain a copied packet, and decrypt one of the packet or the copied packet to identify a destination from the inner IP header. The intermediate network node may update the outer header of the other of the packet or the copied packet with addresses associated with the intermediate network node and the destination, to obtain an updated packet with an updated outer IP header. The network node may then route the updated packet according to the updated outer IP header. 
     In this way, the intermediate network node is able to process and route a packet without performing re-encryption and re-encapsulation of the packet. By eliminating re-encryption and re-encapsulation steps, the intermediate network node conserves computing resources that would otherwise be wasted performing re-encryption and re-encapsulation. As a result, the intermediate network node facilitates faster routing of packets, which reduces network congestion and improves network throughput. Accordingly, significant reductions to network congestion and improvements to network throughput can be achieved when the intermediate network node is one of a plurality of intermediate network nodes through which a packet is transported. 
       FIGS. 1A-1E  are diagrams of one or more example implementations  100  described herein. As shown in  FIGS. 1A-1E , example implementation(s)  100  may include a transmitting network node (shown as Node A in  FIGS. 1A and 1E ), an intermediate network node (shown as Hub in  FIGS. 1A-1E ), and a receiving network node (shown as Node B in  FIGS. 1A and 1E ). 
     The transmitting network node (e.g., an ingress network node), the intermediate network node (e.g., a hub), and the receiving network node (e.g., an egress network node) may form a VPN. In some implementations, the VPN also may include one or more additional network nodes. The VPN may be associated with multiple local area networks (LANs). For example, each LAN may be associated with an office location of an entity. The transmitting network node may be a gateway to a first LAN that includes a sender host (shown as Host A 1  in  FIGS. 1A and 1E ) and the receiving network node may be a gateway to a second LAN that includes a recipient host (shown as Host B 1  in  FIGS. 1A and 1E ). The sender host may be associated with a private sender address (e.g., a private IP address) and the recipient host may be associated with a private recipient address (e.g., a private IP address). 
     A host may include a traffic transfer device, such as a router, a gateway, a switch, a firewall, a hub, a bridge, a reverse proxy, a server (e.g., a proxy server, a server executing a virtual machine, and/or the like), a security device, an intrusion detection device, a load balancer, or a similar type of device. In some implementations, a host may include an endpoint device that is a source or a destination for network traffic. For example, a host may include a computer or a similar type of device. 
     The transmitting network node may communicate with the receiving network node via the intermediate network node. That is, packets originating behind the transmitting network node and terminating behind the receiving network node may be transported through the intermediate network node. Thus, the intermediate network node may be an intermediate hop between the transmitting network node and the receiving network node. In some implementations, the intermediate network node may be one of a plurality of intermediate network nodes between the transmitting network node and the receiving network node. In some scenarios, packets may originate behind the intermediate network node and/or terminate behind the intermediate network node using the transmitting network node or the receiving network node as an intermediate hop. In other words, the transmitting network node, the intermediate network node, and the receiving network node may be nodes of a mesh network. 
     A point-to-point connection between the transmitting network node and the intermediate network node may be established using a network tunnel (e.g., a GRE tunnel), and a point-to-point connection between the receiving network node and the intermediate network node may be established using a network tunnel. Accordingly, the transmitting network node, the intermediate network node, and the receiving network node each may be associated with a tunnel interface address (e.g., a tunnel interface IP address) and a public address (e.g., a public IP address) configured for the tunnel interface that serves as a tunnel endpoint. While the description to follow will be described in terms of an example of a GRE tunneling protocol, the description is not limited to this particular example. Implementations described herein also apply to other tunneling protocols that may be used to configure point-to-point connections over a public network. 
     In addition, the transmitting network node, the intermediate network node, and the receiving network node may share a common security association. For example, the VPN formed by the transmitting network node, the intermediate network node, and the receiving network node may be a group VPN. In a group VPN, a centralized key server may provide encryption and decryption keys to each group member (e.g., the transmitting network node, the intermediate network node, and the receiving network node) so that any group member may decrypt packets encrypted by any other group member. Accordingly, encryption and decryption keys used by the intermediate network node may correspond to (e.g., may be identical to) encryption and decryption keys used by the transmitting network node and encryption and decryption keys used by the receiving network node. 
     As shown in  FIG. 1A , and by reference number  105 , the intermediate network node may receive a packet. For example, the intermediate network node may receive a packet sent by the transmitting network node (shown as Node A in  FIG. 1A ). In such a case, the packet may have originated at a host (shown as Host A 1  in  FIG. 1A ) behind the transmitting network node. For example, the host may have generated an IP packet, provided the IP packet to the transmitting network node, and the transmitting network node may have encapsulated the IP packet according to the GRE tunneling protocol based on determining that a destination for the IP packet was reachable via a GRE tunnel (e.g., according to a routing table of the transmitting network node). 
     Accordingly, the packet received by the intermediate network node may be a GRE packet. For example, the packet may include an outer IP header, and may encapsulate an inner packet (e.g., the IP packet) associated with an inner IP header and a payload (e.g., a payload intended for a host associated with a destination address of the inner IP header). Accordingly, the packet may include an outer IP header and an inner IP header. 
     The outer IP header may include a source address and a destination address. The source address and the destination address of the outer IP header may identify respective tunnel endpoints (e.g., a source tunnel endpoint and a destination tunnel endpoint). For example, when the packet is received by the intermediate network node from the transmitting network node, the source address of the outer IP header may identify a tunnel endpoint associated with the transmitting network node (e.g., 172.16.1.1, as shown in  FIG. 1A ) and the destination address of the outer IP header may identify a tunnel endpoint associated with the intermediate network node (e.g., 172.17.0.1, as shown in  FIG. 1A ). Thus, the source address and the destination address of the outer IP header may identify public IP addresses. 
     The inner IP header also may include a source address and a destination address. The source address of the inner IP header may identify a sender address (e.g., an IP address associated with a host that is sending the inner packet) and the destination address of the inner IP header may identify a recipient address (e.g., an IP address associated with a host that is to receive the inner packet). For example, when the packet is received by the intermediate network node from the transmitting network node, the source address of the inner IP header may identify a sender address associated with the sender host (e.g., 192.168.1.1, as shown in  FIG. 1A ) and the destination address of the inner IP header may identify a recipient address associated with the recipient host (e.g., 192.168.2.1, as shown in  FIG. 1A ). Thus, the source address and the destination address of the inner IP header may identify private IP addresses (e.g., private IP addresses associated with LANs). 
     When the packet is received by the intermediate network node from the transmitting network node, the inner packet, including the inner IP header, may be encrypted. For example, the transmitting network node may have encrypted the inner packet based on an encryption key. Moreover, the transmitting network node may have encrypted the inner packet using an ESP protocol (e.g., ESP in transport mode). Accordingly, when the packet is received by the intermediate network node from the transmitting network node, the packet may include an ESP header that provides encryption to the inner packet, including the inner IP header. In such a case, the inner IP header may be encapsulated by a GRE header, the GRE header may be encapsulated by the ESP header, and the ESP header may be encapsulated by the outer IP header. 
     In some implementations, prior to receiving the packet from the transmitting network node, the intermediate network node may have received an encryption key and a decryption key from the centralized key server (e.g., a centralized key server associated with the group VPN that includes the transmitting network node, the intermediate network node, and the receiving network node). Additionally, the transmitting network node and the receiving network node each may have received, from the centralized key server, an encryption key and a decryption key that correspond to the encryption key and the decryption key of the intermediate network node. In other words, an encryption key and a decryption key associated with a tunnel between the transmitting network node and the intermediate network node may correspond to an encryption key and a decryption key associated with a tunnel between the receiving network node and the intermediate network node. In this way, encryption performed by any of the transmitting network node, the intermediate network node, and the receiving network node can be decrypted by any other of the transmitting network node, the intermediate network node, and the receiving network node. 
     As shown in  FIG. 1B , and by reference number  110 , the intermediate network node may copy the packet that is received from the transmitting network node. In other words, the intermediate network node may generate a copy of the packet to obtain a copied packet, and the copied packet may contain data that is identical to data contained in the packet. The intermediate network node may store one of the packet or the copied packet (e.g., in a buffer of the intermediate network node). For example, the intermediate network node may store the copied packet in the buffer. 
     As shown in  FIG. 1C , and by reference number  115 , the intermediate network node may decrypt the packet. While the description to follow describes decryption of the packet, in some implementations, the intermediate network node may decrypt either of the packet or the copied packet. For example, the intermediate network node may decrypt the one of the packet or the copied packet that is not stored in the buffer. 
     The intermediate network node may perform decryption on the packet by decapsulating the inner packet, and performing decryption on the inner packet, thereby decrypting the inner IP header. The intermediate network node may decrypt the inner packet, including the inner IP header, using the decryption key received from the centralized key server. 
     After decrypting the inner packet, the intermediate network node may identify the recipient address for the inner packet (e.g., according to the destination address of the inner IP header). Moreover, the intermediate network node may identify a next hop network node for reaching the recipient address (e.g., according to a routing table of the intermediate network node) based on determining that the recipient address is not associated with the intermediate network node. For example, the recipient address may be associated with a host (shown as Host B 1  in  FIGS. 1A and 1E ) behind the receiving network node, and the intermediate network node may determine, using the routing table, that the host is reachable via a tunnel having a tunnel endpoint associated with the receiving network node (e.g., 172.16.1.2, as shown in  FIGS. 1A and 1E ). 
     As shown in  FIG. 1D , and by reference number  120 , the intermediate network node may update the outer IP header of the copied packet. For example, the intermediate network node may obtain the copied packet from the buffer and update the outer IP header of the copied packet. While the description to follow describes updating the outer IP header of the copied packet, in some implementations, the intermediate network node may update the outer IP header of either of the packet or the copied packet. For example, the intermediate network node may update the outer IP header of the one of the packet or the copied packet that was not decrypted by the intermediate network node. 
     The intermediate network node may update the source address of the outer IP header of the copied packet to a tunnel endpoint associated with the intermediate network node (e.g., 172.17.0.1, as shown in  FIGS. 1A and 1E ). The intermediate network node may update the destination address of the outer IP header of the copied packet to a tunnel endpoint associated with a next hop network node. For example, the intermediate network node may update the destination address of the outer IP header of the copied packet to a tunnel endpoint associated with the receiving network node (e.g., 172.16.1.2, as shown in  FIGS. 1A and 1E ) based on determining that the receiving network node is a next hop network node for reaching the recipient address for the inner packet, as described above. In some implementations, the intermediate network node may update a checksum value of the outer IP header of the copied packet based on the updated source address and destination address. In some implementations, the intermediate network node may discard the packet when updating the copied packet (e.g., when obtaining the copied packet from the buffer). 
     In this way, the intermediate network node may obtain an updated packet that is the same as the packet originally received from the transmitting network node except for an updated outer IP header. Accordingly, the updated packet remains encapsulated and encrypted according to processing performed by the transmitting network node, thereby eliminating a need for the intermediate network node to perform re-encryption and re-encapsulation and conserving associated computing resources that would otherwise be wasted. 
     As shown in  FIG. 1E , and by reference number  125 , the intermediate network node may route the updated packet. That is, the intermediate network node may route the updated packet according to the updated outer IP header of the updated packet. For example, the intermediate network node may route the updated packet to the receiving network node based on the destination address of the updated outer IP header, which identifies the tunnel endpoint associated with the receiving network node. 
     When the updated packet is received by the receiving network node, the receiving network node may perform decryption on the updated packet by decapsulating the inner packet, and performing decryption on the inner packet, thereby decrypting the inner IP header. The receiving network node may decrypt the inner packet, including the inner IP header, using the decryption key received from the centralized key server (e.g., a decryption key that corresponds to an encryption key used by the transmitting network node). 
     After decrypting the inner packet, the receiving network node may identify the recipient address for the inner packet (e.g., according to the destination address of the inner IP header). In some implementations, the receiving network node may generate a copy of the updated packet, determine that the recipient address is not associated with the receiving network node, identify a next hop network node for reaching the recipient address, update the updated outer IP header of the updated packet to obtain a further updated packet, and route the further updated packet, in a manner similar to that described above. This process may be repeated at one or more intermediate network nodes until the further updated packet reaches an egress network node associated with the recipient address. 
     In some implementations, the receiving network node may determine that the recipient address is associated with the receiving network node. Accordingly, the receiving network node may forward the updated packet to a host associated with the recipient address (e.g., Host B 1 , as shown in  FIG. 1E ). 
     In this way, re-encryption and re-encapsulation steps that would otherwise be performed by intermediate network nodes can be eliminated. Accordingly, intermediate network nodes can process packets with improved speed and efficiency, thereby reducing network congestion and improving network throughput. 
     As indicated above,  FIGS. 1A-1E  are provided merely as one or more examples. Other examples may differ from what is described with regard to  FIGS. 1A-1E . 
       FIG. 2  is a diagram of an example environment  200  in which systems and/or methods described herein may be implemented. As shown in  FIG. 2 , environment  200  may include one or more network nodes  210 - 1  through  210 -N (N≥3) (hereinafter referred to collectively as “network nodes  210 ,” and individually as “network node  210 ”) and a network  220 . Devices of environment  200  may interconnect via wired connections, wireless connections, or a combination of wired and wireless connections. 
     Network node  210  includes one or more devices capable of receiving, providing, storing, generating, and/or processing information. In some implementations, network node  210  may include a firewall, a router, a gateway, a switch, a bridge, a wireless access point, a base station (e.g., eNodeB, NodeB, gNodeB, and/or the like), and/or the like. In some implementations, network node  210  may be implemented as a physical device implemented within a housing, such as a chassis. In some implementations, network node  210  may be implemented as a virtual device implemented by one or more computer devices of a cloud computing environment or a data center. In some implementations, network node  210  may correspond to a transmitting network node, an intermediate network node, and/or a receiving network node. In some implementations, network nodes  210  may form a VPN, such as a group VPN. 
     In some implementations, a first network node  210  may process a packet received from a second network node  210 . For example, the first network node  210  may generate a copy of the packet to obtain a copied packet, perform decryption on one of the packet or the copied packet, update an outer IP header of the other of the packet or the copied packet to obtain an updated packet, and/or route the updated packet. 
     Network  220  includes one or more wired and/or wireless networks. For example, network  220  may include a cellular network (e.g., a long-term evolution (LTE) network, a code division multiple access (CDMA) network, a 3G network, a 4G network, a 5G network, another type of cellular network, and/or the like), a public land mobile network (PLMN), a LAN, a wide area network (WAN), a metropolitan area network (MAN), a telephone network (e.g., a public switched telephone network (PSTN)), a private network, an ad hoc network, an intranet, the Internet, a fiber optic-based network, a cloud computing network, or the like, and/or a combination of these or other types of networks. 
     The quantity and arrangement of devices and networks shown in  FIG. 2  are provided as an example. In practice, there may be additional devices and/or networks, fewer devices and/or networks, different devices and/or networks, or differently arranged devices and/or networks than those shown in  FIG. 2 . Furthermore, two or more devices shown in  FIG. 2  may be implemented within a single device, or a single device shown in  FIG. 2  may be implemented as multiple, distributed devices. Additionally, or alternatively, a set of devices (e.g., one or more devices) of environment  200  may perform one or more functions described as being performed by another set of devices of environment  200 . 
       FIG. 3  is a diagram of example components of a device  300 . Device  300  may correspond to one or more of network nodes  210 . In some implementations, one or more of network nodes  210  may include one or more devices  300  and/or one or more components of device  300 . As shown in  FIG. 3 , device  300  may include one or more input components  305 - 1  through  305 -B (B≥1) (hereinafter referred to collectively as “input components  305 ,” and individually as “input component  305 ”), a switching component  310 , one or more output components  315 - 1  through  315 -C (C≥1) (hereinafter referred to collectively as “output components  315 ,” and individually as “output component  315 ”), and a controller  320 . 
     Input component  305  may be points of attachment for physical links and may be points of entry for incoming traffic, such as packets. Input component  305  may process incoming traffic, such as by performing data link layer encapsulation or decapsulation. In some implementations, input component  305  may send and/or receive packets. In some implementations, input component  305  may include an input line card that includes one or more packet processing components (e.g., in the form of integrated circuits), such as one or more interface cards (IFCs), packet forwarding components, line card controller components, input ports, processors, memories, and/or input queues. In some implementations, device  300  may include one or more input components  305 . 
     Switching component  310  may interconnect input components  305  with output components  315 . In some implementations, switching component  310  may be implemented via one or more crossbars, via busses, and/or with shared memories. The shared memories may act as temporary buffers to store packets from input components  305  before the packets are eventually scheduled for delivery to output components  315 . In some implementations, switching component  310  may enable input components  305 , output components  315 , and/or controller  320  to communicate. 
     Output component  315  may store packets and may schedule packets for transmission on output physical links. Output component  315  may support data link layer encapsulation or decapsulation, and/or a variety of higher-level protocols. In some implementations, output component  315  may send packets and/or receive packets. In some implementations, output component  315  may include an output line card that includes one or more packet processing components (e.g., in the form of integrated circuits), such as one or more IFCs, packet forwarding components, line card controller components, output ports, processors, memories, and/or output queues. In some implementations, device  300  may include one or more output components  315 . In some implementations, input component  305  and output component  315  may be implemented by the same set of components (e.g., an input/output component may be a combination of input component  305  and output component  315 ). 
     Controller  320  includes a processor in the form of, for example, a central processing unit (CPU), a graphics processing unit (GPU), an accelerated processing unit (APU), a microprocessor, a microcontroller, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), and/or another type of processor. The processor is implemented in hardware, firmware, and/or a combination of hardware and software. In some implementations, controller  320  may include one or more processors that may be programmed to perform a function. 
     In some implementations, controller  320  may include a random access memory (RAM), a read only memory (ROM), and/or another type of dynamic or static storage device (e.g., a flash memory, a magnetic memory, an optical memory, and/or the like) that stores information and/or instructions for use by controller  320 . 
     In some implementations, controller  320  may communicate with other devices, networks, and/or systems connected to device  300  to exchange information regarding network topology. Controller  320  may create routing tables based on the network topology information, create forwarding tables based on the routing tables, and forward the forwarding tables to input components  305  and/or output components  315 . Input components  305  and/or output components  315  may use the forwarding tables to perform route lookups for incoming and/or outgoing packets. 
     Controller  320  may perform one or more processes described herein. Controller  320  may perform these processes based on executing software instructions stored by a non-transitory computer-readable medium. As used herein, a computer-readable medium is a non-transitory memory device. A memory device includes memory space within a single physical storage device or memory space spread across multiple physical storage devices. 
     Software instructions may be read into a memory and/or storage component associated with controller  320  from another computer-readable medium or from another device via a communication interface. When executed, software instructions stored in a memory and/or storage component associated with controller  320  may cause controller  320  to perform one or more processes described herein. Additionally, or alternatively, hardwired circuitry may be used in place of or in combination with software instructions to perform one or more processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software. 
     The quantity and arrangement of components shown in  FIG. 3  are provided as an example. In practice, device  300  may include additional components, fewer components, different components, or differently arranged components than those shown in  FIG. 3 . Additionally, or alternatively, a set of components (e.g., one or more components) of device  300  may perform one or more functions described as being performed by another set of components of device  300 . 
       FIG. 4  is a flow chart of an example process  400  for GRE tunneling with reduced packet encryption at intermediate routers. In some implementations, one or more process blocks of  FIG. 4  may be performed by a network node (e.g., network node  210 ). For example, one or more process blocks of  FIG. 4  may be performed by one or more intermediate network nodes (e.g., one or more intermediate network nodes between a transmitting network node and a receiving network node). In some implementations, one or more process blocks of  FIG. 4  may be performed by another device or a group of devices separate from or including the network node. 
     As shown in  FIG. 4 , process  400  may include receiving a packet having an inner IP header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, and wherein the inner IP header is encrypted (block  410 ). For example, the network node (e.g., using input component  305 , switching component  310 , controller  320 , and/or the like) may receive a packet having an inner IP header and an outer IP header, as described above. In some implementations, a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node. In some implementations, a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address. In some implementations, the inner IP header is encrypted. 
     As further shown in  FIG. 4 , process  400  may include generating, after receiving the packet, a copy of the packet to obtain a copied packet (block  420 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may generate, after receiving the packet, a copy of the packet to obtain a copied packet, as described above. 
     As further shown in  FIG. 4 , process  400  may include performing decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header (block  430 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may perform decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header, as described above. 
     As further shown in  FIG. 4 , process  400  may include updating the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address (block  440 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may update the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, as described above. In some implementations, the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address. 
     As further shown in  FIG. 4 , process  400  may include routing the updated packet according to the updated outer IP header (block  450 ). For example, the network node (e.g., using switching component  310 , output component  315 , controller  320 , and/or the like) may route the updated packet according to the updated outer IP header, as described above. 
     Process  400  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, the network node, the transmitting network node, and the receiving network node are associated with a virtual private network. In a second implementation, alone or in combination with the first implementation, the transmitting network node and the network node are associated with a first GRE tunnel and the receiving network node and the network node are associated with a second GRE tunnel. 
     In a third implementation, alone or in combination with one or more of the first and second implementations, the inner IP header is associated with an inner packet of the packet, wherein the inner packet has a payload intended for the recipient address. In a fourth implementation, alone or in combination with one or more of the first through third implementations, the tunnel endpoint of the transmitting network node and the tunnel endpoint of the receiving network node are public addresses, and the sender address and the recipient address are private addresses. 
     In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, process  400  further comprises receiving, prior to receiving the packet, an encryption key and a decryption key from a key server, wherein the encryption key and the decryption key correspond to an encryption key and a decryption key received by the transmitting network node or the receiving network node. In a sixth implementation, alone or in combination with one or more of the first through fifth implementations, encryption of the inner IP header was performed by the transmitting network node, and the network node, the transmitting network node, and the receiving network node share a security association that permits the network node and the receiving network node to decrypt encryption performed by the transmitting network node. 
     Although  FIG. 4  shows example blocks of process  400 , in some implementations, process  400  may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG. 4 . Additionally, or alternatively, two or more of the blocks of process  400  may be performed in parallel. 
       FIG. 5  is a flow chart of an example process  500  for GRE tunneling with reduced packet encryption at intermediate routers. In some implementations, one or more process blocks of  FIG. 5  may be performed by a network node (e.g., network node  210 ). For example, one or more process blocks of  FIG. 5  may be performed by one or more intermediate network nodes (e.g., one or more intermediate network nodes between a transmitting network node and a receiving network node). In some implementations, one or more process blocks of  FIG. 5  may be performed by another device or a group of devices separate from or including the network node. 
     As shown in  FIG. 5 , process  500  may include receiving a packet having an inner IP header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, and wherein the inner IP header is encapsulated by a GRE header, the GRE header is encapsulated by an ESP header that provides encryption, and the ESP header is encapsulated by the outer IP header (block  510 ). For example, the network node (e.g., using input component  305 , switching component  310 , controller  320 , and/or the like) may receive a packet having an inner IP header and an outer IP header, as described above. In some implementations, a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of the network node. In some implementations, a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address. In some implementations, the inner IP header is encapsulated by a GRE header, the GRE header is encapsulated by an ESP header that provides encryption, and the ESP header is encapsulated by the outer IP header. 
     As further shown in  FIG. 5 , process  500  may include generating a copy of the packet to obtain a copied packet (block  520 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may generate a copy of the packet to obtain a copied packet, as described above. 
     As further shown in  FIG. 5 , process  500  may include performing decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header (block  530 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may perform decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header, as described above. 
     As further shown in  FIG. 5 , process  500  may include updating the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address (block  540 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may update the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, as described above. In some implementations, the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to a tunnel endpoint of a receiving network node that is associated with the recipient address. 
     As further shown in  FIG. 5 , process  500  may include routing the updated packet according to the updated outer IP header (block  550 ). For example, the network node (e.g., using switching component  310 , output component  315 , controller  320 , and/or the like) may route the updated packet according to the updated outer IP header, as described above. 
     Process  500  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, the tunnel endpoint of the transmitting network node, the tunnel endpoint of the network node, and the tunnel endpoint of the receiving network node are GRE tunnel endpoints. In a second implementation, alone or in combination with the first implementation, the network node, the transmitting network node, and the receiving network node are associated with a virtual private network. In a third implementation, alone or in combination with one or more of the first and second implementations, the network node, the transmitting network node, and the receiving network node are associated with a group virtual private network. 
     In a fourth implementation, alone or in combination with one or more of the first through third implementations, encryption of the inner IP header was performed by the transmitting network node, and the network node, the transmitting network node, and the receiving network node share a security association that permits the network node and the receiving network node to decrypt encryption performed by the transmitting network node. In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, decryption is performed on the packet, and the outer IP header is updated for the copied packet. In a sixth implementation, alone or in combination with one or more of the first through fifth implementations, encryption of the inner IP header was performed by the transmitting network node using an Encapsulating Security Payload. 
     Although  FIG. 5  shows example blocks of process  500 , in some implementations, process  500  may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG. 5 . Additionally, or alternatively, two or more of the blocks of process  500  may be performed in parallel. 
       FIG. 6  is a flow chart of an example process  600  for GRE tunneling with reduced packet encryption at intermediate routers. In some implementations, one or more process blocks of  FIG. 6  may be performed by a network node (e.g., network node  210 ). For example, one or more process blocks of  FIG. 6  may be performed by one or more intermediate network nodes (e.g., one or more intermediate network nodes between a transmitting network node and a receiving network node). In some implementations, one or more process blocks of  FIG. 6  may be performed by another device or a group of devices separate from or including the network node. 
     As shown in  FIG. 6 , process  600  may include receiving a packet having an inner IP header and an outer IP header, wherein a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of an intermediate network node, wherein a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address, and wherein the inner IP header is encrypted (block  610 ). For example, the network node (e.g., using input component  305 , switching component  310 , controller  320 , and/or the like) may receive a packet having an inner IP header and an outer IP header, as described above. In some implementations, a source address of the outer IP header identifies a tunnel endpoint of a transmitting network node, and a destination address of the outer IP header identifies a tunnel endpoint of an intermediate network node. In some implementations, a source address of the inner IP header identifies a sender address, and a destination address of the inner IP header identifies a recipient address. In some implementations, the inner IP header is encrypted. 
     As further shown in  FIG. 6 , process  600  may include generating a copy of the packet to obtain a copied packet (block  620 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may generate a copy of the packet to obtain a copied packet, as described above. 
     As further shown in  FIG. 6 , process  600  may include performing decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header (block  630 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may perform decryption on one of the packet or the copied packet to identify the recipient address of the inner IP header, as described above. 
     As further shown in  FIG. 6 , process  600  may include determining a tunnel endpoint of a receiving network node that is associated with the recipient address (block  640 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may determine a tunnel endpoint of a receiving network node that is associated with the recipient address, as described above. 
     As further shown in  FIG. 6 , process  600  may include updating the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, wherein the source address of the updated outer IP header is updated to the tunnel endpoint of the network node, and the destination address of the updated outer IP header is updated to the tunnel endpoint of the receiving network node (block  650 ). For example, the network node (e.g., using switching component  310 , controller  320 , and/or the like) may update the outer IP header of the other of the packet or the copied packet to obtain an updated packet with an updated outer IP header, as described above. In some implementations, the source address of the updated outer IP header is updated to the tunnel endpoint of the intermediate network node, and the destination address of the updated outer IP header is updated to the tunnel endpoint of the receiving network node. 
     As further shown in  FIG. 6 , process  600  may include routing the updated packet according to the updated outer IP header (block  660 ). For example, the network node (e.g., using switching component  310 , output component  315 , controller  320 , and/or the like) may route the updated packet according to the updated outer IP header, as described above. 
     Process  600  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, the inner IP header is encapsulated by a GRE header, the GRE header is encapsulated by an ESP header that provides encryption, and the ESP header is encapsulated by the outer IP header. In a second implementation, alone or in combination with the first implementation, the tunnel endpoint of the transmitting network node, the tunnel endpoint of the intermediate network node, and the tunnel endpoint of the receiving network node are GRE tunnel endpoints. 
     In a third implementation, alone or in combination with one or more of the first and second implementations, the inner IP header is associated with an inner packet of the packet, wherein the inner packet has a payload intended for the recipient address. In a fourth implementation, alone or in combination with one or more of the first through third implementations, decryption is performed on the copied packet and the outer IP header is updated for the packet. 
     In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, the transmitting network node and the intermediate network node are associated with a first tunnel and the receiving network node and the intermediate network node are associated with a second tunnel, wherein a decryption key and an encryption key associated with the first tunnel correspond to a decryption key and an encryption key associated with the second tunnel. 
     Although  FIG. 6  shows example blocks of process  600 , in some implementations, process  600  may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG. 6 . Additionally, or alternatively, two or more of the blocks of process  600  may be performed in parallel. 
     The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementations. 
     As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. 
     As used herein, the term traffic or content may include a set of packets. A packet may refer to a communication structure for communicating information, such as a protocol data unit (PDU), a network packet, a datagram, a segment, a message, a block, a cell, a frame, a subframe, a slot, a symbol, a portion of any of the above, and/or another type of formatted or unformatted unit of data capable of being transmitted via a network. 
     It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the implementations. Thus, the operation and behavior of the systems and/or methods are described herein without reference to specific software code—it being understood that software and hardware can be designed to implement the systems and/or methods based on the description herein. 
     Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. 
     No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or,” unless explicitly stated otherwise (e.g., if used in combination with “either” or “only one of”).