US20240022626A1 - Dns-based gslb-aware sd-wan for low latency saas applications - Google Patents

Abstract

Some embodiments of the invention provide a method of routing data message traffic from an edge router at a first location and a SaaS (software as a service) application server provided by a third-party at a second location. The method queries a (global server load balancing) GSLB-aware DNS (domain name system) server for a cloud gateway from multiple cloud gateways at multiple locations through which a particular destination network address for the SaaS application server can be reached. The method receives from the GSLB-aware DNS server an identifier for a first cloud gateway that is farther from the first location than a second cloud gateway in the multiple cloud gateways but closer to the second location than the second cloud gateway. The method uses an optimized SD-WAN (software-defined wide-area network) connection to the first cloud gateway to forward data messages for the first cloud gateway to the SaaS application at the second location.

Description

BACKGROUND
• Today, SD-WAN solutions can provide different networking services according to defined business policies, such as the VMware SD-WAN by VeloCloud®. These networking services can include direct internet, internet via a cloud gateway (e.g., VeloCloud® gateway), and internet via private link (e.g., MPLS) backhaul. Typically, the business policy and default policy direct traffic to the internet via a cloud gateway. However, while this approach may direct traffic to a specific cloud gateway based on proximity to the source location, this specific cloud gateway may not be the best gateway for certain publicly hosted applications, such as applications where the specific cloud gateway is unable to meet low latency requirements of the application.
BRIEF SUMMARY
• Some embodiments of the invention provide a method of routing data message traffic between an edge router at a branch first location for an enterprise network and a SaaS (software as a service) application server provided by a third-party at a second location. The method is performed, in some embodiments, by the edge router at the branch first location. The method queries a (global server load balancing) GSLB-aware DNS (domain name system) server for a cloud gateway from multiple cloud gateways at multiple locations through which a particular destination network address for the SaaS application server can be reached. From the GSLB-aware DNS server, the method receives an identifier for a first cloud gateway that is farther from the branch first location than a second cloud gateway, but closer to the second location than the second cloud gateway. The method then uses an optimized SD-WAN connection to the first cloud gateway to forward data messages for the first cloud gateway to the SaaS application at the second location.
• In some embodiments, each link between the edge router and a cloud gateway is associated with a respective latency score. For instance, a first link between the edge router and the first cloud gateway is associated with a first latency score, in some embodiments, and a second link between the edge router and the second cloud gateway. In some embodiments, after receiving the identifier for the first cloud gateway, the edge router sends requests to the first and second cloud gateways for latency scores associated with the respective links between the first and second cloud gateways and the SaaS application server. In response to the requests, the edge router of some embodiments receives a third latency score from the first cloud gateway associated with a third link between the first cloud gateway and the SaaS application server, and receives a fourth latency score from the second cloud gateway associated with a fourth link between the second cloud gateway and the SaaS application server.
• The first latency score associated with the first link between the edge router and the first cloud gateway and the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server are high latency scores, in some embodiments. Conversely, in some embodiments, the second latency score associated with the second link between the edge router and the second cloud gateway, and the third latency score associated with the third link between the first cloud gateway and the SaaS application server are low latency scores. In some embodiments, the SaaS application server is associated with a low latency requirement that specifies a maximum latency threshold for the last mile connectivity to the SaaS application (i.e., the unmanaged, unoptimized links from the cloud gateways to the SaaS application server). In some such embodiments, the first cloud gateway is identified as the optimal cloud gateway for reaching the SaaS application server based on a determination that the third latency score meets the low latency requirement (i.e., does not exceed the maximum latency threshold), while the fourth latency score does not meet the low latency requirement (i.e., does exceed the maximum latency threshold).
• In some embodiments, the first and second cloud gateways identify the latency scores provided to the edge router by sending probe packets to the SaaS application server. The first and second cloud gateways derive latency measurements from the probe packets to generate the latency scores for the links between the first and second cloud gateways and the SaaS application server, according to some embodiments. The probe packets, in some embodiments, include layer 4 (L4) and layer 7 (L7) probe packets.
• In addition to the first cloud gateway being farther from the first location than the second cloud gateway, the first cloud gateway of some embodiments is also associated with a longer (round-trip time) RTT than the second cloud gateway (i.e., due to the increased distance to each the first cloud gateway). In some embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of physical distance, while in other embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of signal distance. In still other embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of both physical distance and signal distance. The edge router of some embodiments determines that the first cloud gateway is farther than the second cloud gateway based on proximity information provided by a server (e.g., the DNS server or a management and control server), while in other embodiments, the edge router makes this determination by performing a proximity operation to determine the distance to each cloud gateway.
• In some embodiments, the DNS server is a DNS first server that provides a particular destination network address for the SaaS application server to the edge router, while a second server provides the identifier for the first cloud gateway to the edge router. The second server, in some embodiments, is a management and control server for the enterprise network that identifies the most optimal cloud gateways for each edge router in the enterprise network to reach the SaaS application server, and provides identifiers for the most optimal cloud gateways to each edge router.
• The second server, in some embodiments, is also responsible for directing each cloud gateway to compute latency scores (i.e., rather than the edge routers each directing the cloud gateways to compute latency scores), and periodically collects the latency scores to dynamically identify the most optimal cloud gateways for each edge router. In some embodiments, the second server causes the edge router to automatically switch from the first cloud gateway to another cloud gateway upon identifying the other gateway router as the most optimal cloud gateway based on updated latency scores for the first cloud gateway and the other cloud gateway. For instance, in some embodiments, the second cloud gateway is a default gateway assigned to the edge router for forwarding data messages to the SaaS application server until the edge router receives the identifier for the first cloud gateway when the second server determines that the first cloud gateway is the most optimal gateway for use by the edge router to reach the SaaS application server. The second server of some embodiments also provides the location information and latency scores associated with the first cloud gateway to the edge router when providing the identifier for the first cloud gateway.
• The preceding Summary is intended to serve as a brief introduction to some embodiments of the invention. It is not meant to be an introduction or overview of all inventive subject matter disclosed in this document. The Detailed Description that follows and the Drawings that are referred to in the Detailed Description will further describe the embodiments described in the Summary as well as other embodiments. Accordingly, to understand all the embodiments described by this document, a full review of the Summary, the Detailed Description, the Drawings, and the Claims is needed. Moreover, the claimed subject matters are not to be limited by the illustrative details in the Summary, the Detailed Description, and the Drawings.
BRIEF DESCRIPTION OF FIGURES
• The novel features of the invention are set forth in the appended claims. However, for purposes of explanation, several embodiments of the invention are set forth in the following figures.
• FIG.1 conceptually illustrates a block diagram of different routes between a branch office of an enterprise network for an entity and a geographically distant datacenter hosting a SaaS application server, in some embodiments.
• FIG.2 conceptually illustrates a process of some embodiments for identifying a cloud gateway for forwarding data messages to a datacenter hosting a SaaS application server.
• FIG.3, for instance, conceptually illustrates the block diagram ofFIG.1 with latency scores of some embodiments associated with the connections between the LA branch office, cloud gateways, and Japan datacenter.
• FIG.4 conceptually illustrates a block diagram of a workflow of some embodiments for a branch office to identify a cloud gateway from a set of cloud gateways based on latency scores associated with using each cloud gateway in the set.
• FIG.5 conceptually illustrates a process for identifying a cloud gateway for forwarding data messages to a SaaS application server, in some embodiments.
• FIG.6 conceptually illustrates a block diagram of some embodiments in which a branch office obtains cloud gateway information from a controller for use in forwarding data messages to a SaaS application server.
• FIG.7 conceptually illustrates a process of some embodiments for obtaining a cloud gateway from a controller for use in forwarding data messages to a SaaS application server.
• FIG.8 illustrates an example of a standard SD-WAN environment in which some embodiments of the invention are implemented.
• FIG.9 conceptually illustrates a computer system with which some embodiments of the invention are implemented.
DETAILED DESCRIPTION
• In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are set forth and described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention may be practiced without some of the specific details and examples discussed.
• Some embodiments of the invention provide a method of routing data message traffic between an edge router at a branch first location for an enterprise network and a SaaS (software as a service) application server provided by a third-party at a second location. The method is performed, in some embodiments, by the edge router at the branch first location. The method queries a (global server load balancing) GSLB-aware DNS (domain name system) server for a cloud gateway from multiple cloud gateways at multiple locations through which a particular destination network address for the SaaS application server can be reached. From the GSLB-aware DNS server, the method receives an identifier for a first cloud gateway that is farther from the first location than a second cloud gateway, but closer to the second location than the second cloud gateway. The method then uses an optimized SD-WAN connection to the first cloud gateway to forward data messages for the first cloud gateway to the SaaS application at the second location.
• In some embodiments, each link between the edge router and a cloud gateway is associated with a respective latency score. For instance, a first link between the edge router and the first cloud gateway is associated with a first latency score, in some embodiments, and a second link between the edge router and the second cloud gateway. In some embodiments, after receiving the identifier for the first cloud gateway, the edge router sends requests to the first and second cloud gateways for latency scores associated with the respective links between the first and second cloud gateways and the SaaS application server. In response to the requests, the edge router of some embodiments receives a third latency score from the first cloud gateway associated with a third link between the first cloud gateway and the SaaS application server, and receives a fourth latency score from the second cloud gateway associated with a fourth link between the second cloud gateway and the SaaS application server.
• The first latency score associated with the first link between the edge router and the first cloud gateway and the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server are high latency scores, in some embodiments. Conversely, in some embodiments, the second latency score associated with the second link between the edge router and the second cloud gateway and the third latency score associated with the third link between the first cloud gateway and the SaaS application server are low latency scores. In some embodiments, the SaaS application server is associated with a low latency requirement that specifies a maximum latency threshold for the last mile connectivity to the SaaS application (i.e., the unmanaged, unoptimized links from the cloud gateways to the SaaS application server). In some such embodiments, the first cloud gateway is identified as the optimal cloud gateway for reaching the SaaS application server based on a determination that the third latency score meets the low latency requirement (i.e., does not exceed the maximum latency threshold), while the fourth latency score does not meet the low latency requirement (i.e., does exceed the maximum latency threshold).
• In some embodiments, the first and second cloud gateways identify the latency scores provided to the edge router by sending probe packets to the SaaS application server. The first and second cloud gateways derive latency measurements from the probe packets to generate the latency scores for the links between the first and second cloud gateways and the SaaS application server, according to some embodiments. The probe packets, in some embodiments, include layer 4 (L4) and layer 7 (L7) probe packets.
• In addition to the first cloud gateway being farther from the first location than the second cloud gateway, the first cloud gateway of some embodiments is also associated with a longer (round-trip time) RTT than the second cloud gateway (i.e., due to the increased distance to the first cloud gateway). In some embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of physical distance, while in other embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of signal distance. In still other embodiments, the first cloud gateway is farther from the edge router than the second cloud gateway in terms of both physical distance and signal distance. The edge router of some embodiments determines that the first cloud gateway is farther than the second cloud gateway based on proximity information provided by a server (e.g., the DNS server or a management and control server), while in other embodiments, the edge router makes this determination by performing a proximity operation to determine the distance to each cloud gateway.
• In some embodiments, the DNS server is a DNS first server that provides a particular destination network address for the SaaS application server to the edge router, while a second server provides the identifier for the first cloud gateway to the edge router. The second server, in some embodiments, is a management and control server for the enterprise network that identifies the most optimal cloud gateways for each edge router in the enterprise network to reach the SaaS application server, and provides identifiers for the most optimal cloud gateways to each edge router.
• The second server, in some embodiments, is also responsible for directing each cloud gateway to compute latency scores (i.e., rather than the edge routers each directing the cloud gateways to compute latency scores), and periodically collects the latency scores to dynamically identify the most optimal cloud gateways for each edge router. In some embodiments, the second server causes the edge router to automatically switch from the first cloud gateway to another cloud gateway upon identifying the other gateway router as the most optimal cloud gateway based on updated latency scores for the first cloud gateway and the other cloud gateway. For instance, in some embodiments, the second cloud gateway is a default gateway assigned to the edge router for forwarding data messages to the SaaS application server until the edge router receives the identifier for the first cloud gateway when the second server determines that the first cloud gateway is the most optimal gateway for use by the edge router to reach the SaaS application server. The second server of some embodiments also provides the location information and latency scores associated with the first cloud gateway to the edge router when providing the identifier for the first cloud gateway.
• FIG.1 conceptually illustrates a block diagram of different routes between a branch office of an enterprise network for an entity and a geographically distant datacenter hosting a SaaS application server, in some embodiments. As shown, the diagram100 includes a Los Angeles (“LA”)branch office110 and aJapan datacenter120 at which a SaaS application server is located. TheLA branch office110 is connected through an SD-WAN (e.g., to cloudgateways130 and135 through which data messages to theJapan datacenter120 can be forwarded. While only onebranch office110 is shown, the SD-WAN (also referred to herein as a virtual network) may connect multiple branch sites to each other, as well as to, e.g., a controller (not shown).
• The connections between theLA branch office110 and each of the cloud gateways130-135 are between an edge router (e.g., VeloCloud® edge (VCE)) at the branch office and the cloud gateways (e.g., VeloCloud® gateways (VCGs)), according to some embodiments. The edge routers of some embodiments are edge machines (e.g., virtual machines (VMs), containers, programs executing on computers, etc.) and/or standalone appliances that operate at multi-computer locations of the particular entity (e.g., at an office or datacenter of the entity) to connect the computers at their respective locations to other nodes (e.g., gateways, hubs, etc.) in the virtual network. In some embodiments, the nodes are clusters of nodes at each of the branch sites. In other embodiments, the edge nodes are deployed to each of the branch sites as high-availability pairs such that one edge node in the pair is the active node and the other edge node in the pair is the standby node that can take over as the active edge node in case of failover.
• An example of an entity for which such a virtual network can be established includes a business entity (e.g., a corporation), a non-profit entity (e.g., a hospital, a research organization, etc.), and an education entity (e.g., a university, a college, etc.), or any other type of entity. Examples of public cloud providers include Amazon Web Services® (AWS), Google Cloud Platform™ (GCP), Microsoft Azure®, etc., while examples of entities include a company (e.g., corporation, partnership, etc.), an organization (e.g., a school, a non-profit, a government entity, etc.), etc. In other embodiments, hub forwarding elements can also be deployed in private cloud datacenters of a virtual WAN provider that hosts these hubs to establish SD-WANs for different entities.
• In this example, onecloud gateway130 is located in California and theother cloud gateway135 is located in Japan. TheLA branch office110 has two route options using the two cloud gateways for reaching theJapan datacenter120. The first route includesconnection1A from theLA branch office110 to theCalifornia cloud gateway130 andconnection1B from theCalifornia cloud gateway130 to theJapan datacenter120. The second route includesconnection2A from theLA branch office110 to theJapan cloud gateway135 andconnection2B from theJapan cloud gateway135 to theJapan datacenter120. Therespective connections1A and2A from theLA branch office110 to the California andJapan cloud gateways130 and135 are managed by the SD-WAN and therefore can be optimized. In other words, when both forwarding elements (i.e., a forwarding element at theLA branch office110 and either of the California andJapan cloud gateways130 and135) for one hop (i.e., source and destination forwarding elements) are managed by the SD-WAN, controllers for the SD-WAN can configure the two managed forwarding elements to perform their forwarding operations in a way that maximizes QoS (quality of service), or other metrics such as throughput, according to some embodiments.
• In some embodiments, for instance, multiple links of any type (e.g., DSL (digital subscriber line), cable modem, Ethernet, fiber, LTE/3G/4G/5G, MPLS (multiprotocol label switching), radio, satellite, Wi-Fi, etc.), location, or provider can be leveraged to optimize connections between branch offices and cloud gateways. Also, in some embodiments, managed links can be configured to provide a desirable attribute associated with certain metrics such as throughput, QoS, and packet drops. Additional methods of link optimization, in some embodiments, can include utilizing link scores (e.g., assigned based on QoS metrics collected from devices connected by the SD-WAN), alternate path selections, packet replication, forward error correction, etc. For example, some embodiments utilize dynamic multipath optimization (DMPO) to optimize links in the SD-WAN. DMPO, according to some embodiments, is a cloud-delivered architecture for on-premises and cloud applications that enables the use of multiple WAN transports simultaneously, thereby maximizing bandwidth and ensuring application performance.
• Returning to the diagram100, while the distance from theLA branch office110 to theJapan cloud gateway135 is longer than the distance from theLA branch office110 to theCalifornia cloud gateway130, the last mile connectivity from theJapan cloud gateway135 to theJapan datacenter120 is shorter than the last mile connectivity from theCalifornia cloud gateway130 to theJapan datacenter120. Unlike theconnections1A and2A between theLA branch office110 and the California andJapan cloud gateway130 and135, the lastmile connectivity links1B and2B are not managed by the SD-WAN and do not benefit from the same optimizations as the links that are managed by the SD-WAN. As a result, the second route through theJapan cloud gateway135 is the optimal route due to the distance covered by the unmanaged portion of the path, according to some embodiments. That is, while the first route through theCalifornia cloud gateway130 may be associated with better overall metrics (e.g., shorter round-trip time), the combination of the potential for optimizing the link covering the greater distance (i.e., link2A) and the shorter length oflink2B compared to link1B that are associated with using theJapan cloud gateway135 make the second route through theJapan cloud gateway135 the optimal route (i.e., compared to the route through California cloud gateway130).
• FIG.2 conceptually illustrates aprocess200 of some embodiments for identifying a cloud gateway for forwarding data messages to a datacenter hosting a SaaS application server. Theprocess200 is performed in some embodiments by an edge router at a branch office of an enterprise network (e.g., an edge router at theLA branch office110 in the diagram100). Theprocess200 starts when the edge router identifies (at210) a destination datacenter in which a particular SaaS application is located. In some embodiments, the edge router identifies the destination datacenter by requesting a network address (e.g. IP address) associated with the SaaS application from a DNS server, and receiving a network address and location information in response to the request.
• From a set of cloud gateways through which the destination datacenter hosting the SaaS application can be reached, theprocess200 identifies (at220) the most optimal cloud gateway for forwarding data messages to the destination datacenter. In some embodiments, the edge router identifies the most optimal cloud gateway based on receiving an identifier for a particular cloud gateway from the DNS server from which the network address and location of the destination datacenter were received. In other embodiments, the edge router identifies the most optimal cloud gateway based on receiving an identifier for a particular cloud gateway from a management and control server. In still other embodiments, the edge router compares location and latency information associated with the set of cloud gateways to identify the most optimal cloud gateway for itself. For instance, the edge router of some embodiments determines whether a default (e.g., primary) cloud gateway assigned to the edge router and the gateway nearest to the DNS server match, and when these cloud gateways do not match, the edge router identifies the cloud gateway with the lowest latency to the SaaS application server.
• In some embodiments, the edge router obtains latency data from the cloud gateways by directing the cloud gateways to perform probes to the SaaS application server and to compute latency scores based on those probes for providing to the edge router. The edge router of some embodiments also already has latency scores for connections from the edge router to the cloud gateways based on DMPO. As mentioned above, DMPO, according to some embodiments, is a cloud-delivered architecture for on-premises and cloud applications that enables the use of multiple WAN transports simultaneously, thereby maximizing bandwidth and ensuring application performance.
• Returning to theprocess200, theprocess200 then uses (at230) the identified cloud gateway to forward data messages to the SaaS application located at the destination datacenter. In the diagram100, for instance, an edge router at theLA branch office110 would use an optimized SD-WAN connection to either theCalifornia cloud gateway130 or theJapan cloud gateway135 based on which cloud gateway has been identified as the most optimal cloud gateway to reach the SaaS application server at theJapan datacenter120. Following230, theprocess200 ends.
• In some embodiments, the cloud gateway used by the edge router to forward data messages to a SaaS server is selected based on latency scores associated with the links between the edge router, cloud gateways, and destination datacenter.FIG.3, for instance, conceptually illustrates the block diagram100 ofFIG.1 with latency scores of some embodiments associated with the connections between theLA branch office110, cloud gateways130-135, andJapan datacenter120.
• As shown, thelink340 between theLA branch office110 and theCalifornia cloud gateway130 and thelink355 between theJapan cloud gateway135 are indicated as being low latency links. Conversely, thelink345 between theCalifornia cloud gateway130 and theJapan datacenter120 and thelink350 between theLA branch office110 and theJapan cloud gateway135 are indicated as being high latency links. Thus, the first route from theLA office110 to theJapan datacenter120 through theCalifornia cloud gateway130 includes a low latency first connection to the cloud gateway and a high latency second connection for the last mile connectivity from thecloud gateway130 to thedatacenter120, while the second route from theLA office110 to theJapan datacenter120 through theJapan cloud gateway135 includes a high latency first connection to thecloud gateway135 and a low latency second connection for the last mile connectivity from thecloud gateway135 to theJapan datacenter120.
• In some embodiments, the SaaS application at theJapan datacenter120 has low latency requirements, and theJapan cloud gateway135 is the more optimal cloud gateway compared to theCalifornia cloud gateway130 based on the connection between theJapan cloud gateway135 and theJapan datacenter120 having low latency, while the connection between theCalifornia cloud gateway130 andJapan datacenter120 has high latency. In some embodiments, the connection between theJapan cloud gateway135 and theJapan datacenter120 has lower latency than the connection between theCalifornia cloud gateway130 and theJapan datacenter120 based on the shorter distance between theJapan cloud gateway135 andJapan datacenter120.
• FIG.4 conceptually illustrates a block diagram of a workflow of some embodiments for a branch office to identify a cloud gateway from a set of cloud gateways based on latency scores associated with using each cloud gateway in the set. As illustrated, the diagram400 includes anLA branch office410, aJapan datacenter420 that hosts a SaaS application server, acloud gateway430 located in California, acloud gateway435 located in Japan, aDNS server440, and location-basedcontext445.
• The diagram400 will be further described below by reference toFIG.5, which conceptually illustrates aprocess500 for identifying a cloud gateway for forwarding data messages to a SaaS application server, in some embodiments. Theprocess500 is performed in some embodiments by an edge router for a branch office of an enterprise network. Theprocess500 starts when the edge router queries (at510) a DNS server for a cloud gateway for forwarding data messages to a SaaS application server. Like the diagram400, the SaaS application server of some embodiments is located in a datacenter that is geographically distant from the branch office trying to reach the SaaS application server. The edge router at thebranch office410 sends a request for a cloud gateway (at the encircled 1) to theDNS server440.
• In some embodiments, prior to requesting the cloud gateway, the edge router first requests a network address and location information for the SaaS application server. TheDNS server440 of some embodiments obtains location information for the SaaS application server at the resolved network address from the location-basedcontext445, and provides both the network address and location information to the edge router at thebranch office410 in response to the request.
• Theprocess500 receives (at520) an identifier for a cloud gateway from the DNS server. For instance, thebranch office410 receives (at the encircled 2) an identifier for theJapan cloud gateway435. In some embodiments, prior to requesting and receiving the cloud identifier, the edge router is assigned a default cloud gateway for use in forwarding data messages to third-party SaaS application servers, and thus already has an identifier for at least one other cloud gateway. In other embodiments, the DNS server responds to the edge router's request by providing two or more identifiers to the edge router for the edge router to select from.
• Theprocess500 sends (at530) a request for a latency score associated with a connection between the cloud gateway and SaaS application server to the cloud gateway. The SaaS application server of some embodiments is associated with a low latency requirement, and thus the edge router of some such embodiments sends a request to the cloud gateway for a latency score to determine whether the latency score meets the low latency requirement. In the diagram400, for instance, the LA branch office410 (i.e., an edge router at the branch office) sends requests for latency scores (at the encircled 3) to the California and Japan cloud gateways430-435.
• In some embodiments, the cloud gateways compute latency scores by sending probe packets to the SaaS application server and collecting latency measurements using the probe packets. For example, the California and Japan cloud gateways430-435 are each shown (at the encircled 4) performing probes for latency measurements between the cloud gateways430-435 and theJapan datacenter420 that hosts the SaaS application server. The probe packets, in some embodiments, include L4 and L7 probe packets.
• Theprocess500 then receives (at540) a latency score from the cloud gateway, such as the latency scores received (at the encircled 5) at theLA branch office410 in the diagram400, and determines (at550) whether the latency score meets the low latency requirement associated with the SaaS application server. In some embodiments, the distance between a cloud gateway and the destination SaaS application server affects latency such that a cloud gateway that is farther from the SaaS application server has a higher latency than a cloud gateway that is closer to the SaaS application server. When the latency score from the cloud gateway does not meet the low latency requirement (e.g., is higher than a specified latency threshold), theprocess500 returns to510 to query the DNS server for a cloud gateway. In some embodiments, the edge router uses or continues to use a default cloud gateway to forward data messages to the SaaS application server while awaiting the next cloud gateway from the DNS server.
• When the latency score does meet the low latency requirement (e.g., is lower than a specified latency threshold), theprocess500 transitions to use (at560) an optimized SD-WAN connection to the cloud gateway to forward data messages for the cloud gateway to send to the SaaS application server. Following560, theprocess500 ends.
• In some embodiments, rather than obtaining a cloud gateway (i.e., identifier for a cloud gateway) from the DNS server, the edge router instead requests the cloud gateway from a controller for the enterprise network (e.g., a VeloCloud® Orchestrator (VCO)).FIG.6 conceptually illustrates a block diagram600 of some embodiments in which a branch office obtains cloud gateway information from a controller for use in forwarding data messages to a SaaS application server.
• Thecontroller650, in some embodiments, manages business policies for the SD-WAN. Thecontroller650 is hosted by a cloud, in some embodiments, and on-premises in other embodiments. In some embodiments, new business policies may be created (e.g., network preferred DNS) that may trigger different actions, such as configuring or choosing a business policy for a tenant to be implemented by edge routers at the edges of the tenant networks. For example, an edge router of some embodiments may receive a policy specified for a SaaS application, and the edge router then configures a rule to match the business policy. The edge router of some such embodiments may send data messages to each cloud gateway assigned to the edge router to instruct the cloud gateways to perform L4 and/or L7 probes to the SaaS application to collect latency measurements. In other embodiments, thecontroller650 directs the cloud gateways to perform these probes and provides the results to the edge router. As mentioned above, the edge router of some embodiments already has latency data from the edge router to each cloud gateway based on DMPO, and also either stores, or obtains, proximity location information for each cloud gateway.
• As shown, rather than an edge router at thebranch office610 requesting latency scores from the cloud gateways630-635, thecontroller650 collects latency measurements from the California and Japan cloud gateways630-635. In some embodiments, thecontroller650 collects latency measurements periodically to ensure that each edge router is using the most optimal cloud gateway for forwarding data messages to destinations outside of the enterprise network, such as the third-party SaaS application server at theJapan datacenter620. For instance, if a particular cloud gateway's updated latency score increases, thecontroller650 of some embodiments may cause an edge router assigned to that cloud gateway to automatically switch to a different cloud gateway that is associated with a lower latency score.
• In some embodiments, thecontroller650 may assign a default cloud gateway to an edge router for reaching third-party sites within a first region, and assign a secondary cloud gateway to the edge router for reaching third-party sites within a second region. For example, thecontroller650 of some embodiments may assign theCalifornia cloud gateway630 as a default cloud gateway to an edge router at theLA branch office610 for use in reaching third-party sites in California and surrounding states, and subsequently assign theJapan cloud gateway635 as a secondary cloud gateway for use in reaching at least theJapan datacenter620. The edge router of some such embodiments may automatically switch between the different cloud gateways based on the destination network addresses of data messages being forwarded.
• FIG.6 will be further described below by reference toFIG.7, which conceptually illustrates aprocess700 of some embodiments for obtaining a cloud gateway from a controller for use in forwarding data messages to a SaaS application server. Theprocess700 is performed in some embodiments by an edge router at a branch office (e.g., LA branch office610). Theprocess700 starts when the edge router queries (at710) a controller for a cloud gateway for forwarding data messages to a SaaS application server.
• In some embodiments, for example, after the edge router receives a destination network address and location information for a SaaS application, the edge router may use the received destination network address to query the controller for a cloud gateway to use to reach the SaaS application. In the diagram600, theLA branch office610, for example, receives a destination IP for the Japan SaaS application from the DNS server640 (at the encircled 1), and then receives a cloud gateway identifier and location and latency data for the cloud gateway from the controller650 (at the encircled 2).
• Theprocess700 receives (at720) an identifier for a cloud gateway from the controller. In some embodiments, the edge router is assigned a set of cloud gateways by the controller for use in forwarding data messages to entities outside of the enterprise network, and queries the controller for an identifier corresponding to a cloud gateway from the set that is most optimal for reaching the destination IP associated with the SaaS application. As also described above, the controller of some embodiments determines the most optimal cloud gateway for use by an edge router based on latency scores associated with connections between the cloud gateways and the destination.
• For example, in the diagram600, both available routes from theLA branch office610 to theJapan datacenter620 include a high latency connection and a low latency connection. However, the low latency connection for the route that uses theJapan cloud gateway635 is the unmanaged last mile connection (i.e., unoptimized connection) to theJapan datacenter620, whereas the low latency connection for the route that uses theCalifornia cloud gateway630 is the managed connection (i.e., optimized connection) from theLA branch office610 to theCalifornia cloud gateway630. While the route through theCalifornia cloud gateway630 may be identified as the best route (e.g., in a routing table of the edge router based on proximity to the LA branch office610), theJapan cloud gateway635 may be identified by thecontroller650 as the most optimal cloud gateway based on the low latency associated with the unmanaged, unoptimized connection between theJapan cloud gateway635 andJapan datacenter620.
• Theprocess700 uses (at730) an optimized SD-WAN connection to the cloud gateway to forward data messages for the cloud gateway to send to the SaaS application server. TheLA branch office610, for instance, is illustrated (at the encircled 3) as forwarding data messages to theJapan datacenter620 via theJapan cloud gateway635. Following730, theprocess700 ends.
• FIG.8 illustrates an example of a standard SD-WAN environment800 in which some embodiments of the invention are implemented. The SD-WAN800 is created in some embodiments for a particular entity using SD-WAN forwarding elements (FEs) deployed at branch sites, datacenters, and public clouds. Examples of public clouds are public clouds provided by Amazon Web Services (AWS), Google Cloud Platform (GCP), Microsoft Azure, etc., while examples of entities include a company (e.g., corporation, partnership, etc.), an organization (e.g., a school, a non-profit, a government entity, etc.), etc.
• In the SD-WAN800, the SD-WAN FEs include cloud gateway805 (e.g., cloud gateway router) and SD-WAN FEs830,832,834,836. The cloud gateway (CGW) in some embodiments is an FE that is in a private orpublic datacenter810. TheCGW805 in some embodiments has secure connection links (e.g., tunnels) with edge FEs (e.g., SD-WAN edge FEs830,832,834, and836) at the particular entity's multi-machine sites (e.g., SD-WAN edge sites820,822, and824), such as multi-user compute sites (e.g., branch offices or other physical locations having multi user computers and other user-operated devices and serving as source computers and devices for requests to other machines at other sites), datacenters (e.g., locations housing servers), etc. These multi-machine sites are often at different physical locations (e.g., different buildings, different cities, different states, etc.).
• Four multi-machine sites820-826 are illustrated in the SD-WAN800, with three of them being branch sites820-824, and one being adatacenter826. Each branch site is shown to include arespective edge FE830,832, and834 (e.g., edge routers) andrespective resources850,852, and854. The resources850-854, in some embodiments, are machines located at the branch sites820-824. Thedatacenter site826 is shown to include a hub FE836 (e.g., a hub router), anddatacenter resources856. The datacenter SD-WAN FE836 is referred to as a hub FE because in some embodiments this FE can be used to connect to other edge FEs of the branch sites820-824. The hub FE in some embodiments uses or has one or more service engines to perform services (e.g., middlebox services) on packets that it forwards from one branch site to another branch site. The hub FE also provides access to thedatacenter resources856.
• Each edge FE (e.g., SD-WAN edge FEs830-834) exchanges packets with one ormore cloud gateways805 through one or more connection links815 (e.g., multiple connection links available at the edge FE). In some embodiments, these connection links include secure and unsecure connection links, while in other embodiments they only include secure connection links. As shown byedge FE834 andgateway805, multiple secure connection links (e.g., multiple secure tunnels that are established over multiple physical links) can be established between one edge FE and a gateway.
• When multiple such links are defined between an edge FE and a gateway, each secure connection link in some embodiments is associated with a different physical network link between the edge FE and an external network. For instance, to access external networks, an edge FE in some embodiments has one or more commercial broadband Internet links (e.g., a cable modem, a fiber optic link) to access the Internet, an MPLS (multiprotocol label switching) link to access external networks through an MPLS provider's network, a wireless cellular link (e.g., a 5G LTE network), etc. In some embodiments, the different physical links between theedge FE834 and thecloud gateway805 are the same type of links (e.g., are different MPLS links).
• In some embodiments, one edge FE830-834 can also have multiple direct links815 (e.g., secure connection links established through multiple physical links) to another edge FE830-834, and/or to adatacenter hub FE836. Again, the different links in some embodiments can use different types of physical links or the same type of physical links. Also, in some embodiments, a first edge FE of a first branch site can connect to a second edge FE of a second branch site (1) directly through one ormore links815, (2) through a cloud gateway or datacenter hub to which the first edge FE connects through two ormore links815, or (3) through another edge FE of another branch site that can augment its role to that of a hub FE. Hence, in some embodiments, a first edge FE (e.g.,834) of a first branch site (e.g.,824) can use multiple SD-WAN links815 to reach a second edge FE (e.g.,830) of a second branch site (e.g.,820), or ahub FE836 of adatacenter site826.
• Thecloud gateway805 in some embodiments is used to connect two SD-WAN FEs830-836 through at least twosecure connection links815 between thegateway805 and the two FEs at the two SD-WAN sites (e.g., branch sites820-824 or datacenter site826). In some embodiments, thecloud gateway805 also provides network data from one multi-machine site to another multi-machine site (e.g., provides the accessible subnets of one site to another site). Like thecloud gateway805, thehub FE836 of thedatacenter826 in some embodiments can be used to connect two SD-WAN FEs830-834 of two branch sites through at least twosecure connection links815 between thehub836 and the two FEs at the two branch sites820-824.
• In some embodiments, each secure connection link between two SD-WAN FEs (i.e.,CGW805 and edge FEs830-836) is formed as a VPN tunnel between the two FEs. In this example, the collection of the SD-WAN FEs (e.g., FEs830-836 and gateways805) and thesecure connections815 between the FEs forms the SD-WAN800 for the particular entity that spans at least the public orprivate cloud datacenter810 to connect the branch and datacenter sites820-826.
• In some embodiments, secure connection links are defined between gateways in different public cloud datacenters to allow paths through the virtual network to traverse from one public cloud datacenter to another, while no such links are defined in other embodiments. Also, in some embodiments, thegateway805 is a multi-tenant gateway that is used to define other virtual networks for other entities (e.g., other companies, organizations, etc.). Some such embodiments use tenant identifiers to create tunnels between a gateway and edge FE of a particular entity, and then use tunnel identifiers of the created tunnels to allow the gateway to differentiate packet flows that it receives from edge FEs of one entity from packet flows that it receives along other tunnels of other entities. In other embodiments, gateways are single-tenant and are specifically deployed to be used by just one entity.
• The SD-WAN800 includes a cluster ofcontrollers840 that serve as a central point for managing (e.g., defining and modifying) configuration data that is provided to the edge FEs and/or gateways to configure some or all of the operations. In some embodiments, thiscontroller cluster840 is in one or more public cloud datacenters, while in other embodiments it is in one or more private datacenters. In some embodiments, thecontroller cluster840 has a set of manager servers that define and modify the configuration data, and a set of controller servers that distribute the configuration data to the edge FEs, hubs and/or gateways. In some embodiments, thecontroller cluster840 directs edge FEs and hubs to use certain gateways (i.e., assigns a gateway to the edge FEs and hubs). In some embodiments, some or all of the controller cluster's functionality is performed by a cloud gateway (e.g., cloud gateway805). Thecontroller cluster840 also provides next hop forwarding rules and load balancing criteria in some embodiments.
• Many of the above-described features and applications are implemented as software processes that are specified as a set of instructions recorded on a computer-readable storage medium (also referred to as computer-readable medium). When these instructions are executed by one or more processing unit(s) (e.g., one or more processors, cores of processors, or other processing units), they cause the processing unit(s) to perform the actions indicated in the instructions. Examples of computer-readable media include, but are not limited to, CD-ROMs, flash drives, RAM chips, hard drives, EPROMs, etc. The computer-readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections.
• In this specification, the term “software” is meant to include firmware residing in read-only memory or applications stored in magnetic storage, which can be read into memory for processing by a processor. Also, in some embodiments, multiple software inventions can be implemented as sub-parts of a larger program while remaining distinct software inventions. In some embodiments, multiple software inventions can also be implemented as separate programs. Finally, any combination of separate programs that together implement a software invention described here is within the scope of the invention. In some embodiments, the software programs, when installed to operate on one or more electronic systems, define one or more specific machine implementations that execute and perform the operations of the software programs.
• FIG.9 conceptually illustrates acomputer system900 with which some embodiments of the invention are implemented. Thecomputer system900 can be used to implement any of the above-described hosts, controllers, gateway, and edge forwarding elements. As such, it can be used to execute any of the above described processes. Thiscomputer system900 includes various types of non-transitory machine-readable media and interfaces for various other types of machine-readable media.Computer system900 includes abus905, processing unit(s)910, asystem memory925, a read-only memory930, apermanent storage device935,input devices940, andoutput devices945.
• Thebus905 collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of thecomputer system900. For instance, thebus905 communicatively connects the processing unit(s)910 with the read-only memory930, thesystem memory925, and thepermanent storage device935.
• From these various memory units, the processing unit(s)910 retrieve instructions to execute and data to process in order to execute the processes of the invention. The processing unit(s)910 may be a single processor or a multi-core processor in different embodiments. The read-only-memory (ROM)930 stores static data and instructions that are needed by the processing unit(s)910 and other modules of thecomputer system900. Thepermanent storage device935, on the other hand, is a read-and-write memory device. Thisdevice935 is a non-volatile memory unit that stores instructions and data even when thecomputer system900 is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as thepermanent storage device935.
• Other embodiments use a removable storage device (such as a floppy disk, flash drive, etc.) as the permanent storage device. Like thepermanent storage device935, thesystem memory925 is a read-and-write memory device. However, unlikestorage device935, thesystem memory925 is a volatile read-and-write memory, such as random access memory. Thesystem memory925 stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention's processes are stored in thesystem memory925, thepermanent storage device935, and/or the read-only memory930. From these various memory units, the processing unit(s)910 retrieve instructions to execute and data to process in order to execute the processes of some embodiments.
• Thebus905 also connects to the input andoutput devices940 and945. Theinput devices940 enable the user to communicate information and select commands to thecomputer system900. Theinput devices940 include alphanumeric keyboards and pointing devices (also called “cursor control devices”). Theoutput devices945 display images generated by thecomputer system900. Theoutput devices945 include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD). Some embodiments include devices such as touchscreens that function as both input andoutput devices940 and945.
• Finally, as shown inFIG.9,bus905 also couplescomputer system900 to anetwork965 through a network adapter (not shown). In this manner, thecomputer900 can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet), or a network of networks (such as the Internet). Any or all components ofcomputer system900 may be used in conjunction with the invention.
• Some embodiments include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra-density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media may store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter.
• While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some embodiments are performed by one or more integrated circuits, such as application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs). In some embodiments, such integrated circuits execute instructions that are stored on the circuit itself.
• As used in this specification, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms “display” or “displaying” mean displaying on an electronic device. As used in this specification, the terms “computer-readable medium,” “computer-readable media,” and “machine-readable medium” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral or transitory signals.
• While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. In addition, a number of the figures (includingFIGS.2,5, and7) conceptually illustrate processes. The specific operations of these processes may not be performed in the exact order shown and described. The specific operations may not be performed in one continuous series of operations, and different specific operations may be performed in different embodiments. Furthermore, the process could be implemented using several sub-processes, or as part of a larger macro process. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.

Claims (23)

1. A method of routing data message traffic between an edge router at a first location and a SaaS (software as a service) application server provided by a third-party at a second location, the method comprising:

querying a (global server load balancing) GSLB-aware DNS (domain name system) server for a cloud gateway from a plurality of cloud gateways at a plurality of locations through which a particular destination network address for the SaaS application server can be reached;

receiving from the GSLB-aware DNS server an identifier for a first cloud gateway that is farther from the first location than a second cloud gateway in the plurality of cloud gateways but closer to the second location than the second cloud gateway; and

using an optimized SD-WAN connection to the first cloud gateway to forward data messages for the first cloud gateway to the SaaS application at the second location.

2. The method ofclaim 1, wherein a first latency score is associated with a first link between the edge router and the first cloud gateway and a second latency score is associated with a second link between the edge router and the second cloud gateway, wherein after receiving the identifier for the first cloud gateway, the method further comprises:

sending requests to the first and second cloud gateways for latency scores associated with links between each of the first and second cloud gateways and the SaaS application server; and

receiving (i) a third latency score from the first cloud gateway associated with a third link between the first cloud gateway and the SaaS application server, and (ii) a fourth latency score from the second cloud gateway associated with a fourth link between the second cloud gateway and the SaaS application server.

3. The method ofclaim 2, wherein:

the requests for latency scores include the particular destination network address for the SaaS application server; and

each of the first and second cloud gateways compute latency scores by sending probe packets to the SaaS application server at the particular destination network address.

4. The method ofclaim 3, wherein the probe packets comprise layer 4 (L4) and layer 7 (L7) probe packets.

5. The method ofclaim 2, wherein:

the first latency score associated with the first link between the edge router and the first cloud gateway and the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server comprise high latency scores; and

the second latency score associated with the second link between the edge router and the second cloud gateway and the third latency score associated with the third link between the first cloud gateway and the SaaS application server comprise low latency scores.

6. The method ofclaim 5, wherein:

the SaaS application server is associated with a low latency requirement;

the third latency score associated with the third link between the first cloud gateway and the SaaS application server meets the low latency requirement for the SaaS application server; and

the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server does not meet the low latency requirement for the SaaS application server.

7. The method ofclaim 6, wherein using the first cloud gateway to send data messages to the SaaS application at the second location further comprises determining, based on the third latency score meeting the low latency requirement, that the first cloud gateway is an optimal cloud gateway for sending data messages to the SaaS application server.

8. The method ofclaim 6, wherein the third and fourth links comprise unmanaged links.

9. The method ofclaim 1, wherein a first round-trip time (RTT) associated with using the first cloud gateway is longer than a second RTT associated with using the second cloud gateway.

10. The method ofclaim 9, wherein the first RTT associated with using the first cloud gateway is longer than the second RTT associated with the second cloud gateway based on the first cloud gateway being farther from the first location than the second cloud gateway.

11. The method ofclaim 1 further comprising receiving, before querying the GSLB-aware DNS server for the cloud gateway, the particular destination network address resolved for the SaaS application server at the second location.

12. The method ofclaim 11, wherein receiving the particular destination address further comprises receiving location information for the SaaS application server, the location information identifying the second location.

13. The method ofclaim 1, wherein before receiving the identifier for the first cloud gateway, the second cloud gateway is assigned to the edge router as a default cloud gateway for forwarding data messages to the SaaS application server.

14. The method ofclaim 1, wherein the first location comprises a branch office of an enterprise network and the second location comprises a public cloud datacenter.

15. The method ofclaim 1, wherein the cloud gateway comprises a cloud gateway router.

16. A non-transitory machine readable medium storing a program for execution by a set of processing units, the program for routing data message traffic between an edge router at a first location and a SaaS (software as a service) application server provided by a third-party at a second location, the program comprising sets of instructions for:

querying a (global server load balancing) GSLB-aware DNS (domain name system) server for a cloud gateway from a plurality of cloud gateways at a plurality of locations through which a particular destination network address for the SaaS application server can be reached;

receiving from the GSLB-aware DNS server an identifier for a first cloud gateway that is farther from the first location than a second cloud gateway in the plurality of cloud gateways but closer to the second location than the second cloud gateway; and

using an optimized SD-WAN connection to the first cloud gateway to forward data messages for the first cloud gateway to the SaaS application at the second location.

17. The non-transitory machine readable medium ofclaim 16, wherein a first latency score is associated with a first link between the edge router and the first cloud gateway and a second latency score is associated with a second link between the edge router and the second cloud gateway, wherein after receiving the identifier for the first cloud gateway, the program further comprises sets of instructions for:

sending requests to the first and second cloud gateways for latency scores associated with links between each of the first and second cloud gateways and the SaaS application server; and

receiving (i) a third latency score from the first cloud gateway associated with a third link between the first cloud gateway and the SaaS application server, and (ii) a fourth latency score from the second cloud gateway associated with a fourth link between the second cloud gateway and the SaaS application server.

18. The non-transitory machine readable medium ofclaim 17, wherein:

the requests for latency scores include the particular destination network address for the SaaS application server; and

each of the first and second cloud gateways compute latency scores by sending layer 4 (L4) and layer 7 (L7) probe packets to the SaaS application server at the particular destination network address.

19. The non-transitory machine readable medium ofclaim 17, wherein:

the first latency score associated with the first link between the edge router and the first cloud gateway and the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server comprise high latency scores; and

the second latency score associated with the second link between the edge router and the second cloud gateway and the third latency score associated with the third link between the first cloud gateway and the SaaS application server comprise low latency scores.

20. The non-transitory machine readable medium ofclaim 19, wherein:

the SaaS application server is associated with a low latency requirement;

the third latency score associated with the third link between the first cloud gateway and the SaaS application server meets the low latency requirement for the SaaS application server;

the fourth latency score associated with the fourth link between the second cloud gateway and the SaaS application server does not meet the low latency requirement for the SaaS application server; and

the third and fourth links comprise unmanaged links.

21. The non-transitory machine readable medium ofclaim 20, wherein the set of instructions for using the first cloud gateway to send data messages to the SaaS application at the second location further comprises a set of instructions for determining, based on the third latency score meeting the low latency requirement, that the first cloud gateway is an optimal cloud gateway for sending data messages to the SaaS application server.

22. The non-transitory machine readable medium ofclaim 17, wherein:

a first round-trip time (RTT) associated with using the first cloud gateway is longer than a second RTT associated with using the second cloud gateway; and

the first RTT associated with using the first cloud gateway is longer than the second RTT associated with the second cloud gateway based on the first cloud gateway being farther from the first location than the second cloud gateway.

23. The non-transitory machine readable medium ofclaim 17 further comprising a set of instructions for receiving, before querying the GSLB-aware DNS server for the cloud gateway, (i) the particular destination network address resolved for the SaaS application server at the second location and (ii) location information for the SaaS application server, the location information identifying the second location.

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